The Ribes of Colorado 

and New Mexico and 

Their Rust Fungi 

Eugene P. Van Arsdel 

Brian W. Geils 

United States

Department

Of Agriculture

Forest Service

Forest Health

Technology Enterprise 

Team

FHTET 04-13 

September 2004

nodal spine

internodal bristles

Stem

Inflorescence

Racime

Dissected flower

peduncle

peduncle

pedicel

pedicel

bract

stigma &

style

anther &

filament

petal

sepal

hypanthium

bract

fruit

persistent

perianth

stigma &

style anther &

filament

petal

ovary

bract

hypanthium

nodal spine

internodal bristles

Stem

Inflorescence

Racime

Dissected flower

peduncle

peduncle

pedicel

pedicel

bract

stigma &

style

anther &

filament

petal

sepal

hypanthium

bract

fruit

persistent

perianth

stigma &

style anther &

filament

petal

ovary

bract

nodal spine

internodal bristles

Stem

Inflorescence

Racime

Dissected flower

peduncle

peduncle

pedicel

pedicel

bract

stigma &

style

anther &

filament

petal

sepal

hypanthium

bract

fruit

persistent

perianth

stigma &

style anther &

filament

petal

ovary

bract

hypanthium
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endorsement by the U.S. Department of Agriculture. 
The Ribes of Colorado and New Mexico 

and Their Rust Fungi 

Eugene P. Van Arsdel 

Brian W. Geils

United States Department of Agriculture, Forest Service 

Forest Health Technology Enterprise Team 

Fort Collins, Colorado 

FHTET-04-13 

September 2004
Van Arsdel, Eugene P.; Geils, Brian W. 2004. The Ribes of Colorado and New Mexico and 

their rust fungi. FHTET 04-13. Fort Collins, CO: U.S. Department of Agriculture, Forest 

Service, Forest Health Protection, Forest Health Technology Enterprise Team. 32 p. 

Abstract. This document is a guide to the Ribes of Colorado and New Mexico and the rust fungi 

which infect them. Information is presented for 15 species of Ribes with diagnostic, vegetative 

features and notes on their geographic and ecological distribution. The guide is intended as a field 

aid in evaluating sites for blister rust hazard to white pine from associated ribes. Leaf rusts found 

on ribes are also described as a means for distinguishing them from white pine blister rust. The 

significance of each species to forest management is discussed. 

Keywords: currant, gooseberry, Cronartium ribicola, Cronartium occidentale, Coleosporium 

ribicola, plant and rust identification 

Authors. Eugene P. Van Arsdel is Principal Plant Pathologist (retired, volunteer) with the 

Rocky Mountain Research Station. He has a BSF (Forestry, 1947) from Purdue University and 

MS (1952) and PhD (1954) from the University of Wisconsin, Madison in Plant Pathology. His 

graduate training included research on the climatic distribution of white pine blister rust in 

Wisconsin. He started white pine blister rust control work in 1948 as State Supervisor for Indiana. 

He was Principal Plant Pathologist and Project Leader in Northern Conifer Disease Research, at 

the North Central Forest Experiment Station. He was Professor of Forest Pathology at Minnesota, 

Yale, and Texas A&M Universities. His current work is on the epidemiology of rust infection on 

white pines and ribes and on site evaluation for infection hazard classes. 

Brian W. Geils is Research Plant Pathologist with the Rocky Mountain Research Station in 

Flagstaff, AZ. He attended Utah State University (Wildlife), University of Idaho (Forestry) and 

has a PhD in Botany and Plant Pathology from Colorado State University. He has published on 

the hosts, effects, epidemiology, and population genetics of stem rusts. Current assignments 

include describing the epidemiology and ecology of stem rusts and improving methods for 

assessing their effects. 

Contact Information 

Brian W. Geils 

Rocky Mountain Research Station 

2500 South Pine Knoll Drive 

Flagstaff, AZ 86001 

Phone: (928) 556-2076; E-mail: bgeils@fs.fed.us

Acknowledgements. We received beneficial assistance from numerous people in the preparation 

of this work. We are thankful to Joyce VanDe Water for her botanical illustrations. David A. 

Conklin accompanied us on numerous collecting trips and helped us recognize the many other 

plants as well. Maria Newcomb and Kim Hummer provided useful review of an early draft. The 

keen interest and enthusiasm of Detlev Vogler has been an inspiration. We also thank William 

Jacobi, Ronda Koski, Roger Peterson, Paul Zambino, and Don Despain. 

This effort could not have been completed without the gracious help of collection managers at 

several herbaria. In particular, we thank Tina Ayers (ASC), Nan Lederer (UColo), Jennifer 

Owens (CSU), and Jane Mygatt (UNM). William Jennings shared with us his own ribes guide; 

Randal Scott pointed out the local variation for ribes of Arizona. 

This work was supported by Forest Health Protection, Special Technology Development 

Program, Project R3-97-1. We are grateful to Eric L. Smith, Forest Health Technology Enterprise 

Team, for his encouragement, editing, and support in the publication this document.
Contents 

Introduction......................................................................................................................... 1 

Generic Description, Ribes ................................................................................................. 2 

Rusts of Ribes ..................................................................................................................... 4 

Key to the Species of Ribes in Colorado and New Mexico ................................................ 9 

1. Ribes pinetorum ............................................................................................................ 10 

2. Ribes inerme ................................................................................................................. 11 

3. Ribes leptanthum........................................................................................................... 13 

4. Ribes montigenum......................................................................................................... 14 

5. Ribes lacustre................................................................................................................ 15 

6. Ribes viscosissimum...................................................................................................... 16 

7. Ribes cereum................................................................................................................. 17 

8. Ribes mescalerium ........................................................................................................ 18 

9. Ribes nigrum................................................................................................................. 19 

10. Ribes hudsonianum..................................................................................................... 20 

11. Ribes laxiflorum.......................................................................................................... 21 

12. Ribes americanum....................................................................................................... 22 

14. Ribes wolfii ................................................................................................................. 23 

14. Ribes rubrum............................................................................................................... 24 

15. Ribes aureum .............................................................................................................. 25 

Other Ribes ....................................................................................................................... 26 

References......................................................................................................................... 27 

Glossary ............................................................................................................................ 31 
 
Introduction

The family Grossulariaceae represented in our area by the genus Ribes is treated in the floras of 

Colorado, New Mexico, and adjacent regions. Holmgren (1997) in the Intermountain Flora 

provides an excellent, technical description of Ribes in the region west and north of our area 

(including many species not occurring here). Other regional floras are by Harrington (1954), 

Martin and Hutchins (1980), and Weber (1987, 1990). Plant identification books are by Carter 

(1988, 1997), Ivey (2003), and Vines (1960). Because of changes in taxonomy, reliance on floral 

characteristics, and incomplete information for species or regions, none of these references alone 

is sufficient for field crews conducting forest health surveys. 

A serious disease of white pines is white pine blister rust (WPBR) caused by the fungus 

Cronartium ribicola Fisch. The life cycle of this rust fungus requires alternation between white 

pines (aecial hosts) and currants and gooseberries (telia hosts) in the genus Ribes. Several other 

rust fungi also infect ribes (our common name for currants and gooseberries). Because the 

importance of a ribes for blister rust spread and intensification varies by species and region, it is

useful that survey crews properly identify ribes and the rust fungi infecting them. 

This guide describes, with illustrations, the Ribes species and associated rusts occurring in 

Colorado and New Mexico based on published literature and reports, examination of herbarium 

collections, and field observations. Our taxonomy follows the checklists by Hartman and Nelson 

(2001) and the PLANTS Database (USDA, NRCS 2001) with several additions, exceptions, and 

reservations discussed under the various taxa. The PLANTS Database1

 approved common names 

and symbols (unique alphanumeric code for data entry) are provided. We indicate those 

characters that distinguish among Ribes species of the region with an emphasis on commonly

seen field traits in our region. Although ribes are not especially difficult to identify to species, 

vegetative characters are variable and reproductive structures may be absent. Identification should 

be based on a knowledge of the species likely to be encountered (as provided here) and 

familiarity with the local populations developed from field study over the season to observe 

flowers, fruits, vegetative characters, and usual habitat associations. 

Information on ribes distribution and abundance by species is essential (along with an 

understanding of microclimate) for assessing blister rust impacts and evaluating management 

options. For example, in the Sacramento Mountains of New Mexico, Ribes pinetorum, R. cereum, 

and R. mescalerium are widespread and common species; R. inerme occurs at a few locations. 

Although all these species are found in proximity to white pines, only Ribes pinetorum appears to 

be important in the spread and intensification of blister rust (Van Arsdel and others 1998). At 

Gallinas Peak, an isolated range north of the Sacramento Mountains, however, R. inerme is the 

only species present; and there it is responsible for sustaining a blister rust outbreak. Other 

species such as Ribes montigenum and R. lacustre may likewise be of minor important at some 

locations but are the major substrate for inoculum at other locations. Besides the invasive 

Cronartium ribicola, which infects white pines, ribes are infected by several native rusts that 

infect pinyon pines or other wildland plants. Therefore, recognizing ribes and rusts by species and 

understanding their epidemiological importance is useful for assessing blister rust hazard to a 

white pine population and developing effective and efficient forest health management plans. 

 1

 The PLANTS Database has additional general information on each species including distribution, federal 

status, and links to photographs and other useful databases. 

 1
Generic Description 

Ribes L. 

 current (RIBES) 

nodal spine

internodal bristles

Stem

Inflorescence

Racime

Dissected flower

peduncle

peduncle

pedicel

pedicel

bract

stigma &

style anther &

filament

petal

sepal

hypanthium

bract

fruit

persistent

perianth

stigma &

style anther &

filament

petal

ovary

bract

hypanthium

nodal spine

internodal bristles

Stem

Inflorescence

Racime

Dissected flower

peduncle

peduncle

pedicel

pedicel

bract

stigma &

style anther &

filament

petal

sepal

hypanthium

bract

fruit

persistent

perianth

stigma &

style anther &

filament

petal

ovary

bract

nodal spine

internodal bristles

Stem

Inflorescence

Racime

Dissected flower

peduncle

peduncle

pedicel

pedicel

bract

stigma &

style anther &

filament

petal

sepal

hypanthium

bract

fruit

persistent

perianth

stigma &

style anther &

filament

petal

ovary

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hypanthium

Figure 1. Morphological features of ribes (terms described in glossary). The perianth consists of 

a calyx (sepals) and corolla (petals) with inserted stamens (anther and filament) united into a 

hypanthium (or calyx tube) above the inferior ovary to which is attached the stigma and style 

(pistil). A single flower is joined to the stem by a pedicel (immediately inferior) and a peduncle, 

each may be subtended by leaf-like bracts. Multiple flowers are joined to common rachis (central 

stem) to form a raceme. 

Stem: shrub to 3 m in height; erect or trailing; unarmed or armed with nodal spines and/or 

internodal bristles; twigs round, rarely ridged and angular; bark variously colored, some with 

glands; some with a distinctive, strong odor when broken or crushed. 

Leaf: deciduous; petiolate; alternate or appearing fascicled; blade rotund to broadly angular; 

palmately veined and (3)5(7)-lobed; margin dentate or crenate, ciliate or not; base cordate, 

truncate, wedge-shaped, reniform; surface glabrous, pubescent, or glandular. 

Inflorescence: terminating as short lateral branches; racemes axillary or solitary, pendant or 

erect; pedicel jointed below the ovary and disarticulating or not jointed, often with bracts. 

Flower: about 1 cm long, 5-parted, perfect, regular, with an inferior ovary and showy calyx; 

calyx tube saucer-, bell-, funnel-, or cylinder-shaped; sepals erect, spreading, or sharply reflexed, 

often colored; petals usually shorter than sepals; stamens alternate with petals; both petals and 

stamens inserted in calyx tube forming the hypanthium; ovary inferior, 2-carpellate, 1-locular, 

with 2 parietal placenta; styles 2, more or less united. 

Fruit: a berry; globose or subglobose; fleshy or pulpy but edible; mostly smooth, but often 

glandular and/or spiny, usually crowned with persistent flower parts; with numerous seeds. 

Habitat: native and cultivated; mostly temperate and cold regions. 

2 
Notes: name from Danish ribs for red currant or from Arabic ribas for the plant; often among the 

first shrubs to leaf and flower in the spring; fruits often ripe by mid-summer. The family

Grossulariaceae to which Ribes belongs was formerly submerged under Saxifragaceae. The 

phylogeny of Ribes has been recently examined by Messinger and others (1999), but recent 

monographic treatment is only available for the North American section Grossularia (Sinnott

1985). 

In the vernacular, species of the genus Ribes are referred to collectively as “ribes” and our 

representatives are members of three major groups: gooseberries (subgenus Grossularia), the 

spiny currants (subgenus Grossularioides), and currants (subgenus Ribes, with several sections). 

The gooseberries have the base of the flower firmly attached to the pedicel, usually a tapered 

hypanthium, and spines. Gooseberry flowers are solitary or in racemes of two or three flowers; 

and fruits are glabrous, spiny, or spiny and glandular. There are three native, common 

gooseberries in our region:

1. Ribes pinetorum 

2. Ribes inerme

3. Ribes leptanthum. 

The spiny currants and currants have jointed and disarticulating pedicels, several flowers per 

raceme, and glandular or glabrous berries. We recognize 12 native or commonly cultivated 

currants occurring in Colorado and New Mexico. These include two spiny currants (also known 

as gooseberry currants) with both nodal spines and internodal bristles: 

4. Ribes montigenum 

5. Ribes lacustre. 

There are three “stinky” currants with abundant glands and small- or medium-sized leaves: 

6. Ribes viscosissimum 

7. Ribes cereum 

8. Ribes mescalerium

There are five black currants with 5-lobed leaves and black or blue fruits: 

9. Ribes nigrum 

10. Ribes hudsonianum 

11. Ribes laxiflorum 

12. Ribes americanum 

13. Ribes wolfii. 

There are two red or ornamental currants with 3-lobed leaves and fruits colored red, white, 

yellow, or black: 

 14. Ribes rubrum 

 15. Ribes aureum.

A number of other ribes occur as introduced, cultivated, hybrids, or native species with very

limited distribution in our region. These are identified and briefly described following our 

treatment of the common ribes. There is also some disagreement in taxonomy (identification) and 

synonymy (nomenclature). Until we obtain additional information, our treatments of these taxa 

are provisional. 

 3
Rusts of Ribes

Although several groups of fungi infect ribes, we are concerned here only with a few, similar 

appearing rusts (Uredinales). Rusts are distinguished by distinctive yellow, orange, brownish, or 

black sporulating structures on ribes leaves. Although not all of our species are described by

Ziller (1974), he provides useful descriptions, photographs, and information on the life cycle for 

these rusts at the generic level. Bethel (in Goodding and Bethel 1926 and Wyckoff and Bethel 

1923) identifies the rusts on ribes of the western states. 

Cronartium ribicola and C. occidentale Hedgcock, Bethel, and Hunt (1918) produce damaging, 

perennial cankers on the stems of pine trees; and, with care, can be distinguished on ribes. The

rust Coleosporium ribicola Arthur (=C. jonesii (Peck) Arthur) occurs as a leaf rust on pinyon and 

could be confused with one stage of the Cronartium rusts on ribes. Melampsora ribesii-purpureae

Kleb. (=M. confluens Jacks.) alternates to willows; but we have seen no reports from Colorado or 

Arizona (Shope 1940, Yohem and others 1985). Several Puccinia are known to occur on western 

ribes (Arthur and Cummins 1962, Shope 1940). Puccinia micrantha Griff. alternates to rice-grass 

(Oryzopsis), P. caricis var. grossulariata Arthur to sedge (Carex); P. parkerae D.&H. occur only

in the telial stage and is only known from Ribes lacustre (Goodding and Bethel 1926). 

Field identification of these rusts may be difficult. Collections of the suspect rust on the ribes and 

potential alternate hosts for later microscopic or molecular examination are recommended. 

Key to the rusts of Ribes1 

1a. Aecia on leaves of ribes ................................................................................................................. 2 

2a. Aecia within a peridium until mature ....................................................................................... 3

3a. Aecia short, broad, densely aggregated, yellow to pale red .................................................

 ....................................................... 5. Puccinia caricis var. grossulariata 

3b. Aecia long, slender, orange-red ....................................................... 6. Puccinia micrantha

2b. Aecial peridium rudimentary or absent .................................4. Melampsora ribesii-purpureae

1b. Uredia or telia on leaves of ribes .................................................................................................... 4 

4a. Uredia on leaves of ribes .......................................................................................................... 5 

5a. Uredia with a persistent peridium, spores liberated through a pore.....................................

 .......................................Cronartium ribicola or Cronartium occidentale

5b. Uredia appearing as large, flat, naked pustules; developing singly or in concentric 

 rings; ...........................................................................3. Coleosporium ribicola

4b. Telia on leaves of ribes............................................................................................................. 6 

6a. Telia brown to purple, columnar........................................................................................ 7 

7a. Telia long (4 mm), in dense patches covering the infected area....................................

 .........................................................................2. Cronartium occidentale

7b. Telia short (2 mm), in patches within the infected area............1. Cronartium ribicola

6b. Telia not brown to purple, not columnar ........................................................................... 8 

8a. Telia black, breaking through host epidermis, flat; teliospores borne singly on

 pedicles; on Ribes lacustre...........................................................7. Puccinia parkerae

 8b. Telia flattened, subepidermal cushion, orange, and waxy.....3. Coleosporium ribicola 

 1

 Adopted with modifications from Bethel as presented in Goodding and Bethel 1926. 

4 
1. Cronartium ribicola 

white pine blister rust

The most important of the rusts on ribes is the invasive Cronartium ribicola, the cause of white 

pine blister rust (Samman and others 2003). Because the native rust Cronartium occidentale

resembles C. ribicola and both occur in our region, care must be taken in identification of these 

rusts. Although differentiation in the uredial stage is difficult (Colley 1925), these rusts can be

distinguished with careful examination in the telial stage (Table 1). Host differences for these two 

rusts are presented in discussions under the individual ribes. 

These rusts can also be separated by colormetric procedures (Acree and Goss 1937 and Cave 

1944). Vogler (personal communication) has developed a DNA molecular technique for 

identifying among these and other rusts on ribes. He is now accepting collections of rust-infected 

ribes leaves to build a genetic library, make and validate identifications [Det Vogler, Institute of 

Forest Genetics, Placerville, California, dvogler@california.com]. 

Table 1. Signs and symptoms of Cronartium ribicola and C. occidentale on ribesa

. 

Character Cronartium ribicola Cronartium occidentale 

Onset of telial formation later earlier 

Density of telial mats sparse, never “fur-like” very dense, “fur-like” 

Color of mature, un-germinated 

telia 

straw brown, orange-tinge dark brown 

Color of older, germinated telia retains orange color longer but 

may have lavender-purple tinge 

soon develops a lavenderpurple tinge 

Extent of telial production on 

infected portions of the leaf 

much of the infected portion of 

the leaf without telia 

most of the infected 

portion of the leaf with 

telia 

Pattern of infection on leaf small, scattered spots large, continuous areas 

Hardman symptom 

characteristics, by order of 

increasing severityb

slight necrosis by spotting (from

rust or secondary fungi); general 

necrosis of infected area; blister 

necrosis as large raised or 

sunken dead areas; angular 

necrosis delimited by veins; 

necrotic areas bear uredia but no 

telia. 

telia present with no 

visible host reaction; 

chlorosis around telia 

visible on dorsal side of 

leaf; “green island effectc

”; 

purplingd

 on dorsal leaf 

side 

a Table based on descriptions by Kimmey (1946), Miller (1967), and our observations. 

b

 Symptoms by D. Hardman, unpublished work described by Miller (1967). c

 A condition commonly caused by leaf spot fungi where green, infected patches are surrounded 

by yellow or light green areas. 

d

 Marked by a purple black or brown discoloration different from the usual reddening of diseased 

or aging leaves. 

 5
The relative importance of the various ribes species as a host for the spread and intensification of 

Cronartium ribicola depends on two factors—environment and physiology. Critical in rust 

epidemiology are environmental factors including host abundance, distribution, and microclimate. 

The capability of a ribes as a substrate for production of telia depends on physiological factors of 

the host–pathogen interaction. These physiological factors include susceptibility to infection at

the aecial and uredial stages, disease development rate and extent within the infected leaf, and 

leaf retention. Variation is introduced by difference in genetics, microclimate (temperature and 

humidity, Van Arsdel and others 1956) and architecture (leaf morphology and exposure). 

Rankings and ratings of ribes species for blister rust infection and inoculum production have been 

based on studies in laboratory and field experiments and observations. Clinton and McCormick 

(1924) screened about 40 taxa of ribes by inoculating leaves in petri dishes; McDonald and 

Andrews (1981) used petri dish inoculations to examine clonal variation in resistance. 

Inoculations in gardens have been widely used to explore differences in susceptibility; this 

technique has been used by Spaulding (1922), Hahn (1928), Kimmey (1935, 1938), Kimmey and 

Mielke (1944), Hummer and Fin (1999), and others. Several studies (Buchanan and Kimmey

1938, Kimmey and Wagener 1961) had gone beyond rating relative susceptibility to investigating 

disease gradient expressed in pine from point sources of different ribes species. Relevant 

information had also been obtained from careful observation. Taylor (1922) reported the pattern 

and abundance of telia on leaves of several species of ribes. Mielke and Hansbrough (1933), 

Lachmund (1934), and Mielke (1937) observed ribes populations exposed to natural infection.

Mielke and others (1937) also provided a methodology for describing and quantifying the amount 

and distribution of rust. None of these reports, however, included all the ribes species of our 

region and none integrated results into a comprehensive scale of relative importance. 

Based on published literature and observations, we propose a classification scheme (Table 2) for 

describing the relative importance of various species of ribes to blister rust epidemiology. The 

scheme is especially relevant to the spread and intensification of blister rust as it occurs in 

Colorado and New Mexico with some consideration for adjacent, infested areas such as 

Wyoming. The scheme is our subjective opinion of the susceptibility of the ribes to rust infection 

and capability of producing viable inoculum under typical field conditions where the species 

usually occurs. We consider physiological and ecological factors and their usual variability. Class 

A species are those that with exposure to the rust and favorable conditions generally express a 

high level of incidence, more than 66 percent of leaves infected, and a high level of disease 

severity, more than 66 percent of infected leaf area diseased. Class B species are those that 

express intermediate levels of incidence, 6 to 66 percent of leaves infected, and severity, 6 to 66 

percent of infected area diseased, and those whose expression is generally low but occasionally 

results in significant telial production. We grade R. inerme as Class B; it is light to moderately

infected in Colorado and a portion of New Mexico and can be responsible for significant 

infection of the white pine population. We grade R. montigenum as Class B; this high-elevation 

ribes occurs at sites often too cold for good rust development but can be an important inoculum

source where and when more favorable temperatures prevail. Class C species are those that 

express low levels of incidence, less than 6 percent of leaves infected, or severity, less than 6 

percent of area diseased. Class D species are those that are rarely observed with white pine blister 

rust uredia or telia and considered as insignificant to spread and intensification to white pines. 

Low grades for native species in their usual locations relative to white pines can be based on 

either resistance or escape. Ribes aureum is frequently found in Utah to be infected by pinyon 

blister rust, but we seldom find it in close proximity to native white pines. Ribes americanum is 

neither very susceptible nor found very close to native white pines. Both Ribes aureum and R. 

americanum, however, could be important hosts of white pine blister rust to planted white pines 

in urban and suburban areas, especially with sprinkler irrigation. The present scheme and 

classification of species are provisional. 

6 
Table 2. Importance of ribes of Colorado and New Mexico (and adjacent 

regions) to the spread and intensification of white pine blister rust. 

 Species Classa

1. Ribes pinetorum A 

9. Ribes nigrum A 

10. Ribes hudsonianum A 

2. Ribes inerme B 

4. Ribes montigenum B 

5. Ribes lacustre B 

6. Ribes viscosissimum B 

11. Ribes laxiflorum B 

12. Ribes americanum C 

13. Ribes wolfii C 

15. Ribes aureum C 

3. Ribes leptanthum D 

7. Ribes cereum D 

8. Ribes mescalerium D 

14. Ribes rubrum D 

a Ribes are classified on the basis of their susceptibility to infection and 

capability of supporting production of telia under field conditions. Class A 

species have the highest potential for contributing to spread, Class B species 

have moderate or variable potential, Class C species have low potential, and 

Class D species are usually insignificant. 

2. Cronartium occidentale

pinyon blister rust 

The native rust Cronartium occidentale causes of stem rust cankers on pinyon pines (Pinus edulis

Engelm. and P. monophylla Torrey and Fremont). The biology and pathology of pinyon blister

rust is described by Hedgcock and others (1918). Identification of pinyon blister rust on ribes is

treated previously under the discussion for Cronartium ribicola. Pinyon blister rust is widely

distributed across the range of its pine hosts and on ribes much further. Stillinger (1944) suggests 

the extended range of pinyon blister rust may be the result of long distant transport. Pinyon blister 

rust kills pines in heavily infested areas (Van Arsdel and Krebill 1995), but conditions are seldom

suitable for large and sustained outbreaks. Ribes aureum, R. leptanthum, and R. velutinum are 

major hosts of pinyon blister rust; R. inerme is intermediate in infection; R. montigenum is a 

reported host (Anonymous 1921); R. viscosissimum is reported host (Graham 1966); R. nigrum, 

R. americanum, and various red currents are resistant to infection by Cronartium occidentale

(Hedgcock and others 1918). 

 7
3. Coleosporium ribicola

 pinyon leaf rust 

Coleosporium ribicola causes a needle rust of Pinus edulis (Long 1916) and a leaf rust on ribes in 

Colorado, Arizona, and New Mexico (Shope 1940, Yohem and others 1985, and our 

observations). The aecial stage on pinyon appears as a typical needle rust (see Ziller 1974 or 

Nicholls and others 1968 for illustrations of other Coleosporium rusts). Although the rust may 

cause some defoliation, we have not observed nor received reports of any serious damage. Long 

(1916) reports pinyon leaf rust occurring early and at the upper limits of the host. Both Long’s 

and our observations suggest successive uredial spread of the rust through the season to ribes 

populations quite distant from the perennial host (at least 10s of miles). On ribes, the telia stage of 

Coleosporium could be confused with the uredial stage of Cronartium; except that infection spots 

of Coleosporium are more reddish-orange, smaller, rounder, and discrete and the telia form a 

shiny, rounded cushion. This rust was observed in 1921 on Ribes aureum, R. cereum, R. 

leptanthum, R. pinetorum, R. mescalerium, R. wolfii, and cultivated currants and gooseberries in 

New Mexico and on R. cereum in Utah (Anonymous 1921). In New Mexico, pinyon pine is 

seldom damaged by this rust, but Ribes cereum, especially in the Sacramento Mountains and 

many miles from pinyon pine trees, usually bear abundant telia. 

4. Melampsora ribesii-purpureae

Melampsora ribesii-purpureae appears to be typical of the many Melampsora rusts which 

alternate to (and probably overwinter on) willows and cottonwood (Ziller 1974). Although the 

rust is thought to have a wide distribution (including Utah and Wyoming), it is considered 

uncommon and not seriously damaging.

5–7. Puccinia spp. 

The Puccinia rusts on ribes are similar and related. Although they occur infrequently, they not

considered seriously damaging. Puccinia micrantha and P. caricis var. grossulariata (and var.

uniporula) occur on the ribes as aecia composed of small cup-like clusters with white, irregular, 

notched margins (Arthur 1934 but see Ziller 1974 for illustration of similar species). Puccinia 

parkerae, however, is lacking an aecial stage and may be a microcyclic form derived from P.

caricis var. grossulariata with only a telia stage (Arthur 1934). This rust appears as a crowded, 

naked, black to brown cluster of telia (see illustration of an similar appearing species in Ziller 

1974; Figure 107). 

8 
Key to the Species of Ribes in Colorado and New Mexico 

1a. Stems armed with nodal spines or internodal bristles..................................................................... 2 

2a. Stems armed with both nodal spines and internodal bristles.................................................... 3 

3a. Nodal spines large (7 mm or more long)............................................................................ 4 

4a. Leaf blade mostly 5-lobed; leaf base cordate; often with single nodal spines or with 

single large nodal spines with two small satellite spines............. 3. Ribes leptanthum

4b. Leaf blade mostly 3-lobed; leaf base truncate; spines variable ............2. Ribes inerme

3b. Nodal spines small (less than 7 mm long) ......................................................................... 5 

5a. Leaf pubescent, about 2 cm wide; spines of variable size, nodal spines 1–3 in 

number; hypanthium shallow; mature fruit reddish................... 4. Ribes montigenum

5b. Leaf glabrous, about 4 cm wide: spines of uniform size, nodal spines 5–9 or more in 

number; hypanthium deep; mature fruit purplish ..............................5. Ribes lacustre

2b. Stems armed with nodal spines; internodal bristles absent; leaf base cordate ......................... 6 

6a. Stems with sessile, black glands (generally with single nodal spines) 3. Ribes leptanthum

6b. Stems without glands or glands rare (nodal spines generally in threes)1. Ribes pinetorum

1b. Stems unarmed (nodal spines and internodal bristles absent)......................................................... 7 

7a. Leaf blade deeply dissected, mostly 3-lobed; leaf base truncate or wedge-shaped.................. 8 

8a. Stems (especially when young) white, pale, or ash-colored; leaf margin crenate; veins and 

 petioles prominently pubescent..................................................................2. Ribes inerme

8b. Stems never white, pale, or ash-colored; leaf margin entire; blade glabrous......................

 ...................................................................................... 15. Ribes aureum

7b. Leaf blade not deeply dissected, mostly 5-lobed, sometimes 7-lobed, or rarely 3-lobed......... 9 

9a. Leaf blade with sessile or stalked glands......................................................................... 10 

10a. Leaf blade or petiole (especially when young) with stalked glands........................ 11 

 11a. Stems weak, trailing; hypanthium with long-stalked, reddish-purple glands .......

 ..................................................................................11. Ribes laxiflorum

 11b. Stems strong, erect............................................................................................ 12 

 12a. Leaf lobes pointed, distinct; margins dentate; blade with short-stalked, 

 green, yellow, or clear glands.................................................13. Ribes wolfii

12b. Leaf lobes rounded, not distinct; margins crenate...................................... 13 

 13a. Leaf blade large, with abundant glandular hairs; calyx funnel-shaped....

 ..............................................................................6. Ribes viscosissimum

13b. Leaf blade small, with glandular hairs; calyx tubular.......................... 14 

 14a. Leaf blade thick, with short-stalked glands.............7. Ribes cereum

 14b. Leaf blade thin, with long-stalked glands ......8. Ribes mescalerium

10b. Leaf blades with sessile glands, stalked glands absent............................................ 15 

15a. Leaf blade with glands on both upper and lower surface. 12. Ribes americanum

15b. Leaf blade with glands only on lower surface .................................................. 16 

16a. Native plant of moist locations from 5,000–7,000 ft elevation; racemes 

 erect........................................................................... 10. Ribes hudsonianum

16b. Cultivated or escaped plant; racemes pendant......................9. Ribes nigrum

9b. Leaf blade without glands....................................................................... 14. Ribes rubrum 

 9
1. Ribes pinetorum Greene 

orange gooseberry (RIPI) 

Figure 2. Ribes pinetorum. a.

stem armed with nodal spines, 

leaf blade broadly angular, fruit 

spiny and with stalked glands; b.

flower with tapered hypanthium, 

peduncle twice the length of the 

bractate pedicle both with stalked 

glands. 

Stem: shrub armed with only

nodal spines; spines (1)3(5), stout 

and often curved, 8–12 mm long; 

young shoots often orange, 

without black sessile glands. 

Leaf: blade broadly angular, 5-

lobed, deeply incised, 2 to 4 cm

broad, margin crenate, base

cordate; mature blade surface 

pubescent with abundant longstalked glands or smooth and 

glabrous; veins often pubescent; 

petiole pubescent or with longstalked glands. 

Inflorescence: raceme few-flowered; peduncle about twice the length of the pedicel; pedicle 

bractate, bracts tapered, in pairs and with stalked glands. 

Flower: calyx showy orange to orange-red, ca. 18 mm long; hypanthium tapered; flowering from

April through May (rarely to September).

Fruit: berry orange to purplish-red at maturity, 8–15 mm diameter, spiny, with stalked glands.

Habitat: montane forests and meadows; occurs 8,000–11,500 ft; in some deep, north facing 

canyons as low as 7,000 ft and usually only to 10,000 ft. In the Gila ranges where all three species 

are present, R. pinetorum is generally above R. leptanthum and below R. wolfii. 

Range: NM and AZ. In NM—Zuni, Mt. Taylor, San Mateo, Magdalena, Mogollon, Black Range, 

Capitan, Sierra Blanca, and Sacramento Mountains; Catron, Cibola, Lincoln, Otero, Socorro,

Valencia counties. 

Notes: Ribes pinetorum, R. inerme, and R. leptanthum may be confused unless mature fruit are 

present. Differences are described under R. inerme. 

Pathology: the most important ribes in its range for the spread and intensification of WPBR 

(Class A); susceptibility and infection capability similar to Ribes nigrum. Reported as infected by

pinyon leaf rust in Sacramento and Capitan Mountains in 1921 (Anonymous 1921). 

References: Ivey (2003), Martin and Hutchins (1980), Vines (1960).

10 
2. Ribes inerme Rydb. 

whitestem gooseberry (RIIN2) 

Figure 3. Ribes inerme. a. stem with nodal spines and internodal bristles, leaf 3-lobed; b. fruit a 

smooth berry c. flower with reflexed sepals and stamens extending about twice as long as petals; 

d. dissected flower with pilose pistil. 

Stem: shrub sprawling to erect; lightly armed or not; nodal spines if present usually three; 

internodal bristles present or not; bark of some stems white, orange, or light gray, but exfoliating 

to reddish-brown; young twigs with black sessile glands. 

Leaf: blade 3(5) lobed, margin ciliate; base usually truncate or wedge-shaped; upper surface 

smooth to slightly pubescent, lower surface slightly pubescent; veins prominent and pubescent; 

petiole tomentose to pilose or glandular pubescent. Numerous, well-distributed, small clear 

glands on underside of leaf may be present or not. 

Inflorescence: peduncle about same length as pedicel; bracts paired, with stalked glands. 

Flower: calyx translucent to greenish-white; pistil pilose-villose; sepals reflexed; stamens 

glabrous, extend beyond petals. 

Fruit: berry smooth; relatively large (~10 mm); green, maturing to red. 

 11
Habitat: riparian, grassy meadows, under willows, and cool, rocky seeps. Colorado usually 

6,000–10,000 ft; New Mexico 8,000–10,500 ft. 

Range: BC to MT and s from to CA. CO—common in mountain counties. NM—mostly in the 

central mountains: abundant in upper Rio Pecos Canyon and the Sangre de Cristo Mountains, 

found in the Zuni Mountains ands the Brazos Mountains, the only species on Gallinas Peak, and 

uncommon in the Sacramento Mountains and Sandia Crest; Bernalillo, Cibola, Lincoln, Otero,

Rio Arriba, Sandoval, Taos counties. 

Notes: Ribes inerme can be confused with R. leptanthum and R. pinetorum; but these species can 

be distinguished using stems alone. Ribes inerme is the least spiny of the three; nodal spines may

be absent and when present are finer than those of the other species. Ribes inerme occasionally

has fine internodal bristles; R. leptanthum may have a dense mat of internodal bristles on young

twigs but usually not on older twigs; R. pinetorum lacks internodal bristles at all ages. Ribes 

inerme and R. leptanthum have small, sessile, black glands on young twigs. The leaves of R. 

inerme are more strongly 3-lobed, those of R. pinetorum more angular and pentoid, those of R.

leptanthum smaller and more finely dissected. There are a number of other species which may be 

confused with R. inerme, including R. oxyacanthoides var. setosum, R. divaricatum Dougl., R. 

hirtellum Michx., and R. niveum Lindl. (see discussions under Other Ribes). These other ribes, 

however, are more common outside our range. 

Pathology: moderately important for WPBR (Class B), capable alone of supporting a WPBR

outbreak on Gallinas Peak, New Mexico and important inoculum source in Colorado and 

southern Wyoming. Also moderately important for pinyon blister rust. 

References: Harrington (1954), Holmgren (1997), Jennings (personal communication), Mesler 

and Sawyer (1993), Smiley (1921), USDA (2001), Weber (1987, 1990), Welsh and others (1993). 

12 
3. Ribes leptanthum Gray 

trumpet gooseberry (RILE) 

Figure 4. Ribes leptanthum. a. stem with

prominent nodal spines, leaves orbicular, deeply

cleft; b. flower calyx white and cylindrical; c. fruit 

a smooth, lustrous berry maturing to black. 

Stem: nodal spines 1(3–5), prominent (7 to 15

mm); internodal bristles often cover young shoots; 

young twigs ridged, with black, sessile or shortstalked glands; bark straw, orange, gray or rustcolored, exfoliating to brown or gray. 

Leaf: blade orbicular; (3)5(7)-lobed, deeply cleft, 

middle lobe usually prominent and strongly

tapered; base cordate, sometimes truncate; margin 

dentate; blade and veins glabrous or sparsely

glandular-pubescent, underside without clear 

glands; leaf ciliate; petiole with stalked, dark 

glands, pubescent. 

Inflorescence: bracts prominent, close to hypanthium, with clear hairs and long-stalked glands. 

Flower: calyx white, cylindrical; sepals pubescent, with long-stalked glands; stamens purple and 

equaling petals; styles glabrous. 

Fruit: berry smooth, lustrous, red, maturing to black. 

Habitat: generally well-drained slopes, canyon-sides in lower valleys; pinyon–juniper woodlands 

to montane forests. The distributions of R. leptanthum and R. pinetorum overlap; R. leptanthum is 

more common at lower elevations (6,000–8,500 ft) and R. pinetorum at higher elevations. On the 

Sandia and Manzano Mountains, New Mexico, R. leptanthum is common at 8,000 ft and occurs 

as isolated individuals on limestone mountaintop outcrops above 9,000–10,000 ft. 

Range: UT, AZ, CO, NM, w TX. In CO—central and southwestern mountains, rare or absent 

from Rocky Mountain National Park and north. NM—from Torrance Co. north and west of Rio 

Grande, Sandia (abundant), Manzano (abundant), San Andres Mountains, and Carrizo Peak 

(where it is the only ribes and is especially lush and abundant). Not found at Gallinas Peak and in 

Capitan Mountains. 

Notes: Ribes leptanthum, R. pinetorum, and R. inerme may be confused unless mature fruit are 

present. Ciliate leaf edges of R. leptanthum have shorter and fewer hairs than seen on Ribes

inerme. Other differences are described under R. inerme. 

Pathology: very low susceptibility to blister rust infection (Spaulding 1922) and rated among the 

least important species for WPBR in our region (Class D). Highly susceptible to pinyon blister 

rust (Hedgcock and others 1918). Reported as host of pinyon leaf rust in Manzano Mountains

(Anonymous 1921). 

References: Carter (1988, 1997), Correll and Johnston (1970), Holmgren (1997), Ivey (2003),

Martin and Hutchins (1980), McMinn (1939), Vines (1960), Weber (1987, 1990).

 13
4. Ribes montigenum McClatchie 

 gooseberry currant (RIMO2) 

Figure 5. Ribes montigenum. a. leaf 

pubescent, raceme with few fruits; b.

hypanthium shallow, with stalked glands; 

c. spines several per node, internodal 

bristles. 

Stem: shrub armed with 1(3) nodal 

spines, variable in size; internodal bristles 

abundant; winter buds pointed; young 

stems glabrous; pith light tan, less than 1⁄2 

diameter of stem. 

Leaf: blade 1–2 cm broad, pentagonal, 

lobes 3–5, irregular, deeply dissected; 

base cordate; margin crenate-dentate, 

glandular; blade surfaces densely

pubescent-glandular (sticky); petiole 

shorter than blade, with stalked glands. 

Inflorescence: raceme 3–7 flowered; tending to upright. 

Flower: calyx yellowish; hypanthium shallow, saucer-shaped; styles glabrous; with prominent, 

stalked glands, flowering mid to late June–July (e.g., 6/17/51 on Mt. Taylor at 11,000 ft) 

Fruit: berry bright red to purplish-red, bristled with stalked glands; maturing August–Sept. 

Habitat: subalpine and alpine; open slopes and spruce-fir forests; in our area, usually above 

8,500 ft. 

Range: western mountains. CO—mountain counties (we have no record for Jackson Co.). NM—

northern mountains and high peaks: Sangre de Cristo and Brazos Mountains, Sierra Blanca, Mt. 

Taylor, Redondo Peak; Cibola, Rio Arriba, Socorro, Valencia counties. 

Notes: Ribes montigenum and R. lacustre both have long, purple-tinged glands on a saucershaped hypanthium, but they can be distinguished by several distinct features. The leaf blades of 

R. montigenum are pubescent to very pubescent and the mature fruits are bright red. The leaf 

blades of R. lacustre are glabrous to sparsely pubescent and the mature fruits are dark purple. 

Other differences are for R. montigenum compared to R. lacustre that nodal spines are fewer and 

stouter, leaves smaller and more deeply dissected, the petiole shorter than the blade, the raceme 

fewer flowered, and the hypanthium more shallow. 

Pathology: for WPBR, this ribes is rated Class B, Although a high percent of leaves may

infected, usually only a small area of leaf bears telia. This ribes can be responsible for significant 

pine infection in Wyoming (Newcomb 2003). Reported a host for pinyon blister rust in California 

(Anonymous 1921). 

References: Goodding (1926), Harrington (1954), Hitchcock and Cronquist (1973), Holmgren 

(1997), Ivey (2003), Martin and Hutchins (1980), McMinn (1939), Mesler and Sawyer (1993), 

Morris and others (1952), Vines (1960), Weber (1987, 1990)

14 
5. Ribes lacustre (Pers.) Poir. 

prickly currant (RILA) 

Figure 6. Ribes lacustre. a. stem with nodal 

spines and internodal bristles, leaf lustrous, fruits 

with stalked glands; b. spines many per node; c.

raceme with several to many flowers. 

Stem: shrub spreading to sprawling; young 

shoots with dense short pubescence; stems 

ridged; nodal spines 5–9, of uniform size; 

internodal bristles present; winter bud tip round; 

bud scale margins ciliate; pith white, less than 1⁄4 

the diameter of the stem. 

Leaf: blade 2–4 cm broad, pentagonal; lobes 3–5, 

irregular, dissected; base cordate; blade surface 

lustrous, glabrous or appearing so but with 

widely-spaced stalked glands; veins and margins 

sparsely pubescent. 

Inflorescence: raceme long, 7–16 flowered, 

drooping, bractate. 

Flower: calyx diameter 2.5 to 5 mm; hypanthium cup-shaped, with prominent, long-stalked, red 

to purple glands; styles glabrous. 

Fruit: berry red when young, black or dark purple when mature, with long-stalked, red to purple 

glands. 

Habitat: moist woods, boggy, stream banks, and sheltered montane forests with Douglas-fir or 

subalpine slopes; usually below 8,500 ft.

Range: Newfoundland and AK to Northeastern and Lake states, CO and n CA. CO—west slope 

mountains and northern Front Range including Boulder, Larimer, and Jackson Co. NM—High 

mountain peaks: Redondo Peak, Mt. Taylor, Sangre de Cristo Mountains, Brazos Mountains; 

Cibola, Lincoln, Otero, Rio Arriba, San Miguel, Sandoval, Santa Fe, and Taos counties. 

Notes: this northern species overlaps in distribution with a Rocky Mountain species, R. 

montigenum, leading to some difficulty in identification. Ribes lacustre and R. montigenum, 

however, can usually be distinguished (see discussion under R. montigenum). 

Pathology: in Lake States, Pacific Northwest, and northwestern Wyoming may be heavily

infected (Class B); uncommon in our region and pathology not observed. 

References: Carter (1988), Goodding (1926), Harrington (1954), Hitchcock and Cronquist 

(1973), Holmgren (1997), McMinn (1939), Mesler and Sawyer (1993), Van Bruggen (1986), 

Weber (1987, 1990). 

 15
6. Ribes viscosissimum Pursh 

sticky currant (RIVI3) 

Figure 7. Ribes viscosissimum, 

leaf petiole and blade 

pubescent and glandular, 

raceme with 3 to 8 fruits; 

flower with wide, funnelshaped hypanthium. 

Stem: shoots with shortstalked, red-pigmented glands. 

Leaf: petiole and blade with 

abundant sessile or longstalked, clear glands. 

Inflorescence: raceme 3–8 

flowered; bracts large, very

glandular, on short pedicels 

midway from stem to 

hypanthium. 

Flower: calyx white; wide, 

funnel-shaped. 

Fruit: berry black without

bloom; glandular-bristly. 

Habitat: montane and subalpine; moderately moist canyon bottoms and slopes, especially with 

aspen and disturbed sites (road cuts); in Colorado and New Mexico 7,500–8,500 ft. 

Range: BC to MT and south to CO to n CA. CO—rare, Routt and Grand Co. NM—rare Union 

Co. [AZ—Kaibab Plateau.]

Notes: Ribes viscosissimum is the most glandular of our three sticky currants. The calyx of Ribes 

viscosissimum forms a wide funnel in contrast to the tubular flowers of R. cereum and R. 

mescalerium. 

Pathology: Kimmey (1938) and Lachmund (1934) assessed this ribes as moderately susceptible 

to infection by WPBR; the species is common and an inoculum source in the Greater 

Yellowstone area; but very infrequent in our region. We rate it here as Class B. Graham (1966) 

reported a collection of pinyon blister rust on this ribes from Grand Teton National Park. 

References: Harrington (1954), Hitchcock and Cronquist (1973), Holmgren (1997), Martin and 

Hutchins (1980), McMinn (1939), Mesler and Sawyer (1993), Vines (1960), Weber (1987, 1990). 

16 
7. Ribes cereum Dougl. 

wax current (RICE) 

Figure 8. Ribes cereum. a. stem

unarmed, leaves with upper surface 

waxy; b. fruit a red-orange berry,

sparingly glandular-pubescent; c. flower 

calyx tubular, bearing short stalked 

glands. 

Stem: shrub unarmed; shoots with shortstalked glands. 

Leaf: blade lower surface, veins, and 

petiole with abundant short-stalked 

glands; upper surface waxy, glabrous or 

with few short-stalked glands, thick. 

Inflorescence: bracts toothed, adjacent to 

hypanthium, glandular. 

Flower: calyx pink to white with a pinkish tinge, tubular, with short-stalked glands (stalk length 

3–4x diameter of gland). Although Vines (1960) reports that styles are usually hairy, we have not 

observed this feature. 

Fruit: berry red-orange, glabrous to sparingly glandular-pubescent, fleshy but tasteless; seeds 

few. 

Habitat: open fields and partial shade; may be on dry sites; low to very high elevations; in 

Colorado and New Mexico more abundant at lower elevations (5,000–9,000 ft) but can occurs at 

high elevation (9,000–12,000 ft). 

Range: BC to CA, e to MT and NM. CO—widespread in mountains, plateaus, and high plains. 

NM—mountains and plateaus of north, west, and south central. 

Notes: includes several named varieties. Ribes inebrians Lindl. is treated here as a synonym.

There is wide variation in the morphology of R. cereum across its range; our descriptions pertain 

to its appearance as found in Colorado and New Mexico. In the limited region where Ribes 

cereum and R. mescalerium both occur, these species can be easily distinguished (see Notes under 

R. mescalerium). 

Pathology: in our area exhibits very low susceptibility to WPBR (Class D): however, reported, 

and observed by us, to be susceptible in other regions (for example, California and Montana). 

Susceptible to Coleosporium ribicola (Sacramento and Manzano Mountains, New Mexico). 

References: Harrington (1954), Holmgren (1997), Ivey (2003), Martin and Hutchins (1980), 

McMinn (1939), Mesler and Sawyer (1993), Van Bruggen (1986), Vines (1960), Weber (1990). 

 17
8. Ribes mescalerium Coville 

Mescalero currant (RIME2) 

Figure 9. Ribes mescalerium, stem

unarmed, leaf lobes rounded and 

shallow, fruit black. 

Stem: shrub unarmed; shoots with 

stalked glands. 

Leaf: blade surfaces and veins with 

long-stalked glands, thin. 

Inflorescence: raceme bractate; 

bract adjacent to hypanthium, 

pedicle with long-stalked glands 

(stalk length 8–10x diameter of 

gland). 

Flower: calyx white, tubular; 

hypanthium with long-stalked 

glands; style glabrous. 

Fruit: berry black. 

Habitat: widespread; open areas; in New Mexico 6,600–10,400 ft. 

Range: NM and w TX. NM—Sacramento Mountains, Magdalena Mountains, San Mateo 

Mountains; Catron, Lincoln, Otero, Socorro, and Torrance counties. 

Notes: the Southwestern endemic Ribes mescalerium is often confused with the broadly

distributed and greatly variable R. cereum. Ribes mescalerium has thinner, larger leaves, deeper 

lobes, and its glands have longer stalks; R. cereum has thicker, smaller, waxy leaves, shallower 

lobes, and its glands have shorter stalks. The glands of either species may be clear or red 

pigmented. 

Pathology: this ribes has a very low susceptibility to WPBR. In one case, 5 percent of leaves 

were infected with blister rust when 100 percent of the leaves of Ribes pinetorum were infected; 

usually it is even not infected (Class D). There is some pinyon needle rust on R. mescalerium, but 

only a small percentage of leaves on a small percentage of bushes.

References: Carter (1997), Correll and Johnston (1970), Martin and Hutchins (1980), Vines 

(1960). 

18 
9. Ribes nigrum L. 

European black currant (RINI) 

Figure 10. Ribes nigrum. a. leaf distinctly pointed, lower surface with golden resin glands; b.

raceme drooping, fruits 4 to 10 per raceme. 

Stem: twigs and shoots with strong odor when broken or crushed. 

Leaf: blade broader than long; lobes 3–5, distinctly pointed, dentate; lower blade surface with 

small golden resin glands; strong odor when crushed. 

Inflorescence: raceme 4–10 flowered, drooping. 

Flower: calyx bell- or saucer-shaped, tomentose; sepals purplish; petals white to reddish. 

Fruit: berry smooth, mature black with whitish bloom, glandular; taste pungent but pleasing. 

Habitat: cultivated; rarely escapes. Occasionally re-introduced from Europe or Canada by

tourists. 

Range: natural distribution in Europe. 

Notes: cultivated to produce telia used to screen white pines for resistance to WPBR. 

Pathology: the susceptibility of this to WPBR is usually very high (Class A); but there are 

resistant cultivars. Ribes nigrum is the standard by which others species are rated.

References: Hitchcock and Cronquist (1973), Rehder (1940). 

 19
10. Ribes hudsonianum Richards. 

northern black currant (RIHU) 

Figure 11. Ribes 

hudsonianum, a. leaf 

blade lower surface 

with glands, racemes 

erect; b. flower calyx

bell-shaped; c. raceme, 

erect and bearing 

numerous smooth, 

black berries. 

Stem: twigs and shoots 

with strong odor when 

broken or crushed. 

Leaf: blade usually

broader than long; 

lower surface

glandular. 

Inflorescence: raceme 

erect. 

Flower: calyx white; 

bell-shaped. 

Fruit: berry smooth, black when ripe. 

Habitat: moist locations and free-flowing swamps; may be associated with Ribes lacustre but 

more restricted. 

Range: Hudson Bay to AK, s to MN. Reported for northern UT and observed in northeast NV 

(Jarbidge Mountains), and an important ribes in WY and ID as a potential inoculum source for 

WPBR. There is one sample in the Colorado State University herbarium from the southern 

extremity of the Sangre de Cristo Range in Colorado. Ribes hudsonianum is not known to be 

present in New Mexico, and is of doubtful occurrence in Colorado. 

Notes: very closely related to Ribes nigrum (Messinger and others 1999). 

Pathology: well known as Ribes petiolare Dougl. in early blister rust literature as most 

susceptible to blister rust (McMinn 1939); we assign it to Class A. 

References: Hitchcock and Cronquist (1973), Holmgren (1997), Mesler and Sawyer (1993), 

Rehder (1940). 

20 
11. Ribes laxiflorum Pursh 

trailing black currant (RILA3) 

Figure 12. Ribes laxiflorum, a.

stem trailing, leaf 5-lobed, raceme 

borne on 1-year-old stem, fruits 

with bloom and stalked glands; b.

flower calyx saucer-shaped, 

hypanthium with long-stalked 

glands. 

Stem: shrub trailing or erect to 1–

1.5 m and ascending only near the 

ends (then trailing stems may

exceed 1.5 m). 

Leaf: blade 5–10 cm broad, 5-

lobed; veins of young leaf 

pubescent. 

Inflorescence: raceme born on 1-

year-old stems, bractate, 8–15 

flowered. 

Flower: calyx inconspicuous, 

saucer-shaped; hypanthium with long-stalked, reddish-purple glands. 

Fruit: berry black, with a bloom, with reddish-purple stalked glands. 

Habitat: damp areas in subalpine (spruce-fir) timbered and burned-over areas; in Colorado and 

New Mexico above 9,500 ft. 

Range: AK to n CA and e to west side of Cascades, n ID and disjunct in w UT, w CO, and n NM. 

CO—mostly Continental Divide counties. NM—north central mountains; Bernalillo, Sandoval,

Torrance counties. 

Notes: Ribes laxiflorum usually refers to a taxon of ribes in the Northwest and R. coloradense

Coville to a similar current in Colorado. There is, however, for a bridging population in western 

Utah (Deep Creek Range) and the status of these taxa requires additional study (Holmgren 1997). 

We have chosen in this case to follow the taxonomic lead of Holmgren (1997) rather than 

Hartman and Nelson (2001) and treat R. coloradense as a synonym of R. laxiflorum. In our area, 

Ribes laxiflorum may be confused with R. wolfii which may be somewhat procumbent as well. 

These species can best be distinguished by the long-stalked, reddish-purple glands on the 

hypanthium of Ribes laxiflorum in contrast to the short-stalked, green or clear glands of R. wolfii; 

R. laxiflorum is uncommon in our region. 

Pathology: moderate to low susceptibility to WPBR (Class B). 

References: Carter (1988, 1997 as R. coloradense), Harrington (1954 as R. coloradense), 

Hitchcock and Cronquist (1973), Holmgren (1997), Martin and Hutchins (1980 as R. 

coloradense), McMinn (1939), Mesler and Sawyer (1993), Vines (1960 as R. coloradense), 

Weber (1987 as R. coloradense). 

 21
12. Ribes americanum Mill. 

American black currant (RIAM2) 

Figure 13. Ribes 

americanum, racemes 

pendent, leaves with 

golden glands numerous 

on lower surface, sparse 

on upper surface. 

Stem: shrub usually erect 

and tall but some prostrate 

and layering; young twigs 

more or less ridged and 

angled (square); bark 

yellowish-green and 

glandular. 

Leaf: both surfaces of 

blade with golden glands, 

more numerous on lower 

surface. 

Inflorescence: raceme 

drooping and many

flowered; each pedicle 

bractate; bracts linear to 

lanceolate. 

Flower: calyx greenish-yellow or yellow, comparatively large, bell- or funnel-shaped. 

Fruit: berry smooth, black when ripe, spherical. 

Habitat: in Colorado, flood plains such as Cache la Poudre and South Platte at about the 6,000 ft 

level. In New Mexico at 6,000 ft in Tajique Loop canyon, east side of Manzano Mountains. 

Range: Nova Scotia to VA, w to Manitoba, along western edge of high plains to NM. CO—rare; 

central, Arapahoe, Denver, Douglas, El Paso, Jefferson, Larimer. NM—rare but locally abundant 

in Tajique Canyon on east slope Manzano Mountains. 

Pathology: low blister rust susceptibility to WPBR (Class C). 

References: Harrington (1954), Hitchcock and Cronquist (1973), Martin and Hutchins (1980), 

Van Bruggen (1986), Vines (1960), Weber 1990. 

22 
13. Ribes wolfii Rothrock 

 Wolf’s current (RIWO) 

Figure 14. Ribes wolfii. a. racemes 

borne on current years growth, 

flattened or elongate; b. flower 

calyx cup-shaped, fruit berries 

blue-black, with a bloom and short 

stalked glands. 

Stem: green stems with stalked 

glands; bark maturing from tan to 

gray, with abundant black sessile

glands. 

Leaf: blade 5-lobed; lobes pointed, 

distinct but not deeply dissected; 

margins dentate and not ciliate; 

base cordate; upper blade surface 

often sparsely glandular with clear 

glands or occasionally glabrous and 

smooth; lower surface with evenlyspaced, clear, sessile glands; veins 

pubescent with scattered, clear, 

sessile and stalked glands (especially on younger leaves); base of petiole with stalked glands. 

Inflorescence: raceme bractate, flattened or elongate; pedicles bractate; bract ellipticallanceolate, persistent, with yellow-white or reddish stalked glands. 

Flower: calyx white, cup-shaped; hypanthium with short-stalked, green, yellow, or clear glands. 

Fruit: berry blue-black, sometimes with a bloom; with short-stalked yellow or green glands.

Habitat: wet or moist areas; upper montane to subalpine; in Colorado and New Mexico usually 

above 8,000 ft. 

Range: UT, AZ, CO, NM. CO—western and southern counties. NM—western and central 

mountains; in all of the central mountain ranges from the Sacramento Mountains north to the 

Colorado border, including the Manzano, Sandia, Sangre de Christo, and Brazos Mountains; 

Bernalillo, Catron, Cibola, Los Alamos, Rio Arriba, San Miguel, Sandoval, Socorro, and Taos 

counties. 

Notes: in our area Ribes wolfii may be confused with R. laxiflorum. Ribes wolfii tends to be more 

erect and its hypanthium has short-stalked, green, yellow or clear gland. Ribes laxiflorum is 

procumbent and the hypanthium glands are long-stalked and reddish-purple. Our treatment of 

Ribes wolfii includes R. mogollonicum Greene as a synonym. 

Pathology: low susceptibility to WPBR (Class C). Reported as host for pinyon leaf rust in 

Sacramento and Manzano Mountains, New Mexico. 

References: Hitchcock and Cronquist (1973), Harrington (1954), Holmgren (1997), Ivey (2003), 

Martin and Hutchins (1980), Vines (1960), Weber (1987, 1990).

 23
14. Ribes rubrum L. 

 cultivated currant, red currant (RIRU80) 

Figure 15. Ribes rubrum, a. leaf blade 3-lobed, not deeply cleft, base cordate, raceme drooping; 

b. fruits smooth, shiny, red or white when ripe. 

Stem: bark of young twigs gray; buds often cluster at the end of a thick stem. 

Leaf: blade 3-lobed, not deeply dissected, dark green, rather thick; base cordate.

Inflorescence: raceme drooping, many flowered. 

Flower: calyx greenish-yellow; sepals as at least as broad as long; anther sacs separated. 

Fruit: berry smooth, shiny, red or white when ripe; taste tart. 

Habitat: cultivated but may escape. 

Range: natural distribution Europe. 

Notes: like the European black currant, there are numerous cultural varieties of red currant; these 

red currants include Ribes sativum Syme. 

Pathology: usually not very susceptible to WPBR (Class D) or to pinyon blister rust. 

References: Hitchcock and Cronquist (1973), Rehder (1940), Welch and others (1993). 

24 
15. Ribes aureum Pursh 

golden currant (RIAU) 

Figure 16. Ribes aureum, a.

leaf 3-lobed, often cruciform,

surface glabrous; b. flower

calyx salverform, yellow. 

Stem: shrub unarmed; shoots 

glabrous or puberulent. 

Leaf: blade 3-lobed, 

sometimes cruciform; surface 

mostly glabrous but when 

young may be finely pubescent 

with margin ciliate; petioles 

may be pubescent. 

Inflorescence: raceme 5–15 

flowered. 

Flower: calyx salverform, 

glabrous, yellow. 

Fruit: berry smooth, black or purplish-brown, rarely orange (southeast ID). 

Habitat: common on stream sides and wet ditches in the lower valleys and on the plains 

(Colorado and New Mexico 4,000–8,000 ft); native and commonly cultivated. 

Range: WA to MT and s from NM to CA. CO—widespread outside high mountains. NM—

uncommon; Otero, San Miguel, and Torrance counties. 

Notes: here we include Ribes odoratum H. Wendl. as a synonym (Hartman and Nelson 2002). 

Pathology: reported as susceptible to WPBR, but generally grows at a much lower elevation than 

most white pines and where the climate is too warm and dry for Cronartium ribicola infection 

(5,000–7,000 ft); rated as Class C. Ribes aureum (includes R. odoratum) is a major host of pinyon

blister rust in Colorado, Utah, and Arizona. Reported as a host to pinyon leaf rust in Sacramento

and Capitan Mountains, New Mexico (Anonymous 1921). 

References: Correll and Johnston (1970), Harrington (1954), Hitchcock and Cronquist (1973), 

Holmgren (1997), Ivey (2003), Martin and Hutchins (1980), McMinn (1939), Mesler and Sawyer 

(1993), Vines (1960), Weber (1987, 1990). 

 25
Other Ribes

Ribes coloradense Coville: collections of a prostrate black current in Colorado are usually

referred to Ribes coloradense as distinct from the Northwestern species R. laxiflorum. We accept 

the argument of Holmgren (1997) that these taxa may be synonymous. 

Ribes divaricatum Dougl.: this west coast species is only known recently and rarely collected 

from Colorado. Identification of specimens from riparian or other moist habitats which resemble 

Ribes inerme (greenish sepals) but with sepals whitish (R. niveum) or purple-tinged (R. 

divaricatum) requires flowers. See Hitchcock and Cronquist (1973), McMinn (1939), Rehder 

(1940), Weber (1987, 1990). 

Ribes hirtellum Michx.: this species of the eastern and Lake states is imported to Colorado as an 

ornamental. Ribes hirtellum and R. inerme are similar. One of us (Van Arsdel) after noting the 

variation in examined specimens from Michigan, Colorado, and New Mexico felt that it is all the 

same species. The variation in leaf shape, the amount of glands, and pubescence patters found in 

the Sangre de Cristo Mountains (a small area) include all of those found in the Michigan samples 

and conversely all the Michigan samples include the variation seen in the Colorado and New 

Mexico samples. The ranges overlap in the Black Hills (Thilenius 1971), abut in Montana (Morris 

and others 1960; Van Bruggen 1986), and overlap in southern Alberta. We are uncertain whether 

they should be segregated; but for the present time, we list Ribes inerme as the proper name for 

the common, native species of Colorado and other western states. Cultivated plants with leaf base 

wedge-shape are likely to be Ribes hirtellum; wild plants with leaf blades truncate base are likely

to be R. inerme. 

Ribes inebrians Lindl.: treated here as synonym of R. cereum. 

Ribes mogollonicum Greene: we concur with Holmgren (1997) and treat Ribes mogollonicum as a 

synonym of R. wolfii. 

Ribes niveum Lindl.: Colorado. Chumley and Hartman (2000) report a single, small but wellestablished population of ribes near Canon City, Colorado (Fremont county) as Ribes niveum. 

This population is a small disjunct from a species common in the Pacific Northwest and Nevada. 

Ribes ochrocentrum ?: one doubtful specimen collected in 1935 known from El Paso Colorado. 

Ribes odoratum Wendl.: a commonly cultivated taxon of the eastern states, included here as a 

synonym of Ribes aureum. 

Ribes oxyacanthoides L., (including “R. setosum and R. saximontanum”): a single collection at 

Colorado State Herbarium and other early reports may represent very rare plants or confusion 

with R. inerme. R. oxyacanthoides and varieties present in adjacent regions (see Sinnott 1985 and 

Holmgren 1997). 

Ribes quercetorum Greene. Arizona: Kearney and Peebles (1964), McMinn (1939), Mesler and 

Sawyer (1993), Rehder (1940); a species of pine-oak-woodlands not in proximity to white pines. 

Ribes velutinum Greene. Arizona, Utah, and Nevada: Hayes and Garrison (1960), Hitchcock and 

Cronquist (1973), Holmgren (1997), Kearney and Peebles (1964), McDougall (1973), McMinn 

(1939), Mesler and Sawyer (1993), Welch and others (1993); a species of pinyon-juniper 

woodlands. Its presence has not been noted in Colorado or New Mexico. 

26 
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30 
Glossary 

aecium (plural aecia). a cup-like fungal reproductive structure with or without a peridium of the 

first (I) stage of a rust. 

anther. the terminal portion of the stamen which produces pollen. 

axillary. between the leaf and stem. 

bloom. a fine, powdery film. 

bract. a small, specialized leaf of an inflorescence. 

bristle. a small, sharp appendage on a stem internode, derived from epidermis. 

calyx. a collective term for sepals. 

ciliate. with a fringe of marginal hairs. 

cordate. shaped with a central notch such as a stylized heart at the point of attachment. 

corolla. the inner portion of the perianth composed of petals. 

crenate. a margin with rounded teeth. 

cruciform. cross-shaped. 

cuneate. wedge-shaped or triangular, narrow at point of attachment. 

decurrent. with attached wing or margin extending down the stem below the point of attachment. 

dentate. a margin with pointed teeth. 

filament. an elongated portion of the stamen which supports the anther. 

glabrous. smooth, without hairs (trichomes) or glands. 

gland. an appendage on the surface or end of a trichome which produces a sticky, greasy, or 

viscous substance.

hypanthium. a structure derived from the united lower portions of the sepals, petals, stamens

and ovary which appears as a saucer, bell or tube. 

inflorescence. a cluster or flowers on a common axis. 

node. a section of the stem where a leaf is or had been attached. 

ovary. the lower portion of pistil containing the ovules which develop into seeds. 

pedicel. a stalk of an individual flower (or telium). 

peduncle. a stalk of an entire inflorescence or single flower. 

perianth. an outer, sterile portion of a flower, composed of calyx and corolla. 

peridium. the outer, sterile membrane of a reproductive structure of a rust; usually white; 

persistent or not. 

petal. a member of the second set of modified floral leaves internal to the outer set of sepals. 

petiole. a leaf stalk. 

pilose. covered with short, weak hairs. 

pistil. the female flower organ, consisting of ovary, style, and stigma. 

pubescent. bearing hairs (trichomes) of any kind. 

 31
pycnium (plural pycia). the fungal reproductive structure of the initial, (0) stage of rust. 

raceme. an unbranched inflorescence of pediceled flowers that open from bottom to top. 

rachis. an elongate axis of an inflorescence. 

reniform. shaped as a stylized kidney.

salverform. having a slender tube and flaring sepals. 

sepal. a member of the outer set of modified floral leaves external to the petals. 

spine. a sharp-pointed projection derived from a leaf or other organ. 

stamen. the male flower organ, consisting of anther and filament. 

stigma. the terminal section of the pistil receptive to pollen. 

stipitate. on a stalk.

stipule. one of a pair of small, specialized leavers at the base of a petiole. 

style. a slender stalk connecting a stigma and ovary. 

taxon (plural taxa). a taxonomic unit of any rank, such as genus, species subspecies, etc.

telium (plural telia). the fungal reproductive structure of the third stage (III) of a rust. 

trichome. a hair-like outgrowth of the epidermis. 

tomentose. covered with dense, short, rigid hairs (trichomes). 

truncate. shaped with a straight margin (as if cut off). 

uredium (plural uredia). the fungal reproductive structure of the second stage (II) of a rust; also 

termed uredinium.

villosus. covered with long, weak hairs (trichomes). 

32