**Amaranthus albus L. (Amaranthaceae)**

**Tumbleweed, Tumble Pigweed**

**Description**. Plants monoecious, annual, round in outline, from deep
taproots. Stems 20-80 (120) cm tall, central one erect, breaking at base
in fruit, the branches many, spreading to ascending, glabrous to
villous, pale green to whitish. Leaves alternate, lower and cauline
1.5-6 cm long, elliptic or lanceolate to oblanceolate or obovate, often
deciduous in fruit, petiolate to tapered at base, margins entire, apices
obtuse; upper leaves 0.5-3 cm long, elliptic to obovate, generally
persistent, apices mucronate to obtuse. Flowers unisexual, in axillary
clusters or spikes. Each flower subtended by 3 bracts, bracts 2-4 mm
long, green, rigid, often spreading, onlong-lanceolate; sepals 3,
unequal, shorter than bracts, staminate sepals oblong, pistillate ones
oblong to linear; petals absent; stamens 3; styles 3. Fruit a utricle,
circumscissile near the middle, surface rough at maturity. Seed one,
0.6-1 mm in diameter, lenticular, reddish brown to black, shiny. In
California, flowering from May to November. (Abrams 1944, Aellen 1964,
Clapham et al. 1962, Fernald 1950, McGregor 1986, Henrickson 1993, Munz
1959).

**Note:** A related species, *A. deflexus*, is similar in appearance and
habitat to tumbleweed, but differs by its low, mounded habit, flowers
with 2-3 sepals, and indehiscent, hardwalled, and somewhat inflated
fruits (Henrickson 1993, Munz 1959).

**Geographic distribution**. Tumbleweed is considered originally native
to North America and perhaps South America. Widely introduced into
Europe but considered a waif in New Zealand, and South Africa (Aellen
1964, Arnold and de Wet 1993, Webb et al. 1988). The related species,
*A. deflexus*, also occurs sporadically in Australia, New Zealand, and
South Africa (Aellen 1964, Arnold and de Wet 1993, Webb et al. 1988).

*Amaranthus albus* was first reported from California in 1876 (Brewer et
al. 1876), where it was considered common and native. Robbins (1940),
who considered it introduced in southern California, listed records
dating back to the period 1893-1913. Populations occur on Anacapa, Santa
Cruz, and Santa Rosa islands (Junak et al. 1997), and have been reported
from most counties in the state (Anonymous 1998).

**Ecological distribution**. Throughout its geographic range, both
native and naturalized, *Amaranthus albus* occurs on open sites in
abandoned fields, waste areas, and roadsides (Aellen 1964, Fernald 1950,
Great Plains Flora Association 1986, Munz 1959, Robbins 1940).

**Reproductive and vegetative biology**. Although the pollination
biology of tumbleweed has apparently not been studied, other monoecious
species of *Amaranthus* are self-compatible, but generally
wind-pollinated (Proctor et al. 1996). No specific literature was found
pertaining to seed biology and establishment. Other species of
*Amaranthus* considered to be noxious weeds (e.g., *A. hybridus*, *A.
retroflexus*, and *A.* *spinosus*) produce large numbers of seeds that
germinate readily after initial winter and spring rains in Mediterranean
and temperate climates respectively (Holm et al. 1977). *Amaranthus
albus*, like other congeners, possesses a C4 photosynthetic system
(Black et al. 1969, Black 1971) and is thus capable of competing well in
warm temperate and subtropical climates. Experimental studies of
germination and growth rates in soybean fields suggest that tumbleweed
competes well under high light intensities, with performance varying
with respect to plant cover and density (Stoller and Myers 1989).

**Weed status**. *Amaranthus albus* is not considered a serious noxious
weed in agricultural or horticultural practice, at least at a global
level (not listed by Holm et al. 1977), nor is it considered a noxious
weed by the State Dept. of Food and Agriculture (Anonymous 1996). It is
considered a waif in New Zealand (Webb et al. 1988) and only a garden
weed in South Africa (Arnold and de Wet 1993). Lorenzi and Jeffery
(1987) listed it as a weed in the United States.

**Microbial pathogens.** *Aposphaeria amaranthi* has been reported to
infest tumbleweed, (Mintz et al. 1992). Kaiser and Hannan (1983)
reported tumbleweed to be a host of tobacco mosaic virus in bean crops.

**Herbicide control.** Lorenzi and Jeffery (1987) indicate that most
*Amaranthus* species respond similarly to herbicides. They recommended a
broad array, including aciflourfen, alachlor, ametryn, atrazine,
chlorsulfuron, metolachlor, oxyflourfen, 2,4-d, and dicamba, among
others, for field and cropland conditions. Successful control in crop
fields has been reported, using rimsulfuron (Eberlein et al. 1994),
combinations of acifluorfen, lactofen, chlorimuron and imazaquin (Mayo
et al. 1995), clomazone (Wicks et al. 1996), and simazine (Saavedra and
Pastor 1996).

**Literature Cited**

Abrams, L. 1944. Polygonaceae to Krameriaceae. Illustrated Flora of the
Pacific States. Volume II. Stanford University Press, Stanford,
California. 635 pp.

Aellen, P. 1964. *Amaranthus*. pp. 109-110. In Tutin et al.
Lycopodiaceae to Platanaceae. Flora Europaea. Volume 1. Cambridge
University Press, Cambridge, United Kingdom. 464 pp.

Anonymous. 1996. Exotic pest plants of greatest ecological concern in
California as of August 1996. California Exotic Pest Plant Council. 8
pp.

Anonymous. 1998. USDA Plants Database. USDA National Plants Data Center,
New Orleans, Louisiana. URL: plants.usda.gov

Arnold, T. and B. de Wet. 1993. Memoir 62. Plants of southern Africa:
names and distribution. National Botanical Institute, Pretoria. 825 pp.

Black, C. 1971. Ecological implications of dividing plants into groups
with distinct photosynthetic production capacities. pp. 87-114. In J. B.
Gragg (ed.). Advances in ecological research.. Academic Press, London
and New York.

Black, C., T. Chen, and R. Brown. 1969. Biochemical basis for plant
competition. Weed Science 17: 338-344.

Brewer, W., S. Watson, and A. Gray. 1876. Geological Survey of
California. Volume 1. John Wilson, University Press, Cambridge,
Massachusetts. 622 pp.

Clapham, A., T. Tutin, and E. Warburg. 1962. Flora of the British Isles.
Cambridge University Press, Cambridge. 1269 pp.

Eberlein, C., J. Whitmore, C. Stanger, and M. Guttieri. 1994.
Postemergence weed control in potatoes (*Solanum tuberosum*) with
rimsulfuron. Weed Technology. 8: 428-435.

Fernald, M. 1950. Gray's Manual of Botany. Eighth Edition. American Book
Company, New York. 1632 pp.

Henrickson, J. 1993. Amaranthaceae. pp. 130-134. In Hickman, J. (ed.)
The Jepson Manual: Higher plants of California. University of California
Press, Berkeley. 1400 pp.

Junak, S., S. Chaney, R. Philbrick, and R. Clark. 1997. A checklist of
vascular plants of Channel Islands National Park. Southwest Parks and
Monuments Association, Tucson, AZ. 43 pp.

Kaiser, W.J. and R. Hannan. 1983. Additional hosts of alfalfa mosaic
virus and its seed

transmission in tumble pigweed and bean. Plant Disease. 67: 1354-1357.

Lorenzi, H. and L. Jeffery. 1987. Weeds of the United States and their
control. Van Nostrand Company, New York. 355 pp.

Mayo, C., M. Horak, D. Peterson, and J. Boyer. 1995. Differential
control of four *Amaranthus* species by six postemergence herbicides in
soybean (*Glycine max*). Weed Technology. 9: 141-147.

Mintz, A., D. Hieny, and G. Weidemann. 1992. Factors influencing the
biocontrol of Tumble pigweed (*Amaranthus albus*) with *Aposphaeria
amaranthi*. Plant Disease. 76: 267-269.

Munz, P. 1959. A flora of California. University of California Press,
Berkeley. 1681 pp.

Proctor, M., P. Yeo, and A. Lack. 1996. The natural history of
pollination. Timber Press, Portland, Oregon. 479 pp.

Robbins, W. 1940. Alien plants growing without cultivation in
California. Agricultural Experiment Station. Bulletin 637. University of
California, Berkeley. 128 pp.

Saavedra, M. and M. Pastor. 1996. Weed populations in olive groves under
non-tillage and conditions of rapid degradation of simazine. Weed
Research. 36: 1-14.

Stoller, E. and R. Myers. 1989. Response of soybeans (*Glycine max*) and
four broadleaf weeds to reduced irradiance. Weed Science. 37: 570-574.

Webb, C., W. Sykes, and P. Garnock-Jones. 1988. Flora of New Zealand.
Volume 4. Naturalized pteridophytes, gymnosperms, dicotyledons.
Department of Scientific and Industrial Research, Christchurch. 1365 pp.

Wicks, G., G. Mahnken, and G. Hanson. 1996. Weed control in ecofallow
corn (*Zea mays*) with clomazone. Weed Technology. 10: 495-501.