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| ## Royal Penstemon {#royal-penstemon .Title-Header}                   |
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| *Penstemon speciosus* Douglas ex Lindl.                               |
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| Plant Symbol = PESP                                                   |
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Contributed by: Aberdeen Plant Materials Center and Idaho NRCS State
Office

![](media/image2.jpeg){width="3.063888888888889in"
height="4.583333333333333in"}

Derek Tilley, USDA NRCS Idaho PMC

##### Alternate Names {#alternate-names .Header-3}

Sagebrush penstemon, showy penstemon, royal beardtongue

##### Uses {#uses .Header-3}

Royal penstemon is chiefly used as a forb component for wildlife habitat
enhancement projects and restoration efforts. Its showy flowers attract
numerous pollinators and other insects which provide a food source for
birds and other vertebrates. This species is also commonly used in
xeriscaping and other low-water-use landscaping. It is also suited for
roadsides and other beautification projects.

##### Status {#status .Header-3}

Consult the PLANTS Web site and your State Department of Natural
Resources for this plant's current status (e.g. state noxious status).

#####  {#section .Header-3}

##### Description {#description .Header-3}

*General*: Figwort Family (Scrophulariaceae).

Royal penstemon is a perennial herb/forb reaching 3 to 6 dm (1 to 2 ft)
tall. Several ascending to erect stems arise from a branched caudex.
Flowers are sky blue reaching 4 cm (1.5 in) long and about 1 cm (0.4 in)
wide at the mouth. Leaves are entire and narrow, to 15 cm (6 in) long
and 1 to 12 mm (0.04 to 0.5 in) wide, rounded to acute at the tip. The
leaves are mostly sessile with some of the upper leaves clasping the
stem. Anthers are blue-margined, glabrous, with sacs about 2mm (0.08 in)
long, partially dehiscent; the suture line not reaching the connective
(Welsh 2003). Flowering season is from May to July. There are
approximately 400,000 seeds/lb (USDA-NRCS 2008).

![](media/image3.jpeg){width="2.6416666666666666in"
height="3.8041666666666667in"}

Close-up of flowers.

Derek Tilley, USDA NRCS Idaho PMC

*Distribution*: Royal penstemon is found in scattered populations
throughout the Great Basin Floristic Province. The species is common in
western Utah, southern Idaho, and most of Nevada and into east Cascade
and Sierra portions of Washington, Oregon and California.

*Habitat*: Royal penstemon inhabits dry flats, slopes and draws in the
sagebrush-grass, mountain shrub and juniper forestland communities.
Plants typically occur at low to middle elevations in lowlands and
foothills from 0 to over 10,000 feet (Hitchcock et al 1959).

##### Adaptation {#adaptation .Header-3}

This species is adapted to loam to fine sandy loam soils with a pH range
of 6.0 to 8.0 (Las Pilitas 2008). For xeriscaping and low water
gardening the species is recommended for use in USDA hardiness zones 3a
through 7b (Dave's Garden 2008) in areas receiving greater than 10
inches annual precipitation.

##### Management {#management .Header-3}

When planted in a native reclamation mix, royal penstemon will be a
minor component of the establishing plant community; therefore
management should be based on other key species in the mixture. Grazing
on seeded lands should be deferred for at least two growing seasons to
allow for establishment.

##### Pests and Potential Problems {#pests-and-potential-problems .Header-3}

Impact from insect pests on penstemon seed production can be
significant. Penstemon borer larva can infect the crown and upper root
area of all Penstemon species resulting in the loss of individual plants
to entire fields. Presently, penstemon borers are known only from
extreme southwestern Colorado. Penstemon clearwing (*Penstemonia*
spp*.*) attacks multiple *Penstemon* species. The larvae feed within the
stems of the crown and lower above ground portion of the plant. A
pheromone is available for monitoring of adults. Other potentially
significant pests include Lygus bugs and raceme-boring moths (Western
Colorado Extension 2008).

**Seed and Plant Production**

Fields for seed production can be established by transplanting
greenhouse grown containerized stock or from direct seeding. Direct
seeding should take place in the fall to allow for natural
stratification of the seed. Greenhouse materials can be established by
seeding into cones or flats in winter for natural stratification or by
stratifying the seed for 8 to 12 weeks in cold/moist conditions.
Pre-chilling requirements are reduced with a liquid smoke treatment
(Shaw et al. 2003). Germination can also be enhanced by watering with a
weak solution of gibrillic acid (250 ppm) though treated seedlings
appear to be less vigorous than non-treated. Royal penstemon plants have
also been successfully propagated from herbaceous stem cuttings (Dave's
Garden 2008). Seed should be sown to a depth of 0 to 6 mm (0 to 0.25
in).

In herbicide tolerance screening trials royal penstemon has shown
sensitivity to pre-emergence applied pendimethalin and benefin. Limited
damage was observed to plants with post-emergent herbicide treatments.
Plants showed good tolerance to post-emergent applied clethodim,
dimethanamid-P and pendimethalin and had seed yields comparable to
untreated plants, but untreated plots had highest yields overall.
*Penstemon* plants showed high sensitivity to prometryn and linuron
(Shock et al. 2008).

#####  {#section-1 .Header-3}

![](media/image4.jpeg){width="2.9277777777777776in"
height="1.94375in"}Royal penstemon seedlings grown in weed barrier
fabric for seed production.

Derek Tilley, USDA NRCS Idaho PMC

Because of the limited number of available herbicides that can be used
on broadleaf forbs, planting into weed-barrier fabric (pictured above)
is a viable alternative to control weeds in forb seed production fields.
Holes should be three to four inches in diameter at 9 to 16 inch
spacing.

*Pollinators*: Successful pollination is essential for commercial seed
production of royal penstemon. In pollinator studies manual pollination
more than doubled the weight and count of seeds/capsule when compared
with auto-pollination. Outcrossing also yielded five times more seed
than self-pollinating and bumblebee pollinations enhanced seed yield an
additional 25% (Cane 2005).

Royal penstemon is visited by selective pollinators. In one study hived
honey bees favored distant *Dalea ornata*, while wild bumblebees and
ground nesting species were attracted to royal penstemon from
surrounding rangelands. (Cane 2005). Other identified pollinators
include P*seudomasaris vespoides* and *Osmia* spp.

Seed harvest can be accomplished by hand or by direct combining. Harvest
should occur when the stems and capsules begin to dry and open. Seed can
be cleaned with a small clipper or air-screen cleaner. Seed yields range
from 20 to 50 lb/ac.

##### Cultivars, Improved, and Selected Materials (and area of origin) {#cultivars-improved-and-selected-materials-and-area-of-origin .Header-3}

There are currently no selected releases of royal penstemon. Wildland
harvested seed is available through commercial sources.

#####  {#section-2 .Header-3}

##### References {#references .Header-3}

Cane, J. 2005. Pollinator and seed predator studies. In: Great Basin
Native Plant Selection and Increase Project FY05 Progress Report.

Dave's Garden. 2008. http://davesgarden.com/guides/pf/go/91817/
(accessed 7 Aug 2008).

Hitchcock, C.L., Cronquist, A., Ownbey, M. and J.W. Thompson. 1959.
Vascular Plants of the Pacific Northwest, Part 3: Saxifragaceae to
Ericaceae. University of Washington Press. Seattle, WA.

Las Pilatas Nursery. 2008. www.laspilitas.com/plants/486.htm (accessed 7
Aug 2008). San Margarita, CA.

Shaw, N., Walker, S., Jensen, S., Thompson, T. and A. DeBolt. 2003.
Native plant material development and seed and seeding technology for
native Great Basin forbs and grasses. In: Great Basin Native Plant
Selection and Increase Project FY03 Progress Report.

Shock, C., Ishida, J. and E. Feibert. 2008. Identification of herbicides
for use in native forb seed production. In: Great Basin Native Plant
Selection and Increase Project FY07 Progress Report.

USDA Natural Resources Conservation Service. 2008. The PLANTS database,
version 3.5. URL: http://plants.usda.gov (accessed 13 Aug 2008). Baton
Rouge, LA. National Plant Data Center.

Welsh, S. L., N. D. Atwood, S. Goodrich and L. C. Higgins. 2003. *A Utah
Flora*. Brigham Young University Press, Provo, Utah.

Western Colorado Extension: Native Plant Seed Production. 2008.
http://wsprod.colostate.

##### edu/cwis487/wci/seed_production.html. (accessed 13 Aug 2008). {#educwis487wciseed_production.html.-accessed-13-aug-2008. .Header-3}

#####  {#section-3 .Header-3}

##### Prepared By {#prepared-by .Header-3}

*Derek Tilley*, USDA NRCS Plant Materials Center, Aberdeen, Idaho

*Dan Ogle*, USDA NRCS Idaho State Office, Boise, Idaho

*Loren St. John*, USDA NRCS Plant Materials Center, Aberdeen, Idaho

*Nancy L. Shaw*, USDA Forest Service, Rocky Mountain Research Station,
Boise, Idaho

##### Species Coordinator {#species-coordinator .Header-3}

*Dan Ogle*, USDA NRCS Idaho State Office, Boise, Idaho

##### Edited: 090308djt; 081608lsj; 090308dgo; 082508 nls; 081006 jsp {#edited-090308djt-081608lsj-090308dgo-082508-nls-081006-jsp .Header-4}

For more information about this and other plants, please contact your
local NRCS field office or Conservation District, and visit the PLANTS
Web site\<[http://plants.usda.gov](http://plants.usda.gov/)\> or the
Plant Materials Program Web site
\<[http://Plant-Materials.nrcs.usda.gov](http://Plant-Materials.nrcs.usda.gov/)\>

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apply to all programs.) Persons with disabilities who require
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large print, audiotape, etc.) should contact USDA\'s [TARGET
Center](http://www.usda.gov/oo/target.htm) at 202-720-2600 (voice and
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*To file a complaint of discrimination write USDA, Director, Office of
Civil Rights, Room 326-W, Whitten Building, 14th and Independence
Avenue, SW, Washington, DC 20250-9410 or call 202-720-5964 (voice or
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*Read about [Civil Rights at the Natural Resources Conservation
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