Home Native Plant Network
NPN Protocol Details Image

Wyethia (amplexicaulis)

Dave Skinner
PMC Farm Manager
USDA NRCS - Pullman Plant Materials Center
Room 211A Hulbert Hall WSU
Pullman, Washington 99164-6211
509-335-2940 (fax)

Family Scientific Name: Asteraceae
Family Common Name: Sunflower
Scientific Name: Wyethia amplexicaulis (Nutt.) Nutt.
Common Name: Mule's ears
Species Code: WYAM
Ecotype: Paradise Creek drainage near Pullman, Washington.
General Distribution: Western US east to Montana and south to Colorado and Nevada where mean annual precipitation ranges from 12-20 inches (USDA 2004). In eastern Washington it occurs in dry to mesic open slopes and meadows from sagebrush to open Ponderosa pine forest. In the northwestern US its wetland status is classified as FAC- (US Fish and Wildlife Service 1988).
Known Invasiveness: Because livestock do not eat it, it has been considered a range pest and attempts have been made to eradicate it from range (Craighead et al 1963).
Propagation Goal: plants
Propagation Method: seed
ProductType: Container (plug)
Time To Grow: 10 Months
Target Specifications: Tight root plug in container.
Propagule Collection: Fruit is an achene. Seed is collected in late July or early August when the inflorescence is dry and the seeds are dark brown in color. Seedheads are clipped from the plants and stored in paper bags at room temperature until cleaned.
Propagule Processing: Small amounts are crushed by hand to free the seed, then cleaned with an air column separator. Larger amounts are threshed with a hammermill, then cleaned with air screen equipment. Clean seed is stored in controlled conditions at 40 degrees Fahrenheit and 40% relative humidity.
We determined 28,200 seeds/lb for this ecotype (USDA NRCS Pullman Plant Materials Center, 2005).
Pre-Planting Treatments: Seed from northern Nevada and California requires 4 weeks of cool, moist stratification (Young and Evans 1979). Mirov (1936) also reported that California seeds needed prechilling before germination. Baskin and Baskin (2002) report that seeds possess physiologicaldormancy that is broken by cold stratification.
Unpublished data from trials conducted at the Pullman Plant Materials Center revealed that low rates of germination occurred without stratification and with 45 days of cold, moist stratification. 90 or more days of cold, moist stratification resulted in 79% germination.
Growing Area Preparation/
Annual Practices for Perennial Crops:
In November seed is sown in 10 cu. in. Ray Leach Super cell conetainers filled with Sunshine #4 and covered lightly. A thin layer of pea gravel is applied to prevent seeds from floating. Conetainers are watered deeply and placed outside. Alternately, seed can be moist stratified in a refrigerator for 90 days before sowing in the greenhouse.
Establishment Phase: Containers are moved to the greenhouse in mid-February or early March. Germination usually begins in 7-10 days and is complete in 30 days.
Length of Establishment Phase: 2 weeks
Active Growth Phase: Plants are watered deeply every other day and fertilized once per week with a complete, water soluble fertilizer containing micro-nutrients. Plants are moved to the lath house in June. They are watered every other day if the weather is cool, and every day during hot, dry spells. They are fertilized once per week with a water soluble complete fertilizer containing micro-nutrients. Fertilizer and water are reduced as fall approaches. Plants may only develop 2-3 true leaves during this period and may become dormant during the late summer.
Length of Active Growth Phase: 6-7 months
Hardening Phase: Since the plants are grown outside, additional hardening is not needed.
Harvesting, Storage and Shipping: If sufficient root growth has occurred, plants may be transplanted to the field in late fall. If the plants have not yet developed a tight root plug, they should be held over winter. Rapid root growth will occur with the arrival of early spring temperatures and the plants will be ready for outplanting in early May. Those held over winter are left in the lath house with no protection except snow cover, but plants exposed to extreme low temperatures should be afforded some insulation.
It may be possible to grow plants more quickly by using refrigerator stratified seed sown directly in the greenhouse at an earlier date, but we have not tried this approach.
Other Comments: Some insect seed predation has been noted.
A planting made in 1998 yielded its first good crop of seed in 2004.
References: Baskin, Carol C. & Baskin, Jerry M. 2002. Propagation protocol for production of container Wyethia amplexicaulis (Nutt.) Nutt. plants; University of Kentucky, Lexington, Kentucky. In: Native Plant Network. URL: http://www.nativeplantnetwork.org (accessed 17 February 2005). Moscow (ID): University of Idaho, College of Natural Resources, Forest Research Nursery.
Craighead, John J., Frank C. Craighead, and Ray J. Davis. 1963. A Field Guide to Rocky Mountain Wildflowers. Houghton Mifflin Co. Boston, MA.
Hitchcock, C. Leo, and Arthur Cronquist. 1973. Flora of the Pacific Northwest. University of Washington Press. Seattle, WA.
Mirov, N.T. 1936. Germination Behavior of Some California Plants. Ecology 17:667-672.
Rose, Robin, Caryn E.C. Chachulski, and Diane L. Haase. 1998. Propagation of Pacific Northwest Native Plants. Oregon State University Press, Corvallis, OR.
USDA, NRCS. 2004. The PLANTS Database, Version 3.5 (http://plants.usda.gov). National Plant Data Center,Baton Rouge, LA 70874-4490 USA.
USDA, NRCS, Pullman Plant Materials Center. 2005. Seed Weights of Some Palouse Native Species. Pullman Plant Materials Center, Pullman, Washington. Online at http://www.wsu.edu/~pmc_nrcs/Docs/Seed_Weights_Palouse_Native_Species.pdf
US Fish and Wildlife Service. 1988. National list of vascular plant species that occur in wetlands. US Fish & Wildlife Service Biological Report 88 (24).
Young, James A. and Raymond A. Evans. 1979. Arrowleaf Balsamroot and Mules Ear Seed Germination. Journal of Range Management 32:71-74.
Young, James A. and Cheryl G. Young. 1986. Collecting, Processing and Germinating Seeds of Wildland Plants. Timber Press. Portland, OR.


Skinner, David M,. 2008. Propagation protocol for production of Container (plug) Wyethia amplexicaulis (Nutt.) Nutt. plants USDA NRCS - Pullman Plant Materials Center Pullman, Washington. In: Native Plant Network. URL: http://NativePlantNetwork.org (accessed 2021/05/08). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.

Personal tools