Hymenoxys richardsonii (Hook.) Cockerell

by Shalene Yazzie, Native Plants of Arizona 2009
Common names: Pingue rubberweed, Colorado rubberweed (1).
Family: Asteraceae
Synonymy: Hymenoxys richardsonii (Hook.) Cockerell var. floribunda (A. Gray) K.F. Parker, Hymenoxys richardsonii (Hook.) Cockerell var. richardsonii (1).
Etymology: Richardsonii from the Scottish naval surgeon and naturalist Sir John Richardson (1787-1865), whom the specimen was named for, by Sir William Jackson Hooker (1785-1865) (2).

Identification
Growth form: Polycarpic, perennial sub-shrub or herbaceous perennial, usually 7-40 cm tall, with a multi-branched woody base (3).
Stem: Distally branched or multi-stemmed at the woody caudices, normally about 20+cm, either smooth or hairy with uniform coloring (3).
Leaves: Usually divided into 3 linear lobes, rarely simple, smooth or hairy, with an even scattering of small resin glands. Leaves concentrated around the base of the stems (4).
Inflorescence/flowers: Several or many radiate yellow heads, involucres in series of 2 or more with stiff phyllaries with the outer phyllaries united at base(5); yellow ray flowers, papery yellow disc flowers.
Fruit: 2-3 mm achene topped with white translucent aristate pappus scales (5).
Similar species: H. richardsonii is distinguished by long stems that are woolly at the base of the lowest leaves.

Ecology
Life history: Perennial sub shrub/herb, with woody caudices (3).
Native/introduced: Native (1).
Phenology: Flowers mid-June to early September (6).
Distribution: Mostly found from 5,000-8,000ft in the Ponderosa Pine Forest, Pinion Juniper Woodlands to Desert grasslands (5). In Arizona H. richardsonii is found in Yavapai, Coconino, Apache and Navajo counties. Distribution also includes the central U.S. following the Rocky Mountain range into Canada (Texas, Arizona, New Mexico, Colorado, Utah, Idaho, Montana, Wyoming, Alberta and Saskatchewan) (1).

 Ethnobotany/Uses: Hopi and Navajo ethnobotanical uses for H. richardsonii include using the bark of the roots as a chewing gum, due to the roots having a milky sap that contains latex. The stems/leaves are also used to make a tea and poultice used to treat wounds (7). Also used by the Navajo as an emetic in the Evil Way ceremony (6).

 Notes: Hymenoxys richardsonii is toxic to livestock (5).

 References
1. USDA, NRCS. (2009) The PLANTS Database. Retrieved Oct. 14, 2009. http://plants.usda.gov
2. " Sir John Richardson ." Encyclopedia Britannica . 2009. Encyclopedia Britannica Online. 18 Oct. 2009 < http://www.britannica.com/EBchecked/topic/502657/Sir-John-Richardson >.
3. Hooker. "Hymenoxys richardsonii." Flora of North America . www.eFloras.org, Web. 17 Oct 2009.<http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=250066995>.
4. "Colorado Rubber Plant." U.S.Geological Survey . 03 Aug 2006. U.S. Department of the Interior, Web. 19 Oct 2009. <http://www.npwrc.usgs.gov/resource/plants/wildflwr/species/hymerich.htm>.
5. Kearney, Thomas, and Robert Peebles. Arizona Flora . 2 nd edition. Berkeley and Los Angeles: University of California Press, 1964.
6. Mayes, V.O., and Barbara B. Lacy. 1989. Nanise: A Navajo Herbal: 100 Plants from the Navajo Reservation. Navajo Community College Press. Tsaile, AZ.
7. Moerman, Dan. "Hymenoxys richardsonii." Native American Ethnobotany . University of Michigan-Dearborn, Web. 18 Oct 2009. <http://herb.umd.umich.edu/herb/search.pl?searchstring=Hymenoxys+richardsonii>.