Comprehensive DescriptionRead full entry
General: Sumac family (Anacardiaceae). Upright arching native shrubs 0.5-2.5 meters tall, forming rounded, moundlike, or upright thickets, crown diameter often greater than the plant height; roots deep and extensively branched, with woody, shallow, and spreading rhizomes, sometimes connecting shrubs more than 9 m apart; sprouts arising from rhizomes and root crown. Leaves: deciduous, alternate, compound with 3 leaflets, variable in size, shape, lobing, and margin, the leaflets unstalked, ovate to rhomboid, more or less wedge-shaped at the base, coarsely-toothed, usually shiny-glabrous above, the terminal leaflet 3-6.5 cm long; summer foliage green, becoming orange or reddish in the fall. Flowers: yellowish to whitish, in small, dense clusters on short lateral shoots, opening before the leaves, bisexual and unisexual, both types borne on the same plant (the species polygamodioecious); male (staminate) flowers in yellowish catkins, female (pistillate) flowers in bright yellow, short clusters at the ends of branches. Fruits: 5-7 mm in diameter, red at maturity and sparsely hairy, each containing a single nutlet. Rhus trilobata closely resembles R. aromatica and is often treated as part of the latter. The common name is derived from the odor of the leaves, especially when bruised.
Variation within the species: a number of ecotypes are known to occur in skunkbush. Growth form and height vary geographically – plants are more branched and compact in the Southwest and taller in the north part of the range. Current practice recognizes six formal varieties, distinguished by morphological characteristics such as growth form, height, leaf shape and size, fruit shape and pubescence, commonly intergrading where they occur together.
Var. anisophylla (Greene) Jepson - OR, CA, NV, UT, AZ, and NM, south into Mexico.
Var. pilosissima Engelm. - CA to TX, south into Mexico.
Var. quinata (Greene) Jepson – OR, CA, NV, AZ, and NM.
Var. racemulosa (Greene) Barkl. - AZ and NM, south into Mexico.
Var. simplicifolia (Greene) Barkl. – OK, CO, and NM, to CA and OR, south to AZ and Mexico.
Var. trilobata – covers the range of the whole species.
Distribution: Broadly distributed throughout the western North America, from Saskatchewan and Alberta south to Texas and California and into Mexico; not in Washington or British Columbia. See details below for distribution of varieties. For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site.