Plant: Perennial herb; stems to 80 cm tall, usually producing branches along their entire length
Leaves: to 15 cm long, to 3 cm wide, sessile, narrowly elliptic to lanceolate, occasionally oblanceolate; margins toothed to lobed, sometimes pinnatifid, sometimes approaching entire in very narrow leaves; upper leaves commonly with broad, clasping bases and sometimes with clasping basal lobes
INFLORESCENCE: cymose
Flowers: pedicellate, subtended by 0-2 linear-lanceolate entire or few-toothed to lobed bracts, these sometimes fused to ovary; petals yellow, rarely nearly white, 9-23 mm long, 3-10 mm wide, with trichomes at apex only; staminodia 5, occasionally more or fewer, slightly smaller than petals; outer several whorls of stamens with broadened filaments; style (7-)10-14 mm long; stigmatic papillae forming a slight tuft
Fruit: capsules cylindric, sometimes broadly so, mostly 10-20 mm long, sometimes shorter when depauperate. SEEDS horizontal, winged, oval to obovate, flattened; testa cells with sinuate adjoining walls, the surface walls with a finely cobble-stone dome
Misc: on sand and gravel bars, roadcuts and banks; 50-2300 m (100-7500 ft); mostly Mar-Oct, potentially flowering year-round at lower elevations
Notes: staminodia = 5.
References: Kearney & Peebles; Arizona Flora. Christy, Charlotte M., Journal of AZ-NV academy of Science.
Duration: Perennial
Nativity: Native
Lifeform: Forb/Herb
General: Perennial herb to 80 cm tall, from a woody taproot or caudex; stems whitish when mature, usually producing branches along the entire length.
Leaves: Basal leaves petiolate and stem leaves alternate and sessile; blades narrowly elliptic to lanceolate, occasionally oblanceolate, to 15 cm long, to 3 cm wide; margins toothed to lobed or pinnatifid, sometimes approaching entire in very narrow leaves; upper leaves commonly with broad, clasping bases and sometimes with clasping basal lobes.
Flowers: Yellow to cream, in few-flowered cymes at branch tips; most flowers subtended by 1-2 bracts, which are variable in appearance; some bracts resemble the leaves but are smaller, some are linear-lanceolate and unlobed, and some are fused to the ovary; sepals and petals attached to the top of the ovary (epigynous); sepals 5 per flower, 6-12 mm long, persistent in fruit; petals 5, yellow or rarely cream to white, widely spreading, 9-23 mm long and 3-10 mm wide; several outer rows of stamens have enlarged filaments, making them resemble petals.
Fruits: Capsules straight and cylindric, sometimes broadly so, 4-6 mm wide and 10-20 mm long, sometimes shorter when depauperate; seeds oval, 3-4 mm long, with a 0.5 mm wing.
Ecology: Widespread, without specific soil preferences, commonly found on sand or gravel bars, from 100-7,500 ft (30-2286 m); flowers March-October.
Distribution: s CA, UT, AZ, s WY, CO, NM, NE, TX ; south of n MEX.
Notes: Very distinct and easy to recoginize; distinguished by being perennial and taller than many others in the genus; white stems often with short stiff hairs; long narrow leaves with rounded teeth or shallow pinnate lobes, the upper ones clasping the stem; and the showy, large yellow flowers with petals more than 6 mm long. It is morphologically variable species and hybridizes with other species in the genus. Mentzelia is a notoriously difficult genus with an overwhelming number of species and the keys are not easy to use. It is important to make collections with mature seed pods, because many key characters deal with the seeds and capsules, and some can't be seen with a hand lens in the field. The name Mentzelia pumila has been frequently misapplied to this species, including by Kearney and Peebles.
Ethnobotany: Used as a diuretic, a dermatological aid, a gastrointestinal aid, an eyewashash, a tuberculosis remedy, and an emetic; the seeds were eaten; also used ceremonially.
Etymology: Mentzelia is named for Christian Mentzel (1622-1701), a German botanist, botanical author and physician; multiflora means many-flowered.
Synonyms: Mentzelia pumila var. multiflora
Editor: SBuckley 2010, FSCoburn 2015, AHazelton 2017
