Plant: Annual herb; STEMS to 45 cm tall Leaves: to 15 cm long, sessile, narrowly elliptic to lanceolate; margins mostly lobed, often with teeth in the sinuses. BRACTS narrowly lanceolate to ovate, green, sometimes with faintly whitish bases, mostly not on ovary; margins entire or few-toothed INFLORESCENCE: cymose Flowers: sessile; petals yellow, 2-5 mm long; staminodia 0; stamens ca. 15-30, all with linear filaments; style 2-4 mm long Fruit: capsules clavate, often long-tapering to base; base not woody; body 8-28 mm long, straight or arched less than 180 degrees. SEEDS pendulous, not winged, those in upper half of capsule grain-like, several-faceted, irregular in cross-section, the angles sharp; testa cells with straight adjoining walls, the surface walls pointed-papillate Misc: Upper elevations of warm deserts to chaparral and Great Basin Desert on a variety of soil types; 300-2250 m (1000-7400 ft); Feb-Jun References: Charlotte Christy - Loasaceae - JANAS 30:96-111. ASU Specimens.
VPAP (Christy 1998), Heil et al. 2013, Allred and Ivey 2012
Duration: Annual Nativity: Native Lifeform: Forb/Herb General: Annual herbs, to 30 cm tall (rarely to 45 cm), from a taproot; stems white when mature, usually branching throughout. Leaves: Basal leaves petiolate and stem leaves alternate and sessile; blades narrowly elliptic to lanceolate, up to 15 cm long, with deeply lobed margins, which often have teeth in the spaces between the lobes; leaf surfaces sticky due to being covered with barbed hairs. Flowers: Yellow, in few-flowered clusters at branch tips; each flower subtended by one or more ovate, leaflike bracts, these completely green or sometimes with a very small white patch at the base; sepals and petals attached to the top of the ovary (epigynous); sepals 5 per flower, 2-3 mm long, persistent in fruit; petals 5, yellow, spreading, broadly obovate or obcordate, 2-6 mm long and 2-4 mm wide. Fruits: Capsules club-shaped (widens toward tip with a long-tapering base), 8-28 mm long and 3-4 mm wide at the top, with the persistent, tooth-like sepals attached to the top; early fruits of the season are sometimes bent slightly, or occasionally bent up to 90 degrees; seeds irregularly blocky, 1-2 mm long, wingless, pendulous inside the capsule. Ecology: Found in dry places from 1,000-7,500 ft (305-2286 m); flowers February-June. Distribution: Most of western N. Amer. from Saskatchewan and B.C., south to CA and west to TX, NE, SD; south to n MEX. Notes: Distinguished by being an annual with whitish stems with short hairs on the leaves and capsules; deeply pinnately lobed leaves near the base of the plant, and shallowly lobed leaves above; flowers with yellow petals 1-6 mm long; oval-shaped, entire or shallowly toothed green bracts below ovaries; and fruits more than 5 times as long as wide, arched and tapering at least at the base; the fruits are relatively small, no more than 4 mm wide at the tip (not including the sepals that remain attached to the top). 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. Ethnobotany: Gosiute rub seeds on burned skin. Hopi use plant for toothaches. Navajo use leaf concoction for snakebites. Numerous tribes use seed flour as staple for gravy, bread porridge, etc. Etymology: Mentzelia named for Christian Mentzel (1622-1701), a German botanist, botanical author and physician; albicaulis translates to white stem. Synonyms: Acrolasia albicaulis, Mentzelia montana, Mentzelia gracilis, Mentzelia mojavensis Editor: SBuckley 2010, FSCoburn 2015, AHazelton 2017