Plant: perennial herb; enlarged rootstock. STEMS several, divergent, to 35 cm long Leaves: 1.5-6 cm long, 0.6-3.2 cm wide; petiole 0.1-1 cm long; blade broadly lanceolate to ovate, with two large teeth near base; uppermost leaves similar to the lower ones INFLORESCENCE: cymose Flowers: subsessile or pedicel 1-2 mm long; calyx usually deciduous; petals orange, 6-8 mm long, 4 mm wide, with trichomes dorsally on upper half and along midline to near base; staminodia 0; stamens all with linear filaments; style 5-7 mm long Fruit: CAPSULES linear or clavate, often irregularly enlarged, reflexing; body 7-12 mm long. SEEDS 1-3(-4), pendulous, not winged, oblong, the hilum end not constricted; testa cells elongate, striate Misc: Rocky slopes, canyons, on limestone; 1450-1700 m (4800-5500 ft); Aug-Oct REFERENCES: Christy, Charlotte M. 1998. Loasaceae. J. Ariz. - Nev. Acad. Sci. 30(2): 96.
VPAP (Christy 1998), Harrington 1954, Correll and Johnston 1970
Duration: Perennial Nativity: Native Lifeform: Subshrub General: Rounded to matted perennial herb or subshrub, 20-35 cm tall (rarely up to 70 cm tall), from enlarged rootstock; stems several, divergent, ascending to decumbent, becoming tangled; herbage, including leaves, capsules, and younger stems, rough with barbed hairs. Leaves: Alternate along the stems, the upper leaves sessile and lower leaves on petioles up to 1 cm long; blades broadly lanceolate to ovate, 1-6 cm long and 6-32 mm wide, with two large teeth near base and a pointed tip. Flowers: Yellow-orange, solitary and sessile in the axils of upper branches, and also in few-flowered clusters at branch tips, on pedicels 1-2 cm long; sepals and petals attached to the top of the ovary (epigynous); sepals 5, lanceolate or linear, 7-9 mm long, eventually deciduous; petals 5, yellow or orange, 6-8 mm long and 4 mm wide. Fruits: Capsules linear or clavate (club-shaped), straight or bent, often irregularly enlarged; 7-12 mm long, not including sepals; containing seeds 1-3 seeds (rarely 4) which are oblong, more or less 3-sided, and pendulous inside the capsule. Ecology: Found in canyons and rocky areas, on limestone, in sandy or clay soils, and occasionally in distubed areas, from 4,000-5,500 ft (1219-1676 m); flowers Aug-Oct. Distribution: AR to WY, south to TX, NM, se AZ, and n MEX. Notes: Distinguished being a perennial with many divergent, highly branched, ascending-decumbent stems that can become tangled; the small, diamond-shaped leaves with a pair of large teeth or lobes near the base; the orange flowers, a little over 1 cm long, which are sessile in the forks of the stems or on short pedicels at the ends of the branches; the seed pods which are hairy, cylindrical, sometimes curved a bit, and 8-16 mm long; and only 1-3 seeds per capsule (hence, the "few-seeded" epithet). 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: Unknown, but other species in the genus have uses. Etymology: Mentzelia is named for Christian Mentzel (1622-1701), a German botanist, botanical author and physician; oligosperma means few-seeded. Synonyms: None Editor: FSCoburn 2015, AHazelton 2017
Hypanthium ovoid to cylindric or obconic; sep 5; pet 5-10; stamens 10-200, distinct or connate into fascicles; ovules 2-many on 3 parietal placentas; style 3-lobed; fr a capsule; annual or perennial herbs or shrubs, armed with stiff, barbed hairs, with alternate, serrate to pinnatifid lvs and 1-many often large, white to yellow or orange fls terminating the branches. (Nuttallia) 50, New World.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.