PLANTS: Annuals or perennials, ours herbaceous to suffrutescent; hairs often barbed, not stinging. LEAVES: sessile (including those with blades narrowing gradually to the base) or distinctly petiolate; blades linear, lanceolate to elliptic, ovate or oblanceolate; margins dentate to pinnately lobed, sometimes crenate or entire. PLANTS: Annuals or perennials, ours herbaceous to suffrutescent; hairs often barbed, not stinging. INFLORESCENCE: cymose. FLOWERS: subtended by O-several, leaf-like to linear bracts; calyx mostly persistent, the lobes lanceolate to subulate; petals distinct or basally coherent and adherent to filaments, deciduous, white to yellow or orange; stamens 10-ca. 300, shorter than the petals, free or basally coherent, those of outer whorls often with broad filaments and often forming petaloid staminodia; pistil (in ours) 3-carpellate, exceptionally more; stigmas 3 appressed lobes but appearing as 3 grooves, sometimes separating in age. CAPSULES: apically dehiscent by 3 valves. SEEDS: 10-many, rarely fewer, 1-4 mm long, parietal; testa diversely sculptured, smooth, reticulate or striate at low magnification; endosperm present. X = 14. NOTES: At least 100 spp.; New World. (for C. Mentzel). The sections are sufficiently distinctive that several have occasionally been treated as separate genera. Fruit measurements (and the term -body-) refer to the seed-containing portion, exclusive of the calyx lobes when these persist. Specimens that are depauperate or that lack mature fruits and seeds may be impossible to identify. REFERENCES: Christy, Charlotte M. 1998. Loasaceae. J. Ariz. - Nev. Acad. Sci. 30(2): 96.

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.

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