Chylismia exilis
Onagraceae subfam. onagroideae
slender, unbranched or branched, 10–20 cm.
primarily cauline;
petiole 0.3–1.8 cm;
blade unlobed, narrowly ovate to elliptic, 0.3–2 × 0.3–1 cm, margins entire or inconspicuously denticulate, brownish oil cells lining veins abaxially.
stipules present or absent.
erect, elongating in fruit.
opening at sunrise;
buds without free tips;
floral tube 0.4–0.5 mm, glabrous inside;
sepals 1–1.2 mm;
petals yellow, fading pale lavender, 1–1.5 mm;
stamens 4 (or 8), antisepalous, filaments 0.5 mm, anthers 0.5–0.7 mm, glabrous, when 8, then antipetalous ones smaller and abortive;
style 1.5 mm, stigma surrounded by anthers at anthesis.
floral tube present or, rarely, absent;
sepals 2 or 4 (very rarely 3), deciduous with floral tube, petals, and stamens;
petals yellow, white, pink, red, rarely in combination.
spreading or reflexed, clavate, 4–10 mm;
pedicel 3–9 mm.
0.8 mm.
= 14.
Chylismia exilis
Onagraceae subfam. onagroideae
Chylismia exilis, known from Kane and San Juan counties in Utah and northern Coconino and Mohave counties in Arizona, is cryptic due to its small size. It may not be as rare as assumed, since it is difficult to spot in the field. P. H. Raven (1962, 1969) determined this species to be self-compatible and autogamous.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Genera 21, species 582 (16 genera, 246 species in the flora).
Onagroideae encompass the main lineage of the family, after the early branching of Ludwigia (R. A. Levin et al. 2003, 2004). This large and diverse lineage is distinguished by the presence of a floral tube beyond the apex of the ovary; sepals deciduous with the floral tube, petals, and stamens; pollen shed in monads (or tetrads in Chylismia sect. Lignothera and all but one species of Epilobium); ovular vascular system exclusively transseptal (R. H. Eyde 1981); ovule archesporium multicellular (H. Tobe and P. H. Raven 1996); and change in base chromosome number from x = 8 in Ludwigia to x = 10 or x = 11 at the base of Onagroideae (Raven 1979; Levin et al. 2003). Molecular work (Levin et al. 2003, 2004) substantially supports the traditional tribal classification (P. A. Munz 1965; Raven 1979, 1988); tribes are recognized to delimit major branches within the phylogeny of Onagroideae, where the branches comprise strongly supported monophyletic groups of one or more genera.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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