Taraxia tanacetifolia
Onagraceae subfam. onagroideae
tansy-leaf evening primrose
6.5–32 × 0.7–3.3 cm;
petiole not winged, 1–8 cm;
blade very narrowly elliptic, base attenuate to narrowly cuneate, margins deeply and irregularly pinnatifid, apex acute to long-acuminate.
stipules present or absent.
opening near sunrise;
floral tube 4–6.5(–8.5) mm, soft-pilose in proximal 1/2 inside;
sepals 5.5–13 mm;
petals yellow, (8–)10–23 mm; episepalous staminal filaments 5.5–12 mm, epipetalous ones 2.5–8 mm, anthers (2.3–)2.8–3.5 mm;
sterile prolongation of ovary 14–55 mm, style 9.5–20(–25) mm, pilose near base, stigma exserted beyond 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.
subterete, cylindric-ovoid, 7–25 × 3–5 mm, walls thick, evidently distended by seeds;
sessile.
uniformly tan to brown, curved-cylindric, 1.5–2 × 0.6–0.8 mm, pitted in rows.
= 14, 28, 42.
Taraxia tanacetifolia
Onagraceae subfam. onagroideae
P. H. Raven (1969) determined that the majority of plants examined cytologically were tetraploid (2n = 28), making one diploid (2n = 14) determination. Raven also found hexaploid plants in a restricted area from Sierra Valley in Plumas and immediately adjacent Lassen and Sierra counties, California. They do not differ morphologically from diploid and tetraploid plants other than having greater than ten percent of pollen grains 4-pored, but there was no known diploid population that could have combined with tetraploids to give rise to this hexaploid. Raven named it Camissonia tanacetifolia subsp. quadriperforata; however, it is not currently recognized due to the lack of morphological differentiation. Raven also found Taraxia tanacetifolia to be primarily self-incompatible with possibly some self-compatible plants occurring.
Oenothera nuttallii Torrey & A. Gray 1840 (not Sweet 1830) pertains here.
(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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