Oenothera laciniata
Oenothera riparia
cut-leaf evening-primrose, southern evening primrose
erect to ascending, unbranched to much branched, 5–50 cm.
erect or ascending, usually many-branched throughout, proximal branches often somewhat spongy, 50–120 cm.
in a basal rosette and cauline, basal 4–15 × 1–3 cm, cauline 2–10 × 0.5–3.5 cm;
blade green, narrowly oblanceolate to narrowly elliptic or narrowly oblong, margins usually dentate or deeply lobed;
bracts spreading, flat.
in a basal rosette and cauline, softly succulent, 4–13.5 × 0.8–2.1 cm, petiole 0–1.5 cm, blade lanceolate to elliptic-lanceolate, margins remotely denticulate.
erect, flowers in axils of distalmost few nodes.
usually 1 opening per day near sunset;
buds erect, with free tips erect, 0.3–3 mm;
floral tube 12–35 mm;
sepals 5–15 mm;
petals yellow, fading orange or reddish tinged, broadly obovate or obcordate, 5–22 mm;
filaments 3–14 mm, anthers 4–5 mm, pollen ca. 50% fertile;
style 20–50 mm, stigma surrounded by anthers at anthesis.
opening near sunrise;
buds with free tips 0.5–2(–5) mm, erect to spreading;
floral tube 14–20 mm;
sepals 20–30 mm;
petals bright yellow, fading pale pink or lavender, 16–27 mm;
filaments 10–15 mm, anthers 7–8 mm, pollen 85–100% fertile;
style 15–30 mm, stigma exserted beyond anthers at anthesis.
cylindrical, sometimes slightly enlarged toward apex, 20–50 × 2–4 mm.
oblong-clavate to oblong-ellipsoid, 4-angled or 4-winged, and wings 0.1–0.2 mm, 7–15 × 4–6 mm, stipe 2–5 mm;
sessile.
ellipsoid to subglobose, 0.9–1.8 × 0.4–0.9 mm.
0.8 × 0.4 mm.
= 14.
= 56.
Oenothera laciniata
Oenothera riparia
Oenothera laciniata is a PTH species and forms aring of 14 chromosomes in meiosis, and is self-compatible and autogamous (W. Dietrich and W. L. Wagner 1988).
Oenothera laciniata is known in New Mexico from Doña Ana and Roosevelt counties from non-montane habitats and thus do not appear to represent O. pubescens; however, a few collections from Brewster and Jeff Davis counties, Texas, reported by W. Dietrich and W. L. Wagner (1988) as O. laciniata appear to represent collections of O. pubescens. Dietrich and Wagner found that O. laciniata hybridizes not only with O. grandis, but also with O. drummondii subsp. drummondii, O. humifusa, and O. mexicana. It is naturalized nearly worldwide in temperate and subtropical areas.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Oenothera riparia has not been accepted as a distinct species for a long time. The conservative approach used by G. B. Straley (1977) is here followed in recognizing a broadly delimited O. fruticosa, except that the very distinctive coastal tidal-freshwater semi-aquatic octoploid populations (Straley 1982) are recognized as O. riparia. Plants of these coastal populations, which occur from southern Virginia to North Carolina, are more robust, more branched, and less pubescent than those of the two subspecies of O. fruticosa, and have slightly succulent leaves and more prominent adventitious roots (Straley 1982; D. Boufford, pers. comm.). Further field studies and cytological analyses are needed to fully understand the geographical and ecological limits of O. riparia and confirm that it is strictly an octoploid species. K. N. Krakos et al. (2014) determined that Oenothera riparia is self-incompatible and is pollinated by bees (Bombus, Lassioglossum, Megachile, Parallelia, Xylocopa, and Zale).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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