Rorippa sessiliflora
stalkless yellow-cress
(simple or several-branched from base) erect, branched distally, (0.9–)2–4.5(–6.3) dm.
not rosulate;
blade margins dentate.
shortly petiolate or sessile;
blade oblong or oblanceolate to obovate, 1.5–7(–13.3) cm × (5–)10–28(–50) mm, (lateral lobes much smaller than terminal), base auriculate or not, margins dentate or less frequently sinuate, or (lateral lobes) denticulate or entire.
considerably elongated.
sepals ascending to spreading, ovate, 1.2–2 × 0.5–0.8 mm;
petals absent;
median filaments 1–1.6 mm;
anthers ovate, 0.2–0.3 mm.
divaricate-ascending to horizontal, straight, 0.5–2(–4) mm, (slender or stout).
siliques, straight or curved, oblong to oblong-linear, (4–)6–9(–12) × (1.4–)1.8–2.8(–3.5) mm;
ovules 158–242 per ovary;
style 0.1–0.5 mm.
biseriate, yellow-brown, cordiform, 0.4–0.5 mm, foveolate.
= 16.
Rorippa sessiliflora
Both R. L. Stuckey (1972) and R. C. Rollins (1993) indicated that Rorippa sessiliflora has strongly saccate sepals, but all specimens that I examined failed to show any sign of this character. The species is very distinctive and can easily be distinguished by an absence of petals and by having fruiting pedicels 0.5–2(–4) mm.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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