Lepidium didymum
Lepidium ramosissimum
lesser pepper-grass, lesser swine-cress, lesser wart-cress
branch pepper-grass, clasping-leaf pepper-grass, dull peppergrass, manybranch pepperweed
few to several from base, erect to ascending or decumbent, branched distally, 1–4.5(–7) dm.
simple from base, erect, branched (several) distally, (0.6–)1–5.3(–7.7) dm.
(soon withered);
not rosulate;
petiole 0.5–4(–6) cm;
blade 1- or 2-pinnatisect, 1–6(–8) cm, margins (of lobes) entire or dentate (sometimes deeply lobed).
(soon withered);
not rosulate;
petiole 1–4 cm;
blade oblanceolate or pinnatifid, 2–5 cm × 8–15 mm, margins (of lobes) entire serrate or dentate.
shortly petiolate to subsessile;
blade similar to basal, smaller and less divided distally, lobes lanceolate to oblong or elliptic, 1.5–3.5(–4.5) cm ×5–12 mm, base not auriculate, margins (of lobes) entire, serrate, or incised.
shortly petiolate or sessile;
blade oblanceolate or (distal) linear, (0.6–)1.2–4.8(–6) cm × 1–8(–10) mm, base attenuate to cuneate, not auriculate, margins dentate, (distal) entire, or, rarely, lobed.
elongated in fruit;
rachis glabrous or pubescent, trichomes straight, cylindrical.
slightly elongated in fruit;
rachis puberulent, trichomes curved, cylindrical to subclavate.
sepals (tardily deciduous), ovate, 0.5–0.7(–0.9) mm;
petals white, elliptic to linear, 0.4–0.5 × ca. 0.1 mm, claw absent;
stamens 2, median;
filaments 0.3–0.6 mm;
anthers 0.1–0.2 mm.
sepals oblong, 0.6–0.9(–1.1) × 0.3–0.4 mm;
petals (absent or rudimentary), white, linear, 0.2–0.8(–1) × 0.05–0.1 mm, claw absent;
stamens 2, median;
filaments 0.6–0.9 mm;
anthers 0.15–0.2 mm.
divaricate to horizontal, straight slightly recurved, (terete), 1.4–2.5(–4) × 0.15–2 mm, glabrous or sparsely pubescent adaxially.
divaricate-ascending to horizontal, straight or recurved, (terete), (1.6–)2–3.8(–5) × 0.2–0.3 mm, usually puberulent adaxially, rarely throughout.
schizocarpic, didymous, 1.3–1.7 × 2–2.5 mm, apically not winged, apical notch 0.2–0.4 mm deep;
valves thick, rugose, strongly veined, glabrous;
style absent or obsolete, included in apical notch.
elliptic, 2.2–3.2 × 1.7–2.1mm, apically winged, apical notch 0.1–0.3(–0.4) mm deep;
valves thin, smooth, not veined, glabrous or puberulent at least along margin;
style usually obsolete, rarely to 0.1 mm, included in apical notch.
ovate, 1–1.2 × 0.7–0.8 mm.
oblong, 1.2–1.6 × 0.8–0.9 mm.
= 32.
= 32, 64.
Lepidium didymum
Lepidium ramosissimum
As noted by R. C. Rollins (1993, p. 581), the varieties of Lepidium ramosissimum are “weak at best.” They are based largely on the branching habit and, most importantly, on the presence versus absence of trichomes on the fruit valve. In some collections (e.g., Scoggan 4233, GH; Boivin et al., 13221, GH), both puberulent- and glabrous-fruited forms occur. It is almost certain that the same situation exists not only in other populations of this species, but in other North American Lepidium. It is also clear that some populations might consist entirely of one of the two forms, but it is highly unlikely that this variation has any geographical basis. Therefore, we believe that the separation of varieties solely on the basis of presence or absence of the fruit trichomes is taxonomically meaningless.
We are reluctantly including Lepidium divergens in the synonymy of L. ramosissimum because we have not seen its type; the topotypes that we studied have broadly obovate to suborbicular fruits that appear more at home in the L. densiflorum or L. virginicum complexes.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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