Lepidium appelianum
Lepidium densiflorum
globe-pod hoary-cress, hairy whitetop, white-top
baby-seed pepper-weed, common pepper-grass, common pepper-weed, elongate peppergrass, hairy-fruit peppergrass, large-fruit peppergrass, miner's pepper-weed, prairie pepper-grass, prairie pepperweed
simple or several from base, erect or ascending, branched distally, (1–)1.5–3.5(–5) dm.
simple from base, erect, branched distally, (1–)2.5–5(–6.5) dm.
(often withered by anthesis);
not rosulate;
petiole 0.5–1.5 cm;
blade obovate to oblanceolate, (1–)2–6(–7) cm × 3–20 mm, margins dentate to sinuate.
(early withered); rosulate;
petiole 0.5–1.5(–2) cm;
blade oblanceolate, spatulate, or oblong, (1.5–)2.5–8(–11) cm × 5–10(–20) mm, margins coarsely serrate or pinnatifid.
sessile;
blade oblong or lanceolate, 1–5(–8) cm × (3–)5–15(–30) mm, base sagittate, margins dentate or subentire, (surfaces pubescent).
shortly petiolate;
blade narrowly oblanceolate or linear, (0.7–)1.3–6.2(–8) cm × (0.5–)1.5–10(–18) mm, base attenuate to cuneate, not auriculate, margins usually entire or irregularly serrate to dentate, rarely pinnatifid.
(usually corymbose, rarely paniculate), rarely elongated in fruit;
rachis pubescent, trichomes often curved.
considerably elongated in fruit;
rachis puberulent, trichomes straight, slender to subclavate.
sepals oblong, 1.4–2 × 0.7–1 mm;
petals white, broadly obovate, (2.2–)2.8–4 × 1–3 mm, claw 1–1.4 mm;
stamens 6;
filaments 2–2.5 mm, (glabrous);
anthers 0.4–0.5 mm.
sepals oblong, 0.5–0.8(–1) × 0.3–0.5 mm;
petals (absent or rudimentary) white, filiform, 0.3–0.9 mm, claw absent;
stamens 2, median;
filaments 0.6–1(–1.8) mm;
anthers 0.1–0.2 mm.
divaricate to ascending, straight or slightly curved, (terete), 3–9(–12) × 0.2–0.3 mm, pubescent.
divaricate-ascending to horizontal, straight or slightly recurved, (terete), (1.5–)2–3.5(–4) × 0.15–0.25 mm, puberulent adaxially.
(indehiscent), globose or, rarely, subglobose, (2–)3–4.4(–5) mm diam., (inflated), apically not winged, apical notch absent;
valves thin, smooth, not veined, densely puberulent;
style 0.5–1.5 mm.
obovate to obovate-suborbicular, (2–)2.5–3(–3.5) × 1.5–2.5(–3) mm (widest beyond middle), apically winged, apical notch 0.2–0.4 mm deep;
valves thin, smooth, not veined, glabrous or sparsely puberulent (at least on margin);
style 0.1–0.2 mm, included in apical notch.
(brown or dark brown), ovoid, 1.5–2 × 1–1.5 mm.
ovate, 1.1–1.3(–1.5) × 0.8–0.9 mm.
= 16.
= 32.
Lepidium appelianum
Lepidium densiflorum
Lepidium appelianum has become a noxious weed in most of its range in North America.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
North American records of Lepidium apetalum Willdenow mostly represent misidentifications of L. densiflorum. The latter has obovate fruits widest beyond the middle, whereas L. apetalum has elliptic fruits widest at the middle.
The number and limits of the varieties recognized in Lepidium densiflorum, as well as the characters used to delimit them, vary among authors (A. Thellung 1906; C. L. Hitchcock 1936; G. A. Mulligan 1961; R. C. Rollins 1993; N. H. Holmgren 2005b). The variation almost always does not correlate with geography, and the recognition of varieties in this species is neither practical nor very useful. All of those authors admitted that these varieties are “very weak at best” (Rollins, p. 554). Of them, perhaps var. pubicarpum (including var. elongatum) might merit recognition. It is distributed in almost all of the Mountain and Pacific states and is distinguished from the other varieties solely by the presence of trichomes or minute papillae on the fruit valves. The density of these trichomes ranges from moderate and covering the entire valve surface to very sparse and represented by individual papillate trichomes restricted to the valve margin. Furthermore, the length of these trichomes may vary from ca. 0.01 to 0.3 mm. In some species (e.g., L. dictyotum) both glabrous- and pubescent-fruited forms occur, yet none of the above authors gave formal recognition to both forms. It is not known if both glabrous and puberulent fruits occur within the same population in L. densiflorum. The species is autogamous, but nothing is known about the rates of gene flow between and within populations.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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- SEINet
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- Encyclopedia of Life
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- Google Image Search
