Lepidium draba
Lepidium densiflorum
heart-pod hoary-cress, heart-pod pepperweed, hoary cress, hoary pepperwort, whitetop
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
often simple from base, erect or decumbent basally, branched (several) distally, (0.8–)2–6.5(–9) dm.
simple from base, erect, branched distally, (1–)2.5–5(–6.5) dm.
(early withered);
not rosulate;
petiole 1–4 cm;
blade obovate, spatulate, or ovate, (1.5–)3–10(–15) cm × 10–40 mm, margins sinuate to dentate or entire.
(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 ovate, elliptic, oblong, or lanceolate, oblanceolate, or obovate, (1–)3–9(–15) cm × (5–)10–20(–50) mm, base sagittate-amplexicaul or auriculate, margins dentate or entire, (surfaces pubescent or glabrous).
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.
(corymbose panicles), slightly or considerably elongated in fruit;
rachis glabrous or puberulent, trichomes straight or curved, cylindrical.
considerably elongated in fruit;
rachis puberulent, trichomes straight, slender to subclavate.
sepals oblong to ovate, 1.5–2.5 × 0.7–1.2 mm;
petals white, obovate, (2.5–)3–4(–4.5) × (1–)1.3–2(–2.2) mm, claw 1–1.7 mm;
stamens 6;
filaments 2–3 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.
ascending to horizontal, straight, (terete), 5–10(–15) × 0.2–0.3 mm, glabrous or sparsely puberulent adaxially.
divaricate-ascending to horizontal, straight or slightly recurved, (terete), (1.5–)2–3.5(–4) × 0.15–0.25 mm, puberulent adaxially.
(indehiscent), cordate to subreniform, (2–)2.5–3.7(–4.3) × (3.2–)3.7–5(–5.6) mm, apically (obtuse to subacute), not winged, apical notch absent;
valves thin, smooth, reticulate-veined, glabrous;
style (0.6–)1–1.8(–2) 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.
ovate, 1.5–2.3 × 1–1.3 mm.
ovate, 1.1–1.3(–1.5) × 0.8–0.9 mm.
= 32, 64.
= 32.
Lepidium draba
Lepidium densiflorum
Although Lepidium draba is poorly established and known from old collections in the eastern part of the United States, it has become a noxious weed in several western states.
Lepidium draba and its nearest relatives, L. appelianum and L. chalepense, form a monophyletic clade most closely related to L. campestre (K. Mummenhoff et al. 2001). A. Thellung (1906) and C. L. Hitchcock (1936) correctly placed L. draba in Lepidium, as did Linnaeus. The recognition of the first three species in Cardaria and the maintenance of their nearest relative, L. campestre, in Lepidium do not make any sense on both phylogenetic and taxonomic grounds.
(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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- Local floras: BC, CA, OR, WA
- Local Web sites: CalFlora, CalPhotos, Flora NW, Go Botany, IL Wildflowers, KS Wildflowers,
LA Plants, MD Biodiversity, MI Flora, MN Wildflowers, MO Plants, PNW Herbaria - WildflowerSearch
- iNaturalist (observations)
- USDA Plants Database
- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
