Lepidium draba |
Lepidium appelianum |
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heart-pod hoary-cress, heart-pod pepperweed, hoary cress, hoary pepperwort, whitetop |
globe-pod hoary-cress, hairy whitetop, white-top |
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Habit | Perennials; (rhizomatous); hirsute or glabrate. | Perennials; (rhizomatous); often densely hirsute. |
Stems | often simple from base, erect or decumbent basally, branched (several) distally, (0.8–)2–6.5(–9) dm. |
simple or several from base, erect or ascending, branched distally, (1–)1.5–3.5(–5) dm. |
Basal leaves | (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. |
(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. |
Cauline leaves | 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). |
sessile; blade oblong or lanceolate, 1–5(–8) cm × (3–)5–15(–30) mm, base sagittate, margins dentate or subentire, (surfaces pubescent). |
Racemes | (corymbose panicles), slightly or considerably elongated in fruit; rachis glabrous or puberulent, trichomes straight or curved, cylindrical. |
(usually corymbose, rarely paniculate), rarely elongated in fruit; rachis pubescent, trichomes often curved. |
Flowers | 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, 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. |
Fruiting pedicels | ascending to horizontal, straight, (terete), 5–10(–15) × 0.2–0.3 mm, glabrous or sparsely puberulent adaxially. |
divaricate to ascending, straight or slightly curved, (terete), 3–9(–12) × 0.2–0.3 mm, pubescent. |
Fruits | (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. |
(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. |
Seeds | ovate, 1.5–2.3 × 1–1.3 mm. |
(brown or dark brown), ovoid, 1.5–2 × 1–1.5 mm. |
2n | = 32, 64. |
= 16. |
Lepidium draba |
Lepidium appelianum |
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Phenology | Flowering Apr–Aug. | Flowering May–Sep. |
Habitat | Mountain slopes, roadsides, fields, agricultural lands, stream sides, disturbed grounds, pastures, waste areas | Roadsides, sagebrush communities, alkaline meadows, waste grounds, ditch and stream sides, fields, pastures |
Elevation | 0-3300 m (0-10800 ft) | 400-2400 m (1300-7900 ft) |
Distribution |
AZ; CA; CO; CT; DC; IA; ID; IL; IN; KS; MA; MD; MI; MN; MO; MT; ND; NE; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SD; UT; WA; WY; AB; BC; MB; NS; ON; SK; s Europe; sw Asia [Introduced in North America; introduced also in Mexico (Distrito Federal), South America, s Africa, Australia]
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CA; CO; ID; MI; MO; MT; ND; NE; NM; NV; OR; PA; UT; WA; WI; WY; AB; BC; MB; SK; c Asia [Introduced in North America; introduced also in South America, other parts of Asia]
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Discussion | 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.) |
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.) |
Source | FNA vol. 7, p. 581. | FNA vol. 7, p. 576. |
Parent taxa | Brassicaceae > tribe Lepidieae > Lepidium | Brassicaceae > tribe Lepidieae > Lepidium |
Sibling taxa | ||
Synonyms | Cardaria draba, Cochlearia draba, Nasturtium draba | Hymenophysa pubescens, Cardaria pubescens, Cardaria pubescens var. elongata |
Name authority | Linnaeus: Sp. Pl. 2: 645. (1753) | Al-Shehbaz: Novon 12: 7. (2002) |
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