Lepidium didymum |
Lepidium fremontii |
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lesser pepper-grass, lesser swine-cress, lesser wart-cress |
desert pepper grass, desert pepperweed |
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Habit | Annuals; (fetid); glabrous or pilose. | Perennials or subshrubs; (woody base aboveground); (glaucous), glabrous throughout. |
Stems | few to several from base, erect to ascending or decumbent, branched distally, 1–4.5(–7) dm. |
several from base, erect or ascending, branched (several) distally, 2–5.5(–10) dm. |
Basal leaves | (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). |
absent. |
Cauline leaves | 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. |
sessile; blade linear and undivided or pinnately lobed (lobes 3–7(–9), linear), (1.5–)2.2–8.4(–10.2) cm × (0.7–)1–2.8(–4.2) mm, base attenuate, not auriculate, margins entire, (similar, smaller distally). |
Racemes | elongated in fruit; rachis glabrous or pubescent, trichomes straight, cylindrical. |
(panicles), elongated in fruit. |
Flowers | 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 obovate, 1.5–2.5(–3) × 1–1.6 mm; petals white, spatulate, 2.5–4.2 × 1.5–2.2 mm, claw 1–2 mm; stamens 6; filaments 1.8–3 mm; anthers 0.4–0.7 mm. |
Fruiting pedicels | 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, usually straight, rarely slightly curved, (terete), (3.5–)4.3–7.6(–8.5) × 0.15–0.2 mm. |
Fruits | 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. |
obovate to orbicular, (4–)4.5–7(–8) × 4.2–7(–8) mm, apically winged, apical notch (0.1–)0.2–0.5 mm deep; valves thin, smooth, not veined; style 0.2–0.8(–1) mm, exserted beyond apical notch. |
Seeds | ovate, 1–1.2 × 0.7–0.8 mm. |
ovate, 1.6–2.1 × 0.9–1.1 mm. |
2n | = 32. |
= 32. |
Lepidium didymum |
Lepidium fremontii |
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Phenology | Flowering Mar–Jul. | Flowering Mar–Jun. |
Habitat | Roadsides, waste areas, lawns, pastures, fields, gardens, disturbed areas | Desert shrub communities, pinyon-juniper woodlands, sandy washes, gravelly deserts, barren knolls, bluffs, roadsides, steep limestone outcrops, rocky ledges and slopes |
Elevation | 0-1000 m (0-3300 ft) | 400-2100 m (1300-6900 ft) |
Distribution |
AL; AR; AZ; CA; CT; FL; GA; LA; MA; MD; ME; MO; MS; NC; NJ; NY; OH; OR; PA; SC; TN; TX; VA; WI; WV; BC; NB; NF; NS; QC; South America [Introduced in North America; introduced also in Mexico (Sinaloa), Central America (Honduras), Europe, Asia, s Africa, Australia]
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AZ; CA; NV; UT
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Discussion | Rollins established var. stipitatum on the basis of fruits obovate with gynophores 0.5–0.75 mm versus (var. fremontii) fruits orbicular to ovate and sessile. These two characters often do not covary and stipitate fruits occur sporadically throughout the species range, including Arizona (Lemmon s.n., GH), California (Morefield 3427, GH), and Nevada (Comanor 18, GH; Hitchcock 3078, GH). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 7, p. 580. | FNA vol. 7, p. 582. |
Parent taxa | Brassicaceae > tribe Lepidieae > Lepidium | Brassicaceae > tribe Lepidieae > Lepidium |
Sibling taxa | ||
Synonyms | Carara didyma, Coronopus didymus, Senebiera didyma, Senebiera incisa, Senebiera pinnatifida | L. fremontii var. stipitatum, Nasturtium fremontii |
Name authority | Linnaeus: Syst. Nat. ed. 12, 2: 433. (1767): Mant Pl. 1: 92. (1767) | S. Watson: Botany (Fortieth Parallel), 30, plate 4, figs. 3, 4. (1871) |
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