Lepidium virginicum
Lepidium dictyotum
hairy pepper-weed, medium pepper-weed, poor-man's pepper-grass, poor-man's pepperweed, tall pepper-grass, tall pepperweed, Virginia pepperweed, wild pepper grass
alkali pepper-weed, alkali peppergrass, alkali pepperwort, net pepper grass, veiny pepper-grass
simple from base, erect, branched distally, (0.6–)1.5–5.5(–7) dm.
few to several from base, erect to ascending, or (outer ones) decumbent, unbranched, (0.15–)0.3–1.3(–2.1) dm.
(withered by anthesis);
not rosulate;
petiole 0.5–3.5 cm;
blade obovate, spatulate, or oblanceolate, (1–)2.5–10(–15) cm × 5–30(–50) mm, margins pinnatifid to lyrate or dentate.
(soon withered);
not rosulate;
petiole 0.5–2 cm;
blade pinnatifid to pinnatisect (lobes linear to narrowly oblong), (1.5–)2.2–5.7(–7) cm × (0.5–)1–2(–3) mm, margins entire.
shortly petiolate;
blade oblanceolate or linear, 1–6 cm × (1–)3–10 mm, base attenuate to subcuneate, not auriculate, margins serrate or entire.
sessile;
blade usually linear, rarely with linear lobes, 1–5 cm × 0.5–2 mm, base attenuate, not auriculate, margins entire.
considerably elongated in fruit;
rachis usually puberulent, rarely glabrous, trichomes curved, cylindrical.
elongated, (dense) in fruit;
rachis hirsute, trichomes straight, cylindrical.
sepals oblong to ovate, (0.5–)0.7–1(–1.1) × 0.4–0.7 mm;
petals (rarely rudimentary), white, spatulate to oblanceolate, 1–2(–2.5) × 0.3–0.8(–1) mm, claw undifferentiated or to 0.8 mm;
stamens 2, median;
filaments 0.6–1.2 mm;
anthers 0.1–0.2 mm.
sepals oblong to ovate, 0.7–1.1 × 0.2–0.6 mm;
petals absent;
stamens 4, median;
filaments 0.5–1 mm;
anthers ca. 0.1 mm.
divaricate-ascending to nearly horizontal, straight or slightly recurved, (slender, terete or flattened), 2.5–4(–6) × 0.15–0.4 mm, puberulent adaxially or, rarely, throughout or glabrous.
erect to slightly ascending, straight and appressed to rachis or distally slightly recurved, (strongly flattened), (1.6–)1.9–2.5(–3) × 0.4–0.8 mm (width proximal to apex), usually hirsute or, rarely, only adaxially.
orbicular or nearly so, 2.5–3.5(–4) mm diam. (widest at middle), apically winged, apical notch 0.2–0.5 mm deep;
valves thin, smooth, not veined, glabrous;
style 0.1–0.2 mm, included in apical notch.
ovate, 2.5–3.5 × 2–2.8 mm, apically winged, apical notch (closed, often U-shaped), 0.5–0.7(–0.8) mm deep;
valves thin, smooth, strongly reticulate-veined, usually hirsute, rarely glabrous;
style absent or obsolete, included in apical notch.
ovate, 1.3–1.9(–2.1) × 0.7–1(–1.2) mm; (cotyledons accumbent or incumbent).
ovate, 1.2–1.8 × 0.8–1.2 mm.
Lepidium virginicum
Lepidium dictyotum
Subspecies 2 (2 in the flora).
Lepidium virginicum is perhaps the only species in the genus with accumbent cotyledons; the other species have incumbent cotyledons, except for Australian ones with diplecolobal cotyledons. This contradicts N. H. Holmgren’s (2005b) assertion that the genus characteristically has accumbent cotyledons.
Examination of thousands of specimens provides good evidence (e.g., Florida: Lakela et al. 27038, GH; Missouri: Raven & Raven 27501, GH, MO) that Lepidium virginicum hybridizes with L. densiflorum. The ranges of both species overlap in much of the flora area, and this intergradation is, perhaps, the reason behind the recognition of some infraspecific taxa in both species. Molecular studies, along with a critical evaluation of morphology, are needed. Typical L. virginicum is easily distinguished by having well-developed or, rarely, rudimentary petals, accumbent cotyledons, orbicular fruits, and raceme rachises with curved cylindrical trichomes. By contrast, L. densiflorum has rudimentary or, often, no petals, incumbent cotyledons, obovate fruits, and raceme rachises with straight, often subclavate trichomes.
Of the seven varieties recognized by C. L. Hitchcock (1945) and R. C. Rollins (1993) in Lepidium virginicum, three do not occur in the flora area, and they most likely belong to other species. The four present in our area clearly fall into two groups. The first, which corresponds to the species lectotype, has accumbent cotyledons and terete fruiting pedicels. The second group, which includes the holotypes of vars. medium, pubescens, and robinsonii, has incumbent cotyledons and flattened fruiting pedicels. The type of var. medium has completely glabrous raceme rachises and fruiting pedicels, but most authors (e.g., Hitchcock 1936, 1945; Rollins) assigned this varietal name to glabrous plants regardless of whether they have accumbent or incumbent cotyledons. Indeed, the cotyledonary position and indumentum absence (or presence) do not always covary, and some glabrous plants have accumbent cotyledons (e.g., Demaree 47912 (GH), from Arkansas) or incumbent cotyledons (e.g., Demaree 43698 (GH) from Arizona). Therefore, var. medium does not merit recognition. As for var. robinsonii, it was based solely on being shorter plants with or without divided leaves. We believe that delimitation is artificial; such plants occur sporadically in the ranges of the two groups noted above. With the elimination of vars. medium and robinsonii, L. virginicum consists of two infraspecific taxa recognized herein as subspecies.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Cotyledons accumbent; fruit valves glabrous; fruiting pedicels terete, 0.15-0.2 mm wide. | subsp. virginicum |
1. Cotyledons incumbent or obliquely so; fruit valves glabrous or puberulent; fruiting pedicels flattened (at least proximal to apex), (0.2-)0.3-0.4 mm wide. | subsp. menziesii |
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- Local floras: CA, OR, WA
- Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria
- WildflowerSearch
- iNaturalist (observations)
- USDA Plants Database
- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
