Lepidium alyssoides
Lepidium oblongum
mesa pepperwort
lepidium oblongum, veiny pepper grass, veiny pepper-weed
few to several from base, erect to ascending, branched throughout, (0.7–)1–4.8(–6.1) dm.
often several from base, erect to ascending or decumbent, branched distally, (5–)1–2.4(–3.2) dm.
often not rosulate;
petiole 1–6 cm;
blade pinnately lobed, (1–)1.5–8(–11) cm × (5–)10–35 mm, margins (of lobes) entire or denticulate.
not rosulate;
petiole (0.5–)1–3 cm;
blade 1- or 2-pinnatifid, 0.7–3.5 cm, margins (of lobes) entire or dentate.
sessile;
blade linear, (0.8–)1.3–7(–9.5) cm × (0.7–)1–2(–3) mm, base attenuate, not auriculate, margins entire.
usually sessile, rarely shortly petiolate;
blade obovate to oblanceolate (in outline), 0.8–2 cm × 2–9 mm, base cuneate, auriculate or not, margins dentate to laciniate or pinnatifid.
elongated in fruit;
rachis puberulent or glabrous.
elongated in fruit;
rachis hirsute, trichomes mostly straight, cylindrical.
sepals ovate to oblong, 1–2 × 0.8–1 mm;
petals white, suborbicular, 2–3 × 1–2 mm, claw 0.5–1.5 mm;
stamens 6;
filaments 1.5–2 mm, (glabrous);
anthers 0.2–0.4 mm.
sepals (tardily deciduous to somewhat persistent), ovate to broadly oblong, 0.7–1 × 0.4–0.6 mm;
petals (absent or rudimentary), white, linear-oblanceolate, 0.1–0.7 × 0.05–0.15 mm, claw absent;
stamens 2, median;
filaments 0.7–1 mm;
anthers 0.15–0.2 mm.
divaricate to horizontal, straight or recurved to somewhat sigmoid, (terete), 3.5–8(–11) × 0.2 mm, glabrous or puberulent adaxially.
divaricate to horizontal, usually slightly recurved, rarely straight, (terete), 2–3.5(–5) × 0.2–0.3 mm, puberulent adaxially or, rarely, throughout.
broadly ovate, 2–3.7(–4.3) × (1.5–)1.8–2.9(–3.4) mm, apically winged, apical notch 0.1–0.3(–0.4) mm deep;
valves thin, smooth, not veined, glabrous;
style 0.2–0.6 mm, exserted beyond apical notch.
orbicular to broadly obovate or elliptic, 2.2–3.5 × 2–3 mm, apically winged, apical notch 0.2–0.3 mm deep;
valves thin, smooth, not veined, glabrous or sparsely puberulent (along margin);
style to 0.1 mm, included in apical notch.
ovate, 1.5–1.8(–2) × 0.9–1.2(–1.5) mm.
ovate, 1.2–1.6 × 0.7–1 mm.
= 32.
Lepidium alyssoides
Lepidium oblongum
Of the five varieties of Lepidium alyssoides recognized by R. C. Rollins (1993), one (var. mexicanum Rollins) is a short-tufted form of the species restricted to Mexico that does not seem to merit recognition, another (var. junceum) is a glabrescent form of the type variety, a third (var. eastwoodiae) is treated below as a distinct species, and the fourth (var. angustifolium) is included here within L. alyssoides.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Hitchcock distinguished var. insulare from var. oblongum on the basis of having fruits smaller (2–2.5 versus 2.5–3 mm) and rotund to obovate (versus elliptic or obovate-elliptic) and fruiting pedicels puberulent (versus glabrous) abaxially. The shape and size of fruits almost never covary, and some of the insular plants (e.g., Trask 28, GH) have the largest fruits; some populations from Arizona, Oklahoma, and Texas have smaller and perfectly orbicular fruits. As for the pubescence of fruiting pedicels, some of the inland plants cited by Hitchcock as L. oblongum (e.g., Brewer 27, GH) have pedicels pubescent abaxially.
A recent report of Lepidium bonariense naturalized in Skagit County, Washington, was based on misidentified L. oblongum; all the vouchers for it belong to the latter species. Lepidium oblongum often has several stems from base, usually auriculate distalmost leaves, and fruits 2–3 mm wide. By contrast, L. bonariense has single stems from base, non-auriculate distalmost leaves, and fruits 2.7–3.5 mm wide.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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