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mesa pepperwort

globe-pod hoary-cress, hairy whitetop, white-top

Habit Perennials or subshrubs; (woody base often aboveground); glabrous or minutely puberulent. Perennials; (rhizomatous); often densely hirsute.
Stems

few to several from base, erect to ascending, branched throughout, (0.7–)1–4.8(–6.1) dm.

simple or several from base, erect or ascending, branched distally, (1–)1.5–3.5(–5) dm.

Basal leaves

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.

(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 linear, (0.8–)1.3–7(–9.5) cm × (0.7–)1–2(–3) mm, base attenuate, not auriculate, margins entire.

sessile;

blade oblong or lanceolate, 1–5(–8) cm × (3–)5–15(–30) mm, base sagittate, margins dentate or subentire, (surfaces pubescent).

Racemes

elongated in fruit;

rachis puberulent or glabrous.

(usually corymbose, rarely paniculate), rarely elongated in fruit;

rachis pubescent, trichomes often curved.

Flowers

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 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

divaricate to horizontal, straight or recurved to somewhat sigmoid, (terete), 3.5–8(–11) × 0.2 mm, glabrous or puberulent adaxially.

divaricate to ascending, straight or slightly curved, (terete), 3–9(–12) × 0.2–0.3 mm, pubescent.

Fruits

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.

(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, 1.5–1.8(–2) × 0.9–1.2(–1.5) mm.

(brown or dark brown), ovoid, 1.5–2 × 1–1.5 mm.

2n

= 32.

= 16.

Lepidium alyssoides

Lepidium appelianum

Phenology Flowering May–Jul. Flowering May–Sep.
Habitat Pinyon-juniper or sagebrush communities, prairies, grasslands, sandstone outcrops, gypsum flats, sand dunes, dry flats and river bottoms, gravelly roadsides Roadsides, sagebrush communities, alkaline meadows, waste grounds, ditch and stream sides, fields, pastures
Elevation 1200-2800 m (3900-9200 ft) 400-2400 m (1300-7900 ft)
Distribution
from FNA
AZ; CO; NM; NV; TX; UT; WY; Mexico (Chihuahua, Coahuila, Nuevo León, San Luis Potosí)
[WildflowerSearch map]
[BONAP county map]
from FNA
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]
[WildflowerSearch map]
[BONAP county map]
Discussion

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.)

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. 575. FNA vol. 7, p. 576.
Parent taxa Brassicaceae > tribe Lepidieae > Lepidium Brassicaceae > tribe Lepidieae > Lepidium
Sibling taxa
L. acutidens, L. appelianum, L. austrinum, L. barnebyanum, L. campestre, L. chalepense, L. coronopus, L. crenatum, L. davisii, L. densiflorum, L. dictyotum, L. didymum, L. draba, L. eastwoodiae, L. flavum, L. fremontii, L. heterophyllum, L. huberi, L. integrifolium, L. jaredii, L. lasiocarpum, L. latifolium, L. latipes, L. montanum, L. nanum, L. nitidum, L. oblongum, L. ostleri, L. oxycarpum, L. papilliferum, L. paysonii, L. perfoliatum, L. pinnatifidum, L. ramosissimum, L. ruderale, L. sativum, L. sordidum, L. strictum, L. thurberi, L. tiehmii, L. virginicum
L. acutidens, L. alyssoides, L. austrinum, L. barnebyanum, L. campestre, L. chalepense, L. coronopus, L. crenatum, L. davisii, L. densiflorum, L. dictyotum, L. didymum, L. draba, L. eastwoodiae, L. flavum, L. fremontii, L. heterophyllum, L. huberi, L. integrifolium, L. jaredii, L. lasiocarpum, L. latifolium, L. latipes, L. montanum, L. nanum, L. nitidum, L. oblongum, L. ostleri, L. oxycarpum, L. papilliferum, L. paysonii, L. perfoliatum, L. pinnatifidum, L. ramosissimum, L. ruderale, L. sativum, L. sordidum, L. strictum, L. thurberi, L. tiehmii, L. virginicum
Synonyms L. alyssoides var. angustifolium, L. alyssoides var. junceum, L. alyssoides var. minus, L. alyssoides var. polycarpum, L. alyssoides var. streptocarpum, L. montanum subsp. alyssoides, L. montanum var. alyssoides, L. montanum subsp. angustifolium, L. montanum var. angustifolium, L. tortum Hymenophysa pubescens, Cardaria pubescens, Cardaria pubescens var. elongata
Name authority A. Gray: Mem. Amer. Acad. Arts, n. s. 4: 10. (1849) Al-Shehbaz: Novon 12: 7. (2002)
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