OregonFlora: Lepidium didymum

	Lepidium didymum
	lesser swinecress, lesser wartcress
Habit	Plants annual, fetid, glabrous or pilose.
Stems	often decumbent, 1–4.5(7) dm.
Basal leaves	not rosulate, 1–6(8) cm, 1- or 2-pinnatisect; lobes entire or dentate, sometimes deeply lobed; petioles 0.5–4(6) cm.
Cauline leaves	similar to basal, 1.5–3.5(4.5) × 0.5–1.2 cm, bases not auriculate, petiolate to subsessile.
Inflorescences	rachises glabrous or pubescent with straight cylindrical trichomes, fruiting pedicels divaricate to horizontal; terete; straight or slightly recurved, 1.4–2.5(4) mm, glabrous or sparsely pubescent adaxially.
Flowers	sepals caducous, 0.5–0.7(0.9) mm; petals elliptic to linear, 0.4–0.5 × ~0.1 mm, white; stamens 2; median; styles absent or obsolete, included in apical notch.
Fruits	indehiscent, didymous, 1.3–1.7 × 2–2.5 mm; apical notch 0.2–0.4 mm deep; valves thick, rugose, glabrous, strongly veined; wingless.
Seeds	ovate, 1–1.2 × 0.7–0.8 mm; cotyledons incumbent.
2n	=32.

	Lepidium didymum
Distribution	[WildflowerSearch map] [BONAP county map]
Discussion	Disturbed areas, fields, pastures. Flowering May–Oct. 0–300 m. Est, WV. CA, WA; north to British Columbia, eastern Canada and US, southern US; nearly worldwide. Exotic.
Source	Flora of Oregon, volume 2, page 494 Ihsan Al-Shehbaz
Sibling taxa	L. acutidens, L. appelianum, L. campestre, L. chalepense, L. davisii, L. densiflorum, L. dictyotum, L. draba, L. graminifolium, L. heterophyllum, L. latifolium, L. montanum, L. nitidum, L. oblongum, L. perfoliatum, L. pinnatifidum, L. ruderale, L. sativum, L. strictum, L. virginicum
Synonyms	Coronopus didymus
Web links	Local floras: BC, 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

Lepidium didymum

lesser swinecress, lesser wartcress

Habit

Plants annual, fetid, glabrous or pilose.

Stems

often decumbent, 1–4.5(7) dm.

Basal leaves

not rosulate, 1–6(8) cm, 1- or 2-pinnatisect;

lobes entire or dentate, sometimes deeply lobed;

petioles 0.5–4(6) cm.

Cauline leaves

similar to basal, 1.5–3.5(4.5) × 0.5–1.2 cm, bases not auriculate, petiolate to subsessile.

Inflorescences

rachises glabrous or pubescent with straight cylindrical trichomes, fruiting pedicels divaricate to horizontal; terete; straight or slightly recurved, 1.4–2.5(4) mm, glabrous or sparsely pubescent adaxially.

Flowers

sepals caducous, 0.5–0.7(0.9) mm;

petals elliptic to linear, 0.4–0.5 × ~0.1 mm, white;

stamens 2; median;

styles absent or obsolete, included in apical notch.

Fruits

indehiscent, didymous, 1.3–1.7 × 2–2.5 mm; apical notch 0.2–0.4 mm deep;

valves thick, rugose, glabrous, strongly veined; wingless.

Seeds

ovate, 1–1.2 × 0.7–0.8 mm;

cotyledons incumbent.

=32.

Lepidium didymum

Distribution

[WildflowerSearch map]

[BONAP county map]

Discussion

Disturbed areas, fields, pastures. Flowering May–Oct. 0–300 m. Est, WV. CA, WA; north to British Columbia, eastern Canada and US, southern US; nearly worldwide. Exotic.

Source

Flora of Oregon, volume 2, page 494
Ihsan Al-Shehbaz

Sibling taxa