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Richardson's bittercress

hairy bitter-cress, shotweed

Habit Perennials; glabrous throughout. Annuals; sparsely hirsute basally (at least on petiole of basal leaves), often glabrous distally.
Rhizomes

cylindrical, slender, 0.5–1.5 mm diam.

absent.

Stems

erect, unbranched, (0.6–)1–2(–3) dm.

erect, ascending, or decumbent, unbranched or branched basally and/or distally, (0.3–)1–3.5(–4.5) dm, (not flexuous).

Basal leaves

(persistent to anthesis), rosulate, (5–)8–15(–22)-foliolate, (2–)3.5–15(–17) cm, leaflets petiolulate;

petiole 0.5–5 cm, (ciliate);

lateral leaflet blade oblong, ovate, obovate, or orbicular, smaller than terminal, margins entire, repand, crenate, or 3-lobed;

terminal leaflet (petiolule 0.2–1 cm), blade reniform or orbicular, 0.4–2 cm × 6–30 mm, margins entire, repand, dentate, or 3 or 5-lobed.

Rhizomal leaves

pinnately 5 or 7-foliolate, (2–)4–10 cm, (not fleshy), leaflets sessile;

petiole (1.5–)3–7(–9) cm;

lateral leaflets similar to terminal, blade sometimes smaller;

terminal leaflet blade linear to narrowly oblong or narrowly lanceolate, (0.5–)1–2.5(–3.3) cm × 0.5–4(–8) mm, base cuneate to attenuate, margins entire.

Cauline leaves

(1 or) 2 or 3, 5 or 7-foliolate, petiolate, leaflets sessile;

petiole (0.2–)0.5–1.2(–1.5) cm, base not auriculate;

lateral leaflets similar to terminal, blade smaller;

terminal leaflet blade narrowly lanceolate to linear, 1–3.2(–4) cm × 0.8–2.5(–3.5) mm, base cuneate to attenuate, margins entire (apex acute to acuminate).

1–4(–6), compound as basal, petiolate, [(0.5–)1.2–5.5(–7) cm, including petiole], leaflets petiolulate;

blade base not auriculate;

leaflets similar to basal.

Racemes

ebracteate.

ebracteate.

Flowers

sepals ovate, 2.5–3.5 × 1.5–2.5 mm, lateral pair not saccate basally;

petals white, obovate, 5–9 × 2.5–5 mm (clawed, apex rounded);

filaments: median pairs 3–4.5 mm, lateral pair 1.5–2.5 mm;

anthers oblong, 1–1.5 mm.

sepals oblong, 1.5–2.5 × 0.3–0.7 mm, lateral pair not saccate;

petals (sometimes absent) white, spatulate, 2.5–4.5(–5) × 0.5–1.1 mm; (stamens usually 4, lateral pair often absent, rarely 5 or 6);

filaments 1.8–3 mm;

anthers ovate, 0.3–0.5 mm.

Fruiting pedicels

suberect to divaricate-ascending, (7–)10–25 mm.

erect to ascending, (2–)3–10(–14) mm.

Fruits

linear, (1.5–)2–4 cm × 1.5–2 mm;

ovules 6–12 per ovary;

style (1–)1.5–2.5(–4) mm.

linear, (torulose), (0.9–)1.5–2.5(–2.8) cm × (0.8–)1–1.4 mm, (often appressed to rachis);

ovules 14–40 per ovary;

style 0.1–0.6(–1) mm.

Seeds

brown, oblong, 1.8–2.2 × 0.9–1.1 mm.

light brown, oblong or subquadrate, 0.9–1.3(–1.5) × 0.6–0.9(–1.1) mm, (narrowly margined).

2n

= 28, 42.

= 16.

Cardamine digitata

Cardamine hirsuta

Phenology Flowering Jun–Aug. Flowering Feb–Jul.
Habitat Damp flats, stream banks, tundra, meadows, bluffs, hummocks, sandy beaches, slopes, mossy mats, sedge swales Roadsides, clearings, disturbed sites, slopes, cedar glades, mixed woods, meadows, fields, waste grounds, damp places, grassy areas
Elevation 0-1400 m (0-4600 ft) 0-700 m (0-2300 ft)
Distribution
from FNA
AK; NT; YT; ne Asia (Russian Far East, Siberia)
[BONAP county map]
from FNA
AL; AR; CA; CT; DC; DE; FL; GA; IL; KY; LA; MA; MD; MI; MO; MS; NC; NJ; NY; OH; OK; OR; PA; SC; TN; TX; UT; VA; WA; WV; BC; ON; w Eurasia [Introduced in North America; introduced also in Central America, South America, e Asia (Japan), South Africa, Australia]
[WildflowerSearch map]
[BONAP county map]
Discussion

Herbarium specimens of Cardamine hirsuta have been misidentified as C. oligosperma.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 7, p. 472. FNA vol. 7, p. 475.
Parent taxa Brassicaceae > tribe Cardamineae > Cardamine Brassicaceae > tribe Cardamineae > Cardamine
Sibling taxa
C. angulata, C. angustata, C. bellidifolia, C. blaisdellii, C. breweri, C. bulbosa, C. californica, C. clematitis, C. concatenata, C. constancei, C. cordifolia, C. diphylla, C. dissecta, C. douglassii, C. flagellifera, C. flexuosa, C. hirsuta, C. holmgrenii, C. impatiens, C. longii, C. macrocarpa, C. maxima, C. micranthera, C. microphylla, C. nuttallii, C. nymanii, C. occidentalis, C. oligosperma, C. pachystigma, C. parviflora, C. pattersonii, C. penduliflora, C. pensylvanica, C. pratensis, C. purpurea, C. rotundifolia, C. rupicola, C. umbellata
C. angulata, C. angustata, C. bellidifolia, C. blaisdellii, C. breweri, C. bulbosa, C. californica, C. clematitis, C. concatenata, C. constancei, C. cordifolia, C. digitata, C. diphylla, C. dissecta, C. douglassii, C. flagellifera, C. flexuosa, C. holmgrenii, C. impatiens, C. longii, C. macrocarpa, C. maxima, C. micranthera, C. microphylla, C. nuttallii, C. nymanii, C. occidentalis, C. oligosperma, C. pachystigma, C. parviflora, C. pattersonii, C. penduliflora, C. pensylvanica, C. pratensis, C. purpurea, C. rotundifolia, C. rupicola, C. umbellata
Synonyms C. digitata var. oxyphylla, C. hyperborea, C. hyperborea var. oxyphylla, C. richardsonii
Name authority Richardson: in J. Franklin, Narr. Journey Polar Sea, 743. (1823) Linnaeus: Sp. Pl. 2: 655. (1753)
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