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prairie rocket, sand-dune wallflower, wallflower, western wallflower

Habit Biennials or perennials; (short-lived).
Stems

erect, often branched distally, sometimes proximally, (0.5–)1.2–10(–12) dm.

Basal leaves

(often withered by flowering);

blade spatulate to narrowly oblanceolate or linear, 2–18(–27) cm × 3–15(–30) mm, base attenuate, margins entire or dentate to denticulate, apex acute.

Cauline leaves

(distal) sessile;

blade margins entire or denticulate.

Racemes

considerably elongated in fruit.

Flowers

sepals narrowly oblong, 7–14 mm, lateral pair saccate basally;

petals usually orange to yellow, rarely lavender or purplish, suborbicular to obovate, 12–25(–30) × (5–)6–10(–13) mm, claw 8–16 mm, apex rounded;

median filaments 9–18 mm;

anthers linear, 3–4 mm.

Fruiting pedicels

divaricate to ascending, stout or slender, narrower than fruit, 4–17(–25) mm.

Fruits

divaricate or ascending to erect, narrowly linear, straight or curved upward, not torulose, 3.5–11(–15) cm × 1.3–3.3 mm, 4-angled to latiseptate, not striped;

valves with prominent midvein, pubescent outside, trichomes 2–5-rayed, glabrous inside;

ovules (40–)54–82 per ovary;

style cylindrical, usually stout, rarely slender, 0.2–2.5(–3) mm, sparsely pubescent;

stigma 2-lobed, lobes as long as wide.

Seeds

oblong, 1.5–4 × 1–2 mm; winged apically or not winged.

Trichomes

of leaves 2–4(–7)-rayed.

2n

= 36.

Erysimum capitatum

Distribution
from FNA
AK; AR; AZ; CA; CO; IA; ID; IL; IN; MO; MT; NM; NV; OH; OK; OR; TN; TX; UT; WA; WY; YT; n Mexico
[WildflowerSearch map]
[BONAP county map]
Discussion

Varieties 2 (2 in the flora).

Erysimum capitatum is extremely widespread, ecologically diverse, morphologically highly variable, and nomenclaturally complex. It has been divided into infraspecific taxa; G. B. Rossbach (1958) recognized three varieties, R. A. Price (1987) eight subspecies, R. C. Rollins (1993) five varieties, Price (1993) four subspecies, and N. H. Holmgren (2005b) three varieties. The majority of these taxa were based on highly variable characters with considerable overlap, including width, margin, shape, and apex of basal leaves, fruit orientation, and development of elongated versus short caudices. Furthermore, there is a substantial degree of disagreement among these authors as to the limits of a given infraspecific taxon, its distribution, and synonymies involved. Except for two distinctive species that were previously treated as infraspecific taxa (arenicola, perenne) the vast majority of the remaining variation in E. capitatum is divided herein into two varieties.

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

Key
1. Seeds winged (at least distally, rarely wing rudimentary), 2-4 × (0.8-)1-2 mm; fruits latiseptate, rarely 4-angled; petals usually orange, sometimes orange-yellow or yellow; adaxial surfaces of basal and proximalmost cauline leaf blades with mostly 3(-7)-rayed trichomes.
var. capitatum
1. Seeds not winged, 1.5-2(-2.4) × 0.7-1.2 mm; fruits 4-angled, rarely latiseptate; petals yellow, rarely lavender or purplish; adaxial surfaces of basal and proximalmost cauline leaf blades with mostly 2- or 3-rayed trichomes.
var. purshii
Source FNA vol. 7, p. 537.
Parent taxa Brassicaceae > tribe Erysimeae > Erysimum
Sibling taxa
E. ammophilum, E. arenicola, E. asperum, E. cheiranthoides, E. cheiri, E. coarctatum, E. concinnum, E. franciscanum, E. hieraciifolium, E. inconspicuum, E. insulare, E. menziesii, E. occidentale, E. pallasii, E. perenne, E. repandum, E. suffrutescens, E. teretifolium
Subordinate taxa
E. capitatum var. capitatum, E. capitatum var. purshii
Synonyms Cheiranthus capitatus
Name authority (Douglas ex Hooker) Greene: Fl. Francisc., 269. (1891)
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