Capsella bursa–pastoris (L.) Medik, shepherd’s purse. Annual, taprooted, ± flat–rosetted, 1—several–stemmed at base, ascending to erect, 10—70 cm tall; shoots with basal and some cauline leaves, mostly sparsely pubescent with stellate and unbranched hairs.
Stems cylindric, to 3 mm diameter, green, ± glaucous, stellate–pubescent at base and sparsely pubescent to glabrous above.
Leaves helically alternate, pinnately dissected to lobed and petiolate (basal leaves) and unlobed and sessile clasping (upper cauline leaves), without stipules; petiole of basal leaves 3—20 mm long, winged and often indistinct from blade base, to 12 mm across; blade of basal leaves elliptic to oblanceolate in outline, 30—120 × 10—35 mm, if pinnately lobed raggedly cut and incised with an ovate terminal lobe 8—25 mm long, lateral lobes irregular, long–tapered at base, entire to toothed on margins, acute at tip, teeth often with bristlelike tips, pinnately veined with midrib raised on lower surface, having scattered, short, stellate hairs and longer, ascending unbranched hairs; blade of cauline leaves narrowly lanceolate to narrowly oblanceolate, < 35 mm long, arrow–shaped at base with clasping lobes to 10 mm long, entire to subentire or dentate on margins, acute at tip.
Inflorescence raceme or panicle of racemes, terminal, raceme elongating to > 300 mm long, many–flowered, domelike with open flowers overtopping buds and bud cluster depressed in center; peduncle 15—45 mm long in fruit, stellate–pubescent or glabrous; bract subtending raceme (sometimes present also on the lowest pedicel) leaflike, narrowly linear and clasping, 10—25 mm long; axes with ridges descending from pedicels; pedicel ascending, slender, at anthesis, 3—5 mm long increasing to 15 mm long and spreading in fruit, sparsely stellate–pubescent to glabrous.
Flower bisexual, radial, 2—3 mm across; buds often purple above midpoint; sepals 4, ovate, 1.4—2 × 0.6—1 mm, green with pale purple to reddish purple or purple membranous margins and tip, not pouchlike at base, sparsely long–hairy, deciduous; petals 4, spreading, short–clawed, ± obovate, in range 1.5—2 × 0.6—1 mm, white; stamens 6, free, dimorphic with outer 2 short and inner 4 longer; filaments cylindric, 1.1—1.5 mm long (short stamens) and 1.4—1.8 mm long (long stamens), ca. 0.2 mm diameter, whitish to pale green; anthers ± versatile, dithecal, 0.3—0.5 mm long, light yellow, longitudinally dehiscent; pollen light yellow; nectaries 4, ± hemispheric protrusions from receptacle and opposite petals on 2 sides of each lateral stamen, green; pistil 1; ovary superior, rounded to oblong at anthesis, 1.2—1.4 × 0.9—1 mm, becoming heart–shaped in fruit, green, compressed ⊥ to septum, strongly keeled, glabrous, 2–chambered, each chamber with a maximum of 14 ovules in 2 rows; style ca. 0.2 mm long, in center of notch; stigma hemispheric–capitate, ca. 0.5 mm diameter, densely papillate–hairy.
Fruit siliqua (silicle), dehiscent by 2 valves, many–seeded, flattened triangular heart–shaped, 6—8.3(—9) × (4—)5—7.6(—9) mm, straight or slightly convex on lateral margins, before dehiscence with conspicuous midline of septum and slightly inflated chambers, valves separating while seeds still attached to marginal veins of narrowly elliptic, translucent septum (replum); style persistent.
Seed oblong to compressed–ellipsoid, 1—1.1 × 0.6 mm, wingless, orangey brown to brownish, minutely netlike; mucilaginous when wet.
A. C. Gibson & B. A. Prigge