Polygala alba Nutt., white milkwort. Perennial herb, from vertical caudex, many–stemmed at base, principal branches initially lacking lateral branches and ascending with terminal inflorescence, to 35 cm tall; shoots with only cauline leaves, glabrous.
Stems conspicuously ridged, to 2.5 mm diameter, tough, green, internodes < 10 mm long.
Leaves helically alternate, simple, subsessile, without stipules; petiole to 1 mm long; blade ascending, linear to oblanceolate–linear (obovate), (3—)10—30(—43) × 0.6—1.6(—4.5) mm, entire and sometimes slightly inrolled to under side, acute at tip, 1–veined with midrib slightly sunken on upper surface and raised on lower surface.
Inflorescence raceme, terminal, 100+–flowered (fully developed), flowering portion cylindric and ca. 5 mm diameter, flowers overlapping and helically alternate, at anthesis lacking internodes, bracteate, glabrous; peduncle ca. 8–ridged, ± 1.3 mm diameter, ridges descending from bractlets, flexible, green, glabrous, the lowest internode in fruit ± 3 mm long decreasing upward; bractlet subtending pedicel initially appressed to and concealing flower bud, awl–shaped, ca. 1 × 0.6 mm, thickened at base, with raised purplish center and pale pink wide margins, abscising at anthesis, having 2 more delicate lateral bracteoles, narrowly ovate, ± 0.5 mm long, abscised somewhat after bractlet; pedicel ascending, at anthesis ± 0.5 mm long increasing 2× in fruit, white, conspicuously wrinkled.
Flower bisexual, bilateral, 2.5—6 mm across (the widest when wings spreading); sepals 5, dimorphic; upper sepal cupped–broadly ovate, ca. 1.8 × 1.5 mm, white with green base, having yellowish green wart on inner surface at base = nectary from receptacle; lateral sepals 2, petal–like, scooplike and spatulate to obovate, ca. 3 × 1.7—2.2 mm, white (sometimes with tinge of purple), wavy on margins, rounded at tip, somewhat crinkled, with yellow–green nectary tissue on inner surface at base; lower sepals 2, appressed and overlapping, acute–ovate, 0.8—1 × 0.7 mm, center green or mottled purple and margins white (pale lavender), with minute glands on green tissues, margins ± 0.25 mm wide; petals 5 (appearing 3), dimorphic, appearing free but fused to staminal column; upper petals not distinct, fused to lower staminal columnar; lateral petals 2 (wings) fused to staminal column, overlapping on upper side, obovate, 2.6—2.7 mm long, white; lower petal fused on outer surface of staminal column, petal + staminal column ca. 2 mm long, with 5—6 white, fingerlike members of fringe at top incurved and arching over anthers, below fringe green; petal tissues often aging purple or purplish; stamens 6—7(—8), fused at base to form a column (column fused with petals), included; staminal column enveloping ovary and lower style, opened along upper side and constricted at tip; free filaments flat, short—0.3 mm long, greenish; anthers mostly positioned below level of the stigma, basifixed, appearing monothecal, ca. 0.3 mm long, light orange, dehiscent at tip by a 2–lipped opening with 1 lip larger than other lip; pollen light orange, sticky; pistil 1, < 1.5 mm long, short–stalked; ovary superior, roundish compressed top–to–bottom (oblate), ± 1 mm, green but contents visible through wall, somewhat 2–lobed on faces, 2–chambered, each chamber with 1 pendent ovule; style fan–shaped with flat faces and cupped forward 3–lobed at top, pale green, central lobe with spheric, papillate stigma arching downward, stigma ca. 0.3 mm across, white.
Fruit capsule, loculicidal, 2–valved, with 1—2 arillate seeds, ovoid compressed parallel to septum, ca. 3 × 1.5—1.8 mm, appearing shallowly 4–lobed at top with the deeper crease ⊥ septum.
Seed ovoid, ca. 2.5 × 1 mm, deep purple aging black, rounded side covered with colorless, stiff, straight, reclined hairs 0.25—0.35 mm long; aril attached at pointed end of seed, saddlebaglike, rounded–oblong to mid–seed, 1—1.2 × 0.5 mm, fleshy, white.
A. C. Gibson