Vascular Plants of Williamson County

Sisyrinchium minus [Iridaceae]
least blue–eyed grass

Sisyrinchium minus Engelm. & A. Gray, least blue–eyed grass. Annual, fibrous–rooted at base of shoot, lacking rhizome, several–stemmed at base, ascending, each shoot having a terminal inflorescence, in range to 25 cm tall; shoots with several leaves (some = bracts), strongly 2–ranked and flattened, each leaf sharply folded base to tip and appressed lengthwise along midrib (replicate) and with overlapping leaf bases (equitant), leaves oriented vertically, glabrous.

Stems

Stems compressed, to 3 mm wide, bulging at nodes and sometimes with purplish mark on bulge.

Leaves

Leaves alternate distichous, simple and sheathing at base; sheath closed, to 12 mm long; blade linear, strap–shaped, and equally folded from base, to 90 × 2.5—4 mm, entire with membranous margin somewhat above sheath, acuminate at tip, parallel–veined with flat surfaces, keel not thickened, glabrous.

Inflorescence

Inflorescence compound umbel–like cyme, strongly 2–dimensionally flattened side–to–side (rhipidium), to 3 nodes long, having a system of alternate distichous bracts, with an ascending leaflike primary bract at each node; inflorescence axis jointed, somewhat bent at nodes, at ultimate node having flowers arising from within a pair of bracts forming a narrowly ellipsoid involucre enclosing several unopened flowers + bractlets subtending pedicels, flowers within spathe alternate distichous, at anthesis each flower is exserted from the involucre and opening sequentially, glabrous; peduncle of spathe ascending, slender, < 50 mm long, wiry; involucre outer bract of involucre (spathe) closed at base 4 mm, leaflike blade to 25 mm long, sharply folded base to tip concealing most of inner bract, acuminate at tip, with membranous margins; inner bract hidden to midpoint of outer bract, where flowers exserted, open at base; bractlet subtending pedicel included, = a membranous sheath to 7 mm long, reduced to the youngest flower; pedicel with exserted flower from involucre, slender and flexible, green, initially exserted to the opposite side of developing fruits.

Flower

Flower bisexual, radial, ca. 5 mm across; tepals 6 in 2 whorls, forming a bell–shaped to funnel–shaped perianth, arising from green receptacle, ± monomorphic, obovate, ± 5.5 mm long including tail–like tip, 2 mm wide and 5–veined (outer whorl) and 1.5—1.7 mm wide and 3–veined (inner whorl), pale rose–purple with purple veins and having a yellow triangle at base, together forming a 6–pointed bright yellow star in center of perianth, each tepal with a midvein to midpoint and having several scattered nonglandular short hairs and stalked glandular hairs with minute heads; stamens 3, fused into tapered column narrowly lanceolate in outline, 2 × 0.6 mm (0.25 mm diameter at top), whitish, lower portion covered with yellowish glandular hairs and also scattered above midpoint; anthers dorsifixed, dithecal, ± 0.7 mm long, bright yellow, longitudinally and outwardly dehiscent; pollen bright yellow; pistil 1, exserted to level of the top of anther sacs; ovary inferior, oblong 3–lobed, ± 1.5 × 0.9 mm, green, with scattered stalked glandular hairs, 3–chambered, each chamber with 12+ ovules in 2 stacks; style ± 2.3 mm long, white, with 3 erect stigma lobes at tip 0.4 mm long.

Fruit

Fruit capsule, loculicidal, pendent on slender and wiry, recurved pedicel, many–seeded, ± short club–shaped, < 5—5.5 × 2.5 mm, light brown, bulging at seeds.

Seed

Seed subspheroid with 1 side depressed, 0.5—0.8 mm long, minutely bumpy.

A. C. Gibson