Nemastylis geminiflora Nutt., prairie celestial, prairie iris, celestial–lily. Perennial herb, geophytic, fibrous–rooted, 1–stemmed from bulb, to 35 cm tall; shoot with basal leaves and several cauline leaves, foliage pleated with conspicuous folds, glabrous; bulb deep–seated, ovoid.

Stems

Stems cylindric, < 2 mm diameter, tough.

Leaves

Leaves alternate distichous, simple with sheath; sheath open, > 360°, 50+ mm long, with membranous margins, rounded on back; blade strap–shaped long–tapered to tip, to 420 × 10—11 mm, entire, parallel–veined, upper surface cupped upward, lower surface accordionlike.

Inflorescence

Inflorescence cyme, of 1—2 2–flowered branches, each branch with long peduncle, bracteate, glabrous; bract subtending inflorescence leaflike, closed ca. 3 mm at base, to 65 × 7 mm, with membranous margins, long–tapered to tip, parallel–veined; bractlet subtending pedicel = a closed sheath, 30—35 mm long, with 5 parallel green veins; pedicel at anthesis < 40 mm long.

Flower

Flower bisexual, radial, mostly 34—45 mm across, in face view blue with white eye (center); tepals 6 in 2 close whorls, clawed, ± monomorphic, claw wedge–shaped, to 1.5 mm long, glossy white and fleshy, limb widely spreading, ovate, 20—26 × 14—15 mm, of inner whorl slightly shorter, white to 4 mm from claw (white eye) and blue above withering violet–blue, with thickened midvein (= 3 veins) and 10+ veins from base of limb, upper surface with domed cells; stamens 3, free; filaments ascending, flattened front–to–back, 2.6—2.9 mm long, glossy white, flared at base ca. 1.4 mm with wing–like margins; anthers dorsifixed near base on inner side, dithecal, 13—15.7 mm long, bright yellow, longitudinally dehiscent, aging twisted; pollen bright yellow, copious; pistil 1; ovary inferior, inversely conic, ca. 3.5 × 2—2.2 mm, ± glossy green, smooth, glabrous, 3–chambered, each chamber with many ovules attached to central axis, ovule light yellow above midpoint; style 6–branched, lower portion columnar but deeply 3–lobed, ca. 2 mm long, 3–branched and each 2–forked, the branches sharply bent outward and spreading, the 6 arms somewhat compressed side–to–side at base and enlarged upward after fork, in range 5.5—6 mm long, white having violet stripe on upper side approaching stigma, with 6 terminal stigmas.

Fruit

Fruit capsule, septicidal and dehiscing at top, many–seeded, obovoid, 10—20 mm long, with 3 shallow furrows, having seeds in 3 vertical rows.

Seed

Seed prismatic angular–obovoid, 2—2.5 mm long, dark brown, with beadlike tip.

A. C. Gibson