4. Croton michauxii G.L. Webster (slender rushfoil)

Crotonopsis linearis Michx.

Map 1659, Pl. 378 c, d

Plants monoecious, moderately to densely pubescent with minute, peltate, scalelike trichomes (except on the upper surface of the leaf blades), these with a minute, raised, brown attachment point and a relatively slender, thin, white body, the slender, stellate extensions forming a noticeable fringe around the margins, this often slightly raised and thus providing a fuzzy appearance (especially on the fruits); the upper surface of the leaves with moderate minute, nonoverlapping, stellate hairs, the more or less equal branches 0.2–0.3 mm long. Stems (10–)15–40 cm long, usually sparsely alternately branched. Leaves alternate, sessile or very short-petiolate, the petiole without large, saucer-shaped glands at the tip. Leaf blades 1.0–2.5(–4.0) cm long, linear, angled or short-tapered at the base, angled or short-tapered to a sharply pointed tip, the margins entire, the undersurface paler than the upper surface. Inflorescences axillary, mostly elongate, loose spikes with 2–4(–6) pistillate flowers scattered toward the base and several staminate flowers toward the tip. Staminate flowers with the calyx deeply (4)5-lobed, 0.8–1.1 mm long; the petals (4)5, 0.6–1.0 mm long, white; the stamens 4–6. Pistillate flowers with the calyx 0.8–1.1 mm long at flowering, becoming very slightly enlarged at fruiting, (4)5-lobed; the petals absent; the ovary 1-locular, the 3 styles shallowly 2-lobed toward the tip. Fruits 2.5–3.0 mm in length and diameter, elliptic to oblong-ovate in outline, slightly flattened, 1-seeded, indehiscent, thin-walled. Seeds 2.5–3.0 mm long, elliptic to oblong-ovate in outline, slightly flattened, the caruncle absent. July–September.

Uncommon, known only from the Mississippi Lowlands Division and a single historical collection from St. Louis County (eastern [mostly southeastern] U.S. west to Iowa and Texas). Sand prairies, sand savannas; also roadsides and open, sandy, disturbed areas.

See the treatment of C. willdenowii for discussion of the transfer of Crotonopsis species into Croton.