4. Croton michauxii G.L. Webster (slender rushfoil)
Map 1659, Pl.
378 c, d
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.
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
treatment of C. willdenowii for discussion of the transfer of Crotonopsis
species into Croton.