1. Bupleurum rotundifolium L. (thoroughwax, hare’s ear)
Pl. 204 i, j;
Map 845
Plants annual,
often somewhat glaucous. Stems 10–50 cm long, erect or ascending, glabrous.
Leaves alternate and usually also basal (a few basal leaves usually present at
flowering), glabrous, sessile or nearly so (in basal leaves), the sheathing
bases absent or poorly developed, not inflated. Leaf blades 1.5–8.0 cm long,
simple, ovate to elliptic-ovate in outline, rounded at the tip, the margins
entire, the basal and lowermost stem leaves with the bases clasping the stems
and with more or less rounded auricles, those of the median and upper leaves
with the bases perfoliate. Inflorescences terminal and axillary, compound
umbels, mostly long-stalked. Involucre absent. Rays 4–10, 0.5–1.5 cm long.
Involucel of 5 bractlets, these fused at the base, 5–15 mm long, broadly ovate,
tapered to sharp points at the tip. Flowers 10–12 in each umbellet, the stalks
1–3 mm long, giving the umbellets a dense, headlike appearance. Sepals absent.
Petals broadly oblong to nearly circular, rounded at the tip, yellow to
greenish yellow. Ovaries glabrous. Fruits 2.5–3.0 mm long, oblong-elliptic in
outline, slightly flattened laterally, glabrous, purplish brown to black, each
mericarp with 5 slender, inconspicuous ribs lacking wings. 2n=16. May–July.
Introduced,
uncommon in eastern Missouri (native of Europe, Asia; introduced in the eastern
U.S. west to South Dakota and Texas). Glades and dry upland forests; also
roadsides, railroads, pastures, and open, disturbed areas.