Melampodium leucanthum Torrey & A. Gray, black–foot daisy. Perennial herb to subshrub, woody–taprooted, several—many–stemmed at base, having decumbent lower branches and ascending flowering branches, in range to 45 cm tall; monoecious; shoots with only narrow cauline leaves, produced widely spaced to the upper side (appearing 1–sided), foliage somewhat scabrous and strigose and gland–dotted with scattered, mostly sessile, colorless glandular hairs.
Stems cylindric, of young stems ca. 1 mm diameter, often tinged pink to purplish, lower stems to 6 mm diameter with brown bark, strigose hairs 0.3—0.6(—0.8) mm long and upward–pointing.
Leaves opposite decussate, simple to 60lobed, petiolate and pair fused across node, without stipules; petiole winged and indistinct from blade base, to 10 mm long, midvein white and rounded on lower side; blade elliptic–linear to lanceolate–linear, 21—45 × 3—7(—13) mm, broader if shallowly pinnately lobed, long–tapered at base, entire to irregularly low–toothed on margin, the margin sometimes somewhat inrolled under, obtuse to acute with fleshy callous at tip, pinnately veined with only midrib conspicuous and raised on lower surface.
Inflorescence head, generally solitary aging as a leafy, cymelike array of several heads, terminal on a slender peduncle, radiate, with 8—11(—13) pistillate ray flowers and 25—55+ functionally staminate disc flowers, 25—29 mm across, bracteate; bract subtending peduncle leaflike, often somewhat inrolled on margins, at base of inflorescence with one axillary shoot growing before another; peduncle cylindric, to 85 × 0.6—0.7 mm, in depression of involucre, having short hairs arched and bent upward and short–stalked glandular hairs; involucre broadly cup–shaped to hemispheroid, 7—10 mm diameter, phyllaries in 2 distinct series and dimorphic, outer 5 phyllaries fused at least to midpoint and concealing inner phyllaries, flexible, green and herbaceous, with 5 raised midveins, lobes ± broadly ovate, 3—3.5 × 3—3.5 mm, conspicuously short–hairy and gland–dotted, inner phyllaries = ray flowers, each phyllary forming a permanent complex with ovary of ray flower, lower portion tightly enclosing ovary and upper portion forming a peaked collar open on the inner side, at anthesis green, lower portion with conspicuous, peglike projections, having a conic knob at base on inner side; receptacle conic, bractlet subtending disc flower (palea) membranous, 3/4 encircling ovary, ca. 4.5 mm long, ± keeled, colorless at base, top to yellow and deeply cut concealing flower bud, aging scarious.
Ray flower pistillate, bilateral, to 7 mm across (at pollination 2 mm across); calyx (pappus) absent; corolla mostly notched and 2–lobed to 3–lobed or toothed, at pollination 3.5—4 mm long and inrolled; tube compressed top–to–bottom, < 0.5 × 0.5 mm, green, outer surface short–hairy and glandular; limb oblong–obovate to narrowly fan–shaped, 7—11 × (2.5—)5.5—7 mm, at maturity pure white with 7—9 yellowish green (salmon–colored) veins raised on lower surfaces (at pollination with veins reddish), lower surface having sessile glands with colorless heads and aging sparsely short–strigose; stamens absent; pistil 1; ovary inferior, asymmetrically top–shaped compressed side–to–side, ca. 1 × 0.7 mm, white with fine lengthwise veins, 1–chambered with 1 ovule; style to 2 mm long, 2–branched just above base, the branches ascending, narrowly tonguelike with groove on stigmatic inner side, light yellow–green, with glandular colorless heads on outer surface at pollination, aging recurved to coiled and black.
Disc flower appearing bisexual but functionally staminate, radial, ca. 2.5 mm across; calyx (pappus) absent; corolla 5–lobed; tube short, white, minutely hairy; throat funnel–shaped, to 1.5 × 1 mm, yellowish, without hairs; lobes triangular, 0.8 × 0.6 mm, yellow, conspicuously papillate on upper surface and with tuft of short hairs near tip; stamens 5, attached to top of corolla tube; filaments ca. 1 mm long, white; anthers fused into cylinder surrounding style, basifixed, dithecal, ± 1.5 mm long, golden yellow to yellow–orange, longitudinally dehiscent; pollen golden yellow; nectary disc around base of style, 0.1 mm long, white; pistil 1, sterile; ovary wedge–shaped, 0.8—1.2 × 0.4—0.6 mm, greenish, short–hairy; style with tip exserted from anthers, cylindric, 3 mm, white to midpoint and yellowish above midpoint, unbranched, puberulent approaching tip.
Fruits cypselae (achenes) of only ray flowers, each enclosed by inner phyllary (perigynium); cypsela ear–shaped flattened side–to–side, 1.5—2.6 × 1—1.6 mm, black, with fine, lengthwise grooves; perigynium leathery, enclosed around fruit but with slitlike opening on top, fruit chamber powderhorn–shaped, 2.5—3.5 mm long, 3–ribbed on lateral faces with bridges and bumps (tuberculate), free portion of phyllary peaked and collarlike above fruit chamber, ca. 1.5 mm long, short–hairy at top.
A. C. Gibson