Conoclinium coelestinum (L.) DC., blue mistflower, purple mistflower, blue boneset. Perennial herb, rhizomatous, fibrous–rooted, several–stemmed at base, ± erect with spreading to ascending branches but sometimes branches decumbent and when buried rooting at nodes, in range to 75 cm tall; shoots with paired cauline leaves, short–hairy with upward–curved hairs and both short–stalked and sessile glandular hairs, foliage not aromatic; buried stems rhizomelike with adventitious roots forming at nodes.
Stems inconspicuously 8–angled, to 4 mm diameter, tough, internodes to 90 mm long, short–hairy with some stalked glandular hairs; pith of internodes narrowly hollow.
Leaves opposite decussate, simple, petiolate with pair connected as ledges across node, without stipules; petiole deeply channeled base–to–top, to 15 mm long, short–hairy with stalked glandular hairs having yellowish heads; blade triangular to deltate, 15—73 × 13—48 mm, ± truncate at base, serrate to serrate–dentate or shallowly lobed on margins, obtuse to broadly acute at tip, 3–veined from base and pinnately veined above with principal veins slightly sunken on upper surface and raised on lower surface, upper surface sparsely short–hairy along principal veins, lower surface short–hairy and with stalked glandular hairs along veins and uniformly gland–dotted with sessile glandular hairs in pits.
Inflorescence heads, in terminal and axillary, cymelike, flat–topped (domed) arrays, array with 10+ heads, on ascending lateral branches, head discoid, ca. 5 mm across, 70+–flowered, flowers bisexual, bracteate, short–hairy with upward–curved hairs and stalked glandular hairs; lower axis to 25 mm long; bract subtending lateral branch linear, to 5.5 × 0.5 mm decreasing upward, the lowest bract unlobed or minutely several–lobed, 1–veined, upper surface flattish and glabrous, lower surface rounded and short–hairy; peduncle at first anthesis 5—6 mm long increasing 2× during flowering, along axis having immature bracts of future branchlets; involucre bell–shaped, 3.5—4.5 mm diameter, phyllaries 20—35 in 2—3 series, narrowly lanceolate–linear, 2—3.7 × 0.4 mm, slightly ridged on back, with some short nonglandular hairs and scattered short–stalked glandular hairs having reddish heads; receptacle conic, lacking bractlets (paleae), glabrous.
Disc flower bisexual, radial, ± 5 mm across; calyx (pappus) of ca. 20 capillary bristles in 1 whorl, 1.6—2.5 mm long, white; corolla 5–lobed, cylindric; tube 0.7—0.8 mm long, white, inconspicuously 5–veined; throat ca. 1 × 0.5 mm, pale violet, outer surface with scattered glandular hairs; lobes spreading, acute, 0.4 × 0.3—0.35 mm, pale violet to blue–violet, surface with domed cells; stamens 5, attached at top of corolla tube; filaments threadlike, 0.7 mm long, white; anthers fused as cylinder surrounding style, basifixed, dithecal, included, 0.8 mm long, white, longitudinally dehiscent; pollen white; nectary disc at base of style, shallowly 5–lobed, 0.1—0.15 mm tall, purplish; pistil 1; ovary inferior, narrowly wedge–shaped, 1 × 0.4 mm, white, 5–sided, with short–stalked glandular hairs having colorless spheric heads; style exserted, ca. 2.5 mm long, 2–branched, lower portion 0.7—0.9 mm long, white, the branches with flat inner side, blue–violet.
Fruits cypselae, with pappus, prismatic, 1—1.5 × 0.3 mm, satiny brown, conspicuously 5–ribbed, with white callus at base, glabrous; pappus fused in ring at base, of ca. 20 widely spreading bristles, 1.7—2.9 mm long, tannish.
A. C. Gibson