Fleischmannia microstemon (Cass.) R.M. King & H. Rob. var. microstemon, Phytologia 19: 204. 1970.

Robinson, Harold, 2015, The genus Fleischmannia in Argentina, Bolivia, Brazil and Paraguay (Eupatorieae, Asteraceae), PhytoKeys 57, pp. 61-92 : 68

Fleischmannia microstemon (Cass.) R.M. King & H. Rob. var. microstemon, Phytologia 19: 204. 1970.

Eupatorium microstemon Cass., Dict. Sci. Nat. 25: 432. 1822. Weed in Paris botanical Garden, Cassini s.n. (holotype P).

Eupatorium guadaloupense Spreng., Syst. Veg. 3: 414. 1826. Guadeloupe, Bertero s.n. (P?, TO?)

Eupatorium bimatrum Standl. & L.O. Williams, Ceiba 3: 64. 1952. Honduras, Morazán, El Zamorano, ca. 800 m, 18 Oct. 148, Standley 13132 (holotype F).

Description.

Erect annual herbs to 1 m tall, with slender, strongly ascending branches which often overtop the main axis; stems yellowish green to brown, puberulous. Leaves mostly opposite, alternate distally; petioles slender, usually 0.8-4.0 cm long; leaf blades membranaceous, broadly rhombic-ovate, mostly 2.0-3.7 cm long, 1.4-3.0 cm wide, base acuminate at petiole, margins crenate with 7-14 teeth on each side, apex usually short-acute, adaxially sparsely pilose, abaxially pilosulous on veins, with glandular dots; triplinervate from margins of basal acumination. Inflorescence lax cymose panicles with ascending branches, with many shorter lateral branches proximally; peduncles 2-7 mm long, slender typically puberulous. Heads ca. 4 mm high; involucral bracts 15-22 in 3-4 series, 1.5-3.8 mm long, outer narrowly acute, sparsely puberulous, inner bracts broad and mostly scarious at tip, apex apiculate. Florets 20-35 in a head; corollas lavender to white, 2.0-2.2 mm long, basal tube ca. 0.5 mm long, throat ca. 1.5 mm long, lobes ca. 0.2 mm long, without hairs outside; anther thecae ca. 0.7 mm long; style branches narrowly linear. Achenes 1.3-1.5 mm long, ribs persistently yellow, ribs and distal faces setuliferous; pappus white, of ca. 20 slender not or scarcely contiguous bristles ca. 2 mm long.