Monographs Details: Costus congestiflorus Gagnep.
Authority: Maas, Paulus J. M. 1972. Costoideae (Zingiberaceae). Fl. Neotrop. Monogr. 8: 1-140. (Published by NYBG Press)
Synonyms:Costus congestiflorus Gagnep.
Description:Description - Low plants 0.5-1 m tall, stems 2-5 mm wide. Sheaths, ligules, petioles, leaves bracts, bracteoles, and calyx glabrous to densely (minutely) puberulous. Sheaths 5-10(-15) mm wide. Ligule 1-2 mm long. Petiole 1-5 mm long. Leaves narrowly elliptic to narrowly obovate, acuminate at the apex, acumen 5-15 mm long, cuneate, rounded, or rarely cordate at the base, 10-20 cm long, 2.5-6.5 cm wide. Inflorescence broadly obovoid, 3-5 cm long, elongating to 8 cm in fruit, 3-4 cm wide. Bracts green, herbaceous to chartaceous, narrowly triangular to triangular, often mucronate, (12-) 15-22 (-35) mm long, 5-12 mm wide, callus 2-7 mm long, yellow. Bracteole green, herbaceous to chartaceous, tubular but often deeply split on the abaxial side, 13-19 mm long, bicarinate on the adaxial side, two-lobed, lobes deltate, 2-3 mm long. Calyx herbaceous to chartaceous, green, (20-) 25-32 mm long, lobes subulate, i-6(-io) mm long; calyx tube often deeply split by the flowerbud during anthesis. Corolla creamy white, 50-60 mm long, densely puberulous to villose, tube 20 mm long, lobes narrowly obovate, 30-40 mm long, 1 o mm wide, obtuse. Labellum creamy white, broadly angular-obovate when spread out, 35 mm long, 40 mm wide, limb elliptic in outline in living plant, margins densely fimbriate. Stamen creamy white, narrowly obovate, 25 mm long, 7-12 mm wide, apex obtuse, anther 6-8 mm long. Basal part of labellum and stamen joined in a 20 mm long tube. Pollen grains 110-134 µ. Exine 4-7 µ thick. Number of pores 6-9. Porus diam ca 10 µ (Maas 3166 from Suriname). Stigma cup-shaped. Ovary 3-6 mm long, sparsely to densely puberulo-sericeous. Capsule ellipsoid, 10-13 mm long, 6-9 mm in diam, densely minutely puberulous, seeds black.

Discussion:This species is closely related to C. lanceolatus. It differs in the colour of the flowers, the long-fimbriate labellum, and the densely hairy corolla. Ducke 25622 is somewhat aberrant in its very large bracts (25-35 mm long), but since all other essential characters agree with C. congestiflorus there is no reason to describe a variety for a single plant.
Distribution:Venezuela South America| Delta Amacuro Venezuela South America| French Guiana South America| Guyana South America| Suriname South America| Brazil South America| Amapá Brazil South America| Amazonas Brazil South America| Pará Brazil South America|