Monographs Details: Costus
Authority: Maas, Paulus J. M. 1972. Costoideae (Zingiberaceae). Fl. Neotrop. Monogr. 8: 1-140. (Published by NYBG Press)
Scientific Name:Costus
Synonyms:Banksea J.Koenig, Pyxa Noronha, Hellenia, Tsiana J.F.Gmel., Planera, Gissanthe Salisb., Glissanthe Steud., Jacuanga T.Lestib., Cadalvena, Cadalvena spectabilis Fenzl, Costus arabicus Ruiz & Pav.
Description:Description - Gigantic, tall, low, or acaulescent herbs, occasionally branched. Ligule short or long, truncate or two-lobed. Leaves cuneate, rounded, or occasionally cordate at the base, shortly or long-acuminate at the apex. Inflorescence strobilaceous to capitate, terminating a leafy stem, or on a separate, short, leafless shoot. Bracts green, yellow, or orange to red, coriaceous to herbaceous, narrowly to broadly ovate-triangular, often provided with foliaceous appendages, Bracteole folded or tubular. Calyx small to large, rarely exceeding the bracts. Corolla white, yellow, orange, or red. Labellum small or large, white, yellow, or orange to red, lateral lobes in large-flowered species often with reddish venation; basal part of labellum in nearly all species papillate. Stamen with the anther attached at the middle, or rarely at the base; basal part of stamen and labellum joined into a short or long, slender, papillate tube. Pollen grains large, pantoporate. Exine thick or thin. Number of pores medium or large. Diameter of pores medium or large. Stigma bilamellate or cup-shaped. Ovary trilocular, ovules biseriate. Capsule trilocular, ellipsoid to globose, loculicidally dehiscent, or irregularly breaking up with age; seeds glossy black or brown, aril large and lacerate, or rarely short and cushion-like (C. speciosus); all seeds of one locule often cohering by their arils at dehiscence. Floral parts of the subgenus Cadalvena red-brown punctate. Chromosome number 2n = 18 or 36.