Costaceae
Creators: name: Kamer 1, H. Maas-van de
name: Maas 1, P. J. M.
name: Wieringa 1, J. J.
name: Specht, C. D.
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Liliopsida
Zingiberales
Costaceae

description: Costaceae <i>Costaceae</i> Nakai (1941) 203. — Type: <i>Costus</i> L. The African <i>Costaceae</i> (<i>Costus</i> spp. and <i>Paracostus englerianus</i>) are perennial, rhizomatous herbs, terrestrial or epiphytic, rarely gigantic, tall (max. 6 m), low or acaulescent herbs; shoot erect or prostrate, unbranched, generally spirally shaped, composed of nodes and internodes; leaf sheaths, petioles and lig-ules originating at the nodes. <i>Leaves</i> 1, or few to many, spirally arranged along the shoot; shootless species with few leaves ro-sulate; prostrate species with 1 leaf per shoot (<i>Paracostus</i>); leaf sheaths fully closed around the shoot; ligule present or rarely absent, membranous to chartaceous, tubular at the base and truncate to 2-lobed at the apex; petiole present or sometimes absent; lamina generally green, sometimes shiny, or plicate, herbaceous to coriaceous, generally elliptic with acuminate apex and acute base, sometimes extreme base of leaf fleshy surrounding the inflorescence (<i>Paracostus</i>). <i>Inflorescence</i> a many-, several- or few-flowered spike, either terminating a leafy shoot, or terminating a separate leafless shoot, or lateral in the axil of a leaf, sometimes partially enclosed by the overlapping margins of the bases of the leaf lamina and the uppermost 1–3 sheathing leaf bases (<i>Paracostus</i>); inflorescence ellipsoid to ovoid or globose when terminating a leafy shoot, loosely arranged when axillary; bracts spirally arranged, each carrying 1 or 2 flowers, yellow, green, red or brownish, membranous, chartaceous or coriaceous, generally ovate to triangular or elliptic, imbricate, callus linear, nectariferous, absent or present; foliaceous appendages absent or present, generally coloured as the bracts, ascending, horizontally spreading, or reflexed, broadly ovate to narrowly triangular; each flower enclosed by 1 bracteole, generally coloured as the bracts, boat-shaped or tubular and 1-keeled or sometimes 2-keeled, callus absent or 1 or 2 calli present. <i>Flowers</i> epigynous, bisexual, zygomorphic; calyx generally coloured as the bracts, tubular, 3-lobed or rarely 2-lobed, lobes erect, horizontally spreading, or reflexed, cal-lus absent or present; corolla white, yellow, orange, pink, lilac or reddish brown, or a combination of these colours, tubular, 3-lobed, lobes erect, narrowly obovate to elliptic, rarely hyaline; labellum large, longer than or as long as the corolla, white, yellow, orange, pink, lilac, dark red, reddish brown, purple, or a combination of these colours, sometimes with darker lateral parts and/or striped upper margin and central yellow nectar guide, horizontally flattened, funnel-shaped or rarely tubular, narrowly elliptic, ovate, obovate or subcylindrical when spread out, rarely lateral margins curved upwards (<i>C. giganteus</i>), margin undulate to crenate, sometimes fimbriate; stamen 1, petaloid, generally yellow or white, apex recurved or erect and cucullate (<i>C. giganteus</i>), anther longitudinally centred, composed of 2 narrowly elliptic 2-sporangiate thecae; base of stamen and labellum joined into a tube; gynoecium composed of a single ovary with attached style and stigma; ovary inferior, 3-locular, placentation axile, ovules many, organized in 2 rows per locule, anatropous; septal nectaries 2 at the apex of the ovary secreting nectar into the base of the floral tube; style 1, filamentous, supported between the thecae of the anther; stigma 1, 2-lamellate, hooked between the apices of the thecae by a dorsal 2-lobed to rounded appendage. In <i>Paracostus englerianus</i> the stigma is composed of a funnel-shaped upper part and a reflexed lamellate part, and the appendage is absent. <i>Fruit</i> capsular, 3-locular, placentation axile, generally obovoid, crowned by the persistent calyx, dehiscing loculicidally by three longitudinal slits, or indehiscent and irregularly breaking when old. <i>Seeds</i> numerous, black, shiny, irregularly angular reflecting tight packing in fruit; aril white, lacerate. <b>KEY TO THE AFRICAN GENERA OF COSTACEAE</b> 1. Plants erect, leaves generally more than two, occasion-ally in a basal rosette; inflorescence many-flowered, bracts conspicuous and often brightly coloured........ <i>Costus</i> 1. Plants prostrate, leaves solitary, never in a basal rosette; inflorescence few-flowered, bracts inconspicuous and not brightly coloured....................... <i>Paracostus</i>
description: Published as part of <i>Kamer 1, H. Maas-van de, Maas 1, P. J. M., Wieringa 1, J. J. &amp; Specht, C. D., 2016, Monograph of African Costaceae, pp. 280-318 in Blumea 61 (3)</i> on page 288, DOI: 10.3767/000651916X694445, http://zenodo.org/record/7570023