Comprehensive Description

provided by Smithsonian Contributions to Botany
Atractantha falcata McClure

Plantarum habitus non adhuc relatus. Culmi in specimine suppetenti neque satis representati neque descripti, itaque ignoti. Vaginae culmi et vaginae ramorum primariorum in specimene suppetenti deficientes. Vagina foliorum arcta, initio hispida hispidulaque demum subglabrescens; versus apicem tantum nervis interdum debiliter manifestis; auriculis vel subnullis vel sat evolutis glebosisque; setis oralibus paucis, e basi ad apicem sensim angustatis, omnino glabris vel basin versus sparsissime et antrorse scaberulis, fragilissimis, vel mox vel postea effractis; ligula interiore subnulla, truncata; ligula exteriore truncata, margine primo sparse et minutissime ciliolata denique glabrescenti integraque; petiolo vix 2 mm longo, pagina adaxiali hispidulo pagina abaxiali hirsuto; lamina usque 10.5 cm longa et 1.0 cm lata, lineari-lanceata, apice acuta, basi rotundata, basin versus utrinsecus sparse hirsuta, alibi utrinsecus primo antrorse hispidula, denique sensim glabrescenti; costa mediana et tribus paribus nervorum secundariorum pagina abaxiali sat prominulis; pagina adaxiali inter omnes nervos propinquos profunde et angustissime sulcata, prope marginem externam costa alata penitus instructa; venulis transversis extus haud manifestis.

Inflorescentiae ramos ramulosque vel foliigeros vel aphyllos terminantes, ob rhachidibus ramificationibus insertionis sympodialis falcatae diffusaeque. Bracteae e quoque rhachidi proditae pleraeque 2, altera gemmam subtendenti altera vacua, approximatae, laminiferae, paucinerves, substantia indurata sed fragili, dorso sparsim puberulae. Spiculae usque 15 mm longae, maturitate cadentes; ubi unaquaque spicla delapsa relictum est segmentum terminale rhachidis a bractea persistenti fere omnino vestitum. Glumae transitionales nullae. Anthecia papyracea, glabra nitidaque, nervis extus vix vel haud manifestis. Lemma usque 15 mm longum, lanceatum, attenuate acuminatum. Palea lemmate brevior, secus margines sulci angustissimi antrorse ciliata. Lodiculae diaphanae, angustae, margine apicem versus sparsim ciliolatae. Antherae apice emarginatae, basi profunde divisae, ubi desiccatae brunneae. Ovarium vel omnino glabrum vel apice tantum hispidulum. Stylus antrorse hispidulus. Fructus maturus adhuc non visus.

Plants of unrecorded habit. Culms neither represented nor described in the available specimen. Culm sheaths and sheaths of the primary axes of branch complements lacking in the specimen. Leaf sheaths tight, hispid and hispidulous at first, at length subglabrous; nerves sometimes weakly discernible toward the apex only; auricles either sub-obsolete or somewhat developed and lumpy; oral setae few, tapered, glabrous throughout or sparsely and antrorsely scaberulous basally, very fragile, sooner or later broken off; the inner ligule truncate, not at all or barely exserted; the outer ligule truncate, sparsely ciliolate on the margin at first, at length glabrescent and entire; petiole scarcely 2 mm long, hispidulous on the adaxial surface, and hirsute on the abaxial; the blade up to 10.5 cm long and 1.0 cm broad, linear-lanceolate, apically acute, basally rounded, sparsely hirsute on both surfaces at the base, elsewhere antrorsely hispidulous at first, then gradually glabrescent on both surfaces; the conventional midrib and three pairs of secondary nerves moderately prominent on the abaxial surface, narrowly and deeply sulcate between all adjacent nerves of the adaxial surface, with a winglike rib from base to tip near the outer margin and, at the same time, the midrib obsolete toward the apex on this surface; transverse veinlets not at all manifest on either surface.

Inflorescences terminating leafy and subleafless branches of all orders; of diffuse, falcate branching, the rachis branches of sympodial insertion. Bracts at the base of each rachis commonly 2, approximate, laminiferous, few-nerved, of indurate but brittle substance, sparsely puberulent dorsally, one subtending a bud, the other empty. Spikelets up to 15 mm long, falling away at maturity, each at length leaving the ca 5 mm long terminal segment of its rachis almost completely clothed in a persistent bract. Transitional glumes at the base of each spikelet none. Anthecia papyraceous, glabrous and lustrous, without externally discernible nerves. Lemma up to 15 mm long, lanceate, attenuately acuminate. Palea shorter than the lemma, the sulcus very narrow, with its edges marked by a row of antrorse cilia. Lodicules diaphanous, narrow, sparsely ciliate on the margin apically. Anthers dark brown when dry, sagittate basally and emarginate apically, the tip of each half curving outward. Ovary glabrous throughout or antrorsely hispidulous apically. Style antrorsely hispidulous. Mature fruit not yet seen.

ETYMOLOGY.—The trivial name, falcata, alludes to the curvature that characterizes the branches of the inflorescences. This curvature is construed as induced by the sympodial nature of the branching of the individual rachises.

HOLOTYPE.—In the U.S. National Herbarium (no.2040296) collected in a “carrascal” [forest of small trees] at Esplanada, Bahia, Brasil, sometime during 1950–51, by Geraldo Pinto (no. 0681).
bibliographic citation
McClure, F. A. 1973. "Genera of Bamboos Native to the New World (Gramineae: Bambusoideae)." Smithsonian Contributions to Botany. 1-148. https://doi.org/10.5479/si.0081024X.9