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Acroceras zizanioides

(Arrocillo)

Common Names

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Common Names in Spanish:

Arrocillo

Description

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Family Poaceae

Annual or perennial herbs, or tall woody bamboos . Flowering stems (culms ) jointed , internodes hollow or solid; branches arising singly from nodes and subtended by a leaf sheath and 2-keeled prophyll, often fascicled in bamboos. Leaves arranged alternately in 2 ranks , differentiated into sheath, blade , and an adaxial erect appendage at sheath/blade junction (ligule) ; leaf sheath surrounding and supporting culm-internode, split to base or infrequently tubular with partially or completely fused margins , modified with reduced blade in bamboos (culm sheaths) ; leaf blades divergent, usually long, narrow and flat, but varying from inrolled and filiform to ovate , veins parallel, sometimes with cross-connecting veinlets (especially in bamboos) ; ligule membranous or a line of hairs . Inflorescence terminal or axillary , an open, contracted , or spikelike panicle, or composed of lax to spikelike racemes arranged along an elongate central axis, or digitate, paired , or occasionally solitary; axillary inflorescences often many, subtended by spatheoles (specialized bladeless leaf sheaths) and gathered into a leafy compound panicle; spikelets often aggregated into complex clusters in bamboos. Spikelets composed of distichous bracts arranged along a slender axis (rachilla) ; typically 2 lowest bracts (glumes ) empty, subtending 1 to many florets ; glumes often poorly differentiated from accompanying bracts in bamboos. Florets composed of 2 opposing bracts enclosing a single small flower, outer bract (lemma) clasping the more delicate, usually 2-keeled inner bract (palea) ; base of floret often with thickened prolongation articulated with rachilla (callus) ; lemma often with apical or dorsal bristle (awn ), glumes also sometimes awned . Flowers bisexual or unisexual ; lodicules (small scales representing perianth) 2, rarely 3 or absent, 3 to many in bamboos, hyaline or fleshy ; stamens 3 rarely 1, 2, 6, or more in some bamboos, hypogynous, filaments capillary , anthers versatile; ovary 1-celled, styles (1 or) 2(rarely 3), free or united at base, topped by feathery stigmas, exserted from sides or apex of floret. Fruit normally a dry indehiscent caryopsis with thin pericarp firmly adherent to seed, pericarp rarely free, fleshy in some bamboos; embryo small or large; hilum punctate to linear .

About 700 genera and 11,000 species: widely distributed in all regions of the world.[1]

Genus Acroceras

Annuals or perennials . Culms decumbent , often rooting near the base . Leaf blades flat, lanceolate or linear-lanceolate, usually with obscure transverse veins; ligule a narrow membrane . Inflorescence of lax racemes along a central axis, sometimes panicle-like due to irregular secondary branching; spikelets paired or rarely single, pedicels of each pair connate at base. Spikelets lanceolate to oblong , plump, dorsally or weakly laterally compressed , glabrous , florets 2; glumes subequal or lower glume shorter, papery ; upper glume and lower lemma thickened and laterally compressed at apex to form a green crest ; upper lemma dorsally compressed , crustaceous , smooth or finely striate , apex glabrous with a little green crest; upper palea with reflexed apex slightly protruding from lemma. x = 9.

Nineteen species: throughout the tropics (12 species endemic to Madagascar) ; two species in China.

Acroceras species are grasses of damp, shady situations, recognized by the thickened, green crests at the tips of the spikelet scales. The leaf anatomy contrasts with that of the closely related genus Setiacis, with long cells differing in shape on the abaxial and adaxial surfaces, silica bodies short and dumbell-shaped to cross-shaped, and stomatal subsidiary cells dome-shaped.[2]

Habitat

Typically found at an altitude of 0 to 3,051 meters (0 to 10,010 feet).[3]

Taxonomy

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Notes

Publishing author : Dandy Publication : J. Bot. 69: 54 1931 Basionym author: (Kunth)Place of publication: J. Bot. 69:54. 1931

Name verified on 02-Aug-1995 by ARS Systematic Botanists. Last updated: 02-Aug-1995

Similar Species

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Members of the genus Acroceras

ZipcodeZoo has pages for 31 species, subspecies, varieties, forms, and cultivars in this genus:

A. amplectens (Acroceras) · A. attenuatum · A. basicladum · A. boivinii · A. bosseri · A. calcicola · A. chaseae · A. crassiapiculatum · A. diffusum · A. elegans · A. excavatum · A. fluminense · A. gabunense · A. hubbardii · A. ivohibense · A. macrum (Nile Grass) · A. mandrarense · A. manongarivense · A. munroanum · A. oryzoides · A. parvulum · A. paucispicata · A. paucispicatum · A. pilgerianum · A. ridleyi · A. sambiranense · A. sparsum · A. tenuicaule · A. tonkinense · A. zizanioides · A. zizanoides

More Info

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Further Reading

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Notes

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Contributors

Data Sources

Accessed through GBIF Data Portal November 15, 2007:

Identifiers

Footnotes

  1. Shou-liang Chen, De-Zhu Li, Guanghua Zhu, Zhenlan Wu, Sheng-lian Lu, Liang Liu, Zheng-ping Wang, Bi-xing Sun, Zheng-de Zhu, Nianhe Xia, Liang-zhi Jia, Zhenhua Guo, Wenli Chen, Xiang Chen, Yang Guangyao, Sylvia M. Phillips, Chris Stapleton, Robert J. Soreng, Susan G. Aiken, Nikolai N. Tzvelev, Paul M. Peterson, Stephen A. Renvoize, Marina V. Olonova & Klaus Ammann "Poaceae". in Flora of China Vol. 22. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at EFloras.org. [back]
  2. Shou-liang Chen & Sylvia M. Phillips "Acroceras". in Flora of China Vol. 22 Page 500, 514. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at EFloras.org. [back]
  3. Mean = 289.260 meters (949.016 feet), Standard Deviation = 756.890 based on 184 observations. Altitude information for each observation from British Oceanographic Data Centre. [back]
Last Revised: 7/2/2009