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Danthonia holm-nielsenii

Overview

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Vulnerable
Threat status

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 Danthonia

Perennial . Culms tufted , erect , cleistogenes often present in culm sheaths. Leaf blades narrow, flat or rolled; ligule a line of hairs . Inflorescence an open or contracted panicle, sometimes reduced to a raceme . Spikelets large, wedge-shaped, laterally compressed , florets several, rachilla disarticulating above glumes and between florets; glumes subequal , as long as spikelet, membranous or papery , (1-) 3-9-veined; floret callus short, obtuse ; lemmas herbaceous or papery, 7-9-veined, pilose on margins or all over, apex 2-lobed, lobes acute or extended into slender awns ; central awn arising from sinus , flat, column short, strongly twisted, bristle straight or sparsely twisted; palea equal to or shorter than its lemma. Lodicules 2, glabrous . Caryopsis with linear hilum up to 2/3 its length .

About 20 species: Asia, Europe, North and South America; two species in China.

Danthonia had a much broader circumscription in the past, including many species now placed in Rytidosperma. Species of Rytidosperma lack cleistogenes, and also differ from the above description in having lemma hairs in tufts, ciliate lodicules, and a punctiform hilum. Modern molecular studies have shown these two genera belong to different evolutionary lines. It is likely that the Himalayan species will be shown to be members of Rytidosperma, but some morphological characters are intermediate and the species have not yet been included in any molecular analysis. Further research is required to clarify their position.[2]

Taxonomy

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Similar Species

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Members of the genus Danthonia

ZipcodeZoo has pages for 294 species, subspecies, varieties, forms, and cultivars in this genus. Here are just 100 of them:

D. abyssinica · D. acerosa · D. airoides · D. albida · D. alleni · D. alpicola · D. alpina · D. americana · D. andina · D. andongensis · D. angulata · D. angustifolia · D. anisopogon · D. annableae · D. anomala · D. antarctica · D. anthoxanthiformis · D. araucana · D. archboldii · D. archeri · D. aristata · D. aristidoides · D. arundinacea · D. aureocephala · D. aureofulva · D. auriculata · D. australis · D. barbata · D. bipartita · D. boliviensis · D. borussica · D. brachyacme · D. brachyathera · D. brachyphylla · D. breviseta · D. bromoides · D. buchanani · D. buchananii · D. buekeana · D. cachemyriana · D. caespitosa · D. caespitosa var. gracilis · D. california · D. californica (California Oat Grass) · D. californica americana · D. californica var. unispicata · D. californicum · D. calva · D. calycina · D. canadensis · D. candida · D. capensis · D. carphoides · D. carphoides var. angustior · D. carphoides var. carphoides · D. cernua · D. charruana · D. chaseana · D. chiapasensis · D. chilensis · D. chilensis var. chilensis · D. chrysurus · D. cincta · D. cingula · D. circinnata · D. cirrata · D. cirrata var. melanathera · D. cirrhulosa · D. clelandii · D. collina · D. collinita · D. colorata · D. compacta · D. compressa (Flat-Stem Oat Grass) · D. confusa · D. coronata · D. craigii · D. crassiuscula · D. crispa · D. cumminsii · D. cunninghamii · D. curva · D. curvifolia · D. cusickii · D. cyatophora · D. davyi · D. decipiens · D. decora · D. decumbens (Mountain Heath Grass) · D. decumbens decipiens · D. decumbens subsp. decipiens · D. densifolia · D. denudata · D. depressa · D. diemenica · D. dimidiata · D. disticha · D. distichophylla · D. domingensis · D. domingensis shrevei

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 March 16, 2008:

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. Zhen-lan Wu & Sylvia M. Phillips "Danthonia". in Flora of China Vol. 22 Page 450, 451. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at EFloras.org. [back]
Last Revised: 2009-07-03