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Poaceae

禾本科

Flora of Taiwan
Gramineae 禾本科
特徵描述
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特徵描述

[ Gramineae 禾本科 ]

作者

HSU, Chien-Chang

型態特徵

Annuals or perennials herbs, rather rarely with woody perennials culms (subfamily Bambusoideae); hollow or solid, septate at nodes. Perennials herbs or their branches at base usually with scales (cataphylls, transformed leaf sheaths). Leaves two-ranked, consisting of a sheath, ligule, and a blade. Axillary buds when grown out into a branch provided with a usually 2-nerved bract (prophyll) between branch and culm. Leaf blade mostly linear and not petiolate at base, rarely with broad blades and stipitate (pseudo-petiole) at base (especially in Bambusoideae); ligules membranaceous or ciliate, rarely lacking (Echinochloa), margins of sheath of leaf connate at least at base. Inflorescences usually terminal, primarily paniculate, but secondarily extremely variable and transformed into racemes, spikes, digitate umbels, etc. Flowering unit (spikelet) usually with 2 bracteoles (glumes) at base; base occasionally with an obconical blunt to very acute thickening (callus). Flowers alternatingly along a central axis (rachilla) supported by a bract (lemma) and a prophyll (palea), bisexual or occasionally unisexual. Lemma and palea when falling as a unit clasping fruit at base often with an obconical blunt to very acute thickening (also called callus). Perianth usually composed of 2 or 3 minute scales (lodicules), rarely 6, sometimes absent (e.g. in sterile or female florets). Stamens usually 3, sometimes 6 (Bambusoideae), or 1 or 2; filaments filiform; anthers 2-locular. Pistil 1, superior; ovary and single anatropous ovule completely adnate; styles 2 or 3, apical or subapical, stigmas plumose. Caryopsis with rich endosperm; embryo basal, abaxial (facing lemma), opposite to punctiform to linear adaxial hilum (facing palea).

The Gramineae are one of the largest families of vascular plants with an estimated 620 genera and 10,000 species. Keng (1965) reported 201 genera and 775 species for mainland China. Hsu (1974) treated 5 subfamilies (excluding Bambusoideae), 27 tribes, 118 genera, 289 species, 1 subspecies, 39 varieties, and 8 forms in Taiwan.

The following arrangement of subfamilies, tribes and genera is that of Hsu (1978) with very few modifications. The descriptions of most genera are unchanged in this edition except that genera of the subfamily Pooideae (Festucoideae) which was mostly adopted from Clayton and Renvoize (1986). Some critical remarks were provided by Dr. J. F. Veldkamp, National Herbarium of the Netherlands, Leiden. Some line-drawings of Paniceae were drawed by Y. Fujimoto, Botanical Institute of Fujimoto, Kobe, Japan.

參考文獻

Pennisetum 狼尾草屬

作者

LIU, Ho-Yih

型態特徵

Annuals or perennials; culms solid, erect or ascending, sometimes creeping. Ligule short, glabrous or ciliate; blades linear, narrow or wide, flat conduplicate or inrolled, with scabrid margins. Inflorescence a spike-like panicle, composed of spiculate units, arranged on all sides of an elongated central axis, rarely consisting of 2-4-spikelets and remaining partly or totally encloseed in upper-most leaf; units consisting of 1-4-spikelets inside an involucre, consisting of bristles, unites sessile or stipitate, falling off as a whole; bristles free, unequal, scabrid or feathery. Spikelets terete, ovate-lanceolate, 2-flowered; glumes and lemma thin and hyaline, glabrous or hairy; lower glume small, 0-3-veined; upper glume larger, 1-3-veined; upper palea 2-veined, thin or 0; lower lemma slightly shorter than spikelet, or sometimes as long, with broadly incurved margins, 3-8-veined; lower palea present or 0; upper lemma reaching apex of spikelet, with broaldy incurved margins, 4-7-veined; upper palea 2-veined, thin or less thin; lodicules absent; stamens 3, anthers linear with glabrous or penicillate tip, styles connate, stigma long, exserted apically, straight; flower protogynous. Caryopsis free, enclosed inside indurate or nonindurated upper lemma and upper palea, dorsally compressed, elliptic, pear shaped or obovate; hilum punctiform, embryo large.

About 80 species throughou the tropics. Four species in Taiwan.

參考文獻

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