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Gramineae

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特徵描述
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特徵描述

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

Hemarthria 牛鞭草屬

作者

HSU, Chien-Chang

型態特徵

Perennials; culms branched, many noded, prostrate or ascending Ligule short, membranaceous, sometimes ciliate; blades linear, folded in bud, afterwards flat. Inflorescence a spike-like raceme, compressed, narrower and sterile at apex. Spikelets paired, one sessile, other pedicelate, pairs alternate along rachis; rachis not or tardily breaking up; sessile and pedicelate spikelet , dorsi-ventrally arranged, all of a kind towards same side of rachis. Sessile spikelets partially dorsally sunken into cavities formed by joint of rachis and adjacent pedicel, long-acuminate, falling entire, base long-decurrent on and adnate to rachis, acute, glabrous; lower glume abaxial, coriaceous, fiat, long-acuminate, narrowly wing-keeled, margins very narrowly inflexed, closely nerved; upper glume equally long, membranaceous, boat shaped, tightly pressed against wall of cavity; lemmas hyaline, smaller; paleas hyaline, nerveless, or wanting; lower lemma 2-nerved; upper lemma usually nerveless; lodicules 2, cuneate; stamens 3; stigmas laterally exserted. Caryopsis oblong, slightly dorsally compressed, hilum basal, punctiform, embryo ca. 2/3 as long as caryopsis. Pedicelate spikelets, especially higher ones longer, acuminate, pedicel adhering to rachis otherwise like sessile spikelet.

參考文獻

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