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Gramineae

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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

Dactyloctenium 龍爪茅屬

作者

HSU, Chien-Chang

型態特徵

Annuals or perennials; culms more or less compressed, filled with pith, glabrous, long internodes sometimes alternating with one or more short ones; ligule short. Blades flat. Inflorescence consisting of secund, digitately arranged spikes, rarely solitary. Spikelets crowded, sessile, alternate on abaxial side of rachis with upper glume on outer side of spike, at first imbricate, afterward spreading, strongly laterally compressed, 2-4-flowered, ultimate floret rudimentary, others bisexual; rachilla not produced, articulate below lower lemma; glumes shorter than spikelet, deeply cymbiform-keeled, 1-nerved; lower glume acute, persistent; upper glume mucronate or with short awn, rarely obtuse, 2-keeled, long-persistent; lodicules 2, cuneate; stamens 3; ovary glabrous, styles 2, free, stigmas narrow. Caryopsis ellipsoid, terete or compressed, rugose, granulate or smooth, apex notched, truncate or rounded; pericarp thin, free, embryo to 1/2 as long as caryopsis, hilum punctiform, basal.

參考文獻

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