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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

Pogonatherum 金髮草屬

作者

HSU, Chien-Chang

型態特徵

Perennials; culms slender, hard. Leaf blade narrow. Inflorescence of spike-like racemes. Spikelets paired, one sessile, the other pedicelate, laterally compressed, with one broad side turned to rachis; rachis hairy, slender, fragile. Glumes and lemmas of sessile spikelet thinly membranaceous-hyaline; lower glume convex, not keeled; upper glume somewhat longer, strongly compressed, keeled, notched at apex with a long, very slender thread-like awn; lower lemma and lower palea wanting, or lower lemma present and with or without a lower palea; lower lemma convex, muticous, barren or with 3 stamens, rarely bisexual; lower palea nerveless; upper lemma strongly convex, keeled, with a long, slender, thread-like awn from short, acutely 2-lobed apex; upper palea nerveless; lodicules absent; styles 2, free, stigmas plumose, exserted apically. Caryopsis ellipsoid, ventral surface less convex.

參考文獻

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