Ribbed Murainagrass (Ischaemum rugosum)
Description
A vigourous perennial or annual (in strongly desiccating soil) tufted grass, sometimes with stilt roots, rooting at the nodes, with erect, slanting or ascending, often much branched culms, up to 1.5 m tall. Leaf-sheath long-auricled, ciliate along outer margin, densely soft hairy on node; ligule a brownish truncate membrane, 1-7 mm long; leaf-blade linear, 10-40 cm x 1-4 cm, apex acute, rarely hairy with long slender hairs. Inflorescence terminal, well exerted, composed of 2 racemes that are firmly appressed together and interlocked when young, separating when mature, each 3-12 cm long; spikelets binate, dissimilar, one sessile at the abaxial side of the rachis, one stalked at the adaxial side, provided with a short blunt hairy callus; sessile spikelet 5-6 mm long, 2-flowered, lower floret male or neuter, upper one bisexual; lower glume strongly transversely 5-7-ribbed, and winged above; upper lemma deeply 2-cleft and with 1-2 cm long awn which is twisted basally; pedicelled spikelet more or less reduced, pedicel upto 2 mm long, hairy, confluent with the callus. Caryopsis ovoid, 2 mm long, brown. It is a very variable species. Two varieties have been distinguished: var. rugosum, with developed pedicelled spikelets, and var. segetum Hackel, with much reduced pedicelled spikelets; they are not separated geographically (Baki and Manidool 1992).
Taxonomic tree
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Domain: Eukarya
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Kingdom: Plantae
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Phylum: Magnoliophyta
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Class: Liliopsida
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Order: Poales
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Family: Poaceae
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Genus: Ischaemum
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