POACEAE
Dimeria R. Br., Prodr. Fl. Nov. Holland.: 204 (1810).
Haplachne J.Presl; Psilostachys Steud.; Pterygostachyum Nees ex Steud.; Woodrowia Stapf.
By: Watchara Arthan & Atchara Teerawatananon
Taxon Description
Plants annual or perennial. Culm erect, nodes pubescent, occasionally glabrous. Leaf blades linear to lanceolate. Racemes paired or digitate, unilateral, rachis internodes triquetrous or flattened, tough. Spikelets solitary, shortly pedicellate, laterally compressed, with 2 florets, lower floret sterile, reduced to a single lemma, upper floret bisexual, callus truncate, shortly bearded. Lower glumes elliptic, linear, or oblong, 1-keeled or without a keel, keel winged or wingless, apex obtuse to acuminate, chartaceous or coriaceous, puberulous or pilose, upper glumes similar to lower glumes, slightly longer. Lower lemmas linear or lanceolate, apex obtuse or acute, hyaline, glabrous, 1-veined, upper lemmas elliptic or obovate, apex bifid, 1-awned, hyaline, lemma awns geniculate, column glabrous, twisted. Paleas absent. Lodicules 2. Stamens 2. Stigmas 2. Caryopsis narrowly oblong, laterally compressed.
Taxon Statistics
Worldwide 57 species distributed in S Asia, E Asia, SE Asia, SW Asia, Africa and Australasia. Two species in Nepal.
Key to species
1a Rhachis internodes triquetrous. Spikelets 1–3 mm. Upper glumes wingless.………………………………………..…………………………………………… 1. D. ornithopoda
b Rhachis internodes flattened. Spikelets more than 3 mm. Upper glumes winged.………………………………………………………………………….… 2. D. chloridiformis
1. Dimeria ornithopoda Trin., Fund. Agrost.: 167 (1820).
Andropogon filiformis Roxb., nom. illeg.; A. roxburghianus Schult.; A. stipiformis Steud.; Dimeria avenacea subvar. ornithopoda (Trin.) Roberty; D. stipiformis (Steud.) Miq.
Plants annual, tufted. Culm erect, 2–20 cm, nodes pubescent. Leaf blades lanceolate, 2–4 × ca. 0.1 cm, abaxial and adaxial surfaces hairy, hairs tuberculate. Ligules irregularly toothed, less than 1 mm. Racemes 2 or 3(or 4), paired or digitate, 1.8–5 cm, rachis internode triquetrous. Spikelets linear- or elliptic-oblong, 1–3 mm, pedicels concave, glabrous, less than 1 mm, callus hairs less than 1 mm. Lower glumes linear-oblong, ca. 1.5 mm, 1-keeled, keel scabrous, winged or wingless, apex acute, chartaceous, pilose on abaxial side, upper glumes oblong, ca. 2 mm, without a keel, apex acute to acuminate, chartaceous, pilose on abaxial side. Lower lemmas lanceolate, ca. 1.5 mm, apex acuminate, upper lemmas elliptic, ca. 1 mm, apex bifid, 1-awned. Lemma awns 4.5–6.5 mm. Anthers less than 1 mm. Stigmas not seen.
Distribution: Nepal, W Himalaya, E Himalaya, S Asia, E Asia, SE Asia, SW Asia, and Australasia.
Altitude range: 1100–1900 m
Ecology: Grasslands, rice fields, seasonally flooded flatlands, secondary grassland, Schima forests, and stream banks.
Flowering: September–March.
Dimeria ornithopoda specimens collected so far in Nepal are smaller than specimens collected in other areas.
2. Dimeria chloridiformis (Gaudich.) K.Schum. & Lauterb., Fl. Schutzgeb. Südsee: 165 (1900).
Andropogon chloridiformis Gaudich.,Voy. Uranie. Bot.: 412 (1829); Dimeria ciliata Merr.; D. dipteros Reeder; D. fuscescens Trin.; D. pilosissima Trin.; Haplachne pilosissima J.Presl.
Plants perennial. Culm erect, 30–100 cm, nodes pubescent. Leaf blades linear, 3–25 × 0.2–0.5 cm, abaxial and adaxial surfaces hairy, hairs tuberculate. Ligules irregularly toothed, 0.5–1 mm. Racemes 3–6, digitate, 4–15 cm, rachis internode flattened. Spikelets oblong to ovate-oblong, 3.5–6 mm, pedicels concave, glabrous or ciliate, 0.3–1 mm, callus hairs 0.2–1 mm. Lower glumes linear or elliptic, ca. 4 mm, 1-keeled, keel scabrous or ciliate, winged or wingless, apex acute to acuminate, chartaceous, puberulous to pilose on both sides, upper glumes oblong or elliptic, ca. 5 mm, 1-keeled, keel scabrous or ciliate, apex acute, emarginate, chartaceous or coriaceous, scabrous on both sides. Lower lemmas linear or lanceolate, 2.5–4 mm, apex acuminate, upper lemmas elliptic or obovate, 2.5–5 mm, apex bifid, 1-awned. Lemma awns 4–17 mm. Anthers 0.8–3.5 mm. Stigmas ca. 1.5 mm.
Distribution: Nepal, Assam-Burma, S Asia, SE Asia; and Australasia.
Altitude range: 800–1300 m
Ecology: Savannas, wet and swampy places, and wet places
Flowering: August–April
The flowering time is taken from Indian material.