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The grass genera of the world

L. Watson, T.D. Macfarlane, and M.J. Dallwitz

Asthenochloa Buese

Including Garnotiella Stapf

Habit, vegetative morphology. Decumbent annual, or perennial. Culms herbaceous (slender); branched above. Leaves not basally aggregated. Leaf blades linear-lanceolate to lanceolate; narrow; not pseudopetiolate; without cross venation.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant (but obscurely so, the ‘pedicellate spikelet’ being reduced to a minute pedicel hidden in the callus hairs); hermaphrodite, or hermaphrodite and sterile (but the latter rudimentary).

Inflorescence. Inflorescence paniculate (decompound); open; spatheate; a complex of ‘partial inflorescences’ and intervening foliar organs. Spikelet-bearing axes very much reduced (pedicel-like, with cupuliform, long-hairy apices, bearing a plexus of a minute stipe (= rudiment of pedicelled spikelet), and one sessile spikelet); solitary; disarticulating; disarticulating at the joints (i.e., the spikelet and its vestigial companion (plus the bearded callus) articulate with the apex of the pedicel-like branchlet). ‘Articles’ with a basal callus-knob; densely long-hairy. Spikelets paired (but the pedicellate member suppressed); sessile and pedicellate (the latter reduced to their pedicels); consistently in ‘long-and-short’ combinations. Pedicels of the ‘pedicellate’ spikelets free of the rachis (but small and inconspicuous). The ‘shorter’ spikelets hermaphrodite. The ‘longer’ spikelets sterile (reduced to tiny pedicels).

Female-fertile spikelets. Spikelets 2–2.5 mm long; compressed dorsiventrally (?); falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus present (the hairs up to two thirds as long as spikelet).

Glumes two; more or less equal (G2 somewhat longer); long relative to the adjacent lemmas; glumes with ciliate margins; awned (sometimes, G2), or awnless; carinate (G2), or non-carinate (G1); very dissimilar (thinly herbaceous; G1 2-toothed, dorsally flattened; G2 acuminate or short-awned, naviculate). Lower glume flattened on the back; not pitted; relatively smooth; 2 nerved. Upper glume 3 nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.

Female-fertile florets 1. Lemmas less firm than the glumes (thinly membranous); not becoming indurated; incised; awned. Awns 1; median; from a sinus; geniculate; hairless (scabrid); much longer than the body of the lemma. Lemmas hairless (the lobes shortly ciliolate); non-carinate; 1 nerved (?). Palea absent. Lodicules absent. Stamens 2. Anthers not penicillate; without an apically prolonged connective. Ovary apically glabrous. Stigmas 2.

Fruit, embryo and seedling. Hilum short. Embryo large.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present; costal and intercostal. Intercostal papillae not over-arching the stomata; several per cell (one median row of papillae per long-cell). Long-cells markedly different in shape costally and intercostally (the costals narrower). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; elongated; clearly two-celled; panicoid-type; 39–51 microns long; 6–7.5 microns wide at the septum. Microhair total length/width at septum 6–7.5. Microhair apical cells 16–21 microns long. Microhair apical cell/total length ratio 0.33–0.43. Stomata common. Subsidiaries dome-shaped. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare. Costal short-cells conspicuously in long rows. Costal silica bodies ‘panicoid-type’.

Transverse section of leaf blade, physiology. Probably C4 (the material seen very poor). Midrib conspicuous; with one bundle only; with colourless mesophyll adaxially.

Classification. Watson & Dallwitz (1994): Panicoideae; Andropogonodae; Andropogoneae; Andropogoninae. Soreng et al. (2015): Panicoideae; Andropogonodae; Andropogoneae; Sorghinae. 1 species (A. tenera).

Distribution, phytogeography, ecology. Indonesian Archipelago.

Mesophytic. In damp places.

References, etc. Leaf anatomical: studied by us.

Illustrations. • A. philippinensis, as Garnotiella: Stapf in Hook. Ic. Pl. (1896). • A. philippinensis, Stapf description and legend

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, and classifications. See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., Macfarlane, T.D., and Dallwitz, M.J. 1992 onwards. The grass genera of the world: descriptions, illustrations, identification, and information retrieval; including synonyms, morphology, anatomy, physiology, phytochemistry, cytology, classification, pathogens, world and local distribution, and references. Version: 11th December 2017.’.