The grass genera of the world

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

Danthonidium C.E. Hubb.

Habit, vegetative morphology. Annual; caespitose. Culms 10–60 cm high; herbaceous; unbranched above. Leaves not basally aggregated; non-auriculate. Leaf blades narrow; 1–2.5 mm wide (to 7.5 cm long); without cross venation. Ligule a fringe of hairs.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.

Inflorescence. Inflorescence a single raceme (short, many sided); contracted; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; not secund; very shortly pedicellate.

Female-fertile spikelets. Spikelets about 11 mm long; compressed laterally; disarticulating above the glumes. Rachilla prolonged beyond the uppermost female-fertile floret; hairy (above the floret, and spathulate); the rachilla extension with incomplete florets. Hairy callus present (slender, narrowly truncate).

Glumes two; very unequal (G1 longer); exceeding the spikelets; long relative to the adjacent lemmas (the longer much exceeding it); hairless; glabrous; pointed; awned (both shortly awn-tipped); non-carinate; similar (papery, lanceolate). Lower glume 5 nerved. Upper glume 3 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped. Spikelets without proximal incomplete florets.

Female-fertile florets 1. Lemmas cylindrical; convolute (enfolding the palea); decidedly firmer than the glumes (cartilaginous or leathery); becoming indurated; shortly and broadly 2 lobed (the lobes glabrous); not deeply cleft; awned. Awns 3; median and lateral; the median different in form from the laterals; from a sinus (or just behind?); geniculate; hairless (scabrid); much longer than the body of the lemma. The lateral awns shorter than the median (straight, terminating the lobes). Lemmas hairy. The hairs in transverse rows (one row, above the middle, and a dense basal row from the callus). Lemmas non-carinate; 9 nerved. Palea present; relatively long; apically notched; awnless, without apical setae to with apical setae; not indurated (thin); 2-nerved; 2-keeled. Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Anthers not penicillate; without an apically prolonged connective. Ovary apically glabrous. Stigmas 2.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells differing markedly in wall thickness costally and intercostally (the intercostals thicker walled). Mid-intercostal long-cells rectangular, or fusiform (mixed); having markedly sinuous walls. Microhairs present; panicoid-type (slender); 24–27–33 microns long; 3–4.5 microns wide at the septum. Microhair total length/width at septum 5.3–11. Microhair apical cells 18–24 microns long. Microhair apical cell/total length ratio 0.67–0.75. Stomata common; (34–)36 microns long. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs (and solitary); silicified. Costal short-cells conspicuously in long rows (mainly in very long, uninterrupted rows of very short cells, with a silica body in every other cell). Costal silica bodies exclusively oryzoid (small, very regular vertical dumb-bells).

Transverse section of leaf blade, physiology. C3; XyMS+. Midrib conspicuous (as a larger bundle with a large flat-bottomed keel); with one bundle only; with colourless mesophyll adaxially (apparently with some colourless tissue between the adaxial fibres and the bundle). Bulliforms not present in discrete, regular adaxial groups. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders absent (each bundle with a wide adaxial strand and a small abaxial girder). Sclerenchyma all associated with vascular bundles.

Classification. Watson & Dallwitz (1994): Arundinoideae; Danthonieae. Soreng et al. (2015): Danthonioideae. 1 species (D. gammiei).

Distribution, phytogeography, ecology. Bombay.

Species of open habitats. Stony places.

References, etc. Morphological/taxonomic: Hubbard 1937a. Leaf anatomical: studied by us.

Special comments. Fruit data wanting. Illustrations. • D. gammiei, as Danthonia: Bhide, J. As. Soc. Beng. 513 (1912)

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.’.