| # The grass genera of the world |

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

### Tenaxia N.P. Barker & H.P Linder

~ Danthonia stricta Schrad., Merxmuellera

Type species: T. stricta (Schrad.) N.P. Barker & H.P. Linder.

Habit, vegetative morphology. Wiry, perennial; caespitose (without stolons). Culms 12–90 cm high; where recorded, unbranched above. Leaf blades setaceous, or not setaceous; flat, or rolled; not pseudopetiolate. Ligule a fringe of hairs.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets hermaphrodite. Plants without hidden cleistogenes.

Inflorescence. Inflorescence few spikeleted (sometimes), or many spikeleted; a single raceme, or paniculate; open, or contracted. Spikelets secund, or not secund; pedicellate.

Female-fertile spikelets. Spikelets compressed laterally; disarticulating above the glumes; not disarticulating between the florets. Rachilla presumably prolonged beyond the uppermost female-fertile floret (despite the Linder et al. description?); the rachilla extension assuming terminal florets reduced, with incomplete florets. Hairy callus present (villous). Callus shorter than the rachilla internode; blunt (rounded).

Glumes two; more or less equal; about equalling the spikelets to exceeding the spikelets; long relative to the adjacent lemmas; hairless; glabrous, or scabrous (on the keels); pointed; awnless; non-carinate; similar (lanceolate or elliptic, membranous). Lower glume much exceeding the lowest lemma; 1–7 nerved. Upper glume 1–11 nerved. Spikelets dubiously with female-fertile florets only, or with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped; awned. Spikelets without proximal incomplete florets.

Female-fertile florets 2–7. Lemmas elliptic or oblong; decidedly firmer than the glumes; not becoming indurated; incised; 2 lobed (the lobes with or without setae); deeply cleft to not deeply cleft; awned. Awns 1, or 3; median, or median and lateral (thus interpreting long setae - which sometimes arise on the inner sides of the lemma lobes, rather than their apices); median different in form from the laterals; from a sinus; (median) geniculate; about as long as the body of the lemma, or much longer than the body of the lemma (?). The lateral awns (setae) shorter than the median. Lemmas hairy, or hairless. The hairs when lemmas hairy, variously arranged, in tufts (at least some of these usually marginal), or not in tufts; in transverse rows (but not conspicuously 2-rowed, see Rytidosperma), or not in transverse rows. Lemmas non-carinate; without a germination flap; 7–9 nerved. Palea present; relatively long; entire; awnless, without apical setae. Palea back glabrous, or hairy. Lodicules present; 2; free; cuneate or rhomboid, fleshy, or membranous; ciliate (with bristles and microhairs). Stamens 3. Ovary apically glabrous.

Fruit, embryo and seedling. Fruit not grooved. Hilum elliptical to punctate, short, or short to long-linear. Pericarp fused. Embryo large.

Transverse section of leaf blade, physiology. The lamina distinctly asymmetrical on either side of the midrib to symmetrical on either side of the midrib.

Cytology. 2n = 12, or 36, or 56.

Classification. Watson & Dallwitz (1994): genus not recognised. Soreng et al. (2015): Danthonioideae; Danthonieae. 8 species.

Distribution, phytogeography, ecology. Montane Africa to the Himalayas.

Often in seasonably dry montain grassland.

References, etc. Morphological/taxonomic: Linder et al. (2010: poor); Grassbase (2016 - more detailed).

Special comments. Anatomical data wanting.

Illustrations. • Tenaxia stricta: Linder et al, Ann. Miss. Bot. Gard. 97 (2010).

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: 15th June 2025. delta-intkey.com’.

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