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The grass genera of the world

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

Taeniorhachis T.A. Cope

Habit, vegetative morphology. Perennial; rhizomatous and stoloniferous. Culms up to 8 cm high; herbaceous; 2–5 noded (?). Culm nodes hidden by leaf sheaths. Leaves not basally aggregated; conspicuously distichous; non-auriculate; without auricular setae. Leaf blades lanceolate to ovate; ‘rigid, with white cartilaginous margins, densely pubescent especially below’; narrow; about 2–4 mm wide (?); flat, or folded; without cross venation (?); persistent (?). Ligule an unfringed membrane, or a fringed membrane (? - state indistinguishable from the illustration, not mentioned in the description); truncate (very short).

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality.

Inflorescence. Inflorescence of spicate main branches; digitate. Primary inflorescence branches 2 (the pair of conjugate ‘racemes’ 1.5–2.5 cm long, their rachides 2.5–3 mm wide). Rachides hollowed, flattened, and winged (triquetrous, broadly winged laterally, narrowly winged ventrally down the middle). Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes (the conjugate ‘racemes’) paired; disarticulating; falling entire. Spikelets unaccompanied by bractiform involucres, not associated with setiform vestigial branches; paired; secund; biseriate (the pairs alternating on either side of the median ridge on the ventral side of the rachis); pedicellate; imbricate; consistently in ‘long-and-short’ combinations; unequally pedicellate in each combination. Pedicels of the ‘pedicellate’ spikelets free of the rachis. The ‘shorter’ spikelets hermaphrodite. The ‘longer’ spikelets hermaphrodite.

Female-fertile spikelets. Spikelets 6–6.5 mm long; elliptic to lanceolate (lanceolate-elliptic); abaxial (?); compressed dorsiventrally; planoconvex (flattened ventrally, convex dorsally); falling with the glumes (?). The upper floret not stipitate. Rachilla terminated by a female-fertile floret. Hairy callus absent.

Glumes two; (the upper) relatively large; very unequal (the lower a minute scale 0.5–0.6 mm long, the upper much larger and more substantial); shorter than the spikelets (the larger, upper glume being about 2/3 the length of the spikelet); shorter than the adjacent lemmas; hairy (the upper being pilose between the nerves); awnless; non-carinate; very dissimilar (the lower a minute, ovate scale, the upper lanceolate and membranous). Lower glume 0 nerved. Upper glume 3 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. The proximal incomplete florets 1; epaleate; sterile. The proximal lemmas prominently nerved, villous in the outer interspaces; awnless; 9–11 nerved (the nerves close together); more or less equalling the female-fertile lemmas.

Female-fertile florets 1. Lemmas acuminate, chartaceous with hyaline margins, finely longitudinally striate; decidedly firmer than the glumes (chartaceous); finely striate; not becoming indurated; entire; pointed (acuminate); awnless; hairless (?); non-carinate; having the margins lying flat on the palea (the hyaline margins enfolding and concealing most of the palea). Palea present; relatively long (?); tightly clasped by the lemma; awnless, without apical setae.

Fruit, embryo and seedling. Fruit ‘pallid’; ellipsoid.

Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; presumably Paniceae (seemingly a Digitaria relative, but not reliably assignable from the available description). Soreng et al. (2015): Panicoideae; Panicodae; Paniceae; Anthephorinae. 1 species (T. repens Cope).

Distribution, phytogeography, ecology. Collected only once, in Somalia northeast of Mogadishu.

Not known in Australasia.

Xerophytic; species of open habitats; halophytic. On a coastal dune of white sand.

References, etc. Morphological/taxonomic: Cope 1993.

Special comments. These very inadequate data have been encoded, with some tentative guesswork, from the original very poor description and illustration. The former (including Latin diagnosis) occupies only one page, but includes the statement ‘Caryopsis not seen’, separated by 8 lines from ‘fruit ellipsoid, pallid’. Ligule, spikelet orientation, female-fertile palea, lodicules, androecium (etc.) are neither dealt with in the text nor represented in the illustration. Fruit data wanting. Anatomical data wanting.


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: 13th November 2017. delta-intkey.com/grass’.

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