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The grass genera of the world

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

Mosdenia Stent

Name referring to geography (Mosdene, Transvaal).

Habit, vegetative morphology. Perennial; stoloniferous (the stolons with densely imbricate cataphylls). Culms 10–90 cm high; herbaceous; unbranched above. Culm internodes solid. Plants unarmed. Young shoots intravaginal. Leaves mostly basal (those on the culms with reduced blades), or not basally aggregated; non-auriculate. Leaf blades linear to linear-lanceolate; narrow; to 5 mm wide (and to 12 cm long); without abaxial multicellular glands; without cross venation; persistent. Ligule present; an unfringed membrane (laciniate); 0.3–0.5 mm long.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant, or all alike in sexuality; hermaphrodite, or hermaphrodite and sterile (those at the tip of the inflorescence sometimes reduced).

Inflorescence. Inflorescence a single spike (a dense, continuous, elongated bottlebrush, the spikelets spreading at right angles to the axis); espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; not secund; not two-ranked (in whorls or spirals); sessile, or subsessile (‘on minutely tomentose notches’); imbricate.

Female-fertile spikelets. Spikelets 2.5–3.75 mm long (sub-falcate); falling with the glumes; with conventional internode spacings. Rachilla terminated by a female-fertile floret. Hairy callus present. Callus short; blunt.

Glumes two; more or less equal (the G1 slightly longer and broader); about equalling the spikelets (or somewhat longer); long relative to the adjacent lemmas (exceeding them); lateral to the rachis; hairless (glabrous save at callus); pointed; awnless; carinate (G1), or non-carinate; very dissimilar (the G2 narrower, flat-backed). Lower glume about equalling the lowest lemma (slightly exceeding it); 1 nerved. Upper glume 1 nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.

Female-fertile florets 1. Lemmas small, ovate-lanceolate; less firm than the glumes; delicate, hyaline; entire; pointed; awnless; hairless; carinate; without a germination flap; 1 nerved, or 3 nerved. Palea present; relatively long; apically notched (minutely); awnless, without apical setae; textured like the lemma (delicate, hyaline); not indurated; 2-nerved; 2-keeled. Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Anthers 1.3–1.5 mm long; not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles free to their bases. Stigmas 2; red pigmented (purple), or brown.

Fruit, embryo and seedling. Fruit free from both lemma and palea; small (about 1.5 mm long); ellipsoid; longitudinally grooved; compressed dorsiventrally (dorsally). Hilum short (elliptical). Pericarp fused. Embryo large (about 1/3 the length of the fruit).

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (the costals more regularly narrow). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; chloridoid-type. Stomata common. Subsidiaries low dome-shaped. Intercostal short-cells absent or very rare (few). Costal short-cells conspicuously in long rows. Costal silica bodies present in alternate cell files of the costal zones; ‘panicoid-type’; cross shaped (to rectangular, near the leaf margins), or dumb-bell shaped (elsewhere); not sharp-pointed.

Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.

C4; XyMS+. PCR sheaths of the primary vascular bundles interrupted; interrupted both abaxially and adaxially. PCR sheath extensions absent. PCR cell chloroplasts centripetal. Mesophyll with radiate chlorenchyma; traversed by columns of colourless mesophyll cells (seemingly, in places), or not traversed by colourless columns (but the bulliform-plus-colourless cell groups very deeply penetrating). Leaf blade ‘nodular’ in section to adaxially flat. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups; in simple fans and associated with colourless mesophyll cells to form deeply-penetrating fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with all the bundles); forming ‘figures’ (most bundles with rectangular adaxial and winged-crescentic abaxial girders).

Cytology. 2n = 40.

Classification. Watson & Dallwitz (1994): Chloridoideae; main chloridoid assemblage. Soreng et al. (2015): Chloridoideae; Cynodonteae; Perotidinae. 1 species (M. leptostachys).

Distribution, phytogeography, ecology. South Africa.

Mesophytic; species of open habitats; glycophytic. Dry savanna.

References, etc. Morphological/taxonomic: Stent 1922. Leaf anatomical: photos of M. leptostachys provided by R.P. Ellis.

Illustrations. • M. leptostachys, as M. waterbergensis: Stent (1922), Bothalia 1. • General aspect (M. leptostachys): Gibbs Russell et al., 1990

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.’.