| # The grass genera of the world |

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

### Cleistachne Benth.

~ Sorghum

Habit, vegetative morphology. Annual. Culms 60–250 cm high; herbaceous; usually unbranched above (sometimes with stilt roots). Plants unarmed. Leaves non-auriculate. Leaf blades linear; broad, or narrow; 4–15 mm wide; rolled; pseudopetiolate (often), or not pseudopetiolate; without cross venation. Ligule an unfringed membrane (scarious); not truncate (apically rounded).

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

Inflorescence. Inflorescence paniculate (composed of racemes of greatly reduced ‘racemes’); large, terminal, linear to lanceolate; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes ostensibly ‘racemes’ (these long, narrow, with many joints); with very slender rachides; persistent. ‘Articles’ densely long-hairy, or somewhat hairy (the rachis and ostensible ‘pedicels’ with grey or brown hairs). Spikelets solitary (each seemingly representing a ‘raceme’ reduced to a single spikelet, cf. Sorghum, Sorghastrum); not secund; sessile (in that the ostensible ‘pedicels’ represent the peduncles of reduced lateral branches); not in distinct ‘long-and-short’ combinations.

Female-fertile spikelets. Spikelets 3 mm long, or 4–5(–6) mm long; compressed dorsiventrally; falling with the glumes (disarticulating from the apex of the peduncle). Rachilla terminated by a female-fertile floret.

Glumes two; more or less equal; long relative to the adjacent lemmas; hairy; not pointed (truncate); awnless; non-carinate; similar (leathery, with inrolled margins). Lower glume not two-keeled; not pitted; relatively smooth; 7–9 nerved. Upper glume 7–9 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. The proximal incomplete florets 1; epaleate; sterile. The proximal lemmas awnless; 2 nerved; decidedly exceeding the female-fertile lemmas; similar in texture to the female-fertile lemmas (hyaline); not becoming indurated.

Female-fertile florets 1. Lemmas less firm than the glumes (hyaline); not becoming indurated; incised; not deeply cleft (bidentate); awned. Awns 1; median; from a sinus; geniculate; hairless (glabrous); much longer than the body of the lemma. Lemmas hairy (ciliate apically); non-carinate; without a germination flap; 3 nerved. Palea present (but small); conspicuous but relatively short; entire; awnless, without apical setae (but ciliate); not indurated; seemingly nerveless; keel-less. Lodicules present; 2; free; fleshy; ciliate. Stamens 3. Ovary apically glabrous. Styles free to their bases. Stigmas 2.

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

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present. Mid-intercostal long-cells having markedly sinuous walls (thin). Microhairs present; panicoid-type; (45–)48–54(–58) microns long. Microhair apical cells 30–36 microns long. Microhair apical cell/total length ratio 0.65. Stomata common. Subsidiaries triangular. Intercostal short-cells absent or very rare. Costal short-cells conspicuously in long rows. Costal silica bodies ‘panicoid-type’; dumb-bell shaped and nodular.

Transverse section of leaf blade, physiology. C4; XyMS–. Mesophyll with radiate chlorenchyma. Leaf blade adaxially flat. Midrib conspicuous; having a conventional arc of bundles (with numerous bundles); with colourless mesophyll adaxially. Bulliforms present in discrete, regular adaxial groups; in simple fans (these large-celled towards the middle of the blade, the groups irregular towards the margins). Many of the smallest vascular bundles unaccompanied by sclerenchyma. Combined sclerenchyma girders present (with the large bundles). Sclerenchyma all associated with vascular bundles.

Cytology. Chromosome base number, x = 9. 2n = 36.

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

Distribution, phytogeography, ecology. Tropical Africa, India.

Helophytic to mesophytic; species of open habitats; glycophytic. Riverbanks and old farmland.

References, etc. Leaf anatomical: Metcalfe 1960.

Illustrations. • Cleistachne sorghoides: Hook. Ic. Pl. 14 (1882). • Cleistachne sorghoides: 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: 15th June 2025. delta-intkey.com’.

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