| # The grass genera of the world |

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

### Cleistochloa C.E. Hubb.

Type species: Type: C. hubbardiana Henrard.

Excluding Dimorphochloa

Habit, vegetative morphology. Perennial; caespitose. Culms 30–60 cm high; wiry; branched above. The branching suffrutescent, or simple. Culm nodes glabrous. Culm leaf sheaths rounded. Culm internodes hollow. Young shoots usually intravaginal. Leaves not basally aggregated; non-auriculate. Leaf blades narrow; flat, or rolled (rough, with tubercle-based hairs); not pseudopetiolate; without cross venation; disarticulating from the sheaths. Ligule a fringe of hairs.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets; the exposed spikelets chasmogamous; with hidden cleistogenes. The hidden cleistogenes in the leaf sheaths (borne singly, highly modified).

Inflorescence. Inflorescence few spikeleted; a single raceme (spike-like, terminating culm branches); espatheate. Spikelet-bearing axes persistent. Spikelets solitary; not secund; pedicellate (the pedicels very short). Pedicel apices cupuliform.

Female-fertile spikelets. Spikelets 3.5–4.5 mm long; oblong, or elliptic, or obovate; adaxial; compressed dorsiventrally; biconvex; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus absent.

Glumes present; one per spikelet, or two (the lower minute or absent); (the upper) relatively large; very unequal; shorter than the adjacent lemmas; free; dorsiventral to the rachis; not pointed (rounded); awnless; very dissimilar (G1 minute). Lower glume 0 nerved. Upper glume 5–7 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 1; epaleate; sterile. The proximal lemmas awnless (hairy on margins and apex); 7 nerved; more or less equalling the female-fertile lemmas; less firm than the female-fertile lemmas to similar in texture to the female-fertile lemmas; not becoming indurated.

Female-fertile florets 1. Lemmas similar to the L1; striate; not becoming indurated; yellow in fruit, or brown in fruit; entire; blunt; awnless; non-carinate; having the margins lying flat on the palea; with a clear germination flap; 5–7 nerved. Palea present; relatively long (margins hairy towards apex); entire (subacuminate); awnless, without apical setae; 2-nerved. Lodicules present; 2; free; fleshy. Stamens 3. Anthers 2.5 mm long; not penicillate. Ovary apically glabrous. Styles free to their bases. Stigmas 2.

Fruit, embryo and seedling. Fruit small; not noticeably compressed. Hilum short. Embryo large. Endosperm containing only simple starch grains. Embryo without an epiblast; with a scutellar tail; with an elongated mesocotyl internode. Embryonic leaf margins overlapping.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally (fairly thin walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; 48–54 microns long; 7.5–9 microns wide at the septum. Microhair total length/width at septum 5.3–7.2. Microhair apical cells 21–24 microns long. Microhair apical cell/total length ratio 0.44. Stomata common; 33–36 microns long. Subsidiaries dome-shaped (usually), or parallel-sided (rarely). Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs; silicified. Costal short-cells conspicuously in long rows. Costal silica bodies ‘panicoid-type’.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with radiate chlorenchyma; Isachne-type (or tending to this), or not Isachne-type. Leaf blade adaxially flat. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups; in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’. Sclerenchyma all associated with vascular bundles.

Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Paniceae. Soreng et al. (2015): Panicoideae; Panicodae; Paniceae; Neurachninae. 2 species.

Distribution, phytogeography, ecology. Australia.

Xerophytic; species of open habitats. Dry sandstone.

References, etc. Morphological/taxonomic: Hubbard 1933b. Leaf anatomical: studied by us - C. subjuncea Hubbard.

Illustrations. • Cleistochloa subjuncea: Hook. Ic. Pl. 33 (1935).

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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