| # The grass genera of the world |

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

### Cyrtococcum Stapf

From the Greek kurtos (curved, crooked) and kokkos (a fruit), alluding to the gibbous spikelets.

Type species: Type: C. setigerum Stapf = C. chaetophoron (Roem. & Schult.) Dandy.

Habit, vegetative morphology. Annual, or perennial; stoloniferous, or decumbent. Culms 15–100 cm high; herbaceous. Culm nodes glabrous. Culm leaf sheaths compressed. Culm internodes hollow. Leaves not basally aggregated; non-auriculate. Leaf blades linear-lanceolate to ovate; broad, or narrow; cordate, or not cordate, not sagittate; pseudopetiolate, or not pseudopetiolate; cross veined, or without cross venation; persistent; rolled in bud. Ligule an unfringed membrane to a fringed membrane.

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

Inflorescence. Inflorescence paniculate; open, or contracted. Primary inflorescence branches inserted all around the main axis. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate. Pedicel apices cupuliform.

Female-fertile spikelets. Spikelets 1–2.5 mm long; oblong, or elliptic, or obovate; gibbous, compressed laterally; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus absent.

Glumes two; more or less equal; shorter than the spikelets; shorter than the adjacent lemmas; awnless; carinate; similar (membranous, the upper blunt). Lower glume 1–3 nerved. Upper glume 3 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. The proximal incomplete florets 1; paleate, or epaleate. Palea of the proximal incomplete florets when present, reduced. The proximal incomplete florets sterile. The proximal lemmas blunt; awnless; 3–5 nerved; more or less equalling the female-fertile lemmas; less firm than the female-fertile lemmas to decidedly firmer than the female-fertile lemmas; not becoming indurated.

Female-fertile florets 1. Lemmas naviculate, gibbous on the back; saccate; decidedly firmer than the glumes (papery to crustaceous); smooth, or striate; becoming indurated to not becoming indurated; white in fruit; entire; pointed; crested at the tip; awnless; hairless (smooth, shiny); carinate; having the margins inrolled against the palea; with a clear germination flap; 5 nerved. Palea present; relatively long; entire; awnless, without apical setae; textured like the lemma; indurated, or not indurated; 2-nerved. Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Anthers not penicillate. Ovary apically glabrous. Styles free to their bases. Stigmas 2.

Fruit, embryo and seedling. Fruit small; compressed laterally. Hilum short. Embryo large; not waisted.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present, or absent. Intercostal papillae not over-arching the stomata; consisting of one symmetrical projection per cell. Long-cells markedly different in shape costally and intercostally (the costals narrowly rectangular); of similar wall thickness costally and intercostally (very thin walled). Intercostal zones without typical long-cells (these being irregularly equidimensional). Mid-intercostal long-cells having markedly sinuous walls. Microhairs present; panicoid-type; 39–50 microns long; about 4.5 microns wide at the septum. Microhair total length/width at septum about 8.7. Microhair apical cells (17–)18–22(–27) microns long. Microhair apical cell/total length ratio 0.43–0.46. Stomata common. Subsidiaries low dome-shaped, or triangular; including both triangular and parallel-sided forms on the same leaf, or not including both parallel-sided and triangular forms on the same leaf. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare. Costal short-cells conspicuously in long rows. Costal silica bodies sometimes sharp-pointed, ‘panicoid-type’, or saddle shaped; cross shaped, or butterfly shaped, or dumb-bell shaped; sharp-pointed to not sharp-pointed.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with radiate chlorenchyma; without adaxial palisade; Isachne-type. Leaf blade with distinct, prominent adaxial ribs, or ‘nodular’ in section; with the ribs more or less constant in size. Midrib conspicuous, or not readily distinguishable (rarely); with one bundle only, or having a conventional arc of bundles. 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.

Culm anatomy. Culm internode bundles in one or two rings.

Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Isachneae. Soreng et al. (2015): Panicoideae; Panicodae; Paniceae; Boivinellinae. 12 species.

Distribution, phytogeography, ecology. Palaeotropical.

Commonly adventive. Mesophytic; shade species. Forests.

Economic aspects. Significant weed species: C. accrescens, C. oxyphyllum, C. patens. Important native pasture species: e.g. C. patens.

Rusts and smuts. Rusts — Physopella and Puccinia. Taxonomically wide-ranging species: Physopella clemensiae, Puccinia orientalis, and ‘Uromyces’ setariae-italicae.

References, etc. Leaf anatomical: Metcalfe 1960; studied by us - ‘Cyrtococcum sp.’.

Illustrations. • Cyrtococcum trigonum: Hook. Ic. Pl. 31 (1922). • Cyrtococcum. chaetophoron: Jacques-Félix, 1962. • Cyrtococcum sp., inflorescence detail.

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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