| # The grass genera of the world |

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

### Chaetium Nees

Including Berchtoldia Presl

Habit, vegetative morphology. Perennial; caespitose. Culms herbaceous; unbranched above. Culm nodes glabrous. Culm internodes solid. Leaves mostly basal; non-auriculate. Leaf blades narrow; without cross venation; persistent.

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

Inflorescence. Inflorescence a single raceme, or paniculate (of loose racemes from the main axis); espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; not secund; pedicellate.

Female-fertile spikelets. Spikelets compressed dorsiventrally; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus present (the spikelet tapering into a slender, bearded stipe).

Glumes two; more or less equal; long relative to the adjacent lemmas; hairless; scabrous; awned (attenuate into very long, sinuous, scabrid awns); non-carinate; similar, or very dissimilar (the lower reduced to an awn in C. bromoides). Lower glume 3 nerved. Upper glume 9–11 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 1; sterile. The proximal lemmas acuminate to awned; awned to awnless; 7 nerved; more or less equalling the female-fertile lemmas; similar in texture to the female-fertile lemmas; not becoming indurated.

Female-fertile florets 1. Lemmas acuminate-apiculate to short awned; similar in texture to the glumes to decidedly firmer than the glumes; not becoming indurated; entire; awnless to mucronate, or awned (shortly); hairless (scabrid above); non-carinate; having the margins lying flat on the palea; with a clear germination flap; 5 nerved. Palea present; relatively long; apically notched (denticulate); 2-nerved; keel-less. Lodicules present; 2; free; fleshy; glabrous; not or scarcely vascularized. Stamens 3. Anthers not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles fused. Stigmas 2; brown.

Fruit, embryo and seedling. Embryo large.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type; (42–)48–54(–60) microns long; (21–)28.5–31.2(–34.5) microns wide at the septum. Microhair total length/width at septum 3–7.1. Microhair apical cells 8.4–10.2(–14.1) microns long. Microhair apical cell/total length ratio 0.5–0.65. Stomata common; (36–)39–47(–51) microns long. Subsidiaries parallel-sided to triangular; including both triangular and parallel-sided forms on the same leaf. 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 (some veins), or predominantly paired (other veins). Costal silica bodies ‘panicoid-type’.

Transverse section of leaf blade, physiology. C4; XyMS+ (C. bromoides), or XyMS– (C. festucoides, C. cubanum - which Renvoize describes as ‘anatomically intermediate C3/C4’: see below). Mesophyll with radiate chlorenchyma, or with non-radiate chlorenchyma. Leaf blade ‘nodular’ in section; with the ribs more or less constant in size. Midrib conspicuous; having a conventional arc of bundles (one large, two small); with colourless mesophyll adaxially. Bulliforms present in discrete, regular adaxial groups; in simple fans. Many of the smallest vascular bundles unaccompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’ (midribs only). Sclerenchyma all associated with vascular bundles.

Cytology. Chromosome base number, x = seemingly 13. 2n = 26. 2 ploid.

Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Paniceae. Soreng et al. (2015): Panicoideae; Panicodae; Paniceae; Melinidinae. 3 species.

Distribution, phytogeography, ecology. Tropical America, Cuba.

Species of open habitats. Grassland.

Rusts and smuts. Rusts — Puccinia.

References, etc. Leaf anatomical: studied by us - C. cubanum Hitchc.

Special comments. Fruit data wanting.

Illustrations. • Chaetium cubanum: Hitchcock, Manual of West Indies Grasses (1936).

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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