Grass Genera of the World

L. Watson 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, 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; not in distinct ‘long-and-short’ combinations.

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 present; 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 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.

Taxonomy. Panicoideae; Panicodae; Paniceae.

Distribution, ecology, phytogeography. 3 species; tropical America, Cuba. Species of open habitats. Grassland.

Neotropical. Caribbean and Central Brazilian.

Rusts and smuts. Rusts — Puccinia.

References, etc. Leaf anatomical: this project.

Special comments. Fruit data wanting.

Cite this publication as: Watson, L., and Dallwitz, M. J. (1992 onwards). ‘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: 18th August 1999. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993 onwards, 1998), and Watson and Dallwitz (1994), and Watson, Dallwitz, and Johnston (1986) should also be cited (see References).