| # The grass genera of the world |

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

### Calosteca Desv.

~ Briza, Chascolytrum

Including Calotheca P. Beauv.

Habit, vegetative morphology. Perennial (apparently); caespitose. Culms 40–80 cm high; herbaceous; unbranched above. Young shoots intravaginal. Leaves not basally aggregated; non-auriculate. Leaf blades linear; narrow; flat to folded; without cross venation; persistent; once-folded in bud. Ligule an unfringed membrane.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets; exposed-cleistogamous, or chasmogamous (?).

Inflorescence. Inflorescence paniculate; open; with capillary branchlets (?); espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.

Female-fertile spikelets. Spikelets 10–14 mm long; compressed laterally; disarticulating above the glumes; disarticulating between the florets; with conventional internode spacings. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets. Hairy callus present.

Glumes two; more or less equal; shorter than the spikelets; shorter than the adjacent lemmas; hairless; awnless (to mucronate from a minutely bifid apex); non-carinate (?); similar. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped.

Female-fertile florets 5–10. Lemmas cuneate at the base, broad in the middle, narrowed to the apex; not becoming indurated; incised; 2 lobed; not deeply cleft (acuminate from the very broad base, but minutely incised at the tip); awned. Awns 1; median; from a sinus; non-geniculate; hairless; much shorter than the body of the lemma to about as long as the body of the lemma (2–5 mm long); entered by one vein. Lemmas non-carinate; without a germination flap; 7 nerved, or 9 nerved (?). Palea present; conspicuous but relatively short (lanceolate); entire; awnless, without apical setae (but with a conspicuous, hyaline, apical appendage); thinner than the lemma (membranous); not indurated; 2-nerved; 2-keeled (hairy between the keels). Palea keels narrowly winged. Lodicules present; 2; free; membranous; glabrous; toothed. Stamens 3 (presumably?). Ovary apically glabrous. Stigmas 2.

Fruit, embryo and seedling. Fruit small (about 2 mm long); trigonous. Hilum short. Embryo small. Endosperm hard.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous (the costal zones narrow). Papillae absent. Long-cells markedly different in shape costally and intercostally (the costals much shorter and narrower, with markedly sinuous walls). Mid-intercostal long-cells rectangular to fusiform (very long, minimizing the tendency to be fusiform); having straight or only gently undulating walls. Microhairs absent. Stomata absent or very rare (confined to short, discontinuous single files adjoining the costal zones). Subsidiaries parallel-sided. Guard-cells overlapped by the interstomatals (but only very slightly so). Intercostal short-cells absent or very rare. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies horizontally-elongated crenate/sinuous (crenate).

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll without adaxial palisade. Leaf blade with distinct, prominent adaxial ribs; with the ribs more or less constant in size (tall and narrow). Midrib somewhat conspicuous (with a larger rib); with one bundle only. The lamina symmetrical on either side of the midrib. Bulliforms present in discrete, regular adaxial groups; in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders absent (all bundles with a small adaxial strand, the main bundles with an abaxial strand as well). Sclerenchyma all associated with vascular bundles.

Phytochemistry. Leaves without flavonoid sulphates (1 species).

Special diagnostic feature. Lemmas not as in Briza (q.v.).

Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Poeae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Calothecinae. 1 species (C. brizoides).

Distribution, phytogeography, ecology. South America.

References, etc. Morphological/taxonomic: Mattei 1975, Nicora and Rúgolo de Agrasar 1981. Leaf anatomical: studied by us.

Special comments. Briza sect. Calotheca, Bromus brizoides.

Illustrations. • Calosteca brizoides: Nicora & Rúgolo de Agrasar (1987). • Calosteca brizoides, leaf blade TS: this project.

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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