The grass genera of the world

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

Brachyelytrum P. Beauv.

From the Greek brachus (short) and elutron (cover, husk), alluding to short glumes.

Habit, vegetative morphology. Slender perennial; with short, knotty rhizomes. Culms 50–100 cm high; herbaceous. Culm nodes hairy, or glabrous. Culm internodes solid. Leaves non-auriculate. Leaf blades narrowly lanceolate; broad; 10–22 mm wide; pseudopetiolate (basally constricted), or not pseudopetiolate; cross veined, or without cross venation; persistent; rolled in bud. Ligule present; an unfringed membrane to a fringed membrane; 1.7–3.5 mm long.

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

Inflorescence. Inflorescence determinate; paniculate (scanty); espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.

Female-fertile spikelets. Spikelets 7–12 mm long; not noticeably compressed to compressed dorsiventrally; disarticulating above the glumes. Rachilla prolonged beyond the uppermost female-fertile floret; hairy; the rachilla extension naked (bristle-like). Hairy callus present.

Glumes present; two, or one per spikelet (the lower sometimes vestigial or absent); (the upper, larger), minute to relatively large; very unequal; shorter than the adjacent lemmas (the upper no more than about 1/4 of the floret length); awnless. Lower glume 0–1 nerved. Upper glume 1 nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.

Female-fertile florets 1. Lemmas tapering into the awn; herbaceous; not becoming indurated; entire; pointed; awned. Awns 1; median; apical; non-geniculate; hairless (scabrid); much longer than the body of the lemma; entered by several veins (3). Lemmas hairless; scabrous; non-carinate (rounded on the back); 5 nerved. Palea present; relatively long; convolute around the flower; 2-nerved; slightly 2-keeled. Lodicules present; 2; free; membranous; glabrous; not toothed; heavily vascularized. Stamens 3. Ovary apically hairy; without a conspicuous apical appendage (but narrow and hairy above). Styles free to their bases. Stigmas 2; white.

Fruit, embryo and seedling. Fruit small to medium sized (5 mm long); linear; longitudinally grooved; compressed dorsiventrally. Hilum long-linear. Pericarp thick and hard; loosely adherent to fused (removable with difficulty). Embryo small; not waisted. Endosperm hard (Soreng and Davis, 1998); containing only simple starch grains (these relatively large). Embryo with an epiblast; with a scutellar tail, or without a scutellar tail; with a negligible mesocotyl internode. Embryonic leaf margins overlapping.

Seedling with a short mesocotyl. First seedling leaf with a well-developed lamina. The lamina narrow; curved; 11–13 veined.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present; intercostal. Intercostal papillae not over-arching the stomata; often several per cell (large, irregular in shape). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs absent. Stomata common. Subsidiaries non-papillate; parallel-sided. Guard-cells overlapped by the interstomatals (slightly), or overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare. Costal short-cells conspicuously in long rows. Costal silica bodies ‘panicoid-type’.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without arm cells; without fusoids. Leaf blade adaxially flat. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups; in simple fans. Many of the smallest vascular bundles unaccompanied by sclerenchyma. Sclerenchyma all associated with vascular bundles.

Cytology. Chromosome base number, x = 11. 2n = 22. 2 ploid.

Classification. Watson & Dallwitz (1994): Stipoideae (or Bambusoideae?); Brachyelytreae. Soreng et al. (2015): Pooideae; Brachyelytreae. 3 species (B. aristosum, B. erectum, B. japonicum).

Distribution, phytogeography, ecology. North America, Japan & Korea.

Shade species. Woodland.

References, etc. Morphological/taxonomic: Macfarlane and Watson 1980; Campbell, Garwood and Specht 1985. Leaf anatomical: studied by us - B. erectum Beauv.

Illustrations. • B. erectum: P. Beauv. (1812). • B. erectum: Hitchcock and Chase (1950)

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: 11th December 2017.’.