The grass genera of the world
Habit, vegetative morphology. Annual; caespitose (or the culms solitary). Culms 5–60 cm high; herbaceous; unbranched above. Culm nodes glabrous. Culm internodes hollow. Leaves non-auriculate. Leaf blades linear; narrow; 1–4 mm wide; flat, or rolled; not pseudopetiolate; without cross venation. Ligule an unfringed membrane; not truncate; 1–2.5 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality.
Inflorescence. Inflorescence paniculate (the branches whorled, the lower sometimes sterile); open; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 3–8 mm long; compressed laterally to not noticeably compressed; disarticulating above the glumes. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets. Hairy callus absent. Callus short; blunt.
Glumes present; two; very unequal; shorter than the spikelets; shorter than the adjacent lemmas; pointed; awnless; similar (membranous). Lower glume 1 nerved. Upper glume 3 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. Spikelets without proximal incomplete florets.
Female-fertile florets (1–)2–6. Lemmas lanceolate to narrowly oblong in lateral view, by contrast with Poa; not becoming indurated; entire; pointed (acute to acuminate), or blunt; awnless to mucronate; hairy; non-carinate (keeled only towards the tip); without a germination flap; 5 nerved. Palea present; relatively long; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; glabrous; toothed, or not toothed; not or scarcely vascularized. Stamens 3. Anthers 0.4–2.5 mm long. Ovary apically glabrous; without a conspicuous apical appendage. Styles free to their bases. Stigmas 2; white.
Fruit, embryo and seedling. Fruit adhering to lemma and/or palea; medium sized (5 mm long); compressed dorsiventrally. Hilum short. Embryo small. Endosperm containing compound starch grains.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (the costals smaller, more nearly rectangular); differing markedly in wall thickness costally and intercostally (the intercostals thin walled, the costals quite thick walled). Mid-intercostal long-cells fusiform; having straight or only gently undulating walls. Microhairs absent. Stomata common. Subsidiaries parallel-sided. Guard-cells overlapped by the interstomatals. Intercostal short-cells absent or very rare (there being a few solitary cells apparently representing uncompleted stomatal apparati). Costal short-cells neither distinctly grouped into long rows nor predominantly paired (mostly solitary). Costal silica bodies exclusively horizontally-elongated crenate/sinuous.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade. Leaf blade adaxially flat (apart from a constriction on either side of the midrib). Midrib conspicuous; with one bundle only. Bulliforms not present in discrete, regular adaxial groups (save for the midrib hinges). Many of the smallest vascular bundles unaccompanied by sclerenchyma (the blade being very depauperate of sclerenchyma). Combined sclerenchyma girders absent (only small abaxial strands seen). Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 7. 2n = 14, 28, and 42. 2, 4, and 6 ploid. Chromosomes large.
Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Poeae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Poinae. 4 species.
Distribution, phytogeography, ecology. Western and central Asia to the Himalayas.
References, etc. Leaf anatomical: this project.
Illustrations. • E. persica: Fl. Iraq, 1968
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: 13th November 2017. delta-intkey.com/grass’.