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The grass genera of the world

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

Implicit attributes

Unless indicated otherwise, the following attributes are implicit throughout the descriptions, except where the characters concerned are inapplicable.

Habit, vegetative morphology. Not reedy. Culms not scandent; self-supporting; not tuberous. Plants without multicellular glands. The shoots not aromatic. Leaves clearly differentiated into sheath and blade; distichous; without auricular setae. Sheath margins free. Leaf blades not all greatly reduced; neither leathery nor flimsy; not cordate, not sagittate; not setaceous; not needle-like; not pseudopetiolate; parallel veined. Ligule present.

Reproductive organization. The spikelets all alike in sexuality; hermaphrodite. Plants chasmogamous; without hidden cleistogenes. Reproducing sexually.

Inflorescence. Inflorescence determinate; without pseudospikelets; many spikeleted; not deciduous; without conspicuously divaricate branchlets; non-digitate. Inflorescence with axes ending in spikelets. Rachides neither flattened nor hollowed, not winged. Spikelet-bearing axes persistent. The pedicels and rachis internodes without a longitudinal, translucent furrow. Spikelets unaccompanied by bractiform involucres, not associated with setiform vestigial branches; not in distinct ‘long-and-short’ combinations.

Female-sterile spikelets. The staminal filaments free.

Female-fertile spikelets. Spikelets morphologically ‘conventional’.

Glumes present; relatively large; free; not ventricose; without conspicuous tufts or rows of hairs; without a median keel-wing. Lower glume not two-keeled; not pitted. Upper glume not saccate; not prickly. Palea of the proximal incomplete florets not becoming conspicuously hardened and enlarged laterally.

Lemmas not conspicuously non-distichous; not convolute; not saccate; without a crown; not crested. Awns not of the triple/trifid, basal column type; not hooked. The hairs not in tufts; not in transverse rows. The keel wingless. Palea not convolute. Stamens with free filaments. Ovary without a conspicuous apical appendage.

Fruit, embryo and seedling. Fruit not grooved; smooth. Pericarp thin; fused. Seed endospermic.

Abaxial leaf blade epidermis. Intercostal zones with typical long-cells. Subsidiaries not including both parallel-sided and triangular forms on the same leaf. Crown cells absent. Costal zones with short-cells. Costal silica bodies not sharp-pointed.

Transverse section of leaf blade, physiology. Leaf blades ‘laminar’.

The anatomical organization conventional. Mesophyll not Isachne-type; without ‘circular cells’; not traversed by colourless columns; without arm cells; without fusoids. Midrib without colourless mesophyll adaxially. Bulliforms nowhere involved in bulliform-plus-colourless mesophyll arches.

Special diagnostic feature. Spikelets not borne as in ‘Anadelphia scyphofera’ (q.v.). Plant not as in Anomochloa (q.v.). The inflorescences not as in Atractantha (q.v.). Lemmas not as in Briza (q.v.). Lemma not wing-awned. Inflorescence not as in Buchloë (q.v.). Upper glume not as in Centrochloa (q.v.). Pedicels not as in Chaetobromus (q.v.). Inflorescences not as in Coix (q.v.). Spikelets not borne as in Cornucopiae (q.v.). Lemmas without the characteristic Corynephorus awn. Plants not as in Cyperochloa (q.v.). Fruit not as in Diarrhena (q.v.). Plants not as in Dichanthelium (q.v.). Without the sessile/pedicellate spikelet pairs characteristic of Diectomis. No Eriochloa-type ‘callus’. Plants not as in Hubbardia (q.v.). The adaxial surface of the leaf blade not as in Hydrothauma (q.v.). Plants not as in Hygroryza (q.v.). The upper part of the lemma without pappus-like hairs. Not having female spikelets as in Leptaspis and Scrotochloa (q.v.). Female-fertile lemma not as in Lombardochloa (q.v.). Spikelets not as in Lopholepis (q.v.). Plant and inflorescence not as in Lygeum (q.v.). Spikelets not arranged as in Manisuris (q.v.). Spikelets without a terminal clavate appendage. Spikelet not as in Nassella (q.v.). The inflorescence not as in Odontelytrum (q.v.). The lower lemma unlike that of Ophiochloa (i.e., without a central hyaline portion bordered by well developed, conspicously ciliate and terminally setose nerves, and without a pair of hygroscopically active setae at the apex). Seed not as in Phaenosperma (q.v.). Spikelets not borne on a broad, leaflike rachis. Not scandent as in Prosphytochloa (q.v.). Female-fertile lemma not as in Rhynchoryza (q.v.). Not rush-like. Inflorescence not as in Spinifex (q.v.). Plants not as in Steyermarkochloa (q.v.). Flowering culms not as in Thuarea (q.v.). Lower glume without a Thyridolepis-type window (q.v.). The lower glume of the pedicellate spikelet awnless. The inflorescence not as in Viguierella (q.v.). Fruiting inflorescence not as in maize (q.v.). Plants not as in Zygochloa (q.v.).

Distribution, phytogeography, ecology. Not commonly adventive.

Rusts and smuts. Rusts — no rusts recorded. Taxonomically wide-ranging species: no wide-ranging rust species. Smuts not recorded.

Special comments. Anatomical data more or less satisfactory.

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.’.