The grass genera of the world
Habit, vegetative morphology. Perennial; caespitose. Culms herbaceous. Culm nodes glabrous. Leaves not basally aggregated; non-auriculate. Leaf blades narrow; without cross venation; persistent. Ligule an unfringed membrane; not truncate; 2–3 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; open, or contracted; espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 2.5 mm long; compressed laterally; disarticulating above the glumes. Rachilla prolonged beyond the uppermost female-fertile floret; hairy; the rachilla extension naked.
Glumes two; minute; very unequal to more or less equal; shorter than the spikelets; shorter than the adjacent lemmas (the upper less than 1/4 the length of the floret); pointed; awnless; non-carinate; similar. Lower glume 1 nerved. Upper glume 1–3 nerved. Spikelets with female-fertile florets only.
Female-fertile florets 1–2. Lemmas decidedly firmer than the glumes (membranous); not becoming indurated; pointed (acute); awnless, or awned (with or without an awnlet). Awns if present, 1; median; dorsal to apical; from near the top (subapical); non-geniculate. Lemmas hairless (but tuberculate-scabrid); carinate; 3 nerved. Palea present; relatively long; 1-nerved, or 2-nerved; one-keeled. Lodicules present; 2; free; membranous; glabrous; toothed. Stamens 2–3. Anthers not penicillate. Ovary apically glabrous. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit small; compressed laterally. Hilum short. Embryo not waisted. Endosperm containing compound starch grains. Embryo with an epiblast.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells of similar wall thickness costally and intercostally. Mid-intercostal long-cells fusiform; having straight or only gently undulating walls. Microhairs absent. Stomata absent or very rare. Subsidiaries parallel-sided. Intercostal short-cells absent or very rare. Costal silica bodies predominantly horizontally-elongated smooth, or horizontally-elongated crenate/sinuous; not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma. Leaf blade adaxially flat. Midrib conspicuous; with one bundle only. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming figures. Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 7. 2n = 28.
Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Poeae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Poinae. 2 species.
Distribution, phytogeography, ecology. New Zealand.
Species of open habitats. Grassland.
References, etc. Leaf anatomical: studied by us - S. buchananii Zotov.
Illustrations. • S. laxa: Cheeseman (1914), Ill. of New Zealand Flora
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. delta-intkey.com/grass’.