The grass genera of the world
The grass genera of the world | |
Sometimes referred to Sesleria
Habit, vegetative morphology. Perennial; caespitose. Culms 5–15 cm high; herbaceous. Leaves non-auriculate. Sheath margins free. Leaf blades narrow; 1–2 mm wide; sagittate (e.g. S. appendiculata), or not cordate, not sagittate; not setaceous (convolute or flat); flat, or rolled (convolute); without cross venation. Ligule an unfringed membrane; not truncate; 0.5 mm long.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant; hermaphrodite and sterile (the sterile spikelets reduced to bractlike scales at the base of the inflorescence); overtly heteromorphic.
Inflorescence. Inflorescence paniculate; contracted; capitate, or more or less ovoid; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund.
Female-sterile spikelets. The sterile spikelets vestigial, represented by bracts at the base of the inflorescence.
Female-fertile spikelets. Spikelets compressed laterally; disarticulating above the glumes. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets.
Glumes two; more or less equal; shorter than the adjacent lemmas, or long relative to the adjacent lemmas; pointed; shortly awned, or awnless (then mucronate); carinate; similar (ovate, membranous). Lower glume 1 nerved. Upper glume 1 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. Spikelets without proximal incomplete florets.
Female-fertile florets 3–4. Lemmas decidedly firmer than the glumes (silvery or grey); not becoming indurated; incised; not deeply cleft (toothed); awnless, or mucronate (the teeth shortly aristulate); hairy (proximally); carinate; without a germination flap; 5 nerved. Palea present; relatively long; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; glabrous; toothed; not or scarcely vascularized. Stamens 3. Ovary glabrous; without a conspicuous apical appendage. Styles fused. Stigmas 2.
Fruit, embryo and seedling. Fruit small (about 1.5 mm long). Embryo small.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells costal long-cells smaller; of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls (and pitted). Microhairs absent. Stomata absent or very rare. Intercostal short-cells common; in cork/silica-cell pairs (and solitary); silicified (a few only), or not silicified. Costal short-cells neither distinctly grouped into long rows nor predominantly paired (many paired). Costal silica bodies horizontally-elongated crenate/sinuous (often short), or rounded (often irregular, integrading with the sinuous/crenate forms); not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma. Leaf blade with distinct, prominent adaxial ribs, or ‘nodular’ in section; with the ribs more or less constant in size. Midrib conspicuous (by the larger bundle); with one bundle only. Bulliforms not present in discrete, regular adaxial groups (bulliforms not apparent). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’ (I’s). Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 7.
Taxonomy. Pooideae; Poodae; Seslerieae.
Distribution, ecology, phytogeography. 2 species; central and southern Europe.
Holarctic. Boreal and Tethyan. Euro-Siberian. Mediterranean. European.
References, etc. Leaf anatomical: this project.
This description is offered for casual browsing only. We strongly advise against extracting comparative information from it. This is much more easily achieved using 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 specified attributes, summaries of attributes within groups of taxa, geographical distribution, classification, and species sampled for anatomy.
Cite this publication as: ‘Watson, L., 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 February 2012. http://delta-intkey.com’.