The grass genera of the world
The grass genera of the world | |
Including Hesperochloa Rydb.
Sometimes referred to Festuca
Habit, vegetative morphology. Perennial; rhizomatous, or caespitose. Culms 30–120 cm high; herbaceous. Culm internodes hollow. Leaves non-auriculate. Leaf blades narrow; flat; without cross venation. Ligule an unfringed membrane; truncate; 0.1–5 mm long.
Reproductive organization. Plants bisexual, with bisexual spikelets, or dioecious (sporadically); with hermaphrodite florets. The spikelets all alike in sexuality; hermaphrodite, or female-only, or male-only.
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 6–10 mm long; compressed laterally; disarticulating above the glumes; disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets. Hairy callus absent.
Glumes two; very unequal; shorter than the spikelets; shorter than the adjacent lemmas; pointed, or not pointed; awnless; carinate; similar. Lower glume 1 nerved. Upper glume 3 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped. Spikelets without proximal incomplete florets.
Female-fertile florets 3–9. Lemmas less firm than the glumes; not becoming indurated; entire to incised (irregularly serrate); not deeply cleft; awnless; hairless; carinate to non-carinate; without a germination flap; 5 nerved. Palea present; relatively long; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; glabrous; not toothed; not or scarcely vascularized. Stamens 3. Anthers 2.5–4.5 mm long. Ovary hairy; without a conspicuous apical appendage. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit not grooved. Hilum long-linear. Embryo small. Endosperm hard; containing compound starch grains. Embryo with an epiblast.
First seedling leaf with a well-developed lamina. The lamina narrow; erect; 3 veined.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular (mostly), or fusiform (a few); having markedly sinuous walls (thick and pitted). Microhairs absent. Stomata absent or very rare. Intercostal short-cells common; in cork/silica-cell pairs (but the ‘silica cells’ without silica); not silicified. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies rounded (mostly), or crescentic (some); not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma. Leaf blade with distinct, prominent adaxial ribs; with the ribs very irregular in sizes. Midrib not readily distinguishable; with one bundle only, or having a conventional arc of bundles (minor bundles flanking midrib). Bulliforms present in discrete, regular adaxial groups; in simple fans. Many of the smallest vascular bundles unaccompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’. Sclerenchyma all associated with vascular bundles.
Phytochemistry. Leaves without flavonoid sulphates (1 species).
Cytology. Chromosome base number, x = 7. Chromosomes ‘large’.
Taxonomy. Pooideae; Poodae; Poeae.
Distribution, ecology, phytogeography. 6 species; Western & Central Asia to Himalayas, North America.
Holarctic and Paleotropical. Boreal, Tethyan, and Madrean. Indomalesian. Euro-Siberian. Irano-Turanian. Indian. Siberian.
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’.