Leucopoa Griseb.
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; 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.
Cite this publication as: Watson, L., and Dallwitz, M. J. (1992 onwards). ‘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.’ http://biodiversity.uno.edu/delta/. Version: 18th August 1999. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993 onwards, 1998), and Watson and Dallwitz (1994), and Watson, Dallwitz, and Johnston (1986) should also be cited (see References).