Torreyochloa Church
Habit, vegetative morphology. Perennial; stoloniferous, or caespitose. Culms 20–50 cm high; herbaceous. Culm internodes hollow. Leaves non-auriculate. Leaf blades linear; 1–2.5 mm wide; flat; not pseudopetiolate; rolled in bud; an unfringed membrane; not truncate; 0.5–5 mm long.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; open; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 2–6 mm long; compressed laterally to not noticeably compressed; disarticulating above the glumes; disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret. Hairy callus absent.
Glumes two; very unequal; shorter than the adjacent lemmas; not pointed (apically rounded); awnless; non-carinate; similar. Lower glume 1 nerved, or 3 nerved. Upper glume 1–3 nerved. Spikelets with female-fertile florets only, or with incomplete florets. The incomplete florets distal to the female-fertile florets. Spikelets without proximal incomplete florets.
Female-fertile florets 3–7. Lemmas decidedly firmer than the glumes; not becoming indurated; entire, or incised; when entire, blunt; when incised, not deeply cleft (denticulate); awnless; hairless; non-carinate; without a germination flap; 5–7 nerved (these prominent, scaberulous). Palea present; relatively long; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; glabrous; toothed, or not toothed; not or scarcely vascularized. Stamens 3. Anthers 0.3–0.6 mm long. Ovary glabrous (rarely), or hairy. Styles free to their bases. Stigmas 2; white.
Fruit, embryo and seedling. Fruit free from both lemma and palea; compressed laterally; with hairs confined to a terminal tuft. Hilum short. Embryo small. Endosperm hard; containing compound starch grains. Embryo with an epiblast; without a scutellar tail; with a negligible mesocotyl internode. Embryonic leaf margins meeting.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally; of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular, or fusiform; having straight or only gently undulating walls. Microhairs absent. Stomata common; 27–38 microns long. Subsidiaries parallel-sided. Guard-cells overlapped by the interstomatals. Intercostal short-cells absent or very rare. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies horizontally-elongated crenate/sinuous (mostly), or horizontally-elongated smooth (a few), or ‘panicoid-type’ (a few); sometimes nodular; not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups (in the furrows); in simple fans (the fans wide). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present. Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 7. 2n = 14. 2 ploid. Chromosomes ‘large’.
Taxonomy. Pooideae; Poodae; Poeae.
Distribution, ecology, phytogeography. 4 species; northern Asia, North America. Helophytic; species of open habitats; glycophytic. Wet meadows and in shallow water.
Holarctic. Boreal. Euro-Siberian, Eastern Asian, Atlantic North American, and Rocky Mountains. Siberian. Canadian-Appalachian.
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).