Stephanachne Keng
Including Pappagrostis Roshev.
Habit, vegetative morphology. Perennial; caespitose. Culms herbaceous. Leaves non-auriculate. Leaf blades without cross venation; an unfringed membrane; not truncate; 1–2 mm long.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality.
Inflorescence. Inflorescence paniculate; contracted (to spiciform); espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 4.5–7 mm long; not noticeably compressed; disarticulating above the glumes. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension naked. Hairy callus present.
Glumes two; more or less equal; about equalling the spikelets; long relative to the adjacent lemmas; pointed (acuminate); awnless; carinate, or non-carinate; similar (membranous or herbaceous). Lower glume 1–3 nerved. Upper glume 3 nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.
Female-fertile florets 1. Lemmas decidedly firmer than the glumes (thinly leathery); not becoming indurated; incised; 2 lobed; deeply cleft to not deeply cleft (notched, or cleft to a third of its length); awned. Awns 1, or 3 (by extension from the acuminate lobes); median, or median and median and lateral; the median different in form from the laterals; from a sinus; geniculate. Lemmas hairy. The hairs in tufts; in transverse rows (with a long transverse tuft at the base of each glabrous lobe). Lemmas non-carinate; without a germination flap; 5 nerved. Palea present; relatively long; 2-nerved; keel-less. Palea back hairy. Lodicules present; 2 (Pappagrostis), or 3; free; membranous; glabrous; not toothed; not or scarcely vascularized. Stamens 3. Ovary glabrous. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit small (about 3 mm long). Hilum long-linear. Embryo small.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells differing markedly in wall thickness costally and intercostally (costals thicker-walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs absent. Stomata common; 27–30 microns long. Subsidiaries parallel-sided. Guard-cells overlapped by the interstomatals. Intercostal short-cells fairly common; not paired (mostly solitary); not silicified. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies absent, or poorly developed (in the material seen).
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll without adaxial palisade. Leaf blade with distinct, prominent adaxial ribs to ‘nodular’ in section; with the ribs very irregular in sizes. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups; in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with the primaries); forming ‘figures’. Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 12 (or 6). 2n = 24.
Taxonomy. Pooideae; Poodae; Aveneae.
Distribution, ecology, phytogeography. 2 species; China, eastern Russia.
Holarctic. Boreal. Eastern Asian.
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).