Monostachya Merr.
Sometimes referred to Rytidosperma, Danthonia sensu lato
Habit, vegetative morphology. Perennial; low, mat-forming alpines. Culms 2–20 cm high (?); herbaceous. Culm nodes glabrous. Culm internodes hollow. Leaves mostly basal; non-auriculate. Leaf blades narrow; setaceous; without cross venation; persistent; a fringe of hairs (?).
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant, or all alike in sexuality; hermaphrodite, or hermaphrodite and sterile (having vestigial spikelets, much reduced, beneath the terminal perfect one).
Inflorescence. Inflorescence reduced to a single spikelet, or few spikeleted; if of more than one spikelet a single raceme; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets compressed laterally; disarticulating above the glumes; with conventional internode spacings. Rachilla prolonged beyond the uppermost female-fertile floret; hairless. Hairy callus present, or absent.
Glumes two; more or less equal; long relative to the adjacent lemmas; awnless; similar. Lower glume 3 nerved. Upper glume 3 nerved. Spikelets with female-fertile florets only, or with incomplete florets. The incomplete florets distal to the female-fertile florets.
Female-fertile florets 1–10. Lemmas not becoming indurated; incised; 2 lobed; mucronate, or awned. Awns when present, from a sinus; non-geniculate; when present, much shorter than the body of the lemma. Lemmas hairless; non-carinate; 3–5 nerved. Palea present; 2-nerved. Lodicules present; free; fleshy; ciliate. Stamens 3. Anthers not penicillate. Ovary glabrous. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit small; compressed laterally. Hilum short. Embryo small; not waisted.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous (with paired short-cells costally). Papillae absent. Long-cells similar in shape costally and intercostally (long-rectangular); of similar wall thickness costally and intercostally (walls thick and sinuous). Mid-intercostal long-cells having markedly sinuous walls. Microhairs absent (but present adaxially); panicoid type. Stomata absent or very rare (abaxially, but present adaxially). Subsidiaries not available abaxially, but triangles and domes present adaxially. Intercostal short-cells common; in cork/silica-cell pairs; not silicified (usually). Costal short-cells predominantly paired. Costal silica bodies rounded; 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 more or less constant in size. Midrib not readily distinguishable; with one bundle only. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’. Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 5. 2n = 20. 4 ploid.
Taxonomy. Arundinoideae; Danthonieae.
Distribution, ecology, phytogeography. About 4 species; Philippines, New Guinea.
Paleotropical. Indomalesian. Papuan.
References, etc. Morphological/taxonomic: Jacobs 1982. 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).