Ortachne Nees ex Steud.
Sometimes referred to Stipa, cf. Lorenzochloa
Excluding Lorenzochloa
Habit, vegetative morphology. Perennial. Culms 5–35 cm high (?); herbaceous; unbranched above. Leaf blades filiform; narrow; rolled and acicular; without cross venation.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence many spikeleted (at least, usually of 10 or more, by contrast with Aciachne); paniculate (borne well above the leaves); open; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets not noticeably compressed (the floret cylindrical); disarticulating above the glumes. Rachilla terminated by a female-fertile floret. Hairy callus present. Callus short; pointed.
Glumes two; shorter than the spikelets; shorter than the adjacent lemmas; pointed, or not pointed (truncate or acute); awnless; similar (membranous). Lower glume 1 nerved. Upper glume 1 nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.
Female-fertile florets 1. Lemmas covering only the margins of the palea; not convolute; not saccate; without a crown; similar in texture to the glumes (membranous); not becoming indurated; entire; awned. Awns 1; median; apical (from the acuminate lemma); non-geniculate; persistent. Awn bases slightly twisted. Lemmas non-carinate; 5 nerved. Palea present; relatively long; prow-tipped, or not prow-tipped (?); membranous; 2-nerved; keel-less, or one-keeled (?). Lodicules present; 3. Stamens 3.
Abaxial leaf blade epidermis. Costal/intercostal zonation lacking. Papillae absent (though abundant adaxially). Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally (thick walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls (these very heavily pitted). Microhairs absent. Stomata absent or very rare (seen adaxially only, with parallel-sided subsidiaries). Intercostal short-cells common. Costal short-cells neither distinctly grouped into long rows nor predominantly paired (frequently in short rows). Costal silica bodies seemingly ‘panicoid-type’ (but very hard to observe in the material available); not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Leaf blade with distinct, prominent adaxial ribs; with the ribs very irregular in sizes. Midrib not readily distinguishable; with one bundle only. Bulliforms not present in discrete, regular adaxial groups (not seen). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with the primaries); forming ‘figures’. Sclerenchyma not all bundle-associated. The ‘extra’ sclerenchyma in a continuous abaxial layer (this submerging the ‘feet’ of the ‘anchors’).
Cytology. Chromosome base number, x = 11. 2n = 22. 2 ploid.
Taxonomy. Stipoideae; Stipeae.
Distribution, ecology, phytogeography. 2 species; Chile. Xerophytic; species of open habitats. Montane.
Antarctic. Patagonian.
References, etc. Morphological/taxonomic: Hughes 1923; Reeder and Reeder 1968. Leaf anatomical: this project.
Special comments. Fruit data wanting.
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).