Triplachne Link
Habit, vegetative morphology. Annual. Culms 5–25 cm high; herbaceous. Culm nodes glabrous. Leaves non-auriculate. Leaf blades linear; narrow; 2–3 mm wide; flat; without cross venation; persistent; an unfringed membrane; truncate; 2–3 mm long.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate (1–5 cm long); contracted; spicate, or more or less ovoid; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 3–4.5 mm long; compressed laterally; 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; exceeding the spikelets; long relative to the adjacent lemmas; hairless (shiny, scabrid on the keel); pointed; awnless; carinate; similar (membranous, lanceolate, acute). Lower glume 1 nerved. Upper glume 1 nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.
Female-fertile florets 1. Lemmas truncate; somewhat saccate (gibbously ovate in profile); less firm than the glumes (scarious); not becoming indurated; entire; awned. Awns 3; median and lateral (the two outer veins excurrent, plus the median); the median different in form from the laterals; dorsal; from well down the back; geniculate; much longer than the body of the lemma; entered by one vein. The lateral awns shorter than the median (straight, via the outer, excurrent veins). Lemmas hairy (with long appressed hairs); non-carinate; obscurely 5 nerved. Palea present; relatively long; tightly clasped by the lemma; 2-nerved. Lodicules absent. Stamens 3. Anthers 0.5 mm long; not penicillate. Ovary glabrous. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit small. Hilum short. Embryo small.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (the costals long and narrow, the intercostals somewhat diamond-shaped and inflated); of similar wall thickness costally and intercostally. Mid-intercostal long-cells fusiform (strongly so); having straight or only gently undulating walls. Microhairs absent. Stomata common; 37–45 microns long. Subsidiaries dome-shaped, or triangular. Guard-cells overlapped by the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs and not paired (solitary); silicified (when paired), or not silicified. Costal zones with short-cells. Costal short-cells conspicuously in long rows, or neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies horizontally-elongated crenate/sinuous, or ‘panicoid-type’; not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma. Leaf blade with distinct, prominent adaxial ribs, or ‘nodular’ in section; with the ribs more or less constant in size. Midrib conspicuous; 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; forming ‘figures’. Sclerenchyma all associated with vascular bundles.
Taxonomy. Pooideae; Poodae; Aveneae.
Distribution, ecology, phytogeography. 1 species; Mediterranean, Canaries. Xerophytic; species of open habitats. Near the sea.
Holarctic and Paleotropical. Tethyan. African. Macaronesian and Mediterranean. Saharo-Sindian.
References, etc. Leaf anatomical: this project.
Illustrations. • Abaxial epidermis of leaf blade
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).
