Phaenanthoecium C.E. Hubb.
From the Greek phaenestai (becoming visible) and anthos (flower), referring to the lemmas exceeding the glumes.
Including Danthonia kostlinni, Streblochaete kostlinii
Habit, vegetative morphology. Perennial; caespitose (culms decumbent or ascending, sometimes trailing to 2 m). Culms herbaceous; branched above. Leaves not basally aggregated; non-auriculate. Leaf blades narrowly linear; narrow; flat, or rolled (convolute); without cross venation; ligule present; a fringe of hairs.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence determinate; without pseudospikelets; few spikeleted; a single raceme; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets shortly pedicellate.
Female-fertile spikelets. Spikelets slightly compressed laterally; disarticulating above the glumes; disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; hairless (glabrous). Hairy callus present. Callus very short; blunt.
Glumes two; relatively large; more or less equal (or slightly unequal); shorter than the spikelets; free; not pointed (emarginate, bilobed or obtuse); awnless; carinate (G1, somewhat), or non-carinate; similar (narrowly oblong to oblong-elliptic, membranous). Lower glume 1 nerved, or 3 nerved. Upper glume 3 nerved, or 4 nerved. Spikelets with female-fertile florets only, or with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped. Spikelets without proximal incomplete florets.
Female-fertile florets 5–9. Lemmas similar in texture to the glumes (membranous); not becoming indurated; incised; shortly 2 lobed; not deeply cleft; awned. Awns 3; median and lateral (the lateral lobes attenuate into long setae); the median different in form from the laterals; from a sinus; geniculate. Lemmas hairy (on the margins, otherwise glabrous). The hairs in tufts (along the margins). Lemmas non-carinate (dorsally rounded); 9 nerved. Palea present; linear-oblong; entire (obtuse or truncate); awnless, without apical setae; not indurated (membranous); 2-nerved; 2-keeled. Lodicules present (minute); 2; fleshy (cuneate); ciliate (or at least ciliolate). Stamens 3. Ovary glabrous; without a conspicuous apical appendage. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit free from both lemma and palea (loosely included); concavo-convex. Hilum long-linear (about 4/5 of the grain length). Embryo small (about a quarter of the grain length).
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally (the intercostals larger); of similar wall thickness costally and intercostally (walls of medium thickness). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type (large); (52.5–)54–60(–64.5) microns long; (6–)6.3–6.6(–8) microns wide at the septum. Microhair total length/width at septum 6.7–9.8. Microhair apical cells 21–22.5–27 microns long. Microhair apical cell/total length ratio 0.38–0.42. Stomata common; 25.5–28.5 microns long. Subsidiaries mostly high dome-shaped. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; not paired (solitary); not silicified. Costal short-cells conspicuously in long rows. Costal silica bodies ‘panicoid-type’; almost exclusively cross shaped, butterfly shaped, and dumb-bell shaped (short); not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll without adaxial palisade. Leaf blade with distinct, prominent adaxial ribs; with the ribs more or less constant in size. 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; forming ‘figures’ (all the bundles with I’s). Sclerenchyma all associated with vascular bundles.
Taxonomy. Arundinoideae; Danthonieae.
Distribution, ecology, phytogeography. 1 species; northeast Africa. Shade species. Shady cliffs.
Paleotropical. African. Sudano-Angolan. Somalo-Ethiopian.
References, etc. Morphological/taxonomic: Hubbard 1936c. 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).