Alloeochaete (Rendle) C.E. Hubb.
Habit, vegetative morphology. Perennial; caespitose. Culms 40–200 cm high; herbaceous; unbranched above. Culm sheaths persistent. Young shoots intravaginal. Leaves mostly basal; non-auriculate. The sheath bases woolly-tomentose. Leaf blades broad (up to 2 cm in A. oreogena), or narrow; flat, or rolled; without cross venation; disarticulating from the sheaths; a fringe of hairs.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; narrow; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 6–26 mm long; compressed laterally; disarticulating above the glumes; disarticulating between the florets (above the persistent first floret). Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets. Hairy callus present. Callus short; blunt.
Glumes two; more or less equal; shorter than the spikelets; shorter than the adjacent lemmas; hairy (pilose), or hairless; sometimes glabrous; pointed (acute, acuminate or minutely bidentate); more or less awned (mucronate to aristate, apically or from between short teeth); carinate; very dissimilar (with entire G1 and bidentate G2), or similar. Lower glume 3 nerved, or 5 nerved. Upper glume 3 nerved, or 5 nerved. Spikelets with incomplete florets. The incomplete florets both distal and proximal to the female-fertile florets (usually). The distal incomplete florets merely underdeveloped. Spikelets with proximal incomplete florets. The proximal incomplete florets 1; male (usually - though in three species the L1 is occasionally hermaphrodite). The proximal lemmas awned (from a slight or deep sinus, the awn short and straight to long and geniculate); 5 nerved; exceeded by the female-fertile lemmas; less firm than the female-fertile lemmas to similar in texture to the female-fertile lemmas (thinly membranous to papery); not becoming indurated.
Female-fertile florets 5–10. Lemmas similar in texture to the glumes to decidedly firmer than the glumes; not becoming indurated; incised; 2 lobed; deeply cleft, or not deeply cleft (but always strongly bidentate); awned. Awns 1, or 3; median, or median and lateral (the lobes being aristate); the median different in form from the laterals (when laterals present); from a sinus; geniculate; hairless; much shorter than the body of the lemma to much longer than the body of the lemma. Lemmas usually hairy. The hairs in tufts (one on each side); not in transverse rows. Lemmas non-carinate (dorsally rounded); 5 nerved. Palea present; relatively long; entire to apically notched; awnless, without apical setae; not indurated (membranous); 2-nerved; 2-keeled. Stamens 3. Anthers 1–6.4 mm long. Stigmas 2.
Ovule, embryology. Synergids not haustorial.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (intercostals much broader); of similar wall thickness costally and intercostally (rather thin walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present (but scarce in material seen); panicoid-type (probably, but apical cells not seen); 36–45 microns long; 6–7 microns wide at the septum. Microhair total length/width at septum 5–6.5. Microhair apical cells 6–9 microns long. Microhair apical cell/total length ratio 0.15–0.2. Stomata common (but not abundant); 33–39 microns long. Subsidiaries low dome-shaped. Guard-cells overlapped by the interstomatals (sometimes; slightly), or overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs; silicified. Costal short-cells conspicuously in long rows (but the short-cells often quite long). Costal silica bodies ‘panicoid-type’; predominantly elongated dumb-bell shaped.
Transverse section of leaf blade, physiology. C3 (indisputably); XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade. Leaf blade with distinct, prominent adaxial ribs; with the ribs very irregular in sizes (small round-topped, alternating with large flat-topped). Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups; in simple fans (in the furrows). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with the primaries); forming ‘figures’ (the primaries with massive I’s). Sclerenchyma not all bundle-associated (with a small abaxial group opposite each furrow). The ‘extra’ sclerenchyma in abaxial groups; abaxial-hypodermal, the groups isolated.
Taxonomy. Arundinoideae; Danthonieae.
Distribution, ecology, phytogeography. 6 species; Angola, Tanzania, Malawi. Xerophytic; species of open habitats.
Paleotropical. African. Sudano-Angolan. South Tropical African.
References, etc. Morphological/taxonomic: Kabuye and Renvoize 1975. 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).