Trichopteryx Nees
Habit, vegetative morphology. Annual, or perennial (with slender culms); caespitose, or decumbent. Culms 2–90 cm high; herbaceous; branched above, or unbranched above. Culm nodes hairy. Culm internodes hollow. Plants unarmed. Young shoots intravaginal. Leaves not basally aggregated; non-auriculate. Leaf blades linear-lanceolate to lanceolate; narrow; 2–6 mm wide (the base rounded or contracted); without cross venation; a fringe of hairs; 0.3 mm long.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; open, or contracted; with capillary branchlets; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary, or paired; not secund; pedicellate; consistently in ‘long-and-short’ combinations, or not in distinct ‘long-and-short’ combinations; when long-and-short unequally pedicellate in each combination.
Female-fertile spikelets. Spikelets 2.5–6 mm long; brown; compressed laterally to not noticeably compressed; disarticulating above the glumes; disarticulating between the florets (disarticulating readily between L1 and L2, less readily between G2 and L1); with conventional internode spacings. Rachilla terminated by a female-fertile floret; hairless. Hairy callus present. Callus short; blunt.
Glumes two; relatively large; very unequal (G1 one third to one half spikelet length); (the upper) about equalling the spikelets; (the upper) long relative to the adjacent lemmas; hairy, or hairless; pointed (G1 rarely obtuse); awnless (though the G1 can be aristulate and the G2 acuminate); non-carinate; similar (membranous or papery, G1 narrower). Lower glume shorter than the lowest lemma; 3 nerved. Upper glume 3 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 1; paleate. Palea of the proximal incomplete florets fully developed (two keeled, thin). The proximal incomplete florets male, or sterile. The proximal lemmas awnless; (1–)3 nerved; decidedly exceeding the female-fertile lemmas; less firm than the female-fertile lemmas to similar in texture to the female-fertile lemmas; not becoming indurated (resembling the G2 in form and texture).
Female-fertile florets 1. Lemmas similar in texture to the glumes to decidedly firmer than the glumes (membranous, hardening to leathery); incised; 2 lobed; deeply cleft; awned. Awns 1, or 3; median, or median and lateral (with the lobes terminating in awns additional to the median); the median different in form from the laterals (when laterals present); from a sinus; geniculate; hairless; much longer than the body of the lemma; entered by one vein; persistent. The lateral awns when present, shorter than the median (straight). Lemmas hairy. The hairs in tufts (with a sub-marginal tuft of erect hairs, in the middle on each side). Lemmas non-carinate; having the margins inrolled against the palea (the palea embraced and almost enclosed); without a germination flap; 5–7 nerved; with the nerves non-confluent. Palea present; relatively long; minutely apically notched; awnless, without apical setae; not indurated (hyaline); 2-nerved; 2-keeled. Palea keels wingless. Lodicules present; 2; free; fleshy. Stamens 2. Anthers about 1 mm long; not penicillate; without an apically prolonged connective. Ovary glabrous. Styles free to their bases. Stigmas 2; white.
Fruit, embryo and seedling. Fruit longitudinally grooved. Hilum long-linear. Embryo large.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (the costals narrower and more regularly rectangular in T. stolziana and T. dregeana); differing markedly in wall thickness costally and intercostally (the costals thinner walled). Mid-intercostal long-cells rectangular and fusiform; having markedly sinuous walls. Microhairs present; panicoid-type; (36–)39–42(–45) microns long; (5.1–)5.7–6(–6.6) microns wide at the septum. Microhair total length/width at septum 5.9–8.2. Microhair apical cells 21–25.5(–28.5) microns long. Microhair apical cell/total length ratio 0.54–0.68. Stomata common; 31–36 microns long. Subsidiaries triangular, or dome-shaped and triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common (sometimes paired with macrohair bases); not silicified. Costal zones with short-cells. Costal short-cells conspicuously in long rows. Costal silica bodies ‘panicoid-type’; mostly dumb-bell shaped; not sharp-pointed.
Transverse section of leaf blade, physiology. C4. The anatomical organization conventional, or unconventional. Organization of PCR tissue when unconventional Arundinella type. XyMS–. PCR sheath outlines uneven. PCR cell chloroplasts centrifugal/peripheral. Mesophyll exhibiting ‘circular cells’, or without ‘circular cells’. Leaf blade adaxially flat. Midrib not readily distinguishable (at least in the two species seen); with one bundle only. Bulliforms present in discrete, regular adaxial groups, or not present in discrete, regular adaxial groups (T. stolziana having a largely, irregularly bulliform epidermis). Many of the smallest vascular bundles unaccompanied by sclerenchyma. Combined sclerenchyma girders present, or absent (T. stolziana with little sclerenchyma, as strands only); when present, forming ‘figures’. Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 12 (?). 2n = 24. 2 ploid (?).
Taxonomy. Panicoideae; Panicodae; Arundinelleae.
Distribution, ecology, phytogeography. 5 species; southern and tropical Africa, Madagascar. Helophytic, or mesophytic; shade species, or species of open habitats; glycophytic. Streambanks, grasslands and forest margins.
Paleotropical and Neotropical. African and Madagascan. Sudano-Angolan and West African Rainforest. Andean. Sahelo-Sudanian, Somalo-Ethiopian, and South Tropical African.
References, etc. Leaf anatomical: Metcalfe 1960 and this project; photos of T. dregeana provided by R.P. Ellis.
Illustrations. • General aspect. • 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).
