Apoclada McClure
Habit, vegetative morphology. Perennial; caespitose. The flowering culms leafy. Culms 110 cm high (or more?); woody and persistent; branched above. Primary branches/mid-culm node 2–5. Culm internodes hollow. Unicaespitose. Rhizomes pachymorph. Plants unarmed. Leaves not basally aggregated; auricles minute, rudimentary or obsolete; with auricular setae. Leaf blades narrow; to about 1 mm wide; acicular (aculeiform, to 9 cm long); pseudopetiolate; without cross venation; disarticulating from the sheaths; ligule present (very short, dorsally canescent); a fringed membrane to a fringe of hairs. Contra-ligule present.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality.
Inflorescence. Inflorescence determinate; open; spatheate (inflorescence branches subtended by bracts, but no prophylls except when the ‘racemes’ are reduced to single spikelets); a complex of ‘partial inflorescences’ and intervening foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets morphologically ‘conventional’, or unconventional (the number of glumes variable); 70–400 mm long; compressed laterally; disarticulating above the glumes; tardily disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; hairy, or hairless; the rachilla extension with incomplete florets. Hairy callus absent.
Glumes present, or absent; when present, one per spikelet to several (consisting of leaf sheaths with reduced blades, but varying from species to species in form, number, and spatial relation to the first lemma); relatively large; very unequal to more or less equal; shorter than the adjacent lemmas, or long relative to the adjacent lemmas; free; awnless. Spikelets with incomplete florets. The incomplete florets both distal and proximal to the female-fertile florets. The distal incomplete florets merely underdeveloped. Spikelets with proximal incomplete florets. The proximal incomplete florets 1–2 (?). The proximal lemmas awned, or awnless; exceeded by the female-fertile lemmas; similar in texture to the female-fertile lemmas.
Female-fertile florets (1–)3–15. Lemmas acuminate; not becoming indurated (papery); entire; pointed; awnless, or mucronate, or awned. Awns when present, 1; apical; non-geniculate; much shorter than the body of the lemma. Lemmas hairy, or hairless; carinate, or non-carinate (but then keeled towards the tip); ‘several nerved’. Palea present; relatively long; apically notched (and 2 or 4 dentate); awnless, without apical setae; not indurated (papery); 2-nerved; 2-keeled. Lodicules present; free; membranous; ciliate; not toothed; heavily vascularized. Stamens 3 (occasionally 3–6 in A. diversa). Anthers not penicillate; without an apically prolonged connective. Ovary glabrous, or hairy; with a conspicuous apical appendage. The appendage broadly conical, fleshy. Styles fused. Stigmas 2 (rarely showing a vestigial third).
Fruit, embryo and seedling. Fruit longitudinally grooved; compressed dorsiventrally. Hilum long-linear. Embryo small.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present; costal and intercostal. Intercostal papillae from the ends of the interstomatals over-arching the stomata (and almost enclosing them); several per cell (a single, median row of large, circular or bifurcated papillae per long-cell). Long-cells markedly different in shape costally and intercostally (the costals much more regularly rectangular); of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls (with conspicuous pits). Microhairs present; elongated; clearly two-celled; panicoid-type; 42–51 microns long; 7.5–10.5 microns wide at the septum. Microhair total length/width at septum 5–6.8. Microhair apical cells 21.6–24 microns long. Microhair apical cell/total length ratio 0.42–0.57. Stomata common; 28.5–31.5 microns long. Subsidiaries obscured. Intercostal short-cells common; in cork/silica-cell pairs and not paired; not silicified (in the silica-deficient material seen). Costal short-cells predominantly paired. Costal silica bodies poorly developed; rounded (but most of the very few silica bodies in the material seen poorly developed).
Transverse section of leaf blade, physiology. C3. Mesophyll without adaxial palisade; with arm cells (these very conspicuous); without fusoids (sic). Leaf blade more or less ‘nodular’ in section (the adaxial ribs low, round- to flat-topped). Midrib conspicuous (as indicated by a distinct longitudinal fold nearer to one margin of the lamina); with one bundle only. The lamina distinctly asymmetrical on either side of the midrib (assuming the fold is indicative of a laterally displaced midrib). Bulliforms present in discrete, regular adaxial groups (a conspicuous group in each adaxial groove); in simple fans (a few only), or associated with colourless mesophyll cells to form deeply-penetrating fans (most of the groups being associated internally with a large, deeply-penetrating median colourless cell). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’ (nearly all the bundles with a conspicuous ‘I’ or ‘anchor’). Sclerenchyma not all bundle-associated. The ‘extra’ sclerenchyma in abaxial groups and in adaxial groups (there being occasional abaxial groups opposite the bulliforms, and single layers of fibres lining the bulliforms -cf. Atractantha); abaxial-hypodermal, the groups isolated and adaxial-hypodermal, contiguous with the bulliforms.
Taxonomy. Bambusoideae; Bambusodae; Bambuseae.
Distribution, ecology, phytogeography. 4 species; Brazil.
Neotropical. Central Brazilian and Pampas.
References, etc. Leaf anatomical: this project.
Illustrations. • Abaxial epidermis of leaf blade. • Transverse section 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).
