Apluda L.
From the Latin apluda (chaff), referring to conspicuously spatheate groups of spikelets, or to spathes persisting on old inflorescences.
Including Calamina P. Beauv.
Habit, vegetative morphology. Perennial; decumbent (often scrambling). Culms 50–120 cm high; branched above. Culm nodes glabrous. Culm internodes solid. Leaves not basally aggregated; non-auriculate. Leaf blades broad (to 15 mm), or narrow; pseudopetiolate; without cross venation; persistent; an unfringed membrane.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant; hermaphrodite, male-only, and sterile (in combination). Apomictic.
Inflorescence. Inflorescence paniculate; open; spatheate (each naviculate spathe enclosing a raceme reduced to a single joint, with 3 spikelets); a complex of ‘partial inflorescences’ and intervening foliar organs. Spikelet-bearing axes very much reduced (to 1 sessile and 2 pedicelled spikelets); clustered (at the tips of the usually fascicled branchlets); with substantial rachides; disarticulating (the whole triplet deciduous from the minute peduncle). Spikelets in triplets; not secund; sessile and pedicellate; consistently in ‘long-and-short’ combinations; in pedicellate/sessile combinations (the pedicels flat and broad). Pedicels of the ‘pedicellate’ spikelets free of the rachis. The ‘shorter’ spikelets hermaphrodite. The ‘longer’ spikelets male-only and sterile (one male, the other reduced to a small glume).
Female-fertile spikelets. Spikelets compressed dorsiventrally; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus absent.
Glumes two; more or less equal; long relative to the adjacent lemmas; awnless; very dissimilar (lower leathery, upper thinner and naviculate). Lower glume 11 nerved. Upper glume 3–5 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; male. The proximal lemmas awnless; similar in texture to the female-fertile lemmas (thinly membranous to hyaline).
Female-fertile florets 1. Lemmas less firm than the glumes; not becoming indurated; entire, or incised; when incised 2 lobed; mucronate, or awned (entire and mucronate, or deeply bilobed/awned). Awns when present, 1; from a sinus; geniculate; much shorter than the body of the lemma to much longer than the body of the lemma. Lemmas hairless; non-carinate; 1 nerved. Palea present; very reduced; not indurated (hyaline); nerveless. Lodicules present; 2; free; fleshy; glabrous. Stamens 2–3. Anthers not penicillate. Ovary glabrous; without a conspicuous apical appendage. Styles free to their bases. Stigmas 2; red pigmented.
Fruit, embryo and seedling. Fruit compressed dorsiventrally. Hilum short. Embryo large. Endosperm containing compound starch grains. Embryo without an epiblast; with a scutellar tail.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present. Intercostal papillae over-arching the stomata; consisting of one oblique swelling per cell (the interstomatal cells papilliform). Long-cells similar in shape costally and intercostally (the costals narrower); of similar wall thickness costally and intercostally (fairly thin walled). Intercostal zones with typical long-cells (but these rather short). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type; 39–42 microns long; 6–7.5 microns wide at the septum. Microhair total length/width at septum 6.5–9. Microhair apical cells (12–)13.5–18 microns long. Microhair apical cell/total length ratio 0.31–0.43. Stomata common; 21–22.5(–24) microns long. Subsidiaries dome-shaped. Intercostal short-cells absent or very rare. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies ‘panicoid-type’; butterfly shaped, or dumb-bell shaped, or nodular.
Transverse section of leaf blade, physiology. C4; XyMS–. Mesophyll with radiate chlorenchyma. Leaf blade ‘nodular’ in section, or adaxially flat; with the ribs more or less constant in size. Midrib conspicuous; having a conventional arc of bundles; with colourless mesophyll adaxially. Bulliforms present in discrete, regular adaxial groups; in simple fans (or in irregular groups). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’. Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 10. 2n = 20 and 40. 2 and 4 ploid. Chromosomes ‘small’.
Taxonomy. Panicoideae; Andropogonodae; Andropogoneae; Andropogoninae.
Distribution, ecology, phytogeography. 1 species; Mauritius & Socotra to Formosa & New Caledonia. Mesophytic. In thickets and forest margins.
Holarctic and Paleotropical. Tethyan. African, Madagascan, Indomalesian, and Neocaledonian. Irano-Turanian. Saharo-Sindian and Sudano-Angolan. Indian, Indo-Chinese, Malesian, and Papuan. Somalo-Ethiopian.
Rusts and smuts. Rusts — Dasturella and Puccinia. Taxonomically wide-ranging species: ‘Uromyces’ schoenanthi. Smuts from Tilletiaceae and from Ustilaginaceae. Tilletiaceae — Tilletia. Ustilaginaceae — Sorosporium and Sphacelotheca.
References, etc. Leaf anatomical: Metcalfe 1960; this project.
Illustrations. • Abaxial epidermis of leaf blade. Apluda mutica. • Transverse section of leaf blade. Apluda mutica. Midrib region.
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).
