Louisiella C.E. Hubb. & Léonard
Habit, vegetative morphology. Perennial; rhizomatous, or decumbent. Culms herbaceous; branched above. Culm nodes hairy. Culm internodes spongy. Leaves not basally aggregated; non-auriculate. Leaf blades narrow; without cross venation; persistent; a fringed membrane (very short).
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; open; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets paired or in short appressed racemelets; secund (?); pedicellate.
Female-fertile spikelets. Spikelets 8–9 mm long; lanceolate; compressed dorsiventrally; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus absent.
Glumes two; very unequal; (the longer) long relative to the adjacent lemmas; hairless; awnless; non-carinate; very dissimilar (the lower very small, nerveless and truncate, the upper equalling the spikelet, long acuminate, strongly nerved). Lower glume 0 nerved. Upper glume 5–7 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 1; epaleate; sterile. The proximal lemmas long acuminate; awnless; 7–9 nerved; decidedly exceeding the female-fertile lemmas; similar in texture to the female-fertile lemmas; not becoming indurated.
Female-fertile florets 1. Lemmas lanceolate; similar in texture to the glumes to decidedly firmer than the glumes; not becoming indurated (membranous to leathery); entire; pointed; awnless; hairy to hairless (glabrous, with a scabrid or hairy tip); non-carinate; having the margins lying flat on the palea; with a clear germination flap; 5–7 nerved. Palea present; relatively long; entire (pointed); awnless, without apical setae; textured like the lemma; not indurated; 2-nerved (near the margins); keel-less. Lodicules present; 2; free; fleshy; glabrous; not or scarcely vascularized. Stamens 3. Anthers not penicillate; without an apically prolonged connective. Ovary glabrous. Styles fused to free to their bases. Stigmas 2; red pigmented.
Fruit, embryo and seedling. Fruit small (2.5 mm long). Hilum long-linear. Embryo large to small (up to 1/3 as long as the grain).
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present. Intercostal papillae over-arching the stomata; several per cell (numerous per cell, in 1-several (average 2) rows, and large and ornamented at the blade margin). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type; 27–36 microns long; 15–21 microns wide at the septum. Microhair total length/width at septum 5.3–7.7. Microhair apical cells (3.9–)4.5–5.7(–6) microns long. Microhair apical cell/total length ratio 0.5–0.7. Stomata common; 19–24 microns long. Subsidiaries high dome-shaped and triangular; including both triangular and parallel-sided forms on the same leaf. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs. Costal short-cells neither distinctly grouped into long rows nor predominantly paired (‘short-cells’ much longer than usual, and the files interrupted by prickles). Costal silica bodies ‘panicoid-type’; small, cross shaped and dumb-bell shaped; not sharp-pointed.
Transverse section of leaf blade, physiology. C4; XyMS+. PCR sheath outlines uneven. Mesophyll with radiate chlorenchyma. Leaf blade ‘nodular’ in section; with the ribs more or less constant in size. Midrib not readily distinguishable (one slightly larger bundle); 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; nowhere forming ‘figures’. Sclerenchyma all associated with vascular bundles.
Special diagnostic feature. No Eriochloa-type ‘callus’.
Taxonomy. Panicoideae; Panicodae; Paniceae.
Distribution, ecology, phytogeography. 1 species; tropical Africa. Hydrophytic, or helophytic (floating, or decumbent on mud).
Paleotropical. African. West African Rainforest.
References, etc. 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).