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The grass genera of the world

L. Watson, T.D. Macfarlane, and M.J. Dallwitz

Guaduella Franch.

Including Microbambus K. Schum.

Habit, vegetative morphology. Perennial (of zingiberaceous aspect); rhizomatous. The flowering culms leafless, or leafy (with some segregation into fertile/sterile-vegetative). Culms herbaceous; sparsely branched above to unbranched above. The branching simple. Culm nodes exposed, or hidden by leaf sheaths; glabrous. Culm leaves present. Culm leaf sheaths present; deciduous. Culm internodes hollow. Rhizomes pachymorph. Plants unarmed. Leaves not basally aggregated; non-auriculate; without auricular setae. Leaf blades ovate-lanceolate to elliptic; broad; 25–75 mm wide; flat; pseudopetiolate; without cross venation; disarticulating from the sheaths. Ligule a fringed membrane. Contra-ligule absent.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.

Inflorescence. Inflorescence determinate; a single raceme, or paniculate (branching at the base); open; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelets solitary; not secund; shortly pedicellate, or sessile to subsessile.

Female-fertile spikelets. Spikelets morphologically ‘conventional’; 20–90 mm long; elliptic, or lanceolate, or ovate, or linear (G. macrostachys); compressed laterally to not noticeably compressed; disarticulating above the glumes; disarticulating between the florets; with distinctly elongated rachilla internodes between the florets. Rachilla prolonged beyond the uppermost female-fertile floret. Callus absent.

Glumes two; very unequal; shorter than the adjacent lemmas; free; hairy, or hairless; glabrous, or scabrous; pointed, or not pointed; awnless; carinate to non-carinate; similar. Lower glume about 0.5–0.75 times the length of the upper glume; 3 nerved, or 5 nerved, or 7 nerved. Upper glume 5 nerved, or 7 nerved, or 9 nerved, or 11 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets, or both distal and proximal to the female-fertile florets. The distal incomplete florets merely underdeveloped. Spikelets with proximal incomplete florets. The proximal incomplete florets 1–3; paleate; male. The proximal lemmas awnless; more or less equalling the female-fertile lemmas; similar in texture to the female-fertile lemmas.

Female-fertile florets 5–12. Lemmas ovate-lanceolate; decidedly firmer than the glumes; smooth; not becoming indurated; entire; pointed; awnless; hairy, or hairless; carinate to non-carinate; without a germination flap; 9 nerved, or 11–12 nerved; with the nerves non-confluent. Palea present; relatively long; not convolute; entire (truncate), or apically notched; awnless, without apical setae (apically fringed); thinner than the lemma to textured like the lemma; not indurated; several nerved (5–11 nerved); 2-keeled. Palea back hairy. Palea keels more or less winged, or wingless; hairy. Lodicules present; 3; free; membranous; ciliate; not toothed. Stamens 6. Anthers 4–6 mm long; penicillate; with the connective apically prolonged. Ovary apically hairy; without a conspicuous apical appendage. Styles free to their bases. Stigmas 2.

Fruit, embryo and seedling. Hilum long-linear. Embryo small.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present (in G. oblonga (Metcalfe 1960)), or absent (in the three species seen). Intercostal papillae over-arching the stomata. Long-cells markedly different in shape costally and intercostally (the costals much narrower); of similar wall thickness costally and intercostally (of medium thickness). Mid-intercostal long-cells rectangular; having markedly sinuous walls (coarsely, fairly evenly sinuous). Microhairs present; elongated; consistently uniseriate (all three celled, very large in G. foliosa); ostensibly panicoid type, but with two collapsing apical cells. Stomata common. Subsidiaries non-papillate; dome-shaped. Guard-cells overlapping to flush with the interstomatals (when recordable). Intercostal short-cells common; in cork/silica-cell pairs; silicified. Intercostal silica bodies saddle shaped (smaller and narrower than the costals). Small macrohairs and bulbous prickles abundant intercostally in G. zenkeri, scarce in G. marantifolia, absent in G. foliosa. Costal short-cells conspicuously in long rows. Costal silica bodies present and well developed; saddle shaped.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with adaxial palisade (fairly clear in G. foliosa and G. marantifolia), or without adaxial palisade; with arm cells (very conspicuous in G. marantifolia), or without arm cells (seemingly, in G. foliosa); with fusoids. The fusoids external to the PBS. Leaf blade adaxially flat; with the ribs more or less constant in size. Midrib conspicuous; with one bundle only (this large, in G. zenkeri), or having a conventional arc of bundles (three bundles, in G. foliosa and G. marantifolia), or having complex vascularization (G. oblonga); with colourless mesophyll adaxially. The lamina symmetrical on either side of the midrib. Bulliforms present in discrete, regular adaxial groups; in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’.

Classification. Watson & Dallwitz (1994): Bambusoideae; Bambusodae; Guaduelleae. Soreng et al. (2015): Puelioideae; Guaduellieae. 8 species.

Distribution, phytogeography, ecology. Tropical Africa.

Shade species. Rainforest.

References, etc. Leaf anatomical: Metcalfe 1960; this project.

Special comments. Fruit data wanting. Illustrations. • G. oblonga: Fl. W. Trop. Afr. (1936). • Spikelet of G. foliosa. Guaduella foliosa. Long rachilla internodes. • G. marantifolia and G. longifolia (= marantifolia), with Thyrsostachys siamensis: Camus, 1913. • Abbreviations for Camus (1913) figures


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Cite this publication as: ‘Watson, L., Macfarlane, T.D., and Dallwitz, M.J. 1992 onwards. The 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. Version: 13th November 2017. delta-intkey.com/grass’.

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