Semiarundinaria Makino
Including Brachystachyum Keng
Habit, vegetative morphology. Shrubby perennial (or small tree); rhizomatous. The flowering culms leafy. Culms 300–1000 cm high; woody and persistent; to 4 cm in diameter; cylindrical; branched above. Primary branches/mid-culm node 3–8 (?). Culm sheaths deciduous in their entirety (leathery). Culm internodes hollow. Pluricaespitose. Rhizomes leptomorph (metamorph type I). Plants unarmed. Leaves not basally aggregated; auriculate; without auricular setae. Leaf blades broad; pseudopetiolate; cross veined; disarticulating from the sheaths; rolled in bud.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence indeterminate; with pseudospikelets (apparently); compound paniculate (in spatheolate racemes od 1–3 spikelets in fascicles at the nodes of the branches); spatheate; a complex of ‘partial inflorescences’ and intervening foliar organs (and each spikelet or raceme with an outer, basal bract with a reduced lamina). Spikelet-bearing axes very much reduced, or ‘racemes’ (of 1–3 spikelets); persistent. Spikelets not secund.
Female-fertile spikelets. Spikelets 5–10 mm long; compressed laterally; disarticulating above the glumes (?); disarticulating between the florets (?). Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets. Hairy callus absent.
Glumes two; relatively large; shorter than the adjacent lemmas; pointed; awnless; similar. Spikelets with incomplete florets (presumably). The incomplete florets distal to the female-fertile florets (assuming terminal florets may be imperfect). Spikelets without proximal incomplete florets.
Female-fertile florets 3–4. Lemmas ovate-lanceolate, acuminate; entire; pointed; awnless, or mucronate, or awned. Awns 1; median; apical; non-geniculate; much shorter than the body of the lemma. Lemmas non-carinate; 7–11 nerved. Palea present; relatively long (about equalling the lemma); apically notched; several nerved; 2-keeled. Lodicules present; 3; free; membranous; ciliate; not toothed; heavily vascularized. Stamens 3. Anthers not penicillate; without an apically prolonged connective. Ovary glabrous; with a conspicuous apical appendage. The appendage broadly conical, fleshy. Styles fused (into one long style). Stigmas 3 (feathery).
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present (especially in the stomatal bands). Intercostal papillae over-arching the stomata. Mid-intercostal long-cells having markedly sinuous walls (thin). Microhairs present; panicoid-type (but variable in shape). Stomata common. Subsidiaries low to high dome-shaped. Intercostal short-cells common; not paired (but paired with hooks). Costal short-cells predominantly paired (and solitary). Costal silica bodies saddle shaped; not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with arm cells; with fusoids. Leaf blade with distinct, prominent adaxial ribs (slight ribs and furrows), or adaxially flat; with the ribs more or less constant in size. Midrib conspicuous; having complex vascularization. Bulliforms present in discrete, regular adaxial groups; in simple fans, or in simple fans and associated with colourless mesophyll cells to form deeply-penetrating fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with all the bundles); forming ‘figures’ (with most bundles).
Cytology. Chromosome base number, x = 12. 2n = 48. 4 ploid. Chromosomes ‘small’.
Taxonomy. Bambusoideae; Bambusodae; Bambuseae.
Distribution, ecology, phytogeography. About 5 species; China, Japan, Vietnam.
Holarctic and Paleotropical. Boreal. Indomalesian. Eastern Asian. Indo-Chinese.
Hybrids. May hybridize with Sasa (×Hibanobambusa Maruyama and Okamura).
Rusts and smuts. Rusts — Stereostratum and Puccinia. Taxonomically wide-ranging species: Stereostratum corticoides and Puccinia kusanoi.
References, etc. Leaf anatomical: Metcalfe 1960.
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).