| # The grass genera of the world |

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

### 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 3, or 4–10; horizontally aligned. The branching dendroid. Culm leaf sheaths present; commonly deciduous; conspicuously auriculate, or not conspicuously auriculate. Culm leaves with conspicuous blades. Culm leaf blades linear, or lanceolate. 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. Contra-ligule absent.

Reproductive organization. Plants bisexual, all 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; lanceolate, or linear; 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).

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); not convolute; 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 apically glabrous; with a conspicuous apical appendage (rarely), or without a conspicuous apical appendage. The appendage where recorded, 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’.

Classification. Watson & Dallwitz (1994): Bambusoideae; Bambusodae; Bambuseae. Soreng et al. (2015): Bambusoideae; Arundinarodae; Arundinarieae; Arundinariinae. About 5 species.

Distribution, phytogeography, ecology. China, Japan, Vietnam.

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.

Illustrations. • Semiarundinaria fastuosa (as Arundinaria: Camus, 1913.). • Abbreviations for Camus (1913) figures.

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, and classifications. See also Guidelines for using data taken from Web publications.

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: 15th June 2025. delta-intkey.com’.

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