The grass genera of the world
~ Arundinaria megalothyrsa Hand.-Mazz.
Type species: G. megalothyrsa.
Habit, vegetative morphology. Perennial; caespitose. Culms 100–350(–800) cm high; erect, woody and persistent; to 1.5 cm in diameter; cylindrical; branched above. Primary branches 1 (as thick as the stem). The branching suffrutescent. Culm leaf sheaths present (about half the length of the internodes); persistent; conspicuously auriculate (setose on the shoulders). Culm leaves with conspicuous blades. Culm leaf blades about 4 cm long, spreading, lanceolate. Rhizomes pachymorph. Leaves auriculate (the auricles falcate, purple); with auricular setae (these dark). The sheaths about 10 mm long, glabrous, keeled. Leaf blades apically attenuate, lanceolate, or elliptic (basally cuneate); broad; 15–30 cm long, 30–57 mm wide; pseudopetiolate; with 18 secondary veins, and indistinctly cross veined. Ligule present; an unfringed membrane; truncate; 1–2 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets hermaphrodite.
Inflorescence. Inflorescence determinate; without pseudospikelets; paniculate; open; effuse, about 40 cm diameter capitate. Primary inflorescence branches 1-nate. Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelets solitary; not secund; pedicellate (the pedicels 10–40 mm long).
Female-fertile spikelets. Spikelets 2–3 mm wide, 20–40 mm long; linear; compressed laterally to not noticeably compressed (subterete); disarticulating above the glumes; disarticulating between the florets; with distinctly elongated rachilla internodes between the florets (these about 4 mm long). Rachilla prolonged beyond the uppermost female-fertile floret; hairy (pubescent); the rachilla extension with incomplete florets. Hairy callus present (the hairs about 1 mm long).
Glumes two; shorter than the spikelets; shorter than the adjacent lemmas; hairless; scabrous; pointed; attenuate or acuminate, awned (the upper, with a 4 mm awn), or awnless (the lower); non-carinate; persistent, chartaceous, similar. Lower glume 5 nerved. Upper glume 5 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped; awned.
Female-fertile florets 4–9. Lemmas lanceolate,, about 8 mm long; chartaceous, similar in texture to the glumes; smooth; entire; pointed; mucronate to awned, or awned (with a 5 mm awn). Awns 1; median; apical; non-geniculate; much shorter than the body of the lemma. Lemmas hairless (puberulous); non-carinate; 5 nerved. Palea present; relatively long; textured like the lemma; 2-keeled. Palea keels ciliolate. Lodicules present (abour 2 mm long); 3; ciliate. Stamens 3. Ovary apically glabrous. Stigmas 3.
Fruit, embryo and seedling. Pericarp fused.
Classification. Watson & Dallwitz (1994): not described separately. Soreng et al. (2015): Bambusoideae; Arundinarodae; Arundinarieae; Arundinariinae. 1 species (G. megalothyrsa).
Distribution, phytogeography, ecology. China.
References, etc. Morphological/taxonomic: Clayton et al. (2016), GrassBase; Flora of China vol. 22.
Special comments. Fruit data wanting. Anatomical data wanting. Illustrations. • G. megalothyrsa, with Acidosasa purpurea: Wu Zhengyi, Flora Yunnanica 9 (2003)
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: 11th December 2017. delta-intkey.com/grass’.