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The grass genera of the world

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

Pseudosasa Makino

Greek, false Sasa (q.v.).

~ Arundinaria

Including Yadakeya Mak.

Habit, vegetative morphology. Shrubby perennial; rhizomatous. The flowering culms leafy. Culms 200–500 cm high; woody and persistent; to 1.5 cm in diameter; branched above. Buds from which the primary culm branches arise (where recorded) 1. Primary branches 1–3 (very rarely 4 or more). The branching dendroid (nearly always), or suffrutescent (e.g., P. pubiflora). Culm leaf sheaths present; deciduous, or persistent; leaving a persisten girdle (sometimes), or not leaving a persistent girdle; conspicuously auriculate, or not conspicuously auriculate. Culm leaves with conspicuous blades. Culm leaf blades linear, or lanceolate, or triangular. Culm internodes hollow. Rhizomes pachymorph and leptomorph (metamorph type I). Plants unarmed. Leaves not basally aggregated; with auricular setae. Leaf blades broad; 10–50 mm wide (‘to 5 cm’); pseudopetiolate; cross veined; where recorded, disarticulating from the sheaths; rolled in bud. Contra-ligule consistently absent.

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

Inflorescence. Inflorescence without pseudospikelets; paniculate (terminal). Inflorescence with axes ending in spikelets. Inflorescence spatheate; a complex of ‘partial inflorescences’ and intervening foliar organs. Spikelet-bearing axes ‘racemes’ (seemingly); persistent. Spikelets not secund; pedicellate.

Female-fertile spikelets. Spikelets 15–45 mm long; oblong, or lanceolate, or linear; compressed laterally to not noticeably compressed; disarticulating above the glumes (?); disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret. Hairy callus absent.

Glumes two; very unequal; shorter than the adjacent lemmas; pointed; awnless; similar. Lower glume 5 nerved (in material seen). Upper glume 9 nerved (in material seen). Spikelets with female-fertile florets only, or with incomplete florets. The incomplete florets distal to the female-fertile florets (assuming the distal florets may be imperfect).

Female-fertile florets 2–7. Lemmas entire; pointed; awnless, or mucronate (?); non-carinate; 17 nerved (in material seen). Palea present; relatively long; not convolute; apically notched; awnless, without apical setae; several nerved (8–13, 13 in material seen); 2-keeled. Lodicules present; 3; free; membranous; ciliate; not toothed; heavily vascularized. Stamens 3(–4). Anthers not penicillate; without an apically prolonged connective. Ovary apically glabrous; without a conspicuous apical appendage (the apex not swollen). Styles fused. Stigmas 3.

Fruit, embryo and seedling. Fruit not grooved. Pericarp thin (seemingly). Embryo small. Endosperm containing only simple starch grains. Embryo with an epiblast; with a scutellar tail; with a negligible mesocotyl internode. Embryonic leaf margins overlapping.

Ovule, embryology. Micropyle not noticeably oblique. Outer integument extensive, being absent only from the micropylar region; two cells thick at the micropylar margin. Inner integument continuous, the micropyle constricted; thickened around the micropyle. Synergids not haustorial; without large, globular starch grains.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present; costal and intercostal. Intercostal papillae over-arching the stomata (and obscuring them); several per cell (abundant, narrow-elongated). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type; without ‘partitioning membranes’ (in Pseudosasa japonica); (42–)49–51(–60) microns long; (4.2–)4.5–5.4(–6) microns wide at the septum. Microhair total length/width at septum 7.8–14.3. Microhair apical cells (21–)22.5–25.5(–27) microns long. Microhair apical cell/total length ratio 0.43–0.51. Stomata common; 27–28.5–30 microns long. Intercostal short-cells common; in cork/silica-cell pairs; silicified. Intercostal silica bodies crescentic, or saddle shaped, or tall-and-narrow (smallish). Costal short-cells conspicuously in long rows. Costal silica bodies saddle shaped (predominantly, very large), or oryzoid (a few approaching this); not sharp-pointed.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; with adaxial palisade (in places); with arm cells; with fusoids. The fusoids external to the PBS. Leaf blade adaxially flat. Midrib conspicuous (and with the usual bamboo asymmetry); having complex vascularization. Bulliforms present in discrete, regular adaxial groups (these large); in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with most bundles - a few with strands only); forming ‘figures’ (sometimes). Sclerenchyma all associated with vascular 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. 8 species.

Distribution, phytogeography, ecology. Eastern Asia.

Rusts and smuts. Rusts — Puccinia. Taxonomically wide-ranging species: Puccinia longicornis and Puccinia kusanoi.

References, etc. Leaf anatomical: studied by us - P. japonica (Sieb. & Zucc. ex Steud.) Makino ex Nakai.

Illustrations. • P. hindsii (as Thamnocalamus, with Neomicrocalamus prainii: Camus, 1913). • Abbreviations for Camus (1913) figures. • P. japonica and P. humilis (as Sasa: Camus, 1913). • Psdeudopetiole, auricular (oral) setae (P. japonica). Pseudosasa japonica. Auricular setae, pseudopetiole with basal disarticulation zone. • a flower of P. japonica. Pseudosasa japonica, Three large, membranous, heavily vascularized, ciliate lodicules; ovary with the styles joined into one and three free stigmas. • P. japonica, abaxial epidermis of leaf blade: this project. • P. japonica, TS leaf blade: this project. • P. japonica, vertical LS young leaf blade intercostal zone: original. Pseudosasa japonica . Showing distended young fusoid cells. • P. japonica, vertical L.S. mature leaf blade intercostal zone: this project. Pseudosasa japonica. Showing collapsed fusoids, separated by wide intercellular spaces. • ‘Panicoid-type’ microhairs of P. japonica and Rytidosperma linkii: longitudinal EM sections (Amarasinghe)

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.’.