Sphaerocaryum Nees ex Hook.f.
Including Graya Steud., Steudelella Honda
Habit, vegetative morphology. Annual; stoloniferous and decumbent. Culms 5–15 cm high; herbaceous. Culm nodes hairy. Culm internodes hollow. Leaves not basally aggregated; non-auriculate. Leaf blades ovate; broad, or narrow; 3–10 mm wide (small but relatively broad, Commelina-like); cordate (amplexicaul); obscurely cross veined; persistent; a fringe of hairs.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; open; with capillary branchlets; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets seemingly morphologically ‘conventional’; 0.8–1.4 mm long; not noticeably compressed; falling with the glumes (but the glumes often deciduous). Rachilla terminated by a female-fertile floret. Hairy callus absent.
Glumes present; assumed to be two (since the inflorescence is not contracted); relatively large; more or less equal; shorter than the adjacent lemmas; not pointed (obtuse); awnless; similar (cymbiform, hyaline). Lower glume 0 nerved. Upper glume 1 nerved. Spikelets with female-fertile florets only (i.e., a necessary corollary, assuming there are 2 glumes); without proximal incomplete florets.
Female-fertile florets 1. Lemmas similar in texture to the glumes (hyaline); not becoming indurated; entire; pointed to blunt; hairy; non-carinate (cymbiform); having the margins lying flat on the palea; without a germination flap; 1 nerved, or 2 nerved. Palea present; entire (oblong,obtuse); awnless, without apical setae; textured like the lemma; not indurated; 2-nerved. Lodicules present (minute); 2. Stamens 3. Anthers not penicillate. Ovary glabrous. Styles fused. Stigmas 2.
Fruit, embryo and seedling. Fruit free from both lemma and palea; small (about 0.5 mm long). Hilum short.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present (many intercostal cells papillate). Intercostal papillae over-arching the stomata; consisting of one oblique swelling per cell to consisting of one symmetrical projection per cell. Intercostal zones without typical long-cells (cf. Isachne). Mid-intercostal long-cells having straight or only gently undulating walls. Microhairs present; chloridoid-type (the apical cell somewhat pointed, but thick-walled and broader than long); 16.5 microns long; 7.5 microns wide at the septum. Microhair total length/width at septum 2.2. Microhair apical cells 9 microns long. Microhair apical cell/total length ratio 0.55. Stomata common. Subsidiaries parallel-sided to triangular (rather irregular forms, owing to bulbously-intruding surrounding cells); including both triangular and parallel-sided forms on the same leaf. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare (simply not detectable in this kind of epidermis). Costal short-cells conspicuously in long rows. Costal silica bodies ‘panicoid-type’ to acutely-angled; acutely angled cross shaped; sharp-pointed (acutely angled crosses).
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with radiate chlorenchyma; Isachne-type. Leaf blade with distinct, prominent adaxial ribs; with the ribs more or less constant in size. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups (in the shallow furrows); in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’. Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 10. 2n = 20.
Taxonomy. Panicoideae; Panicodae; Isachneae.
Distribution, ecology, phytogeography. 1 species; India to southern China, Formosa, Malay Peninsula, Banka. Helophytic to mesophytic.
Paleotropical. Indomalesian. Indian, Indo-Chinese, and Malesian.
References, etc. Leaf anatomical: Metcalfe 1960; this project.
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).