Streptogyna P. Beauv.
Including Streptia Doell
Habit, vegetative morphology. Perennial; stoloniferous to caespitose. The flowering culms leafy. Culms 60–100 cm high; herbaceous; to 0.5 cm in diameter; unbranched above. Rhizomes pachymorph. Plants unarmed. Leaves mostly basal (S. americana), or not basally aggregated (S. crinita); auriculate (at the top of the sheath - inconspicuous or absent in S. americana); with auricular setae (better developed in S. crinita). Leaf blades linear to lanceolate; broad; 13–36 mm wide (15–25 cm long); pseudopetiolate, or not pseudopetiolate; cross veined (few laterals, above the base); disarticulating from the sheaths; a fringed membrane; truncate. Contra-ligule present (in the form of a hard rim).
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence a single raceme (inilateral, spiciform); espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes ‘racemes’; persistent. Spikelets secund; pedicellate.
Female-fertile spikelets. Spikelets 25–35 mm long; compressed laterally to not noticeably compressed; disarticulating above the glumes; disarticulating between the florets (the rachilla joint at the base of each floret forming a hook, aiding in dispersal); with distinctly elongated rachilla internodes between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; hairless; the rachilla extension with incomplete florets. Hairy callus present, or absent.
Glumes two; very unequal (G2 much longer); shorter than the adjacent lemmas; hairless; awnless; papery. Lower glume 1–3(–5) nerved. Upper glume (5–)7–17 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets (with glabrous lemmas). The distal incomplete florets merely underdeveloped.
Female-fertile florets 2–4. Lemmas convolute; similar in texture to the glumes to decidedly firmer than the glumes (rigidly leathery); not becoming indurated; incised; 2 lobed; not deeply cleft (bidentate); awned. Awns 1; median; from a sinus; non-geniculate; straight; hairless (antrorsely scabrous); much shorter than the body of the lemma to about as long as the body of the lemma. Lemmas hairy (silky villous below the middle); non-carinate; 7–13 nerved. Palea present (narrowly linear); relatively long; apically notched; awnless, without apical setae; not indurated; 2-nerved (these median, contiguous). Lodicules present; 3; free; membranous; ciliate (only inconspicuously so in S. americana); not toothed; heavily vascularized. Stamens 2. Anthers not penicillate; without an apically prolonged connective. Ovary glabrous, or hairy. Styles fused (only at the base in S. americana). Stigmas 2 (S. crinita), or 3 (S. americana - in both species, they elongate after anthesis to entangle with one another and with the lemma awns).
Fruit, embryo and seedling. Fruit free from both lemma and palea; large; linear; compressed laterally; when present, with hairs confined to a terminal tuft. Hilum long-linear. Embryo small; not waisted. Endosperm hard; containing only simple starch grains, or containing compound starch grains (some, in S. crinita). Embryo with an epiblast; with a scutellar tail; with a negligible mesocotyl internode. Embryonic leaf margins overlapping.
Seedling with a short mesocotyl; with a loose coleoptile (with a short mucro). First seedling leaf with a well-developed lamina. The lamina narrow; erect.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally; differing markedly in wall thickness costally and intercostally (the costals rather thicker walled). Mid-intercostal long-cells rectangular (mostly); having markedly sinuous walls. Microhairs absent. Stomata common; 18–24 microns long. Subsidiaries dome-shaped (in S. americana), or dome-shaped and triangular (in S. crinita). Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs (mostly); silicified. Intercostal silica bodies narrowly saddle shaped. Costal short-cells conspicuously in long rows (S. crinita), or predominantly paired (S. americana). Costal silica bodies saddle shaped (predominating), or tall-and-narrow to crescentic; not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade; with arm cells (S. crinita), or without arm cells (no trace of these in S. americana); with fusoids. The fusoids external to the PBS. Leaf blade adaxially flat. Midrib conspicuous; having complex vascularization (the large keel with an abaxial arc, plus one small adaxial bundle); with colourless mesophyll adaxially. Bulliforms present in discrete, regular adaxial groups (these large); in simple fans. All the vascular bundles accompanied by sclerenchyma (or a few without, in S. crinita). Combined sclerenchyma girders present (with most bundles); forming ‘figures’ (a few with I’s and T’s). Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 12. 2n = 24.
Taxonomy. Bambusoideae; Bambusodae; Streptogyneae.
Distribution, ecology, phytogeography. 2 species; Africa, India, Central and South America. Shade species; glycophytic. In dry forests.
Paleotropical and Neotropical. African and Indomalesian. Sudano-Angolan and West African Rainforest. Indian. Caribbean, Amazon, and Central Brazilian. Sahelo-Sudanian and South Tropical African.
References, etc. Morphological/taxonomic: Soderstrom and Judziewicz 1987. 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).