Eriochrysis P. Beauv.
Including Plazerium Kunth
Excluding Leptosaccharum
Habit, vegetative morphology. Perennial; caespitose. Culms 40–120 cm high; herbaceous; unbranched above. Culm nodes hairy, or glabrous. Culm internodes hollow. Leaves mostly basal; non-auriculate. Leaf blades linear; narrow; flat (usually), or folded (rarely); without cross venation; a fringed membrane, or a fringe of hairs.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant; hermaphrodite and female-only; more or less homomorphic (but the pedicelled members smaller); all in heterogamous combinations.
Inflorescence. Inflorescence of spicate main branches, or paniculate (of spiciform ‘racemes’, in a raceme or panicle, with tawny-red hairs); contracted (narrow); non-digitate. Primary inflorescence branches 6–12. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes ‘racemes’; solitary; with substantial rachides; disarticulating; disarticulating at the joints. ‘Articles’ linear to non-linear (clavate); not appendaged; disarticulating transversely; densely long-hairy (at the disarticulation line). Spikelets paired; sessile and pedicellate; consistently in ‘long-and-short’ combinations; in pedicellate/sessile combinations. Pedicels of the ‘pedicellate’ spikelets free of the rachis. The ‘shorter’ spikelets hermaphrodite. The ‘longer’ spikelets female-only.
Female-fertile spikelets. Spikelets compressed dorsiventrally; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus present.
Glumes two; more or less equal; long relative to the adjacent lemmas; free; hairy; awnless; non-carinate; very dissimilar (the G2 thinner, not 2-keeled). Lower glume two-keeled; convex on the back; not pitted; relatively smooth; indistictly many nerved. Upper glume 1 nerved, or 3 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 1; epaleate; sterile. The proximal lemmas awnless; 0 nerved; decidedly exceeding the female-fertile lemmas; similar in texture to the female-fertile lemmas (hyaline); not becoming indurated.
Female-fertile florets 1. Lemmas less firm than the glumes (hyaline); not becoming indurated; entire to incised (truncate to serrate); not deeply cleft; awnless; non-carinate; without a germination flap; 0 nerved. Palea absent. Lodicules present; 2; free; fleshy; glabrous. Stamens 3 (in the sessile spikelets, rudimentary in the pedicellate spikelets). Anthers not penicillate; without an apically prolonged connective. Ovary glabrous. Stigmas 2; red pigmented, or brown.
Fruit, embryo and seedling. Hilum short. Embryo large.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally to markedly different in shape costally and intercostally (the costals narrower); of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular and fusiform; having markedly sinuous walls. Microhairs absent. Stomata common; 24–28.5 microns long. Subsidiaries triangular. Guard-cells overlapped by the interstomatals (sic). Intercostal short-cells absent or very rare (unless the rows over minor veins called ‘intercostal’). With numerous complex-based macrohairs over the veins. Costal short-cells predominantly paired. Costal silica bodies ‘panicoid-type’, or acutely-angled (a few); short dumb-bell shaped, or cross shaped; sharp-pointed (a few ‘crosses’ of Isachne type).
Transverse section of leaf blade, physiology. C4; XyMS– (but the PCR sheath cell walls very thick and pitted, resembling a mestome sheath). PCR cell chloroplasts centrifugal/peripheral. Leaf blade adaxially flat. Midrib conspicuous; having a conventional arc of bundles (one large keel bundle, 3 small ones on each side); with colourless mesophyll adaxially (this ‘colourless tissue’ lignified). Bulliforms present in discrete, regular adaxial groups (the groups of large cells); in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (nearly all bundles); forming ‘figures’ (mid-rib constituting a large anchor. Other main bundles with I’s). Sclerenchyma all associated with vascular bundles.
Cytology. 2n = 20.
Taxonomy. Panicoideae; Andropogonodae; Andropogoneae; Andropogoninae.
Distribution, ecology, phytogeography. 7 species; tropical America and tropical Africa. Helophytic; species of open habitats; glycophytic. In swamps and moist places.
Paleotropical and Neotropical. African. Sudano-Angolan and West African Rainforest. Caribbean, Venezuela and Surinam, Central Brazilian, Pampas, and Andean. Sahelo-Sudanian, Somalo-Ethiopian, and South Tropical African.
References, etc. Leaf anatomical: this project.
Illustrations. • General aspect
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).
