Erianthus Michx.
From the Greek erion (wool) and anthos (flower), alluding to woolly glumes.
Including Ripidium Trin.
Sometimes referred to Saccharum
Habit, vegetative morphology. Perennial; sometimes reeds (or reedlike); caespitose. Culms 200–400 cm high; unbranched above. Culm nodes glabrous. Culm internodes solid. Leaves not basally aggregated; non-auriculate. Leaf blades broad (always?); without cross venation; persistent; an unfringed membrane to a fringed membrane.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality; homomorphic (save in glume nervation). Plants exposed-cleistogamous, or chasmogamous.
Inflorescence. Inflorescence paniculate (silky-hairy); open; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes ‘racemes’; with very slender rachides; disarticulating; disarticulating at the joints. ‘Articles’ linear; not appendaged; disarticulating transversely; densely long-hairy (plumose), or somewhat hairy. Spikelets paired; not secund; 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 hermaphrodite.
Female-fertile spikelets. Spikelets compressed dorsiventrally; falling with the glumes (the pedicelled member falling from its pedicel, the sessile falling with the joint and pedicel). Rachilla terminated by a female-fertile floret. Hairy callus present.
Glumes two; more or less equal; long relative to the adjacent lemmas; awnless; very dissimilar (the lower bicarinate, the upper naviculate). Lower glume two-keeled; not pitted; relatively smooth; 2 nerved. Upper glume 3 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. The proximal incomplete florets 1; epaleate; sterile. The proximal lemmas awnless; 1 nerved; more or less equalling the female-fertile lemmas; similar in texture to the female-fertile lemmas (thinly membranous); not becoming indurated.
Female-fertile florets 1. Lemmas less firm than the glumes (hyaline); not becoming indurated; entire, or incised; when entire pointed (to aristate), or blunt; not deeply cleft; mucronate, or awned. Awns 1; median; apical; non-geniculate; hairless; much shorter than the body of the lemma to much longer than the body of the lemma. Lemmas ciliate; non-carinate; 3 nerved. Palea present; (when present) conspicuous but relatively short, or very reduced; entire; awnless, without apical setae; not indurated (hyaline); nerveless. Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Anthers not penicillate. Ovary glabrous. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit free from both lemma and palea; small. Hilum short. Endosperm hard; without lipid; containing compound starch grains. Embryo without an epiblast; with a scutellar tail; with an elongated mesocotyl internode. Embryonic leaf margins overlapping.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type; 42–54 microns long; 3.3–5.4 microns wide at the septum. Microhair total length/width at septum 8.5–13.8. Microhair apical cells (10–)19.5–25 microns long. Microhair apical cell/total length ratio 0.39–0.47. Stomata common; 24–25.5(–27) microns long. Subsidiaries triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells absent or very rare; not paired (solitary); not silicified. Costal short-cells conspicuously in long rows. Costal silica bodies ‘panicoid-type’; cross shaped to dumb-bell shaped.
Transverse section of leaf blade, physiology. C4; XyMS–. PCR cell chloroplasts with reduced grana. Mesophyll with radiate chlorenchyma. Leaf blade with distinct, prominent adaxial ribs, or ‘nodular’ in section; with the ribs very irregular in sizes. Midrib conspicuous; having a conventional arc of bundles; with colourless mesophyll adaxially. Bulliforms present in discrete, regular adaxial groups; in simple fans, or associated with colourless mesophyll cells to form deeply-penetrating fans; associating with colourless mesophyll cells to form arches over small vascular bundles, or nowhere involved in bulliform-plus-colourless mesophyll arches. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; nowhere forming ‘figures’. Sclerenchyma all associated with vascular bundles.
Phytochemistry. Leaves containing flavonoid sulphates (E. maximus), or without flavonoid sulphates (8 species).
Cytology. Chromosome base number, x = 5 and 10. 2n = 10, 15, 20, 30, and 60. Chromosomes ‘small’.
Taxonomy. Panicoideae; Andropogonodae; Andropogoneae; Andropogoninae.
Distribution, ecology, phytogeography. 28 species; tropical America, southeast Europe to eastern Asia, Indomalayan region, Polynesia, Sahara, Madagascar. Helophytic, or mesophytic.
Holarctic, Paleotropical, and Neotropical. Boreal and Tethyan. African, Madagascan, Indomalesian, and Polynesian. Euro-Siberian. Irano-Turanian. Saharo-Sindian, Sudano-Angolan, and West African Rainforest. Indian, Indo-Chinese, Malesian, and Papuan. Polynesian and Fijian. Venezuela and Surinam, Amazon, and Andean.
Hybrids. Intergeneric hybrids with Saccharum.
Rusts and smuts. Rusts — Puccinia. Taxonomically wide-ranging species: Puccinia microspora. Smuts from Ustilaginaceae. Ustilaginaceae — Sphacelotheca and Ustilago.
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).