The grass genera of the world
Type species: Type: E. distachya Kunth.
Including Aglycia Steud., Glandiloba (Raf.) Steud., Helopus Trin., Oedipachne Link
Habit, vegetative morphology. Annual, or perennial; stoloniferous, or caespitose to decumbent. Culms 20–170 cm high; herbaceous; branched above, or unbranched above. The branching simple, or fastigiate (rarely). Culm nodes hairy. Culm leaf sheaths rounded. Culm internodes hollow. Leaves mostly basal, or not basally aggregated; non-auriculate. Leaf blades narrow; setaceous (sometimes?), or not setaceous; usually flat; without cross venation; persistent; rolled in bud. Ligule a fringed membrane (very reduced), or a fringe of hairs.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality. Apomictic, or reproducing sexually.
Inflorescence. Inflorescence of spicate main branches, or paniculate (usually of simple or compound racemes, very rarely a single raceme (E. distachya) or a contracted panicle (E. meyeriana)); open. Primary inflorescence branches borne biseriately on one side of the main axis, or inserted all around the main axis. Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary, or paired (or in clusters); secund. Pedicel apices discoid. Spikelets consistently in long-and-short combinations, or not in distinct long-and-short combinations.
Female-fertile spikelets. Spikelets elliptic, or lanceolate, or ovate; adaxial (nearly always with a small basal swelling representing fusion of the usually vestigial G1 to the swollen internode); compressed dorsiventrally; biconvex; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus absent.
Glumes two (but G1 nearly always very reduced); very unequal (nearly always), or more or less equal (the lower usually vestigial, but as long as the spikelet in E. rovumensis); (the upper) long relative to the adjacent lemmas; dorsiventral to the rachis; pointed (G2 pointed to aristulate); awned (G2, when aristulate), or awnless; non-carinate; very dissimilar (the lower nearly always reduced to a small cupuliform strip adherent to the thickened rachilla internode). Upper glume 5 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. Spikelets with proximal incomplete florets. The proximal incomplete florets 1; paleate, or epaleate. Palea of the proximal incomplete florets (when present) fully developed to reduced. The proximal incomplete florets male, or sterile. The proximal lemmas awnless; 5 nerved (similar to the G2, or shorter); decidedly exceeding the female-fertile lemmas; less firm than the female-fertile lemmas (membranous); not becoming indurated.
Female-fertile florets 1. Lemmas decidedly firmer than the glumes; rugose; becoming indurated to not becoming indurated (papery to crustaceous); yellow in fruit; entire; mucronate to awned (the mucro or awn barbellate). Awns apical; non-geniculate; much shorter than the body of the lemma. Lemmas hairless (glabrous or apically puberulous); non-carinate; having the margins inrolled against the palea; with a clear germination flap; 5 nerved. Palea present; relatively long; entire (rounded apically); awnless, without apical setae; textured like the lemma; 2-nerved; 2-keeled (the keels thickened). Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Anthers not penicillate. Ovary apically glabrous. Styles fused, or free to their bases. Stigmas 2; red pigmented.
Fruit, embryo and seedling. Fruit small; compressed dorsiventrally. Hilum short. Embryo large. Endosperm hard; containing only simple starch grains. Embryo without an epiblast; with a scutellar tail; with an elongated mesocotyl internode. Embryonic leaf margins overlapping.
Seedling with a long mesocotyl.
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; 54–64.5 microns long; 6–6.6 microns wide at the septum. Microhair total length/width at septum 9–10. Microhair apical cells 22.5–27 microns long. Microhair apical cell/total length ratio 0.4–0.42. Stomata common; 33–36 microns long. Subsidiaries dome-shaped, or triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs, or not paired (solitary); silicified (when paired), or not silicified. Costal short-cells conspicuously in long rows. Costal silica bodies panicoid-type; cross shaped, or dumb-bell shaped, or nodular.
Transverse section of leaf blade, physiology. C4; biochemical type PCK (5 species); XyMS+. PCR sheath outlines uneven. PCR sheath extensions absent. PCR cells with a suberised lamella. PCR cell chloroplasts with well developed grana; centrifugal/peripheral. Mesophyll with radiate chlorenchyma, or with non-radiate chlorenchyma. Leaf blade adaxially flat; with the ribs more or less constant in size. Midrib conspicuous; having a conventional arc of bundles; with colourless mesophyll adaxially. Bulliforms present in discrete, regular adaxial groups; in simple fans. Many of the smallest vascular bundles unaccompanied by sclerenchyma. Combined sclerenchyma girders present; nowhere forming figures. Sclerenchyma all associated with vascular bundles.
Culm anatomy. Culm internode bundles in one or two rings.
Special diagnostic feature. Spikelets supported on a peculiar, hardened, cupuliform callus (representing the G1).
Cytology. Chromosome base number, x = 9. 2n = 36, 54, and 72. 4, 6, and 8 ploid. Chromosomes small.
Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Paniceae. Soreng et al. (2015): Panicoideae; Panicodae; Paniceae; Melidininae. 30 species.
Distribution, phytogeography, ecology. Subtropical.
Commonly adventive. Helophytic to mesophytic; species of open habitats; glycophytic. Damp ground and weedy places.
Economic aspects. Significant weed species: E. gracilis, E. punctata. Cultivated fodder: E. polystachya. Important native pasture species: E. gracilis, E. procera.
Rusts and smuts. Rusts Puccinia. Taxonomically wide-ranging species: Puccinia levis and Uromyces setariae-italicae. Smuts from Tilletiaceae and from Ustilaginaceae. Tilletiaceae Tilletia. Ustilaginaceae Sorosporium and Ustilago.
References, etc. Leaf anatomical: this project.
Illustrations. • E. pseudoacrotricha: Gardner, 1952. • E. grandiflora: Lamson-Scribner (1890). • General aspect (E. meyeriana): Gibbs Russell et al., 1990. • E. meyeriana, spikelet opened to show details: this project. Eriochloa meyeriana. Opened, showing large, hairy upper glume (right) and similar proximal lemma; a bisexual floret with short, mucronate, rugose, indurated lemma (above) and palea of similar texture; and a cupuliform callus (lower right) representing the lower glume. • Inflorescence detail of E. meyeriana. Eriochloa meyeriana. Shiny, cupuliform callus representing the lower glume. • E. pseudoacrotricha TS leaf blade: this project
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: 13th November 2017. delta-intkey.com/grass’.