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The grass genera of the world

L. Watson, T.D. Macfarlane, and M.J. Dallwitz

Eleusine Gaertn.

Named after Eleusis, the Greek town where the Temple of Ceres was located.

Type species: Type: E. coracana (L.) Gaertn.

Habit, vegetative morphology. Annual, or perennial (the culms flattened); caespitose (or mat-forming). Culms 10–150 cm high; herbaceous; branched above, or unbranched above. The branching simple, or fastigiate. Culm nodes glabrous. Culm internodes solid, or hollow. Young shoots intravaginal. Leaves not basally aggregated; non-auriculate. Sheath margins free. The sheaths keeled. Leaf blades linear; narrow; flat, or folded; without abaxial multicellular glands; without cross venation; persistent; rolled in bud, or once-folded in bud. Ligule a fringed membrane. Contra-ligule absent.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets; inbreeding; exposed-cleistogamous, or chasmogamous; without hidden cleistogenes. Viviparous (sometimes), or not viviparous.

Inflorescence. Inflorescence of spicate main branches; open, or contracted (sometimes forming a capitulum); digitate, or subdigitate (then shortly racemose, but clustered at the top of the culm). Primary inflorescence branches 1–16. Rachides flattened. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. The racemes spikelet bearing to the base. Spikelet-bearing axes with substantial rachides; persistent. Spikelets secund; biseriate; sessile to subsessile; imbricate.

Female-fertile spikelets. Spikelets 3.5–11 mm long; adaxial; strongly compressed laterally; disarticulating above the glumes, or not disarticulating (E. coracana); disarticulating between the florets (except in E. coracana). Rachilla prolonged beyond the uppermost female-fertile floret; hairy, or hairless. Hairy callus absent. Callus absent.

Glumes two; very unequal, or more or less equal; shorter than the spikelets; shorter than the adjacent lemmas; dorsiventral to the rachis to lateral to the rachis; awnless; carinate; with the keel conspicuously winged, or without a median keel-wing. Lower glume 1 nerved. Upper glume 3–5(–7) nerved. Spikelets with female-fertile florets only, or with incomplete florets. The incomplete florets distal to the female-fertile florets. Spikelets without proximal incomplete florets.

Female-fertile florets 3–15. Lemmas not becoming indurated; entire; pointed, or blunt; awnless to mucronate; hairless; glabrous; carinate; 3 nerved. Palea present; apically notched; awnless, without apical setae; 2-nerved; 2-keeled. Palea keels winged, or wingless. Lodicules present; 2; joined, or free; fleshy, or membranous; glabrous; toothed, or not toothed. Stamens 3. Anthers 0.5–0.8 mm long; not penicillate. Ovary apically glabrous. Styles free to their bases. Stigmas 2; white, or brown.

Fruit, embryo and seedling. Fruit free from both lemma and palea; small (0.9–2 mm long); ellipsoid to subglobose; longitudinally grooved (E. multiflora), or not grooved; not noticeably compressed (globose), or trigonous; sculptured. Hilum short. Pericarp thin (hyaline); free. Embryo large; not waisted. Endosperm hard; without lipid; containing compound starch grains. Embryo with an epiblast; with a scutellar tail; with an elongated mesocotyl internode. Embryonic leaf margins meeting.

Seedling with a long mesocotyl. First seedling leaf with a well-developed lamina. The lamina broad; curved; 6–12 veined.

Ovule, embryology. Outer integument extensive, being absent only from the micropylar region; two cells thick at the micropylar margin. Inner integument continuous, the micropyle constricted; not thickened around the micropyle. Synergids not haustorial; without large, globular starch grains.

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; more or less spherical, or elongated; ostensibly one-celled, or clearly two-celled; chloridoid-type (often with hidden bases). Microhair apical cell wall of similar thickness/rigidity to that of the basal cell. Microhairs with ‘partitioning membranes’ (in E. indica). The ‘partitioning membranes’ in the basal cell. Microhairs 19–21 microns long. Microhair basal cells 12–14 microns long. Microhairs 7.5–9 microns wide at the septum. Microhair total length/width at septum 2.17–2.8. Microhair apical cells 13.5–16.5 microns long. Microhair apical cell/total length ratio 0.64–0.8. Stomata common; 30–33 microns long. Subsidiaries triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; not paired. Intercostal silica bodies absent. Costal short-cells conspicuously in long rows. Costal silica bodies present in alternate cell files of the costal zones; rounded to saddle shaped.

Transverse section of leaf blade, physiology. C4; biochemical type NAD–ME (2 species); XyMS+. PCR sheath outlines even. PCR sheaths of the primary vascular bundles complete. PCR sheath extensions absent. PCR cells without a suberised lamella. PCR cell chloroplasts with well developed grana; centripetal. Mesophyll with radiate chlorenchyma; traversed by columns of colourless mesophyll cells. Leaf blade adaxially flat; with the ribs more or less constant in size. Midrib conspicuous; with one bundle only. Bulliforms present in discrete, regular adaxial groups; associated with colourless mesophyll cells to form deeply-penetrating fans, or in simple fans and associated with colourless mesophyll cells to form deeply-penetrating fans (often linked with traversing colourless girders). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’, or nowhere forming ‘figures’. Sclerenchyma all associated with vascular bundles. The lamina margins with fibres.

Culm anatomy. Culm internode bundles in one or two rings, or in three or more rings.

Phytochemistry. Leaf blade chlorophyll a:b ratio 3.43–4.3.

Cytology. Chromosome base number, x = 9. 2n = 18, 20, 36, and 40. 2 and 4 ploid. Chromosomes ‘small’. Haploid nuclear DNA content 0.7–0.8 pg (2 species, 2x and 4x). Mean diploid 2c DNA value 1.4 pg (1 species). Nucleoli persistent.

Classification. Watson & Dallwitz (1994): Chloridoideae; main chloridoid assemblage. Soreng et al. (2015): Chloridoideae; Cynodonteae. 9 species.

Distribution, phytogeography, ecology. Tropical and subtropical.

Commonly adventive. Mesophytic, or xerophytic; species of open habitats. Savanna, grassland, weedy places.

Economic aspects. Significant weed species: E. africana, E. coracana, E. indica, E. tristachya. Grain crop species: E. coracana (Finger Millet, Ragi) widely grown in uplands of India, China and Africa.

Rusts and smuts. Smuts from Ustilaginaceae. Ustilaginaceae — Ustilago.

References, etc. Leaf anatomical: Metcalfe 1960; studied by us - Eleusine indica (L.) Gaertn.

Illustrations. • E. indica: Gardner, 1952. • Inflorescence of E. indica. • Inflorescence of E. tristachya. • Spikelet of E. tristachya. • Spikelet (upper part). • E. coracana, with Schismus marginatus (= barbatus), Megastachya owariensis (= mucronata) and Uniola maritima (= paniculata): P. Beauv. (1812). • E. coracana: Gibbs Russell et al., 1990. • E. coracana, leaf blade TS - chloroplast distribution: this project. Eleusine coracana. Mature minor bundles with centripetal chloroplasts. • Microhairs of E. indica and Leptochloa digitata: longitudinal EM sections (Amarasinghe)

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: 11th December 2017.’.