The grass genera of the world
The grass genera of the world | |
Eragrostiella: a diminutive of Eragrostis (a related genus, q.v.).
Habit, vegetative morphology. Perennial; compactly caespitose. Culms 20–50 cm high; herbaceous. Culm internodes hollow. Leaves usually mostly basal; non-auriculate. Leaf blades narrow; setaceous, or not setaceous (often filiform, rarely flat); without abaxial multicellular glands; without cross venation; persistent. Ligule a fringed membrane; short.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality.
Inflorescence. Inflorescence a single spike, or a single raceme (long-pedunculate). Inflorescence with axes ending in spikelets. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets secund; biseriate; subsessile, or pedicellate.
Female-fertile spikelets. Spikelets 6–20 mm long; compressed laterally; disarticulating above the glumes; tardily disarticulating between the florets, or not disarticulating between the florets (the paleas persistent). Rachilla prolonged beyond the uppermost female-fertile floret; hairy; the rachilla extension with incomplete florets. Hairy callus absent.
Glumes present; two; more or less equal; shorter than the spikelets; shorter than the adjacent lemmas, or long relative to the adjacent lemmas; awnless; carinate (the lower), or non-carinate (the upper being keeled only at the tip); very dissimilar. Lower glume 1 nerved. Upper glume 3 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped. Spikelets without proximal incomplete florets.
Female-fertile florets 6–50. Lemmas less firm than the glumes to similar in texture to the glumes (membranous to cartilaginous); not becoming indurated; entire to incised (acute to emarginate); not deeply cleft; awnless; hairless; glabrous; carinate. The keel wingless. Lemmas without a germination flap; 3 nerved. Palea present (persistent); relatively long; entire; awnless, without apical setae; 2-nerved; 2-keeled. Palea keels narrowly to broadly winged. Lodicules present; 2; fleshy. Anthers not penicillate. Ovary glabrous. Stigmas 2.
Fruit, embryo and seedling. Fruit ellipsoid; not noticeably compressed (terete), or trigonous; sculptured (reticulate-striate). Pericarp fused (?). Embryo large; with an epiblast; with a scutellar tail; with an elongated mesocotyl internode. Embryonic leaf margins meeting.
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; clearly two-celled; chloridoid-type. Microhair apical cell wall of similar thickness/rigidity to that of the basal cell. Microhairs 14–18 microns long. Microhair basal cells 9 microns long. Microhairs 12(–13.5) microns wide at the septum. Microhair total length/width at septum 1.4–1.8. Microhair apical cells 7–12 microns long. Microhair apical cell/total length ratio 0.4–0.73. Stomata common; 22.5–25.5 microns long. Subsidiaries low dome-shaped, or triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs; silicified. Intercostal silica bodies imperfectly developed; saddle shaped (small), or tall-and-narrow. Costal short-cells conspicuously in long rows, or neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies present in alternate cell files of the costal zones; saddle shaped.
Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.
C4; XyMS+. PCR sheath outlines even. PCR sheaths of the primary vascular bundles interrupted; interrupted abaxially only. PCR sheath extensions present, or absent. Maximum number of extension cells 1–2. Mesophyll with radiate chlorenchyma; traversed by columns of colourless mesophyll cells. Leaf blade with distinct, prominent adaxial ribs, or adaxially flat; with the ribs more or less constant in size. Midrib not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups; associated with colourless mesophyll cells to form deeply-penetrating fans (these linked with traversing columns of colourless cells). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’. Sclerenchyma all associated with vascular bundles. The lamina margins with fibres.
Taxonomy. Chloridoideae; main chloridoid assemblage.
Distribution, ecology, phytogeography. 5 species; India, Burma, Ceylon, Australia. Xerophytic; species of open habitats. Dry grassland and bush, on thin soils.
Paleotropical and Australian. African and Indomalesian. Saharo-Sindian and Sudano-Angolan. Indian and Indo-Chinese. North and East Australian. Somalo-Ethiopian. Tropical North and East Australian.
Rusts and smuts. Smuts from Tilletiaceae. Tilletiaceae — Tilletia.
References, etc. Leaf anatomical: Metcalfe 1960; this project.
This description is offered for casual browsing only. We strongly advise against extracting comparative information from it. This is much more easily achieved using 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 specified attributes, summaries of attributes within groups of taxa, geographical distribution, classification, and species sampled for anatomy.
Cite this publication as: ‘Watson, L., 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 February 2012. http://delta-intkey.com’.