Eremochloa Buese
From the Greek eremos (desert) and chloa (grass), referring to habitat.
Including Pectinaria (Benth.) Hack.
Habit, vegetative morphology. Perennial; caespitose. Culm nodes hairy. Culm internodes solid. Young shoots extravaginal. Leaves mostly basal; non-auriculate. Leaf blades narrow; without cross venation; persistent; once-folded in bud; an unfringed membrane.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant; hermaphrodite and sterile; overtly heteromorphic (the ‘pedicelled spikelets’ very reduced); all in heterogamous combinations. Plants outbreeding.
Inflorescence. Inflorescence comprising axillary or terminal spike-like, slender flattened ‘racemes’; espatheate; not comprising ‘partial inflorescences’ and foliar organs (or not usually interpreted as such). Spikelet-bearing axes spikelike (exserted on long slender peduncles, curved, with imbricate spikelets); solitary, or paired (rarely); with substantial rachides (these swollen, 3-angled); tardily disarticulating; disarticulating at the joints. ‘Articles’ non-linear (clavate); with a basal callus-knob; densely long-hairy to somewhat hairy. Spikelets paired; secund (the sessile members in two alternating rows, on one side of the rachis); sessile and pedicellate; imbricate; consistently in ‘long-and-short’ combinations; in pedicellate/sessile combinations. Pedicels of the ‘pedicellate’ spikelets free of the rachis (flattened). The ‘shorter’ spikelets hermaphrodite (or those near the tip o sterile). The ‘longer’ spikelets sterile (reduced to a pedicel only, or with rudiments of a spikelet which may take the form of a bristle or mucro).
Female-sterile spikelets. Vestigial.
Female-fertile spikelets. Spikelets compressed dorsiventrally; falling with the glumes (and with the adjacent internode and pedicel). Rachilla terminated by a female-fertile floret. Hairy callus present, or absent.
Glumes two; very unequal; (the longer) long relative to the adjacent lemmas; awnless; very dissimilar (the lower 2-keeled and spiny on the margins, the upper naviculate, smooth, glabrous). Lower glume two-keeled; not pitted; prickly (the lower keels with filiform or flattened scabrid curved or horizontal spines); 5–9 nerved. Upper glume 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; paleate; male. The proximal lemmas awnless; more or less equalling the female-fertile lemmas to 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; pointed; awnless; hairless; non-carinate; 0 nerved. Palea present; textured like the lemma (hyaline); not indurated; nerveless. Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Anthers not penicillate. Ovary glabrous. Styles free to their bases. Stigmas 2; red pigmented.
Fruit, embryo and seedling. Fruit small; compressed dorsiventrally. Hilum short. Embryo large. Endosperm containing only simple starch grains. Embryo without an epiblast; with a scutellar tail; with an elongated mesocotyl internode.
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 (but sometimes with rounded ends); having markedly sinuous walls. Microhairs present; panicoid-type; 53.7–58.6 microns long; 10.7–12.2 microns wide at the septum. Microhair total length/width at septum 4.4–5.5. Microhair apical cells 29–39 microns long. Microhair apical cell/total length ratio 0.55–0.67. Stomata common; 36.6–41.5 microns long. Subsidiaries triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs; silicified. Costal short-cells conspicuously in long rows. Costal silica bodies ‘panicoid-type’.
Transverse section of leaf blade, physiology. C4; XyMS–. PCR sheath outlines uneven. PCR cell chloroplasts with reduced grana; centrifugal/peripheral. Mesophyll with radiate chlorenchyma. Leaf blade adaxially flat. Midrib conspicuous (with a large adaxial bulliform group); having a conventional arc of bundles; with colourless mesophyll adaxially. Bulliforms not present in discrete, regular adaxial groups (the epidermis extensively bulliform). Many of the smallest vascular bundles unaccompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’. Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 9. 2n = 18. 2 ploid. Nucleoli persistent.
Taxonomy. Panicoideae; Andropogonodae; Andropogoneae; Rottboelliinae.
Distribution, ecology, phytogeography. 9 species; India, Ceylon, southern China, Southeast Asia, western Malaysia, Australia. Mesophytic; species of open habitats. Short grassland.
Paleotropical and Australian. Indomalesian. Indian, Indo-Chinese, Malesian, and Papuan. North and East Australian. Tropical North and East Australian.
Rusts and smuts. Smuts from Ustilaginaceae. Ustilaginaceae — Sorosporium and Sphacelotheca.
Economic importance. Lawns and/or playing fields: E. ophiuroides.
References, etc. Leaf anatomical: this project.
Illustrations. • Leaf blade transverse section. Eremochloa bimaculata.
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).
