The grass genera of the world
~ Chloris boivinii
Habit, vegetative morphology. Prostrate annual; stoloniferous. Culms 10–30 cm high; herbaceous. Culm nodes glabrous. Plants unarmed. Leaves not basally aggregated; non-auriculate. Leaf blades narrow; 2–4 mm wide (and to 20 mm long); flat; without abaxial multicellular glands; without cross venation; persistent. Ligule a fringed membrane (short-fringed). Contra-ligule absent.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence of spicate main branches; digitate. Primary inflorescence branches 2–4. Rachides flattened. Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; secund (on unilateral rachides); biseriate; subsessile; imbricate.
Female-fertile spikelets. Spikelets 2 mm long; adaxial; strongly compressed laterally (trigonous); disarticulating above the glumes. Rachilla briefly prolonged beyond the uppermost female-fertile floret; the rachilla extension naked (by contrast with Chloris). Hairy callus present.
Glumes two; relatively large; more or less equal; shorter than the spikelets; shorter than the adjacent lemmas; dorsiventral to the rachis to lateral to the rachis; hairless (glabrous, save for the scabrid keel and margins); awnless; carinate (G1), or non-carinate (G2); very dissimilar (membranous, thin). Lower glume 1 nerved. Upper glume 1 nerved. Spikelets with female-fertile florets only.
Female-fertile florets 1. Lemmas similar in texture to the glumes to decidedly firmer than the glumes (membranous to cartilaginous); not becoming indurated; incised; 2 lobed; not deeply cleft (bidentate); awned (usually), or awnless (rarely). Awns 1; median; from a sinus to dorsal; from near the top (just behind the slight notch); non-geniculate; hairless (scabrid); much longer than the body of the lemma; entered by one vein. Lemmas hairless (scabrid marginally and on the nerves); carinate; without a germination flap; 3 nerved. Palea present; relatively long; apically notched; awnless, without apical setae (ciliate on nerves); not indurated (thin); 2-nerved; 2-keeled. Lodicules present; 2; free; fleshy; glabrous; not or scarcely vascularized. Stamens 3. Anthers short; not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit ellipsoid; compressed laterally. Pericarp free.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present; intercostal. Intercostal papillae not over-arching the stomata (or scarcely so); several per cell (a row of large, cylindrical, thick-walled papillae along each long-cell and interstomatal). Long-cells of similar wall thickness costally and intercostally (walls of medium thickness). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; more or less spherical; clearly two-celled; chloridoid-type (small). Microhair apical cell wall of similar thickness/rigidity to that of the basal cell. Microhair basal cells 9 microns long. Microhair total length/width at septum 2. Microhair apical cell/total length ratio 0.5. Stomata common. Subsidiaries irregularly dome-shaped and triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; not paired (solitary). Intercostal silica bodies absent. Costal short-cells conspicuously in long rows. Costal silica bodies present in alternate cell files of the costal zones; saddle shaped (predominating), or panicoid-type (a few).
Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section open.
C4; XyMS+. PCR sheaths of the primary vascular bundles interrupted; interrupted abaxially only. PCR sheath extensions absent. Leaf blade adaxially flat (to slightly adaxially ribbed). Midrib conspicuous (by virtue of a large bulliform group above it); with one bundle only. Bulliforms present in discrete, regular adaxial groups (but inconspicuous save near the centre of the blade); in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (most bundles with minute girders). The lamina margins with fibres.
Classification. Watson & Dallwitz (1994): Chloridoideae; main chloridoid assemblage. Soreng et al. (2015): Chloridoideae; Cynodonteae; Eleusininae. 1 species (D. boivinii).
Distribution, phytogeography, ecology. Madagascar and Aldabra I.
Species of open habitats; halophytic. Maritime sand.
References, etc. Leaf anatomical: studied by us.
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. delta-intkey.com/grass’.