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The grass genera of the world

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

Dissochondrus (Hillebr.) Kuntze

Habit, vegetative morphology. Perennial; caespitose. Culm nodes hairy. Leaves not basally aggregated; auriculate. Leaf blades broad; pseudopetiolate; without cross venation; disarticulating from the sheaths.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.

Inflorescence. Inflorescence paniculate; contracted; spicate. Inflorescence axes not ending in spikelets. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets subtended by solitary ‘bristles’, or with ‘involucres’ of ‘bristles’ (these long, sinuous, antrorsely scabrid). The ‘bristles’ persisting on the axis. Spikelets not secund; pedicellate. Pedicel apices cupuliform.

Female-fertile spikelets. Spikelets 3 mm long; compressed dorsiventrally; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus absent.

Glumes two; very unequal; (the longer) long relative to the adjacent lemmas; hairless; scabrous; pointed; awnless; non-carinate; similar. Lower glume 5 nerved. Upper glume 7–9 nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.

Female-fertile florets 2 (i.e. both the florets hermaphrodite). Lemmas decidedly firmer than the glumes; becoming indurated, or not becoming indurated (leathery or crustaceous); entire; pointed; awnless; hairless; non-carinate; having the margins inrolled against the palea; with a clear germination flap; 3–5 nerved. Palea present; relatively long; textured like the lemma; 2-nerved; keel-less. Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Anthers not penicillate; without an apically prolonged connective (but the anthers divaricate). Ovary apically glabrous. Styles free to their bases. Stigmas 2.

Fruit, embryo and seedling. Fruit small.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Mid-intercostal long-cells fusiform; having markedly sinuous walls. Microhairs present (equalling the long-cells in length); panicoid-type; (60–)66–81(–87) microns long; (27–)30–44(–57) microns wide at the septum. Microhair total length/width at septum 6.1–19.3. Microhair apical cells (4.2–)5.4–6 microns long. Microhair apical cell/total length ratio 0.45–0.66. Stomata common; 21–24 microns long. Subsidiaries dome-shaped. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common (fairly); in cork/silica-cell pairs. Costal short-cells conspicuously in long rows. Costal silica bodies ‘panicoid-type’; cross shaped, dumb-bell shaped, and nodular (mostly nodular).

Transverse section of leaf blade, physiology. C4. The anatomical organization unconventional. Organization of PCR tissue Arundinella type. XyMS–. Mesophyll with radiate chlorenchyma (slightly); exhibiting ‘circular cells’ (solitaries, small groups and some obviously ‘reduced bundles’). Leaf blade adaxially flat. Midrib with one bundle only to having a conventional arc of bundles (a small bundle under each midrib ‘hinge’). Bulliforms present in discrete, regular adaxial groups; in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’. Sclerenchyma all associated with vascular bundles.

Classification. Watson & Dallwitz (1994): Panicoideae; Panicodae; Paniceae. Soreng et al. (2015): Panicoideae; Panicodae; Paniceae; Cenchrinae. 1 species (D. biflorus).

Distribution, phytogeography, ecology. Hawaii.

Shade species. On slopes.

References, etc. Leaf anatomical: studied by us.

Special comments. Fruit data wanting.

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.’.