The grass genera of the world
Type species: Type: D. dives (F.Muell.) Vickery.
Habit, vegetative morphology. Perennial; caespitose. Culms 115–500 cm high; herbaceous; unbranched above; 4–8 noded. Culm nodes exposed; glabrous. Culm internodes hollow. Leaves not basally aggregated; non-auriculate. Sheaths not keeled, terete, striate. Leaf blades linear-lanceolate (and long-acuminate); apically flat; broad to narrow; 7–18(–24) mm wide; flat; not pseudopetiolate; without cross venation; persistent. Ligule an unfringed membrane; not truncate; 6–18(–20) mm long (striate-veined, cartilaginous).
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality.
Inflorescence. Inflorescence paniculate; open (broadly pyramidal, 20–50 cm long, up to 50 cm wide); with capillary branchlets (towards the extremities). Primary inflorescence branches borne distichously. Inflorescence with axes ending in spikelets. Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; long pedicellate.
Female-fertile spikelets. Spikelets 6–11.9 mm long; broadly elliptic; compressed laterally; disarticulating above the glumes; disarticulating between the florets; with distinctly elongated rachilla internodes between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; hairy; the rachilla extension with incomplete florets. Hairy callus present. Callus short; blunt.
Glumes two; more or less equal; shorter than the spikelets; shorter than the adjacent lemmas (half as long to somewhat shorter); hairless; pointed; awnless; carinate (the keels scabrid); similar (membranous). Lower glume (1–)3 nerved. Upper glume 3(–5) nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets 1; merely underdeveloped (rudimentary). Spikelets without proximal incomplete florets.
Female-fertile florets 3–5(–6). Lemmas narrowly elliptic; decidedly firmer than the glumes (thinly cartilaginous); very firm; entire, or incised; pointed; entire or shortly 2 lobed; not deeply cleft (at the most minutely incised); awnless to awned. Awns when present, 1; median; from a sinus (subapically), or dorsal; from near the top; non-geniculate; straight; hairless (scabrous); much shorter than the body of the lemma (to 2 mm long); entered by one vein. Awn bases not twisted; not flattened. Lemmas hairless; scabrous; slightly carinate; without a germination flap; 5(–7) nerved (the nerves raised and scaberulous); with the nerves non-confluent. Palea present; relatively long (slightly exceeding the lemma); tightly clasped by the lemma; entire (and pointed, but easily splitting); awnless, without apical setae; textured like the lemma; not indurated (thinly cartilaginous); 1-nerved (ciliolate), or 2-nerved; 2-keeled. Palea keels wingless; minutely, densely hairy. Lodicules present; 2; free; membranous; glabrous; toothed, or not toothed; not or scarcely vascularized. Stamens 3. Anthers 2.5–3.4 mm long; not penicillate; without an apically prolonged connective. Ovary apically hairy (the hairs apical, minute, stiff). Styles free to their bases. Stigmas 2; white.
Fruit, embryo and seedling. Fruit free from both lemma and palea; small (about 2.5 mm long); brown, green beneath the pericarp; obovoid; longitudinally grooved to not grooved (sometimes with a shallow depression); slightly compressed dorsiventrally (ventrally); hairy (hispid); with hairs confined to a terminal tuft. Hilum short to long-linear (0.5–0.8 mm long, narrowly elliptical). Pericarp loosely adherent (readily removeable). Embryo small; not waisted. Endosperm hard. Embryo with an epiblast.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (the costals elongated-rectangular, narrower); of similar wall thickness costally and intercostally (thin walled). Mid-intercostal long-cells fusiform; having straight or only gently undulating walls. Microhairs absent. Stomata fairly common (but confined to the zones adjoining the costae). Subsidiaries parallel-sided. Guard-cells overlapped by the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs and not paired (often solitary); not silicified. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies horizontally-elongated crenate/sinuous (a few), or horizontally-elongated smooth (a few), or rounded (e.g. some potato shaped, many malformed), or crescentic (a few, malformed).
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade; with a suspicion of arm-cells in some of the poor material seen. Leaf blade with distinct, prominent adaxial ribs to nodular in section; with the ribs more or less constant in size (these wide and low). Midrib conspicuous; having a conventional arc of bundles (three, corresponding with ridges on the midrib), or with one bundle only (towards the upper third of the blade, or throughout the narrower blades). Bulliforms present in discrete, regular adaxial groups (in each furrow); in simple fans (these wide). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (with all the bundles); nowhere forming figures. Sclerenchyma all associated with vascular bundles.
Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Poeae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Scolochloinae. 1 species (D. dives).
Distribution, phytogeography, ecology. Southeast Australia, Tasmania.
References, etc. Morphological/taxonomic: Vickery 1963. Leaf anatomical: studied by us.
Illustrations. • Inflorescence detail (D. dives). • Spikelet (D. dives)
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’.