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The grass genera of the world

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

Clausospicula M. Lazarides

~ Anadelphia sensu lato

Habit, vegetative morphology. Annual. Culms herbaceous; sparsely branched above. Leaves not basally aggregated. Leaf blades linear; 1.4–2.6 mm wide; flat, or folded; without cross venation; persistent. Ligule present; an unfringed membrane; truncate; 0.3–0.5 mm long. Contra-ligule absent.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets of sexually distinct forms on the same plant; hermaphrodite and sterile. The male and female-fertile spikelets mixed in the inflorescence. The spikelets overtly heteromorphic; all in heterogamous combinations. Plants inbreeding; exposed-cleistogamous.

Inflorescence. Inflorescence paniculate; open; spatheate (and spatheolate); a complex of ‘partial inflorescences’ and intervening foliar organs. Spikelet-bearing axes very much reduced (each ‘raceme’ reduced to one ‘triplet’, clasped basally by the peculiar, trumpet-shaped tip of the peduncle); the spikelet-bearing axes with only one spikelet-bearing ‘article’; solitary; disarticulating; disarticulating at the joints (i.e. each at its only joint). The pedicels and rachis internodes without a longitudinal, translucent furrow. ‘Articles’ without a basal callus-knob; disarticulating obliquely. Spikelets in triplets (one of the pedicellate members sometimes missing); sessile and pedicellate; consistently in ‘long-and-short’ combinations; in pedicellate/sessile combinations. Pedicels of the ‘pedicellate’ spikelets free of the rachis. The ‘shorter’ spikelets hermaphrodite. The ‘longer’ spikelets sterile (sometimes reduced to the glabrous pedicels).

Female-sterile spikelets. The sterile spikelets, when present, 5–12 mm long, linear to lanceolate, awnless, disarticulating horizontally.

Female-fertile spikelets. Spikelets about 10 mm long; not noticeably compressed to compressed dorsiventrally; falling with the glumes. Rachilla terminated by a female-fertile floret. Hairy callus present. Callus long; pointed.

Glumes present; two; more or less equal; about equalling the spikelets, or exceeding the spikelets; long relative to the adjacent lemmas (more or less exceeding the L1); hairy and hairless (usually tubercled basally and towards the tip, otherwise glabrous); without conspicuous tufts or rows of hairs; awned; non-carinate; very dissimilar (both becoming indurated, the lower abruptly contracted above and with or without a short bristle from the narrow, truncate to notched apex, the upper attenuate into a long, slender scabrous awn 14–19 mm long which is often twisted around the lemma awn). Lower glume not two-keeled; convex on the back; not pitted; relatively smooth and tuberculate; 4 nerved (without a median). Upper glume 3 nerved. Spikelets with incomplete florets. The incomplete florets proximal to the female-fertile florets. The proximal incomplete florets 1; epaleate; sterile. The proximal lemmas awnless; 2 nerved, or 4 nerved; 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; not becoming indurated; entire (the hyaline margins of the stipe antero-laterally decurrent on the base of the awn, with no indication of lobes); awned. Awns 1; median; apical; geniculate; hairless to hairy; much longer than the body of the lemma (8–11 cm long); entered by several veins. Awn bases twisted; not flattened. Lemmas hairless; glabrous; non-carinate; without a germination flap; 3 nerved; with the nerves non-confluent. Palea present; conspicuous but relatively short; entire to apically notched; awnless, without apical setae; textured like the lemma (hyaline); not indurated; 2-nerved, or nerveless. Lodicules present; 2; free; fleshy; glabrous. Stamens 3 (short). Anthers 0.5–1.5 mm long; not penicillate; without an apically prolonged connective. Ovary apically glabrous. Styles free to their bases. Stigmas 2, or 3.

Fruit, embryo and seedling. Fruit free from both lemma and palea; medium sized (about 5.6 mm long); ellipsoid; compressed laterally (above), or compressed dorsiventrally to not noticeably compressed (below); glabrous. Hilum short. Embryo large.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular to fusiform; having markedly sinuous walls. Microhairs present; panicoid-type; 39–47 microns long; 6–12 microns wide at the septum. Microhair total length/width at septum 3.25–7.5. Microhair apical cells 22–30 microns long. Microhair apical cell/total length ratio 0.57–0.67. Stomata common; 31–41 microns long. Subsidiaries triangular. Guard-cells overlapping to flush with the interstomatals. Intercostal short-cells common; in cork/silica-cell pairs; silicified. Intercostal silica bodies cross-shaped. Costal zones with short-cells. Costal short-cells conspicuously in long rows, or predominantly paired, or neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies ‘panicoid-type’; not sharp-pointed.

Transverse section of leaf blade, physiology. C4; XyMS–. PCR sheath outlines uneven. PCR sheath extensions absent. Leaf blade with distinct, prominent adaxial ribs (the ribs low, variable in width). Midrib conspicuous; having a conventional arc of bundles (a large median, with four or five laterals on either side in a deep arc); with colourless mesophyll adaxially. Bulliforms present in discrete, regular adaxial groups (in places), or not present in discrete, regular adaxial groups (mainly, the epidermis largely bulliform); in simple fans (in places), or associated with colourless mesophyll cells to form deeply-penetrating fans (mainly); associating with colourless mesophyll cells to form arches over small vascular bundles (noticeable only in Barritt 772), or nowhere involved in bulliform-plus-colourless mesophyll arches. Many of the smallest vascular bundles unaccompanied by sclerenchyma. Combined sclerenchyma girders present; nowhere forming ‘figures’. Sclerenchyma all associated with vascular bundles.

Special diagnostic feature. Spikelets in much-reduced andropogonoid ‘racemes’, each of the latter reduced to a single triplet and enclosed at its base by a trumpet-like development of the peduncle tip.

Classification. Watson & Dallwitz (1994): Panicoideae; Andropogonodae; Andropogoneae; Andropogoninae. Soreng et al. (2015): Panicoideae; Andropogonodae; Andropogoneae; Anthistiriinae. 1 species (C. extensa).

Distribution, phytogeography, ecology. Northern Australia.

References, etc. Morphological/taxonomic: Lazarides et al. 1990. 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.’.