The grass genera of the world

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L. Watson and M. J. Dallwitz

Austrodanthonia H.P. Linder

From the Latin australis (southern), thus the southern Danthonias.

Sometimes referred to Danthonia sensu lato, Rytidosperma sensu lato, Notodanthonia sensu lato

Excluding Joycea, Chionochloa, Notodanthonia, Rytidosperma

Habit, vegetative morphology. Perennial; caespitose, or decumbent (rarely). Culms 5–140 cm high; herbaceous; cylindrical; unbranched above; 1–5 noded. Culm nodes exposed; glabrous. Culm leaves absent. Culm internodes solid. Plants without multicellular glands. Young shoots extravaginal (rarely), or intravaginal. Leaves mostly basal; non-auriculate; without auricular setae. Sheath margins free. Leaf blades linear-lanceolate; neither leathery nor flimsy; narrow; 0.2–5 mm wide; flat; without cross venation; persistent. Ligule present; a fringe of hairs. Contra-ligule absent.

Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality; hermaphrodite. Plants without hidden cleistogenes. Not viviparous.

Inflorescence. Inflorescence many spikeleted; of spicate main branches, or paniculate; open, or contracted; more or less irregular; non-digitate. Inflorescence with axes ending in spikelets. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelets solitary; not secund; not two-ranked; pedicellate; not imbricate; not in distinct ‘long-and-short’ combinations.

Female-fertile spikelets. Spikelets morphologically ‘conventional’; 6–22 mm long; cuneate, or elliptic; green or purplish; compressed laterally; disarticulating above the glumes; disarticulating between the florets; with conventional internode spacings. Rachilla prolonged beyond the uppermost female-fertile floret; hairless; the rachilla extension with incomplete florets. Hairy callus present. The callus hairs white. Callus long (always substantially longer than rhachilla); blunt.

Glumes present; two; relatively large; more or less equal; shorter than the spikelets (rarely), or about equalling the spikelets, or exceeding the spikelets (slightly); long relative to the adjacent lemmas; free; hairless; scabrous; pointed; not subulate; awnless; carinate; without a median keel-wing; similar. Lower glume much exceeding the lowest lemma; not two-keeled; 3–13 nerved. Upper glume 3–13 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped; awnless. Spikelets without proximal incomplete florets.

Female-fertile florets 3–10. Lemmas smooth; not becoming indurated; white in fruit; incised; 2 lobed (lobes tapering into setae, which may be substantial, but usually shorter than the awn); usually deeply cleft; awned. Awns not of the triple/trifid, basal column type; 1, or 3; if solitary median, or median and lateral (if three); if three, different in form from the laterals; from a sinus; non-geniculate (rarely), or geniculate; when non-geniculate, straight; hairless; much shorter than the body of the lemma, or about as long as the body of the lemma, or much longer than the body of the lemma; entered by several veins. Awn bases twisted; flattened. Lemmas hairy. The hairs usually in tufts (at least the upper margin of the indumentum being usually tufted); generally in transverse rows (although in some species hairs are also present and evenly distributed between the transverse rows). Lemmas non-carinate; without a germination flap; 9 nerved; with the nerves confluent towards the tip. Palea present; relatively long; tightly clasped by the lemma; entire (rarely), or apically notched; awnless, without apical setae; thinner than the lemma; not indurated; 2-nerved; 2-keeled. Palea back glabrous, or hairy. Palea keels scabrous, or hairy. Lodicules present; 2; free; fleshy; ciliate, or glabrous (rarely, possibly artifactual); not or scarcely vascularized. Stamens 3; with free filaments. Anthers 0.2–3.4 mm long. Ovary glabrous. Styles free to their bases; free. Style bases widely separated. Stigmas 2; white.

Fruit, embryo and seedling. Disseminule a caryopsis enclosed in but free of the lemma and palea. Fruit free from both lemma and palea; small; golden-brown; obovate; not grooved; compressed dorsiventrally; glabrous; smooth. Hilum short (usually less than 1/10 of the caryopsis length). Pericarp thin; fused. Embryo large; waisted.

Transverse section of leaf blade, physiology. C3; XyMS+.

Cytology. Chromosome base number, x = 12. 2n = 24. 2 ploid.

Taxonomy. Arundinoideae; Danthonieae.

Distribution, ecology, phytogeography. 28 species; New Zealand, Australia and Papua New Guinea. Not commonly adventive. Mesophytic; species of open habitats; glycophytic.

Australian. North and East Australian, South-West Australian, and Central Australian.

Economic importance. Important native pasture species: A. caespitosa, A. richardsonii.

References, etc. Morphological/taxonomic: This description prepared by H.P. Linder (1997).

Illustrations. • Lemmas (penicillata, pilosa = Austrodanthonia, semiannularis = Notodanthonia). • Spikelet of A. eriantha. • Spikelet of A. eriantha, details. • Floret details (A. eriantha). Austrodanthonia eriantha. Two-keeled, two-nerved, notched palea; glabrous ovary, fleshy, ciliate lodicules. • Spikelet of A. eriantha. • Disarticulating spikelet. Austrodanthonia sp. • Abaxial epidermis of leaf blade (A. carphoides). • A. carphoides, T.S. of leaf blade (fluorescence image). • Pollen antigens

The descriptions are offered for casual browsing only. We strongly advise against extracting comparative information from them. This is much more easily achieved using 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, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG).

Cite this publication as: ‘Watson, L., 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: 7th December 2015.’.