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The grass genera of the world

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

Erythranthera Zotov

~ Rytidosperma, Danthonia sensu lato

Habit, vegetative morphology. Perennial; rhizomatous, or caespitose, or decumbent (often sward-forming). Culms 3–12 cm high; herbaceous. Culm nodes glabrous. Culm internodes hollow. Leaves mostly basal; non-auriculate. Sheath margins free. Leaf blades narrow; setaceous; flat, or folded (to 3 cm long); without cross venation; disarticulating from the sheaths. Ligule a fringed membrane (very short), or a fringe of hairs.

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

Inflorescence. Inflorescence few spikeleted; a single raceme, or paniculate; open, or contracted; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.

Female-fertile spikelets. Spikelets 2.5–5 mm long; compressed laterally; disarticulating above the glumes; with distinctly elongated rachilla internodes between the florets (internodes up to 1/3 as long as the lemmas). Rachilla prolonged beyond the uppermost female-fertile floret. Hairy callus absent. Callus short; blunt (flattened).

Glumes two; more or less equal; long relative to the adjacent lemmas; free; awnless; similar. Lower glume 3–5 nerved. Upper glume 3 nerved. Spikelets with female-fertile florets only, or with incomplete florets. The incomplete florets distal to the female-fertile florets. Spikelets without proximal incomplete florets.

Female-fertile florets 3–5. Lemmas not becoming indurated; incised; minutely 3 lobed; not deeply cleft (with 3 minute apical teeth); awnless; hairy, or hairless (glabrous). The hairs when present, not in tufts; not in transverse rows (scattered). Lemmas carinate to non-carinate; 7–9 nerved. Palea present; 2-nerved; 2-keeled. Palea keels hairy (ciliate). Lodicules present; 2; joined, or free; fleshy, or membranous; glabrous; toothed. Stamens 3. Anthers not penicillate. Ovary apically glabrous. Styles free to their bases. Stigmas 2; brown.

Fruit, embryo and seedling. Fruit small. Hilum short. Embryo large. Endosperm containing compound starch grains. Embryo without an epiblast; with a scutellar tail; with an elongated mesocotyl internode.

Ovule, embryology. Micropyle not noticeably oblique. Outer integument covering no more than the chalazal half of the ovule; more than two cells thick at the micropylar margin. Inner integument discontinuous distally; not thickened around the micropyle. Synergids haustorial; exhibiting large, globular starch grains.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally (long and narrow); of similar wall thickness costally and intercostally (thick walled). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present; panicoid-type; 45–55.5(–60) microns long; 9.6–14.4 microns wide at the septum. Microhair total length/width at septum 3.1–5.8. Microhair apical cells 24–36 microns long. Microhair apical cell/total length ratio 0.43–0.59. Stomata absent or very rare. Subsidiaries dome-shaped, or triangular. Intercostal short-cells common; in cork/silica-cell pairs; silicified. Intercostal silica bodies mainly crescentic. Costal short-cells conspicuously in long rows, or neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies rounded (including potato-shaped), or crescentic, or ‘panicoid-type’.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with radiate chlorenchyma, or with non-radiate chlorenchyma; without adaxial palisade. Leaf blade with distinct, prominent adaxial ribs, or adaxially flat; with the ribs more or less constant in size. Midrib conspicuous, or not readily distinguishable; with one bundle only. Bulliforms present in discrete, regular adaxial groups (in the furrows); 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): Arundinoideae; Danthonieae. Soreng et al. (2015): Danthonioideae; Danthonieae. 3 species.

Distribution, phytogeography, ecology. Australia, New Zealand.

Species of open habitats. Alpine.

References, etc. Morphological/taxonomic: Zotov 1963. Leaf anatomical: this project.


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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: 13th November 2017. delta-intkey.com/grass’.

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