| # The grass genera of the world |

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

### Monodia S.W.L. Jacobs

From the Greek monos (alone, single) and odous (tooth), referring to the single lemma awn.

Type species: Type: M. stipoides S.W.L.Jacobs.

Habit, vegetative morphology. Stipa-like, hummock-forming perennial; caespitose. Culms 70–150 cm high; herbaceous. Plants conspicuously armed. Leaves non-auriculate. Leaf blades narrow (about 60 cm long); flat (at first), or folded (later); hard, woody, needle-like (pungent); without abaxial multicellular glands; without cross venation; persistent (the persistent, older blades becoming recurved). Ligule a fringe of hairs; up to 3 mm long.

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

Inflorescence. Inflorescence of spicate main branches (?), or paniculate; contracted (to about 50 cm long); espatheate; not comprising ‘partial inflorescences’ and foliar organs. The racemes spikelet bearing to the base. Spikelet-bearing axes persistent. Spikelets not secund; shortly pedicellate.

Female-fertile spikelets. Spikelets 16–24 mm long; compressed laterally; disarticulating above the glumes; with conventional internode spacings. The upper floret not stipitate. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension naked. Hairy callus present. Callus long; pointed (oblique).

Glumes two; more or less equal; exceeding the spikelets; long relative to the adjacent lemmas; hairless; glabrous to scabrous; pointed (acute); awnless; similar. Lower glume 9 nerved, or 11 nerved. Upper glume 3 nerved, or 5 nerved. Spikelets with female-fertile florets only.

Female-fertile florets 1. Lemmas convolute; not becoming indurated; incised; 2 lobed; not deeply cleft (the lobes short, membranous, unequal); awned. Awns 1; median; from a sinus; geniculate (the column lightly twisted, the bristle falcate); hairless; much longer than the body of the lemma (5–6 cm long); entered by one vein; persistent. Lemmas hairy (with a line of appressed hairs on each margin, but otherwise glabrous); non-carinate; 3 nerved. Palea present; relatively long; awnless, without apical setae (and glabrous); not indurated; 2-nerved; 2-keeled (the rachilla borne within the groove between). Palea keels wingless. Lodicules present; 2; free; fleshy; glabrous. Stamens 3. Anthers 4–6 mm long; not penicillate; without an apically prolonged connective. Ovary apically glabrous. Stigmas 2; pale.

Fruit, embryo and seedling. Fruit ellipsoid.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous (in the central part, although the grooves are easily overlooked in surface view), or lacking (on the wide lateral flanges). Papillae present; intercostal (mainly confined to the grooves and their margins). Intercostal papillae consisting of one oblique swelling per cell. Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally (thick walled, and pitted). Mid-intercostal long-cells rectangular; having markedly sinuous walls. Microhairs present (but hidden in the very narrow grooves); chloridoid-type. Stomata not visible. Subsidiaries non-papillate. Costal short-cells conspicuously in long rows. Costal silica bodies ‘panicoid-type’; mostly small, dumb-bell shaped; not sharp-pointed.

Transverse section of leaf blade, physiology. Lamina mid-zone in transverse section infolded permanently; U-shaped. The adaxial channel parallel-sided, with a digitate base.

C4. The anatomical organization unconventional. Organization of PCR tissue Triodia type (with ‘draping’ PCR tissue). XyMS+. Mesophyll traversed by columns of colourless mesophyll cells (linking the bases of the deep and narrow adaxial and abaxial grooves); with arm cells (the PCA tissue exhibiting conspicuous ingrowths, cf. Triodia etc.). Leaf blade with the ribs very irregular in sizes (and shapes). Midrib conspicuous (by its position); with one bundle only; with colourless mesophyll adaxially (this and most of the large bundles with a large, colourless more or less lignified group between the top of the bundle and the adaxial sclerenchyma group). Bulliforms present in discrete, regular adaxial groups (at the bases of the central adaxial grooves); associated with colourless mesophyll cells to form deeply-penetrating fans (these continuous with the traversing columns of colourless cells). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present (if the colourless groups are regarded as part of the sclerenchyma); forming ‘figures’ (massive). Sclerenchyma not all bundle-associated. The ‘extra’ sclerenchyma in a continuous abaxial layer (the massive lateral flanges of the leaf blade with a heavy, continuous layer of fibres, beneath a mass of large-celled sclerenchyma abaxial to the vascular bundles and mesophyll - cf. Triodia).

Classification. Watson & Dallwitz (1994): Chloridoideae; Triodieae. Soreng et al. (2015): Chloridoideae; Cynodonteae; Triodiinae. 1 species (M. stipoides).

Distribution, phytogeography, ecology. Western Australia.

Xerophytic; species of open habitats. Stony ground.

References, etc. Morphological/taxonomic: Jacobs 1984. Leaf anatomical: studied by us.

Special comments. Fruit data wanting.

Illustrations. • Monodia stipoides: E. Hickman, in Jacobs 1984. • Monodia stipoides, abaxial epidermis of leaf blade: this project.

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: 15th June 2025. delta-intkey.com’.

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