| # The grass genera of the world |

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

### Milium L.

Milium: old Latin name for millet.

Including Milearium Moench

Habit, vegetative morphology. Annual, or perennial; stoloniferous, or caespitose. Culms 10–180 cm high; herbaceous; unbranched above. Culm nodes glabrous. Culm internodes hollow. Young shoots extravaginal. Leaves non-auriculate. Leaf blades linear to linear-lanceolate; broad, or narrow; 2–18 mm wide; flat; not pseudopetiolate; without cross venation; persistent; rolled in bud. Ligule an unfringed membrane; not truncate; 4–5 mm long.

Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets. The spikelets all alike in sexuality.

Inflorescence. Inflorescence paniculate; open; with capillary branchlets; espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.

Female-fertile spikelets. Spikelets 2–4 mm long; somewhat compressed dorsiventrally; disarticulating above the glumes. Rachilla terminated by a female-fertile floret. Hairy callus absent. Callus short; blunt.

Glumes two; more or less equal; about equalling the spikelets to exceeding the spikelets; long relative to the adjacent lemmas; free; pointed (acute); awnless; non-carinate; similar (membranous). Lower glume 3 nerved. Upper glume 3 nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.

Female-fertile florets 1. Lemmas rounded; not convolute; decidedly firmer than the glumes (leathery); becoming indurated (shiny in fruit); entire; blunt; awnless; hairless; non-carinate; 5 nerved. Palea present; relatively long; entire; textured like the lemma (leathery); indurated; 2-nerved; keel-less. Lodicules present; 2; free; membranous; glabrous; toothed, or not toothed; not or scarcely vascularized. Stamens 3. Anthers 1.3–3 mm long; not penicillate. Ovary apically glabrous. Styles free to their bases. Stigmas 2; white.

Fruit, embryo and seedling. Fruit small (about 2 mm long); compressed dorsiventrally, or not noticeably compressed. Hilum short (1/5 to almost 1/2 grain length). Embryo small; not waisted. Endosperm hard; with lipid; containing compound starch grains. Embryo with an epiblast; without a scutellar tail; with a negligible mesocotyl internode. Embryonic leaf margins meeting.

Seedling with a long mesocotyl; with a loose coleoptile. First seedling leaf with a well-developed lamina. The lamina broad; erect; 3–5 veined.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (the costals narrower, rectangular); of similar wall thickness costally and intercostally (thin walled). Mid-intercostal long-cells fusiform; having straight or only gently undulating walls. Microhairs absent. Stomata common. Subsidiaries parallel-sided. Guard-cells overlapped by the interstomatals. Intercostal short-cells absent or very rare. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies absent (in the material seen).

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade. Leaf blade adaxially flat. Midrib conspicuous, or not readily distinguishable; with one bundle only; with colourless mesophyll adaxially, or without colourless mesophyll adaxially. Bulliforms present in discrete, regular adaxial groups (between the vascular bundles). All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present; forming ‘figures’.

Cytology. Chromosome base number, x = 4, 5, 7, and 9. 2n = 8, 10, 28, and 42. 2, 4, and 6 ploid. Chromosomes ‘large’.

Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Aveneae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Miliinae. 3–4 species.

Distribution, phytogeography, ecology. North temperate.

Commonly adventive. Mesophytic and xerophytic; shade species and species of open habitats.

Rusts and smuts. Rusts — Puccinia. Taxonomically wide-ranging species: Puccinia graminis, Puccinia coronata, Puccinia striiformis, Puccinia brachypodii, Puccinia recondita, and ‘Uromyces’ dactylidis. Smuts from Tilletiaceae and from Ustilaginaceae. Tilletiaceae — Urocystis. Ustilaginaceae — Ustilago.

References, etc. Morphological/taxonomic: Macfarlane and Watson 1980. Leaf anatomical: studied by us - M. effusum L.

Illustrations. • Milium effusum, general aspect: Eng. Bot. (1872). • Milium pedicellare: Bor, Flora of Iraq (1968). • Milium vernale: Bor, Flora of Iraq (1968).

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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