| # The grass genera of the world |

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

### Micropyrum Link

~ Festuca

Habit, vegetative morphology. Annual. Culms 50–100 cm high; herbaceous. Leaves non-auriculate. Leaf blades linear; narrow; flat, or rolled (convolute when dry); without cross venation. Ligule an unfringed membrane; truncate; 0.2–1 mm long.

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

Inflorescence. Inflorescence a single raceme (spiciform), or paniculate (sparingly branched); espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; when in a raceme, distichous; pedicellate.

Female-fertile spikelets. Spikelets 4–16 mm long; compressed laterally; disarticulating above the glumes; disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets. Hairy callus absent.

Glumes two; very unequal to more or less equal; shorter than the adjacent lemmas; dorsiventral to the rachis; pointed, or not pointed (acute to rounded); awnless; carinate, or non-carinate; similar (leathery). Lower glume 1–3 nerved. Upper glume 3–5 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. Spikelets without proximal incomplete florets.

Female-fertile florets 3–9(–14). Lemmas decidedly firmer than the glumes (papery); not becoming indurated; entire to incised (obtuse to emarginate); awnless (but apiculate), or mucronate, or awned. Awns when present, 1; from a sinus, or apical; non-geniculate; much shorter than the body of the lemma to about as long as the body of the lemma; entered by one vein. Lemmas hairless; non-carinate (dorsally rounded); without a germination flap; 5 nerved. Palea present; relatively long; apically notched (shortly bifid); awnless, without apical setae; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; glabrous; toothed; not or scarcely vascularized. Stamens 3. Anthers 0.5–3.2 mm long. Ovary apically glabrous; without a conspicuous apical appendage. Styles free to their bases. Stigmas 2.

Fruit, embryo and seedling. Fruit adhering to lemma and/or palea; medium sized (2.5–3.2 mm long); not grooved; compressed dorsiventrally. Hilum long-linear. Embryo small. Endosperm hard; without lipid; containing compound starch grains. Embryo with an epiblast.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally. Mid-intercostal long-cells rectangular; having markedly sinuous walls (and pitted). Microhairs absent. Stomata absent or very rare. Intercostal short-cells absent or very rare. Costal short-cells predominantly paired. Costal silica bodies rounded (numerous); not sharp-pointed.

Transverse section of leaf blade, physiology. C3; XyMS+. Leaf blade with distinct, prominent adaxial ribs; with the ribs more or less constant in size. Midrib not readily distinguishable; with one bundle only. Bulliforms poorly defined, in the poor material seen. Combined sclerenchyma girders absent. Sclerenchyma all associated with vascular bundles.

Cytology. Chromosome base number, x = 7. 2n = 14. 2 ploid.

Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Poeae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Loliinae. 3 species.

Distribution, phytogeography, ecology. Central Europe, Mediterranean.

Species of open habitats. Dry places.

References, etc. Leaf anatomical: studied by us - M. tenellum L.

Illustrations. • Micropyrum tenellum: Sturm (1796), Flora in Abbildungen.

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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