DELTA home

The grass genera of the world

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

Mibora Adans.

Type species: Type: M. minima (L.) E.Desv.

Including Chamagrostis Borkh., Knappia Sm., Micagrostis Juss., Rothia Borkh., Sturmia Hoppe

Habit, vegetative morphology. Diminutive annual; caespitose. Culms 2–15 cm high (filiform); herbaceous. Leaves mostly basal; non-auriculate. Leaf blades linear; apically flat; narrow; 0.3–1 mm wide; flat, or folded; not pseudopetiolate; without cross venation; persistent. Ligule an unfringed membrane; truncate; 0.5–1.5 mm long.

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

Inflorescence. Inflorescence a single raceme (unilateral, spikelike); espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; secund; distichous; shortly pedicellate.

Female-fertile spikelets. Spikelets 1.8–3 mm long; compressed laterally; disarticulating above the glumes. Rachilla terminated by a female-fertile floret. Hairy callus absent. Callus very short.

Glumes two; more or less equal; exceeding the spikelets; long relative to the adjacent lemmas; not pointed (obtuse to emarginate); awnless; non-carinate; similar (thinly membranous). Lower glume 1 nerved. Upper glume 1 nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.

Female-fertile florets 1. Lemmas less firm than the glumes (hyaline); not becoming indurated; entire to incised (truncate-denticulate); awnless; hairy; non-carinate; 5 nerved. Palea present; relatively long; awnless, without apical setae (hairy); 2-nerved; keel-less. Lodicules present; 2. Stamens 3. Anthers 1.4–1.7 mm long; not penicillate. Ovary apically glabrous. Styles fused. Stigmas 2.

Fruit, embryo and seedling. Fruit free from both lemma and palea; small. Hilum short. Embryo small. Endosperm liquid in the mature fruit, or hard; with lipid.

Seedling with a loose coleoptile. First seedling leaf with a well-developed lamina. The lamina narrow; 1–3 veined.

Abaxial leaf blade epidermis. Costal/intercostal zonation lacking. Papillae absent. 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 (none seen). Costal silica bodies absent.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma. Leaf blade with distinct, prominent adaxial ribs; with the ribs more or less constant in size. Midrib conspicuous; with one bundle only. Bulliforms not present in discrete, regular adaxial groups (no bulliform cells). Many of the smallest vascular bundles unaccompanied by sclerenchyma. Combined sclerenchyma girders absent. Sclerenchyma all associated with vascular bundles.

Cytology. Chromosome base number, x = 7. 2n = 14. 2 ploid. Chromosomes ‘large’. Haploid nuclear DNA content 2.8 pg (1 species, 2x). Mean diploid 2c DNA value 5.5 pg.

Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Aveneae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Sesleriinae. 2 species.

Distribution, phytogeography, ecology. Mediterranean.

Commonly adventive. Mesophytic; species of open habitats. Damp, sandy soils.

References, etc. Leaf anatomical: studied by us - M. minima (L.) Desv., M. verna Beauv. (= M. minima.

Illustrations. • M. minima, as M. verna: Lamson-Scribner (1890). • M. minima: Gardner, 1952. • M. minima, as Chamagrostis: Eng. Bot. (1872). • M. minima, abaxial epidermis of leaf blade: this project. • M. minima, 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: 11th December 2017.’.