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The grass genera of the world

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

Maillea Parl.

~ Phleum (IP. crypsoides)

Habit, vegetative morphology. Annual. Culms 2–10 cm high; herbaceous. Leaves non-auriculate. Sheath margins free. The upper sheaths inflated. Leaf blades linear; narrow; flat; without cross venation. Ligule an unfringed membrane; truncate; 1.5–2.5 mm long.

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

Inflorescence. Inflorescence paniculate (sessile among the leaves); contracted; more or less ovoid (to 5 cm long); espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund.

Female-fertile spikelets. Spikelets 2–4.5 mm long; compressed laterally; disarticulating above the glumes. Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension naked. Hairy callus absent.

Glumes two; more or less equal; exceeding the spikelets; long relative to the adjacent lemmas (about three times as long); free; pointed (apiculate); awnless; carinate; with the keel conspicuously winged; similar. Lower glume 1 nerved. Upper glume 1 nerved. Spikelets with female-fertile florets only; without proximal incomplete florets.

Female-fertile florets 1. Lemmas truncate; less firm than the glumes to similar in texture to the glumes (and only about 1/3 of glume length); not becoming indurated; entire; blunt; awnless; hairless; non-carinate; without a germination flap; 1(–3) nerved. Palea present; relatively long (exceeding the lemma); 1-nerved; keel-less. Lodicules absent. Stamens 2. Ovary apically glabrous. Styles free to their bases. Stigmas 2.

Fruit, embryo and seedling. Fruit free from both lemma and palea; not noticeably compressed. Hilum short. Embryo small.

Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae present; costal and intercostal. Intercostal papillae over-arching the stomata (over-arching them laterally); consisting of one oblique swelling per cell, or consisting of one symmetrical projection per cell. Long-cells similar in shape costally and intercostally; of similar wall thickness costally and intercostally. Intercostal zones exhibiting many atypical long-cells (many of them short to more or less round). Mid-intercostal long-cells fusiform (to round); having straight or only gently undulating walls. Microhairs absent. Stomata common; (42–)45–52(–66) microns long. Subsidiaries non-papillate; parallel-sided. Guard-cells overlapped by the interstomatals (the stomata distinctly sunken). Intercostal short-cells common to absent or very rare; not paired (solitary, large, rounded, merging into the range of long-cell forms); not silicified. Costal short-cells neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies present and well developed; horizontally-elongated crenate/sinuous (mostly), or horizontally-elongated smooth (very few); not sharp-pointed.

Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with non-radiate chlorenchyma; without adaxial palisade. Leaf blade with distinct, prominent adaxial ribs; with the ribs more or less constant in size. Midrib not readily distinguishable; with one bundle only. The lamina symmetrical on either side of the midrib. All the vascular bundles accompanied by sclerenchyma (except for the outermost bundle on either side, in the material seen). Combined sclerenchyma girders absent (the sclerenchyma confined to small adaxial and abaxial strands). Sclerenchyma all associated with vascular bundles.

Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Aveneae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Poinae. 1 species (M. crypsoides).

Distribution, phytogeography, ecology. Eastern Mediterranean islands and Greece.

References, etc. Leaf anatomical: studied by us.

Illustrations. • M. crypsoides: Coste (1906), Fl. de la France

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.’.