The grass genera of the world
Habit, vegetative morphology. Annual. Culms 10–40 cm high; herbaceous. Leaves non-auriculate. Leaf blades linear; narrow (?); without cross venation. Ligule an unfringed membrane; truncate; 2–4 mm long.
Reproductive organization. Plants bisexual, all with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate (2–10 cm long, with up to 4 branches at each node); open (the branches and pedicels pulvinate); without conspicuously divaricate branchlets (by contrast with Cutandia); espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes disarticulating; falling entire (branches disarticulating at the pulvini). Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 8–25(–40) mm long; compressed laterally; disarticulating above the glumes and falling with the glumes; disarticulating between the florets (each lemma falling with the internode below, rather than the one above). Rachilla prolonged beyond the uppermost female-fertile floret; the rachilla extension with incomplete florets. Hairy callus absent.
Glumes two; very unequal; shorter than the adjacent lemmas; dorsiventral to the rachis; hairless (scabrid on the midribs); pointed (acuminate); shortly awned; non-carinate; similar. Lower glume 1 nerved. Upper glume 1–3 nerved. Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets.
Female-fertile florets 5–12(–18). Lemmas aculeolate, acuminate; similar in texture to the glumes; not becoming indurated (firm); entire; pointed; awned (the awn to 8 mm long). Awns 1; median; 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; without a germination flap; 3 nerved. Palea present; relatively long; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; glabrous; toothed, or not toothed; not or scarcely vascularized. Stamens 3. Ovary apically glabrous. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit adhering to lemma and/or palea (to the palea); small (3 mm long); longitudinally grooved; compressed dorsiventrally. Hilum short (oblong-linear). Embryo small. Endosperm hard; containing compound starch grains.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally; of similar wall thickness costally and intercostally. 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 zones with short-cells. Costal short-cells conspicuously in long rows (mainly, sometimes paired). Costal silica bodies horizontally-elongated crenate/sinuous, or horizontally-elongated smooth (few); not sharp-pointed.
Transverse section of leaf blade, physiology. C3. 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. Bulliforms present in discrete, regular adaxial groups; in simple fans. Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 7.
Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Poeae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Parapholiinae. 1 species (V. stipoides).
Distribution, phytogeography, ecology. Mediterranean.
Xerophytic; species of open habitats. Dry sandy places.
References, etc. Leaf anatomical: studied by us.
Illustrations. • V. stipoides, as Vulpia incrassata: Coste, Fl. de France (1906)