Avellinia Parl.
After Giulio Avellino, a Neapolitan botanist.
Sometimes referred to Trisetum, Trisetaria
Habit, vegetative morphology. Annual; caespitose. Culms 2–30 cm high; herbaceous. Culm nodes glabrous. Culm internodes hollow. Leaves not basally aggregated; non-auriculate. Leaf blades linear; narrow; flat, or rolled (involute); without cross venation; persistent; an unfringed membrane to a fringed membrane (short, often hairy outside); truncate; 0.4–1 mm long.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets.
Inflorescence. Inflorescence paniculate; open, or contracted; when contracted spicate, or more or less irregular. Primary inflorescence branches borne distichously. Inflorescence espatheate; not comprising ‘partial inflorescences’ and foliar organs. Spikelet-bearing axes persistent. Spikelets not secund; pedicellate.
Female-fertile spikelets. Spikelets 3–5 mm long; compressed laterally; disarticulating above the glumes. Rachilla prolonged beyond the uppermost female-fertile floret; hairy.
Glumes two; very unequal; (the longer) long relative to the adjacent lemmas; pointed; awnless; carinate; similar. Lower glume 1 nerved. Upper glume 3 nerved. Spikelets with female-fertile florets only, or with incomplete florets. The incomplete florets distal to the female-fertile florets. Spikelets without proximal incomplete florets.
Female-fertile florets 2–4. Lemmas often apically split; similar in texture to the glumes; not becoming indurated; entire (but often splitting); not deeply cleft; awned. Awns 1; median; dorsal; from near the top (though often described as ‘from the sinus’); non-geniculate; much shorter than the body of the lemma; entered by one vein. Lemmas hairless; non-carinate; 3 nerved. Palea present; conspicuous but relatively short; deeply bifid; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; glabrous; not toothed. Stamens 3. Anthers 0.5 mm long; not penicillate. Ovary glabrous. Styles free to their bases. Stigmas 2.
Fruit, embryo and seedling. Fruit small. Hilum short. Embryo small. Endosperm liquid in the mature fruit; with lipid.
Abaxial leaf blade epidermis. Papillae absent. Mid-intercostal long-cells 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 horizontally-elongated crenate/sinuous to horizontally-elongated smooth, or saddle shaped, or ‘panicoid-type’ (sometimes); sometimes indisputably nodular.
Transverse section of leaf blade, physiology. C3; XyMS+. Mesophyll with radiate chlorenchyma. 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 inconspicuous in the poor material seen. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders absent. Sclerenchyma all associated with vascular bundles.
Cytology. Chromosome base number, x = 7. 2n = 12.
Taxonomy. Pooideae; Poodae; Aveneae.
Distribution, ecology, phytogeography. 2 species; Mediterranean. Not commonly adventive. Mesophytic, or xerophytic.
Holarctic. Boreal and Tethyan. Euro-Siberian. Mediterranean. European.
Rusts and smuts. Rusts — Puccinia. Taxonomically wide-ranging species: Puccinia hordei. Smuts from Tilletiaceae. Tilletiaceae — Tilletia.
References, etc. Leaf anatomical: this project.
Illustrations. • General aspect
Cite this publication as: Watson, L., and Dallwitz, M. J. (1992 onwards). ‘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.’ http://biodiversity.uno.edu/delta/. Version: 18th August 1999. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993 onwards, 1998), and Watson and Dallwitz (1994), and Watson, Dallwitz, and Johnston (1986) should also be cited (see References).
