Lolium L.
Latin Lolium: name given by Virgil to a troublesome weed.
Including Arthrochortus Lowe, Craepalia Schrank, Crypturus Link
Habit, vegetative morphology. Annual, or perennial; rhizomatous, or stoloniferous, or caespitose, or decumbent. Culms 10130 cm high; herbaceous; unbranched above. Culm nodes glabrous. Culm internodes hollow. Leaves not basally aggregated; auriculate. Sheath margins free. Leaf blades linear; usually narrow; 212 mm wide; flat, or folded, or rolled; without cross venation; persistent; rolled in bud, or once-folded in bud; an unfringed membrane; truncate; 0.82 mm long.
Reproductive organization. Plants bisexual, with bisexual spikelets; with hermaphrodite florets; outbreeding and inbreeding.
Inflorescence. Inflorescence a single spike (with partially embedded spikelets). Rachides hollowed. Inflorescence espatheate; not comprising partial inflorescences and foliar organs. Spikelet-bearing axes persistent. Spikelets solitary; not secund; conspicuously distichous; sessile.
Female-fertile spikelets. Spikelets 726 mm long; compressed laterally; disarticulating above the glumes; disarticulating between the florets. Rachilla prolonged beyond the uppermost female-fertile floret; hairless; the rachilla extension with incomplete florets. Hairy callus absent. Callus short.
Glumes one per spikelet (except that the terminal spikelet has two); shorter than the adjacent lemmas, or long relative to the adjacent lemmas; dorsiventral to the rachis; pointed, or not pointed; awnless; non-carinate. Upper glume (i.e. the only glume) 37 nerved (membranous). Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped.
Female-fertile florets 222. Lemmas less firm than the glumes to decidedly firmer than the glumes (membranous to papery, sometimes turgid or hardening in fruit); becoming indurated to not becoming indurated; entire, or incised; when entire pointed, or blunt; awnless, or awned. Awns when present, 1; from a sinus, or dorsal; when dorsal, from near the top; non-geniculate; hairless; much shorter than the body of the lemma; entered by one vein. Lemmas hairless; non-carinate; 57 nerved. Palea present; relatively long (usually ciliate); apically notched; awnless, without apical setae; not indurated; 2-nerved; 2-keeled. Lodicules present; 2; free; membranous; glabrous; toothed, or not toothed; not or scarcely vascularized. Stamens 3. Anthers 1.34.5 mm long; not penicillate. Ovary glabrous. Styles free to their bases. Stigmas 2; white.
Fruit, embryo and seedling. Fruit somewhat adhering to lemma and/or palea; small, or medium sized, or large; longitudinally grooved; compressed dorsiventrally. Hilum long-linear. Embryo small; not waisted. Endosperm hard; without lipid; containing compound starch grains. Embryo with an epiblast; without a scutellar tail; with a negligible mesocotyl internode. Embryonic leaf margins meeting.
Seedling with a short mesocotyl, or with a long mesocotyl; with a tight coleoptile. First seedling leaf with a well-developed lamina. The lamina narrow; erect; 37 veined.
Abaxial leaf blade epidermis. Costal/intercostal zonation conspicuous. Papillae absent. Long-cells markedly different in shape costally and intercostally (costals rectangular, intercostals longer, fusiform); of similar wall thickness costally and intercostally (but the walls of the costals sinuous). Mid-intercostal long-cells fusiform; having straight or only gently undulating walls (those bordering the veins sinuous, by contrast). Microhairs absent. Stomata common. Subsidiaries low dome-shaped, or parallel-sided. Guard-cells overlapped by the interstomatals. Intercostal short-cells absent or very rare. Costal short-cells predominantly paired, or neither distinctly grouped into long rows nor predominantly paired. Costal silica bodies horizontally-elongated crenate/sinuous, or horizontally-elongated smooth, or rounded (some almost cubical); not sharp-pointed.
Transverse section of leaf blade, physiology. C3; XyMS+. PBS cells without a suberised lamella. 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 present in discrete, regular adaxial groups; in simple fans. All the vascular bundles accompanied by sclerenchyma. Combined sclerenchyma girders present, or absent; nowhere forming figures. Sclerenchyma all associated with vascular bundles.
Phytochemistry. Tissues of the culm bases with little or no starch. Fructosans predominantly short-chain. Leaves without flavonoid sulphates (1 species).
Special diagnostic feature. Plant and inflorescence not as in Lygeum (q.v.).
Cytology. Chromosome base number, x = 7. 2n = 14 and 28. 2 and 4 ploid. Chromosomes large. Haploid nuclear DNA content (2.2)3.26.9 pg (8 species, mean 5.0). Mean diploid 2c DNA value 9.9 pg (5 species, (4.3-)6.413.6).
Taxonomy. Pooideae; Poodae; Poeae. Ryegrasses.
Distribution, ecology, phytogeography. 8 species; temperate Eurasia, north Africa. Commonly adventive. Mesophytic; species of open habitats.
Holarctic, Paleotropical, Neotropical, and Cape. Boreal, Tethyan, and Madrean. Indomalesian. Euro-Siberian, Eastern Asian, and Atlantic North American. Macaronesian and Irano-Turanian. Indian. Pampas and Andean. European and Siberian. Canadian-Appalachian, Southern Atlantic North American, and Central Grasslands.
Hybrids. Intergeneric hybrids with Festuca - ×Festulolium Aschers. & Graebn. (several species of each genus involved).
Rusts and smuts. Rusts Puccinia. Taxonomically wide-ranging species: Puccinia graminis, Puccinia coronata, Puccinia striiformis, Puccinia brachypodii, Puccinia hordei, and Puccinia recondita. Smuts from Tilletiaceae and from Ustilaginaceae. Tilletiaceae Tilletia and Urocystis. Ustilaginaceae Ustilago.
Economic importance. Significant weed species: L. multiflorum, L. perenne, L. persicum, L. remotum, L. rigidum, L. temulentum (darnel - with toxic grain). Cultivated fodder: L. multiflorum, L. perenne. Lawns and/or playing fields: L. perenne.
References, etc. Leaf anatomical: Metcalfe 1960; this project.
Illustrations. General aspect. Leaf auricles. Lolium perenne. Spikelet. Lolium perenne. Spikelet with only one (outer) glume and two open florets; hollowed rachis. Rachis and spikelet. Lolium perenne. Hollowed rachis (left), the single (‘upper’) glume to the right, the spikelet dorsiventral to the rachis. Floret and rachilla. Lolium perenne. Spikelet tip, showing terminal rachilla prolongation within the palea groove of the uppermost floret, flanked by lemma margins. Pollen antigens. Pollen antigens. Pollen antigens: cross-reactions against anti-Lolium serum. Heat stable pollen antigens (allergens): cross-reactions against anti-Lolium serum. Pollen antigens: cross-reactions against anti-Cynodon serum. Pollen antigens: cross-reactions against anti-Zea serum. Pollen antigens: cross-reactions against anti-Zea serum
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).