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The grass genera of the world

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

Lolium L.

Latin Lolium: name given by Virgil to a troublesome weed.

Ryegrasses.

Type species: Type: L. perenne L.

Including Arthrochortus Lowe, Craepalia Schrank, Crypturus Link

Habit, vegetative morphology. Annual, or perennial; rhizomatous, or stoloniferous, or caespitose, or decumbent. Culms 10–130 cm high; herbaceous; unbranched above. Culm nodes glabrous. Culm internodes hollow. Leaves not basally aggregated; auriculate. Leaf blades linear; apically cucullate, or apically flat; usually narrow; 2–12 mm wide; flat, or folded, or rolled; without cross venation; persistent; rolled in bud, or once-folded in bud. Ligule an unfringed membrane; truncate; 0.8–2 mm long.

Reproductive organization. Plants bisexual, all 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 7–26 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) 3–7 nerved (membranous). Spikelets with incomplete florets. The incomplete florets distal to the female-fertile florets. The distal incomplete florets merely underdeveloped.

Female-fertile florets 2–22. 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; 5–7 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 1.3–4.5 mm long; not penicillate. Ovary apically 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; 3–7 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).

Cytology. Chromosome base number, x = 7. 2n = 14 and 28. 2 and 4 ploid. Chromosomes ‘large’. Haploid nuclear DNA content (2.2–)3.2–6.9 pg (8 species, mean 5.0). Mean diploid 2c DNA value 9.9 pg (5 species, (4.3-)6.4–13.6).

Classification. Watson & Dallwitz (1994): Pooideae; Poodae; Poeae. Soreng et al. (2015): Pooideae; Poodae; Poeae; Loliinae. 8 species.

Distribution, phytogeography, ecology. Temperate Eurasia, north Africa.

Commonly adventive. Mesophytic; species of open habitats.

Economic aspects. 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.

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.

References, etc. Leaf anatomical: Metcalfe 1960; this project.

Illustrations. • L. temulentum, general aspect: Eng. Bot. (1872). • L. temulentum var., general aspect: Eng. Bot. 1872). • L. temulentum, general aspect. • L. multiflorum, as L. bouchéanum: Kunth (1835). • L. multiflorum (as L. italicum), general aspect: Eng. Bot. (1872). • L. perenne, general aspect: Eng. Bot. (1872). • Leaf auricles (L. perenne). • Spikelet close-up (L. perenne). Lolium perenne. Spikelet with only one (outer) glume and two open florets; hollowed rachis. • Rachis and spikelet in close-up (L. perenne). Lolium perenne. Hollowed rachis (left), the single (‘upper’) glume to the right, the spikelet dorsiventral to the rachis. • Floret and rachilla detail (L. perenne). Lolium perenne. Spikelet tip, showing terminal rachilla prolongation within the palea groove of the uppermost floret, flanked by lemma margins. • L. perenne, abaxial epidermis of leaf blade: this project. • L. perenne, abaxial epidermis of leaf blade: this project. • L. perenne, abaxial epidermis of leaf blade, detail: this project. • L. perenne, abaxial epidermis of leaf blade, detail: this project. • Pollen antigens: Watson and Knox (1976). • Pollen antigens: cross-reactions against anti-Lolium serum. • 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. • X Festulolium loliaceum (as F. pratensis var. loliacea), = Festuca. pratensis x L. perenne: Eng. Bot. (1872)


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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: 13th November 2017. delta-intkey.com/grass’.

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