Edward E. Terrell, emended by Mary E. Barkworth (2020)

Plants annual or perennial; cespitose, sometimes shortly rhizomatous. Culms 10–150 cm, slender to stout, erect to decumbent, rarely prostrate. Sheaths open, rounded, glabrous, sometimes scabrous; ligules to 4 mm, membranous, glabrous; auricles usually present, falcate; blades flat, linear. Synflorescences paniculate and spikelets pedicillate or spicate and spikelets sessile, radial to the rachises and perpendicular to the rachis concavities. Spikelets laterally compressed, with 2–22 florets, distal florets reduced; rachillas glabrous; disarticulation above the glumes, beneath the florets. Glumes 2 or, in spicate inflorescences, 1, the lower glume absent on all but the terminal spikelets, all glumes lanceolate to oblong, rounded over the midvein, membranous to indurate, 3–9-veined, unawned; calluses short, blunt, glabrous; lemmas lanceolate, ovate or oblong, rounded over the midvein, membranous, chartaceous, 3–7-veined, apices sometimes hyaline, unawned or awned, awns subterminal, more or less straight; paleas membranous, usually smooth, keels ciliolate; lodicules 2, free, lanceolate to ovate; anthers 3; ovaries glabrous, styles attached below the top of the ovaries. Caryopses dorsally compressed, oblong, broadly elliptic or ovate, longitudinally sulcate, adhering to the paleas; hila linear, in the furrow; embryos 1/5–1/3 as long as the caryopses. x = 7. Lolium, first mentioned in Virgil’s Georgics, is an old Latin name for darnel, Lolium temulentum.

The circumscription presented here reflects expansion of Lolium to include Schedonorus and  Micropyropsis Romero Zarco & Cabezudo, as recommened by Darbyshire (1993) and Kellogg (2015). Under this exapnded interpretion, Lolium includes about 26 species that are native to Europe, temperate Asia, and northern Africa. There are no species native to the Americas but several have been introduced, usually as forage grasses; most have become established.

Lolium used to be included in the Triticeae, but evidence from genetics, morphology, and other studies shows its closest relationship to be to the species previously treated as Schedonorus. Artificial hybrids have been produced among L. perenne, L. multiflorum, L. pratense, and L. arundinaceum. Cultivars of these crosses have been registered for commercial use and are sometimes used for forage. Natural hybrids are not uncommon in Europe.

SELECTED REFERENCES Aiken, S.G., M.J. Dallwitz, C.L. McJannet, and L.L. Consaul. 1997. Fescue Grasses of North America: Interactive Identification and Information Retrieval. DELTA, CSIRO Division of Entomology, Canberra, Australia. CD-ROM; Dannhardt, G. and L. Steindl. 1985. Alkaloids of Lolium temulentum: Isolation, identification and pharmacological activity. Pl. Med. (Stuttgart) 1985:212–214; Darbyshire, S.L. 1993. Realignment of Festuca subgenus Schedonnorus with the genus Lolium (Poaceae). Novon 3:293-243. Dore, W.G. 1950. Persian darnel in Canada. Sci. Agric. (Ottawa) 30:157–164; Kellogg, E.A. 2015. Poaceae in K. Kubitzki (Ed.)., The families and genera of vascular plants vol. 13. Springer. Heidelberg.  Soreng, R.J. and E.E. Terrell. 1997 [publication date 1998]. Taxonomic notes on Schedonorus, a segregate genus from Festuca or Lolium, with a new nothogenus, ×Schedololium, and new combinations. Phytologia 83:85–88; Terrell, E.E. 1968. A Taxonomic Revision of the Genus Lolium. Technical Bulletin, United States Department of Agriculture No. 1392. U.S. Government Printing Office, Washington, D.C., U.S.A. 65 pp.