Realignment of Festuca subgenus Schedonorus with the genus Lolium (Poaceae)

Evidence from the literature of the close relationship of Festuca subg. Schedonorus to Lolium and its relatively distant relationship to Festuca subg. Festuca is briefly discussed. New combinations, Lolium subg. Schedonorus, Lolium arundinaceum, Lolium giganteum, Lolium mazzettianum, and Lolium pratense, are proposed to reconcile classification with known phylogeny. The relationship between Festuca L. and Lolium L. (Poaceae) has long been an interesting classification problem. Lolium is readily distinguished from Festuca by its spicate inflorescence and lateral spikelets with a single glume. This morphology suggests the spikelike inflorescence structure in the tribe Triticeae Dumortier, where Lolium, in early treatments, was often placed. Nevski (1934) was the first to place Lolium in the Poeae (= Festuceae) rather than the Triticeae. Information from diverse nonmorphological sources, such as hybridization and cytology (e.g., Jenkin, 1959), oligosaccharides and water-soluble polysaccharides in caryopses (MacLeod & McCorquodale, 1958), endosperm structure (Tateoka, 1962), seed protein electrophoresis (Bulinska-Rodomska & Lester, 1988; Butkute & Konarev, 1982), serology (Butkute & Konarev, 1980, 1982; Fairbrothers & Johnson, 1961; Smith, 1969; Watson & Knox, 1976), chloroplast DNA (cpDNA) restriction endonuclease site patterns (Lehvaslaiho et al., 1987; Soreng et al., 1990), cpDNA reassociation (Hilu & Johnson, 1991), and thermal denaturation of genomic DNA (King & Ingrouille, 1987), has supported the placement of Lolium in Poeae. Spontaneous hybridization occurs commonly between species of Festuca subg. Schedonorus (P. Beauvois) Petermann and chasmogamous species of Lolium, particularly the type species of the genus, L. perenne L. (Barker & Stace, 1986; Humphries, 1980; Gymer & Whittington, 1973). Hybridization between Lolium and Festuca subg. Festuca rarely occurs spontaneously and is reported only for Festuca rubra L. (Stace, 1975). The latter is, however, also reported to hybridize with species in Festuca subgenera Festuca and Schedonorus as well as Vulpia C. C. Gmelin (Ainscough et al., 1986; Knobloch, 1968; Saint-Yves 1929; Stace, 1975). Hybridization between Festuca (Schedonorus) pratensis Hudson and Lolium perenne (= x Festulolium loliaceum (Hudson) P. V. Fournier) was suspected as early as 1790 (see Jenkin, 1933). Reproductive barriers are not appreciably greater for this hybridization than for interspecific hybridization within Festuca subg. Schedonorus or between many species of Lolium (Jenkin, 1933; Stace, 1975). The degree of difficulty in producing artificial L. perenne x F. pratensis hybrids and the differential success of reciprocal crosses is similar to interspecific hybridization reported in various plant genera (e.g., Borrill et al., 1977; Gymer & Whittington, 1973). Extensive studies of artificial hybrids and their chromosome behavior (for references, see Jauhar, 1974, 1975; Terrell, 1966), as well as chromosome banding (Dawe, 1989; Thomas, 1981), have indicated the homology of chromosomes and their genetic compatibility. In auto-allotriploids and amphidiploids of L. perenne, L. multifiorum L. , and F. pratensis, synapsis of homeologous chromosomes usually occurs as multivalents or even bivalents, in spite of the presence of true homologues (Jauhar, 1974, 1975). Diploid crosses of these taxa show high bivalent formation (87-100%) with 0.783-0.896 chiasmata per chromosome pair (Jauhar, 1975). Such observations have led many taxonomists and cytogeneticists to suggest that Festuca and Lolium could be combined, in whole (e.g., Jauhar, 1975; Knobloch, 1963; Love, 1963; Stebbins, 1956; Terrell, 1966; Ullmann, 1936) or in part (e.g., Tutin, 1956). Amalgamation of Festuca and Lolium has been proposed as early as 1898 (M'Alpine, 1898), but no valid combinations of Festuca subg. Schedonorus taxa within Lolium are available. Raspail (1829), however, included F. pratensis (under the name F. elatior L.) and F. loliaceum Hudson (= F. pratensis x L. perenne) in his examination of Lolium as L. festuca Raspail and L. festucoides Raspail, respectively. Proposed on the basis of morphological and ecological continua observed between these taxa and NOVON 3: 239-243. 1993. This content downloaded from 157.55. 39.147 on Wed, 21 Sep 2016 05:43:37 UTC All use subject to http://about.jstor. org/terms