Relationships and taxonomy of New Zealand wheatgrasses

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Abstract
Studies of the genomic constitution of the New Zealand grasses of the tribe Triticeae confirm their relationship to the widespread genus Elymus L. as typified by E. sibiricus L., and defined by an alloploid genome. That genome is composed of the haplome H, derived from Critesion Rafin. (Hordeum subgenus Hordeastrum) , and the haplome S, derived from Pseudoroegneria (Nevski) Löve (Elytrigia sect. Pseudoroegneria). Five species found in New Zealand and previously included in Agropyron are referable to the East African-Central Asiatic-Australasian section Anthosachne (Steud.) Tzvelev of Elymus. These species are (chromosome numbers and synonyms in parentheses): Elymus reetisetus (Nees) Löve et Connor (2n = 42, Agropyron scabrum p.p, A. youngii), E. multiflorus (Hook. L) Löve et Connor (2n = 42, A. kirkii) with var. multiflorus and var. longisetus (Hack.) Löve et Connor; E. enysii (Kirk) Löve et Connor (2n = 28, A. enysii); E. tenuis (Buch.) Löve et Connor (2n = 56, A. tenue); E. apricus Löve et Connor described as new (2n = 42, A. scabrum p.p.). The tetraploid has the genomic formula HS, the octoploid HHSS, and the hexaploids have the constitution HSS. Two species, formerly placed in Cockaynea Zotov, also share the genomic formula HS, but represent in Elymus the endemic section Stenostachys (Turcz.) Löve et Connor. Their correct names are E. narduroides (Turcz.) Löve et Connor (2n = 28, Cockaynea gracilis), and E. laevis (Petrie) Löve et Connor (2n = 28, C. laevis). All 7 species are obligately sexual and at least facultatively autogamous, but E. rectisetus includes populations that are facultatively to obligately agamospermous and obligately pseudogamous.