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H austorial synergids: an important character in the systematics of danthonioid grasses (A rundinoideae : P oaceae )?
Author(s) -
Verboom G. Anthony,
Linder H. Peter,
Barker Nigel P.
Publication year - 1994
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1994.tb11472.x
Subject(s) - biology , polyphyly , monophyly , systematics , botany , paraphyly , genus , zoology , clade , taxonomy (biology) , phylogenetic tree , genetics , gene
The mature ovule and megagametophyte of 42 grass species (23 genera), mostly from the taxonomically troublesome subfamily Arundinoideae, was investigated. Haustorial synergids, first described from the Arundineae, are reported for a further 26 species (ten genera) of danthonioid grasses, a group for which they appear to be synapomorphic. The evolution of this character and a suite of associated integument and nucellar characters is discussed. The danthonioid clade, as defined by haustorial synergids, includes Cortaderia (often treated as nondanthonioid) but excludes a number of taxa currently contained in the Arundineae. The full extent of the group remains undetermined, however, since several of its potential members remain unstudied. The data provide some indication of phylogenetic structure within the clade. At least two of the species of Merxmuellera studied appear to occupy a basal position, while three do not, suggesting that this genus may be paraphyletic, or even polyphyletic. Also, the reduction or absence of synergid haustoria in Prionanthium, Pentaschistis , and Pentameris is considered to be secondarily derived and weakly corroborates the monophyly of this generic cluster as indicated by spikelet morphology.