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Haustorial Synergids: An Important Character in the Systematics of Danthonioid Grasses (Arundinoideae: Poaceae)?

G. Anthony Verboom, H. Peter Linder and Nigel P. Barker
American Journal of Botany
Vol. 81, No. 12 (Dec., 1994), pp. 1601-1610
Stable URL: http://www.jstor.org/stable/2445338
Page Count: 10
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Haustorial Synergids: An Important Character in the Systematics of Danthonioid Grasses (Arundinoideae: Poaceae)?
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Abstract

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.

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