The pollination mechanisms of Acmopyle pancheri (Brongn. & Gris) Pilg. and Phyllocladus hypophyllus Hook.f. were investigated by conventional microscopical techniques and by nuclear magnetic resonance (NMR) imaging. Dissimilarities include the orientation of the ovule and type of pollen; Phyllocladus has erect ovules and wettable pollen with vestigial sacci, whereas Acmopyle has more-or-less erect ovules and non-wettable, functionally saccate pollen. Similarities include the mode of formation of the pollination drop and its response upon pollination. In both genera, pollination triggers pollination drop retraction and drop secretion ceases. Neither NMR imaging nor conventional histology of Phyllocladus ovules revealed any specific tissue beneath the ovule which could be responsible for pollination drop retraction. It is more likely, therefore, that the drop is channelled into the vascular supply or the apoplast. These findings invalidate the taxonomic value of the pollination mechanism as a suite of characters traditionally used to separate Phyllocladaceae from Podocarpaceae. Copyright 2000 Annals of Botany Company

Received: 25 January 2000 ; Returned for revision: 10 March 2000 . Accepted: 27 March 2000


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