Authors: Anderson Erika D Owens John N
Publish Date: 2000/11/01
Volume: 86, Issue: 5, Pages: 1033-1042
Abstract
Taxus brevifolia Nutt commonly known as Pacific or western yew is a conifer native to the Pacific northwest of North America Contrary to other Taxus species T brevifolia staminate strobili are usually located on 2yearold foliage although they may occur on foliage from 1 to 5yearsold This delayed staminate strobilus development may be an adaptation to the low light environment where T brevifolia grows Microsporogenesis occurred in the autumn preceding pollination Successive divisions produced isobilateral tetrads visible as early as midOctober Overwintering staminate strobili usually contained separate microspores In 1996 to 1999 pollination occurred in March and April in two natural forest sites on southern Vancouver Island British Columbia Canada The low amounts of airborne pollen and prolonged pollination period indicated low pollination success within T brevifolia Female receptivity was measured by the presence of a pollination drop Protandry up to 18 d was observed In vitro pollen germination was moderate to good ranging from 65 to 88 depending on the tree and year DAPI fluorescence staining showed successful male gametophyte development in vitro The microspore divided forming a tube nucleus and generative cell within 3 d of culture The generative cell then divided forming a sterile nucleus and spermatogenous nucleus after 17 d The spermatogenous nucleus acquired a cell wall then divided forming two equal sperm after 24 d Copyright 2000 Annals of Botany Company
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