Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Factors affecting seed and cone development in Pacific silver fir (Abies amabilis).

Abstract

The reproductive development from pollination until seed maturity for Abies amabilis was studied at two sites in British Columbia. Ten old-growth trees at varying altitudes at each site were flagged and two or more cones were collected from each tree every 1 or 2 weeks from May/June to September 1996. Following size measurements, cones were dissected and 20 ovules from each cone were sampled, fixed, embedded in paraffin, sectioned, and stained for anatomical study. Ovule, megagametophyte, and embryo size was measured and stage of ovule or seed and embryo was determined. At both sites the phenology and details of development were similar. The major causes of cone loss were frost at pollination and insect damage following pollination. The seed potential per cone was 359-408, but the filled seeds per cone based on cutting tests and X-raying was only 18-22%. The major causes of seed loss were insect damage (32-39%) during ovule and seed development and failure of ovules to be pollinated (26-31%). Although the amount of insect damage was similar at both sites, damage at site 1 was primarily caused by Megastigmus sp. larvae in the seeds whereas at site 2, damage was to seeds, scales, and the cone axis and due to Earomyia abietum larvae. Megagametophyte and embryo development is described and the time and causes of the seed loss are related to development. Anomalous types of development are described and possible causes discussed.