Flowering of Pinus caribaea var. hondurensis Barr. and Golf. in Northern Australia

Abstract

Observations were made on the flowering of Pinus cavibaea var. hondurensis Barr, and Golf, covering the formation of floral buds to the pollination of conelets at four locations in Northern Australia: Howard Springs and Snake Bay near Darwin and Cardwell and Byfield in Queensland. Times of pollen fly and conelet receptivity varied at each location and the two types of flowering appeared to be out of phase at Byfield and Howard Springs and coincident at Cardwell and Snake Bay, To determine the effectiveness of pollination of conelets a new technique was devised for this study and from this it was shown that the amount of pollen arriving in individual conelets depends on the time that the cones become receptive relative to the peak period of pollen shed. Thus potential of seed production would appear to be greatestat Cardwell and Snake Bay. The intensity of pollen fly was similar at all locations however conelet production appeared most intense at Cardwell. Variations in seed and pollen viability between clones were significant, however there was no correlation between pollen viability and seed viability.