Cross-pollination is by wind action only. The ratio and distance of male to female plants is important, as the number of female trees in each planting directly affects the total yield. Recommendations for male and female ratio vary from 6 to 12%, while the distance within which the female plant can be pollinated is about 100m. It has been shown that as the distance from the female plant to the male plant (polliniser) increases (64m), the yield of the female plant decreases.