Relative reproductive effort in males and females of the dioecious shrub Oemleria cerasiformis.

We derived an index of reproductive effort (g reproductive tissue per g leaf) from data collected over two seasons on 28 males and 28 females of the dioecious shrub Oemleria cerasiformis. Males produced an average of three times as much flower and flower-stalk tissue as females, but because of their large fruits, females produced four times as much total reproductive biomass. Reproductive effort of both sexes was related to light. Fruit set in females (% carpels producing drupes) averaged 11.2% and was related to spring light levels. Male-biased sex ratios in this species may be related to the greater reproductive effort of females.