On fertility, pleiomery and meiomery in the fruits of some Canarium species

In continuation of a previous publication by Lam, in which meiomery and pleiomery in male flowers of Canarium decumanum were described, the same phenomenon is now discussed concerning the fruits of C. Mehenbethene (176 of one single tree) and C. commune (1126 fruits mixed from more than one tree). An investigation of the material gave the following results: 1. C. commune and C. Mehenbethene are closely related; the latter may prove to be a polyploid of the former. Their areas are partly overlapping, but C. commune has its centre in the Moluccas, C. Mehenbethene in New Guinea and W. Polynesia. 2. A tendency to reduce the number of ovules and carpels in the ovary is assumed. By means of a statistical method (”phase index“) the position of either species in the phases of this regression is indicated. 3. From this, it is concluded that C. Mehenbethene represents a more advanced phase than C. commune and that therefore an eastward migration must be accepted. This agrees with other facts stated earlier, both in the Burseraceae and in other plant families of western origin. 4. In Canarium commune pleiomery is found in 2.3% of the fruits, meiomery in 0.45%, which agrees fairly well with the figures found earlier for the corolla and the androeceum of the male flowers of C. decumanum (0.9% and 0.3% respectively). 5. The desirability is expressed to investigate the following points: a. the ontogeny and the fertilization of ovaries and ovules in Canarium. b. cytological relations between related trees in the tropics, especially as far as they may supply indications towards migration tracks (cf. the work of Hagerup on Vaccinium [Hereditas 18, 1933]). c. the ”phase index“ of a number of related Canarium species. d. the exact distribution of some of the phases mentioned along those migration tracks which are both geologically and biogeographically supported (e.g. Sunda centre—Philippines, Philippines—Moluccas—New Guinea, New Guinea—Moluccas—Central Celebes, Malay Peninsula—Sumatra—Java, etc.).