Quercus costaricensis Liebm. and the problem of multi-seeded acorns
Quercus costaricensis Liebm, growing near Cerro de la Muerte, Cartago Province, Costa Rica has been found to produce 42% multi-seeded acorns. With the addition of Q. costaricensis there are now 10 species of Quercus known to produce acorns that contain more than one seed. The only published explanation suggests that insect seed predation may be the selective agents producing an advantage to trees that make multi-seeded acorns period. Q. costaricensis was found to experience little insect predation, forcing us to generate an alternative explanation for the multi-seeded acorn habit of some oaks. We hypothesize that the production of multi-seeded acorns is selectively neutral, being found only in oaks that produce a wide range of seed weights even within the single seeded acorns they produce. Abnormalities in cotyledon number within acorns are also noted.