XVI International Botanical Congess

Cyrilla racemiflora L., a montane rain forest tree of the Luquillo Mountains, Puerto Rico was evaluated for xylem cell production in the lower stem of trees growing on four sites, two at the upper forest border for the species at 750 and 770m and two near the lower forest border at 430 and 470m elevation. The former had consistently alternating earlywood and latewood xylem comprising uniform annual rings whereas those near the lower forest border had higher incidence of intra-annual false rings, making it difficult to recognize individual annual xylem increments. Lower sites were warmer and drier than the upper elevations sites where a cool, wet environment was the norm.