LEAF MORPHOLOGICAL CHARACTERISTICS OF SOME UNDERSTOREY SPECIES IN A SRI LANKAN LOWLAND RAIN FOREST

Abstract

Variations in leaf morphological characters were studied among tree seedlings of fourunderstorey species grown in shade houses (full sun and shade) in the Sinharaja lowland rainforest over a one-year period from January 2000 to January 2001. Study species were Psychotrianigra, Geartnera vaginans, Byrsophyllum el/ipticum (Rubiaceae) and Agrostistachisintramaginalis (Euphobiaceae). All are understorey specialists and Byrsophyl/um ellipticum,Agrosttstachis intramaginalis are endemic to Sri Lanka. Measurements of leaf area, length ofdrip tip, petiole length, petiole diameter, fresh weight, and margin length were taken and specificleaf area was calculated. The greatest specific leaf area and margin length values were recordedfor all species in shade while smallest values were in full sun. In contrast the greatest leaf freshweight of these species were observed in fullsun. Petiole length of Psycho/ria nigra, Geartneravaginans, and Byrsophyllum ellipttcum was highest the greatest in shade and for Agrostistachisintramaginalis it was highest in full sun. The greatest length of drip tip and leaf area values wererecorded in shade and petiole diameter in full sun for Psycho tria nigra and for Byrsophyllume//ipticum. For other two species, length of drip tip and Jeaf area values were the greatest infullsun and petiole diameter in shade. A significant difference (p<=0.05) was found on specificleaf area between sun and shade for all species except Agrostistachis intramaginalis. Leaf area,margin length or drip tip showed no significant. The results indicate that these understoreyspecialists showing similar morphological characteristics when grown in shade and in fullsun intheir early seedling stage. Studied two genera has differed by specific lead area than othermorphological characters. Continuation of this study with other leaf ontogenic characters isimportant to understand the variation of understorey species