COMPARISONS AMONG BIOMASS ALLOCATION AND SPATIAL-DISTRIBUTION PATTERNS OF SOME VINE, PTERIDOPHYTE, AND GYMNOSPERM SHOOTS

The interspecific allometry of leaf, stem, and reproductive biomass distal to stem diameter was determined for a total of 12 angiosperm vine, gymnosperm, and pteridophyte species to compare allocation patterns to vegetative and reproductive shoot organs. The allometry of stem diameter in terms of the distance from shoot apices also was determined to quantify the manner in which vines, gymnosperms, and pteridophyte stems tapered along their length. The stems of vine species were found to weigh more than those of arborescent gymnosperm species distal to any point of equivalent stem diameter. Vine species also distribute more of their stem mass to shoot length as opposed to girth than gymnosperm species. Vine stems also supported proportionally larger leaf and reproductive biomass in comparison to gymnosperm stems of equivalent diameter, yet partitioned their total shoot biomass more or less equally between leaf and stem biomass in the same manner as the gymnosperm species examined. The allometry of vine as well as gymnosperm leaf biomass with respect to stem biomass appeared to be slightly anisometric and negative, suggesting that more massive stems had proportionally less leaf biomass than their smaller, less massive counterparts. Vine stems could be approximated as very slender cones; the shape and geometry of gymnosperm stems complied with those of stubby, truncated cones whose top diameter (for those examined), on the average, equaled 28% of the basal diameter. In general terms, the interspecific allometry of vines was most similar to that of pteridophytes. Collectively, these data refute the commonly held notion that vine stems are simply more slender than those of species with self-supporting stems.