Wood Anatomy of Hawaiian and New Guinean Species of Tetramolopium (Asteraceae): Ecological and Systematic Aspects

Qualitative and quantitative features are reported for five Hawaiian and one New Guinean species of Tetramolopium. Tetramolopium humile differs from the other Hawaiian species in its numerous narrow vessels, numerous vasicentric tracheids, and wide rays. Although these features are adaptive in the dry alpine localities of T. humile, they would be adaptive also in the remaining species, which are from dry to moderately dry lowland localities. Thus, one can consider these features of T. humile as systematic indicators. The wood of T. pumilum (New Guinea) has distinctive wide, tall rays that may be related to the short stems in this species; T. pumilum has wood more mesomorphic than that of any of the Hawaiian species. Within Hawaiian Tetramolopium, wood anatomy correlates with dryness of habitat. The species of Tetramolopium studied have highly xeromorphic wood in comparison with woods of dicotyledons at large.