SEED MORPHOLOGY AND ITS SYSTEMATIC IMPLICATIONS IN PYROLOIDEAE (ERICACEAE)

A survey of the seed morphology of 24 species and all of the four genera, Pyrola, Orthilia, Moneses, and Chimaphila, of the subfamily Pyroloideae of the Ericaceae showed that the testa and the endosperm dimensions, and especially the pitting patterns on the inner periclinal walls of the testa cells, are significant taxonomically at or below the generic level and even at the infraspecific level in some species. Seeds of Moneses are clearly distinguished from those of the other three genera in having transversely elongated large pits (pitting type 5) on the inner periclinal walls. Chimaphila species are uniform in having smooth or slightly pitted inner periclinal walls (pitting types commonly 1-2). Thus, the seed morphology of Moneses is clearly different from that of Chimaphila. Seed morphology of Pyrola shows considerable variability and no seed characters define the genus. Orthilia seeds do not have any peculiar characteristics and are more similar to those of Chimaphila than Pyrola according to principal component analysis. Within the genus Pyrola, the monotypic subgenus Amelia is distinct in having densely arranged large pits (type 4) on the inner periclinal walls. In the other subgenus Pyrola, section Scotophylla is uniform in having low ratios of seed length to width and seed length to endosperm length, but the other two sections, Pyrola and Chlorantha, vary widely in their seed morphology. Infraspecific differentiation of the seed morphology is noted for P. asarifolia and C. umbellata, respectively.