The presence of single grains and polygranular aggregates has been noticed in the leaf starch of Smilax aspera. The electron microscope shows that the polygranular aggregates present both compound grains by juxtaposition and complex grains by “twinning”. The presence of complex grains by “twinning” and subsequent enveloping overgrowth, however, cannot be excluded. Several morphogenetic schemes due to such factors as exocorrosion, growth by apposition, growth by “twinning,” polycentric crystallization, and spatial disposition of the preexisting chloroplast structures are postulated. The formation of polygranular aggregates is probably caused by the fact that not all the leaf starch of a full-grown plant of Smilax aspera is strictly “transitory” starch. On the fracture surface of the grains, the fracture ridges have preferential directions very likely correlated with the spatial arrangement of the macromolecules. Smilax leaf starch has a marked degree of crystallinity, which is evidenced by birefraction properties. The diffractogram of Smilax leaf starch is of the B-starch type. Smilax leaf starch is compared with storage starch from the underground stems of the same plant.