An electron-microscopic study of the starch-containing plastids in the fern Todea barbara.

Gametophytes of Todea barbara grown in vitro have two types of starch-containing plastids. The first type are chloroplasts having well-developed grana regions connected by intervening membranes and little deposition of starch. The other type are amyloplasts usually containing abundant starch deposits and stacks of membranes which resemble the grana of the chloroplast but are not connected. Even when little starch is present, the latter type has very few internal membranes. Membrane spacing and gross organization of the mature plastid of both types suggests similar morphological development. However, when and where in this development known physiological differences arise is not yet known.