[Fine structure of sieve-tube plastids of Aristolochia and Asarum (Aristolochiaceae)].
Sieve-tube plastids of Aristolochia (5 species investigated) contain several starch grains and always one large crystalloid. In Asarum (3 species investigated) starch has not been found in the sieve-tubes. Their plastids contain several cuneate crystalloids that are sometimes arranged around an invisible centre. Asarum sieve-tube plastids look almost like typical plastids of monocotyledon sieve-tubes.-Crystalloids of Aristolochia and of Asarum sieve-tube plastids are composed of 50-60 Å subunits in straight and parallel order as crystalloids in monocotyledon sieve-tube plastids are.The results of the investigations of the fine structure are discussed in relation to the position of the Aristolochiaceae in the system of angiosperms.
Botanisches Institut der Universität Bonn, Bonn, Deutschland.
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