Ultrastructural characters of angiosperm sieve-element plastids (Behnke, 1988, 1991,2000) suggest a slightly different evolution of the monocotyledons: The probably most basal angiosperms (Qiu et al., 2000), the ANITA grade (Amborellaceae, Nymphaeales, Austrobaileyaceae, Trimeniaceae, and
Illiciales) plus Chloranthaceae and Ceratophyllaceae, exclusively contain S-type plastids.