Fig. 7.

Number of companion cells per sieve tube element in the variant phloem. (A) Transverse section of Perianthomega vellozoi. Sieve tube elements are accompanied by one companion cell (arrows). (B) Transverse section of Tynanthus cognatus. Sieve tube elements are accompanied by two or three companion cells lying at the same side of the sieve tube (arrows). (C) Transverse section of Adenocalymma flaviflorum. Sieve tube elements are accompanied by two companion cells, each at one corner of the sieve tube element (arrows). (D) Ancestral character state reconstruction of the number of companion cells per sieve tube element. Scale bars = 50 µm.