Mention the conducting elements of phloem

Mention the conducting elements of phloem.How will you segregate them on the basis of speciality?

The conducting elements of phloem are collectively called sieve elements. On the basis of speciality, they are segregated into less specialised sieve cells (in the phloem of pteridophytes and gymnosperms) and more specialised sieve tube members or sieve tube elements (in angiosperms).