Final answer:
In conifers and ferns, sieve cells have albuminous cells that serve a similar role to companion cells in angiosperms. Albuminous cells provide metabolic support and energy to the sieve cells, analogous to the relationship between sieve-tube elements and companion cells in flowering plants.
Step-by-step explanation:
In conifers and ferns, sieve cells have albuminous cells, which are the equivalent to companion cells. Phloem tissue in these plants is composed of sieve-tube cells, with these albuminous cells providing metabolic support. Unlike sieve-tube elements in flowering plants, which are connected to the actual companion cells, sieve cells in conifers and ferns pair with a slightly different type of cell, the albuminous cell, for their functioning. Just like companion cells in angiosperms, albuminous cells contain high amounts of ribosomes and mitochondria to assist with metabolic activities and produce energy for the sieve cells.
In conifers and ferns, sieve cells have companion cells, which are the equivalent of companion cells.