Botany - Anatomy of Flowering Plants Question with Solution | TestHub

Sieve elements are the chief conducting elements of the phloem which are of two types: sieve cells and sieve-tube members. Pores in sieve cells are narrow, there is seemingly uniformity in the structure of sieve areas and are found to be distributed evenly on all walls. The presence of sieve plates in sieve-tube members is one of the principal differences between sieve cells (absent) and sieve-tube members. In most gymnosperms and seedless vascular plants, sieve cells are the only kind of food-conducting cells whereas sieve-tube members are present in angiosperms. Sieve tubes are made of sieve tube members arranged terminally to one another.