Complex Tissue Phloem

A common structural feature of vessel elements and sieve tube elements is:

1. thick secondary walls

2. pores on lateral walls

3. presence of P-protein

4. enucleate condition

Companion cells are closely associated with:

Phloem in gymnosperms lacks:

1. Both sieve tubes and companion cells

2. Albuminous cells and sieve cells

3. Sieve tubes only

4. Companion cells only