Question

A concentric amphivasal (leptocentric) vascular bundle is one in which ___________________.

• A. Centrally located phloem is surrounded by the xylem or
  xylem surrounds phloem
• B. Centrally located xylem is surrounded by phloem
• C. Xylem is flanked by phloem on the interior and exterior
  side only
• D. Phloem is flanked by the xylem on interior side only

Answer 1

The correct option is A Centrally located phloem is surrounded by the xylem or

xylem surrounds phloem

Amphivasal vascular bundle: one of the phloem which is surrounded by xylem. Though collateral bundles are most common in seed plants. Many monocot species have amphivasal bundles instead or it has amphicribral ones (in which phloem surrounds xylem).

Types of Vascular bundles

A Concentric, periphloematic

B Concentric, perixylematic

C Radial with inner xylem, with four xylem-poles which are left closed and right open.

D Collateral closed

E Collateral open

F Bicollateral open

So, the correct answer will be centrally located phloem is surrounded by xylem.

The correct option is A.