Question

Which of the following does not contain pith?
A. Siphonostele
B. Protostele
C. Eustele
D. None of the above

Answer 1

Hint: Protostele is the most crude kind of stele with central xylem encompassed by phloem and pericycle.

Complete Answer:
- The stele is the focal aspect of the root or stem containing the tissues obtained from the procambium. These incorporate vascular tissue, in some ground tissue and a pericycle, which, if present, characterizes the peripheral limit of the stele.
- Protostele is the most primitive vascular plant had stems with a central core of vascular tissue.This consists of a round and hollow strand of xylem, encircled by a locale of phloem.
- Siphonosteles have a locale of ground tissue called the pith interior to xylem. The vascular strand contains a chamber encompassing the pith. Siphonosteles regularly have breaks in the vascular strand where leaves (commonly megaphylls) begin.
- Siphonosteles can be ectophloic (phloem present just outer to the xylem) or they can be amphiphloic (with phloem both outside and interior to the xylem).
- In eustele ,the essential vascular tissue comprises vascular bundles, ordinarily in a couple of rings around the pith. The vascular packs in an eustele can be collateral (with the phloem on just one side of the xylem) or bicollateral (with phloem on the two sides of the xylem).

So, the correct answer is option B.

Note: Pith is missing in Pericycle. Medullation (appearance of essence) of a protostele with central pith is called as siphonostele and along these lines has central pith encircled by xylem, phloem and pericycle. Partitions of vascular strands by parenchyma in siphonostele offer ascent to eustele.