Question

Which of the following has amphiphloic-siphonostele?
A. Rhizome of Marsilea
B. Stem of Lycopodium
C. Rhizome of Pteris
D. Stem of Equisetum

Answer 1

Hint: The stelar organization in which phloem is present external and internal to the xylem. This type of organization is commonly found in ground tissues.

Complete answer: Siphonostele is a stelar organization of vascular tissues in which the vascular tissues are surrounded by a central pith.
It is of two types-
1. Ectophloic siphonostele- This type of organization is commonly found in Osmunda in which phloem is present external to the xylem.
2. Amphiphloic siphonostele- In the rhizome of Marsilea, where phloem is present as a ring outside the ring of xylem and the pith is encircled by inner and outer endodermis, pericycle, xylem, and phloem. It is a type of monostele.
This type of stele occupies the center of the rhizome.

Additional information: The stem of Lycopodium sp. shows plectostele and the stem of Equisetum shows ectophloic siphonostele. But, the rhizome of Pteris shows siphonostele.

Hence, the correct option is (A) Rhizome of Marsilea.

Note: Siphonostele is commonly observed in vascular cryptogams that have vascular bundles in the form of a cylinder around a pith.