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

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.