Question

Ectophloic siphonostele is found in
A) Osmunda and Equisetum
B) Marsilea and Botrychium
Adiantum and Cucurbitaceae
Dicksonia and Maidenhair fern

Answer 1

Ectophloic siphonostele a monostele type of siphonostele in which a ring of xylem occurs around the pith, and a ring of phloem outside the xylem. For example, Osmunda and Equisetum'

Complete answer:
This plant has one of the largest and most impressive brakes.There is a central part in the root or stem called a stele. It contains the tissues which are derived from the procambium.Outside the stele lies the endodermis, which is the innermost cell layer of the skin.
Protostele and Siphonostele Are two types of organisation in plants.
There are usually three basic types of protostele:-

Haplostele
Actinostele
Plectostele
Siphonosteles have pith internal to xylem. Pith is a region of ground tissue.
Siphonosteles is of two types.
Ectophloic siphonostele- In it, the xylem surrounds pith. This xylem is surrounded by phloem, pericycle and endodermis respectively. It is found in Osmunda and Equisetum.
Amphiphloic siphonostele- In it, there is a central pith. Xylem is surrounded by phloem, pericycle and endodermis but on both sides. In many living plants, many ferns and flowering plants contain amphiphloic stele.

Additional Information: An amphiphloic siphonostele can be called as-
Solenostele(non-overlapping leaf gaps)- This type of stele is primarily found in fern stems today.
dictyostele (overlapping leaf gaps)- Among living plants, this type of stele is found only in the stems of ferns.

Thus the correct answer is option “A” i.e., Osmunda and Equisetum.

Note: The concept of the stele was developed in the late 19th century by French botanists. Researchers are examining how the functions of organs are affected by the anatomy (sizes and shapes) of different steles.