Question

2. Two types of plant specimens were given to students for microscopical observation. They were directed to note down the features they observed. Major features noted by students were summarized in the box below a) Radial vascular bundle and are 20 in number b) Collateral vascular bundle arranged in the form of a ring and vascular bundles are few in number c) Xylem round in shape d) Cambium present between xylem and phloem e) Xylem is exarch f) Xylem is endarch a)Name the two specimen b)Substantiate your answer by picking up the features of specimens from the box and write them in two columns

Answer 1

Answer:

Outer side of the xylem

A vascular bundle in which a strand of phloem is present external to the strand of xylem on the same radius side by side is known as a collateral bundle. Cambium may be present or absent in between xylem and phloem, and so there are the following two types of a collateral bundle:

(a) Closed collateral bundle: In this type cambium is absent in between xylem and phloem. Therefore stems having this type of bundle does not have normal secondary growth. Ex. Monocotyledonous stem. Usually, these bundles are enclosed within bundle sheath made up of sclerenchyma and those that lack the sheath are considered as anomalous (e.g. Asparagus stem).

(b) Open collateral bundle: An open collateral vascular bundle has cambium called fascicular cambium between xylem and phloem. The bundles can increase in diameter by normal secondary growth with the help of fascicular cambium. Ex. Dicotyledonous stem.

So, the correct answer is 'Outer side of the xylem'.