Question

In Pinus, the spur (dwarf shoot) has
(A) One needle
(B) Two needles
(C) Three needles
(D) All of the above

Answer 1

Hint:The genus pinus is the largest genus in family pinaceae pine belongs to conifers since they are cone bearings plants. The conifers belong to gymnosperms. These plants produce seeds without fruit or flowers. Conifers produce two types of cones male cones called pollen and female cones that produce seeds.

Complete answer:
 In the pinus, the spur (dwarf shoot) can have one to five needle-like structures. The pinus are cone bearing plants. In pinus, two types of leaves are formed by normally foliage leaves and scaly leaves.
(A) Scaly leaves: the leaves give scale-like appearance and so are named scaly. These leaves are thin in structure and are brown in color. These leaves can be found in long axial stems as well as dwarf shoots.
(B) Foliage leaves: the foliage leaves are green in colour. They are long and needle shaped(acicular) in structure. These leaves are found on the apex of dwarf shoots only.
The dwarf shoot with needle-shaped leaves called foliage leaves is called spur. In pinus, the spur found on dwarf shoots can possess one to five needles.

If a single leaf is present at the apex of dwarf shoot, it is called a unifoliar spur. A spur is called a bifolar if the dwarf shoots possess two leaves. If a dwarf shoots possess three leaves at the apex they can be called trifoliar leaves.

Hence the correct answer is option ‘D’.

Note: In the dwarf shoot of pinus, two scaly leaves prophylls are present. These are followed by cataphylls that are 5-13 are in numbers.