Short Note on Pinus

 

Habitat:

 

Pinus is found growing at an altitude of 5000-8000 feet.

 

 

Structure:

 

1. i) It is sporophyte, evergreen and quite tall tree.

 

1. ii) It consists of extensive root system and strong branches.

 

iii) Upper branches becomes short and tree assume the shape of a cone.

 

 

Branches:-

 

It has two types of branches.

 

1. i) Long shoots are produced on the main stem and continue growth by buds. They are covered by scale leaves.

 

1. ii) Dwarf shoots originate in the axles of the scale leaves on long shoots. It bears 1-5 foliage leaves in addition to scale leaves. Each dwarf shoot with its cluster of needles is called a spur.

 

 

Leaves:-

 

It has two types of leaves:

 

1. i) Scale leaves are small and brown in colour. They cover the stem.

 

1. ii) Foliage leaves are long, narrow and leathery. They are green.

 

 

Cones:-

 

It has two types of cones:

 

1. i) Male cones

 

1. ii) Female cones

 

Both male and female cones are produced on same tree but on different branches.

 

 

Seed Formation:

 

1. i) Fertilization results in embryo formation.

 

1. ii) Then ovule ripens to form seed.

 

iii) Female cones normally remain attached for three years on the plant.

 

1. iv) When it matures the cones open and seeds are set free and dispersed.

 

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