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Morphology of Pinus

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Systematic position (Five Kingdom Classification)

Kingdom :Plantae

Division: Tracheophyata 

Sub- division: Gymnospermae 

Class: Coniferospida 

Order: Coniferales 

Family: Pinaceae 

Genus: Pinus 

Occurrence : Pinus is found in arid places usually on slope of hills . Pinus is a xerophytic plant.

The two major species of Pinus found in Nepal are:

Pinus roxburghii: It is a large tree measures about 10- 20m in height. It is about in altitude between 1200 to 2100m above the sea level. Forest of Pinus roxburghii are most abundant in south facing sunny slope hills of Central and Eastern Nepal.

Pinus wallichiana: It is a large tree and measures 20 m or more. In Nepal, vertical distribution ranges from 1800m to 3300m above sea level. It's forest is found in Karnali region and extends to central Nepal in Kaligandaki region.

Pinus wallichiana, having 3 foliage leaves on dwarf shoot and oval female cone can be distinguished from P. roxburghii on having five foliage leaves on dwarf shoot and cylindrical pendent female cone.

Morphology 

Root 


  • Branched tap root is present.
  • Root hairs are absent.
  • Mychorrhizal roots are present I e. the roots have symbiotic association with fungi. Fungi provide water and minerals to root and root provide nutrition to fungi.

Stem

The stem is erect, branched and woody and are covered with characteristic bark.

The branching is monopodial. Stem bears two types of shoots:



Long shoot or branch of unlimited growth: Long shoots arise from main stem. It possesses apical bud that grow indefinitely. These branches spread out horizontally and has scaly leaves.

Dwarf shoot or branch of limited growth: Dwarf shoots arise from long shoot. They don't possess apical bud and grow for short period of time. They develop from axile of scale leaves on long shoot. They bear both foliage and scaly leaves.

Leaves 

Pinus possesses two types of leaves. So the leaves are dimorphic:


Scaly Leaves: Scaly leaves are thin, brown, flattened and minute structures. Scaly leaves are found on both dwarf and long shoot. They fall off with maturity of branches. They protect young buds and young shoot and reduces excess loss of water from young part.

Foliage leaves: They are long, needle like and green. They are found in dwarf shoot only. The dwarf shoot bearing foliage leaves is called spur. They are evergreen and last for 3 to 10 or more years.