Question

The wood of Pinus is
A. Pycnoxylic
B. Pycnoxylic and heterozygous
C. Manoxylic and homozygous
D. Manoxylic and heterozygous

Answer 1

Hint: Pine is the gymnosperm plant found in hilly areas of the tropical and temperate regions. It is evergreen, coniferous trees. It is considered a long lived plant having a life of 100-1000 years. It is mostly monoecious( bearing male and female on the same plant).

Complete Answer:
- Pinus is the evergreen conifers that belong to gymnosperm plants due to the presence of naked cone shaped seeds.
- The bark of this plant is thick and scaly. It grows well in acidic soils.
- They are generally called as softwoods consisting of wood without vessels or pores with fewer xylem fibers.
- Due to the absence of pores it is also called as non-porous wood.
- It is having a pycnoxylic type of wood. In this type of wood, a large amount of xylem tracheid and a small amount of cortex and pith is present that is responsible for making the wood compact and dense. It is having little parenchyma. Due to this, the woods are durable.

The correct answer is A i.e. pycnoxylic.

Additional information: Manoxylic woods are the wood having large amounts of parenchyma with large pith and cortex mixed with less amount of xylem tracheid thus they are non compact wood. The parenchyma in this type of wood is filled with starch grains. It is not durable thus not used commercially. Examples include Cycas.

Note: The pine having various uses like:
- It is used for the production of lumber, paper and resin.
- It is having ornamental uses.
- It acts as a source of food for some lepidopterans hence it causes disease in the plant.
- It is responsible for establishing a symbiotic relationship with Mycorrhiza fungi.