Page 157 - Biology_F5

Biology for Advanced Level Secondary Schools

Adaptations of Pinus to its mode of life
Pinus are able to adapt to their environment Activity 3.8: Observation of Pinus
due to presence of the following features: sporophyte and reproductive
structures
(a) The root and shoot systems of Pinus
are well developed to provide the plant Materials
with a good contact to the soil and Branches of pine (Pinus) plants with
FOR ONLINE READING ONLY
atmosphere.
male and female cones, hand lens or
(b) They have roots for absorption of light microscope
water and nutrients from the soil.
(c) The Pinus plant has mechanical tissues Procedure
for support and vascular tissues for (a) You are provided with branches of the
transportation of water and food. Pinus species, with male and female
cones. Examine the mature female
(d) They have an elaborate mechanism
for reducing water loss through cones, which are relatively woody.
transpiration. This becomes possible At the base of each cone are two
due to presence of thick cuticle, winged seeds; however, they might
needle-like leaves to reduce their sometimes be missing, because they
surface area and a reduced number of fall off when mature, especially if
stomata pores. Additionally, their bark the cones are disturbed by wind or
is coated with waxy material called any other mechanical force. If seeds
suberin to reduce water loss. are missing, two small depressions,
(e) They produce lighter pollen grains, showing the mark of where the seeds
each with two wing-like structures, were attached should be seen.
which make them float in air, hence
easily they are carried by wind for (b) Carefully, examine the male cones,
pollination. which are relatively small and much
(f) They can reproduce sexually without herbaceous compared to the woody
necessity of using water, because the female cones. Normally, male cones
transfer of male gametes to female are borne in clusters at the axils of
gametes is through pollen tube, which lower branches. Take some pollen
ensures reproduction in terrestrial grains from the male cones and
environment where water is limited. mount a few in a drop of water on a
(g) The seeds are winged; hence, they can slide for examination under the light
be easily dispersed by wind. microscope to observe the wings on
each.

Questions
1. Describe the male and female
cones.
2. Describe the pine pollen grain.

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