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Conifers
Complete the following sentences on gymnosperms:
1. Gymnosperms are plants that produce seeds in cones. Conifers are the most common gymnosperms.
2. Conifers are usually evergreen trees, ranging in size from 8 cm to over 91 m.
3. Many pines have woody cones, however some conifers such junipers have softer, fleshier cones.
4. Conifers usually produce male and female cones on the same tree.
5. Male cones:
usually grow on the lower branches, on the tips of branches
i. Generally smaller and softer than female cones.
ii. They produce tiny grains of pollen that contain the sperm cells.
iii. After the male cones lose their pollen, they disintegrate and fall off the tree.
iv. Each species of conifer has a uniquely textured pollen grain.
v. The pollen is dispersed by the wind.
6. Female cones grow in the upper branches of trees.
i. Some pine trees have female cones that are small and green or brown.
ii. Others have purple or reddish cones.
iii. Each cone has at least one ovule at the base of the scale.
iv. The wind blows the pollen into the slightly opened scales of the female cones.
v. After the pollen enters the scales close.
vi. The pollen grain begins to slowly grow a long tube toward the egg cell in the ovule.
vii. The sperm cell then travels down the long tube and fertilizes the egg cell, forming a zygote.
viii. After fertilization, the ovule develops into a seed.
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ix. The zygote becomes the embryo of the seed.
x. The rest of the ovule develops into the seed coat and stores food for the seed.
xi. As the seed matures the female cone grows larger.
xii. The scales of the cone open, and the fully developed seed is carried away by the wind.
xiii. Many conifer seeds have a winglike structure that causes them to spin in the air as the drop
to the ground.
xiv. This slow descend allows the breeze to spread them further away from the parent plant.
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Label the following diagram: