Gymnosperms are seed plants that reproduce through cones and do not have flowers. They have woody stems and needles or scales instead of broad leaves. Their adaptations for life on land include woody growth for support, needles with less surface area for photosynthesis and water retention, and seeds that enclose embryos with stored food for greater survival. Their life cycle involves heterosporous male and female cones that produce pollen and ovules, with fertilization occurring through pollen tubes leading to the formation of seeds containing a sporophyte embryo.

1. GymnospermsGymnosperms

2. Gymnosperms
“Naked Seed Plants”
Cycads Ginkos Conifers
● Reproductive structures housed in cones
● No protective structure surrounding the seed
● Sporophyte generation dominant

3. Adaptation to Life on Land
● Woody growth – Support large plant and position
leaves (needles) optimally for photosynthesis
● Needles – Modified leaves
- Less surface area for water loss
- Covered by a waxy cuticle
● Roots – Strong woody system allows for optimal
collection of water and nutrients
● Pollen – Male gametes transported by wind or
pollinators instead of swimming in water
● Seeds – embryo enclosed with stored food allows for
greater survival & germination

4. Adaptation to Life on Land
● Woody growth – Support large plant and
position leaves (needles) optimally for
photosynthesis
● Needles – Modified leaves
- Less surface area for water loss
- Covered by a waxy cuticle
● Roots – Shallow, wide root system allows for
optimal collection of water and nutrients where
soil is poor/thin
● Seeds – embryo enclosed with stored food
allows for greater survival & germination

5. Woody Stems

6. Woody Stems
https://youtu.be/mbdur2TjTbk - Tree Rings

7. Needles

8. Gymnosperm Life Cycle

9. Gymnosperm Life Cycle
● Typical gymnosperms are monoecious and produce
heterospores from male and female cones
● Male cones give rise to microspores, which produce pollen
grains (meiosis)
● Female cones give rise to megaspores, which produce
ovules (meiosis)
● Pollen grains land on the female cone (pollination)

10. Gymnosperm Life Cycle
● Pollen tube develops from the pollen grain to initiate
fertilization; the pollen grain divides into two sperm
cells by mitosis; one of the sperm cells unites with the
egg cell during fertilization.
● Fertilized ovule develops into diploid sporophyte
embryo
● Seed that is formed is made up of three tissues: the
seed coat (parent sporophyte), food (gametophyte),
and the embryo (new sporophyte).

11. Gymnosperm Life Cycle

12. Gymnosperm Seed