Gymnosperms vs. Angiosperms

Growth HabitWoody trees & shrubsWoody or herbaceous
XylemTracheidsVessels and Tracheids
Reproductive structuresCones (usually)Flowers & fruits
PollinationWindAnimals, wind, water
FertilizationEgg + Sperm = zygoteEgg + Sperm = zygote
Polar nuclei + sperm = endosperm
SeedsExposedEnclosed within fruit

Why are Angiosperms so successful?

1. Seed production in closed carpels with nutrient reserve.

2. Efficient water-conducting cells (vessel elements + tracheids).

3. Efficient carbohydrate-conducting cells (sieve tube elements + sieve cells).

4. Leaves -- broad, expanded blades for maximum photosynthesis; many are deciduous and can be shed during times of stress.

5. Modified stem and root storage organs.

6. Adaptation to animal pollination and seed dispersal mechanisms.

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Last updated April 11, 1997.