General characters
- Gymnosperms are mostly tall trees, the tallest being Sequoia, which reaches up to 120 m in height.
- Gymnosperms are the first seed-forming plant group, i.e. the first spermatophytes.
Habit
- Gymnosperms are mostly tall or medium-sized trees, while a few species are found as woody shrubs.
Habitat
- Mostly found in temperate areas at high altitudes; some are found in tropical or subtropical regions.
Life cycle
- Gymnosperms show a diplontic life cycle.
Body structure
- The main plant body is the diploid sporophyte, which is well differentiated into roots, stem and leaves.
STEM
- Woody, i.e. secondary growth is present
- Branched – Pinus, Cedrus
- Unbranched – Cycas
ROOTS
- Tap roots
- Pinus – symbiotic (mycorrhizal) association with fungi
- Cycas – coralloid roots, in symbiotic association with BGA (Anabaena cycadae)
LEAVES
- Either simple (Pinus) or pinnately compound (Cycas)
- Leaves are modified to withstand extreme conditions: they are thin and needle-like to reduce surface area, with a thick cuticle and sunken stomata to reduce water loss
Reproduction
- Asexual reproduction and vegetative propagation are generally absent in gymnosperms (exception: bulbils in Cycas).
- Gymnosperms are heterosporous; sexual reproduction involves the formation of gametes.