Plant Reproduction: Seed Plants

Seed Plants• Seed plants reproduce sexually – Fertilization from male and female sex cells

• Two types:– Gymnosperms• E.g. Pine trees with cones

– Angiosperms• E.g. Most have flowers

Gymnosperms• Means ‘naked seed’ = needs the cone to protect it!• Cones are the reproductive structures on

gymnosperms and each species has a different type of cone

• Male and female cones are produced on the same plant: – Female cones have ovules, which

contain the egg cells– Male cones develop pollen

grains, which contain sperm cells

Gymnosperms continued…

• Male cones release a cloud of pollen

• Wind usually carries the pollen to the female cone

• The pollen is trapped by a sticky substance and develops into a pollen tube – Grows towards the ovule

and sperm can fertilize the egg cell

– Can take 15 months!

Gymnosperms…there’s more!• After fertilization, an embryo forms and

develops into a seed• When female pine cones mature, they open

and release their seeds – These can be carried away, or are eaten or buried

by animals• Buried seeds may grow into new pine trees!

Angiosperms• All produce flowers• Can be brightly colored or have a nice

smell to attract animals– Animals like birds (hummingbirds) or

insects (bees) can help spread pollen to other flowers

• When pollen from the stamen lands on the stigma, this is called pollination– The same process occurs in

gymnosperms, where a pollen tube grows into the ovule and eventually a seed will develop)