2.22 Cross Pollination

Question 1

Insect Pollinated Flowers

Answer 1

Brightly coloured petals
May produce nectar
May produce scent
Pollen grains large and rough.sticky

Question 2

Wind Pollinated Flowers

Answer 2

Reduced (inconspicuous) petals and sepals
Anthers and stigmas which hang outside the flowers
Stigmas often feathery or sticky
No smell
No nectar
Pollen grains small, light, smooth and produced in huge numbers

Question 3

Mixed Pollination

Answer 3

Some flowers have features associated with wind pollination but are also visited by insects (best of both worlds or in intermediate stage of evolution?)

Question 4

Genetic and Evolutionary Importance of Cross Pollination

Answer 4

Genetic variation

Question 5

Cross Pollination Methods - Self Incompatibility

Answer 5

E.g. Apple
• Stigma will not accept pollen from same flower.
• Apple requires another tree of different variety but
flowering at same time.
• Types A-B-C-D
• Early-mid season-mid/late

Question 6

Cross Pollination Methods - Protogyny and Protandry

Answer 6

Protogyny - Stigma developes before the stamens.
Protandry -Stamens ripen before stigma. This is more
common as in Rosebay Willow Herb (Chamerion
augustifolium)

Question 7

Cross Pollination Methods - Heterostyly

Answer 7

Lengths of styles and stamens differ in different plants so that pollen lodged on one part of an insect is deposited on the style at the same height in another flower
The two types of pollen is different

Question 8

Cross Pollination Methods - Monoecious Plants

Answer 8

Separate male and female flowers on the same plant (Hazel)

The two sexes separated spatially and may ripen at different times

Question 9

Cross Pollination Methods - Dioeceous

Answer 9

Plants may be of different sexes (Sallow and Holly)

Mimics the situation in most animals - self pollination impossible