Question

1. Observe pictures of cycad leaves.
   1. Cycad leaves are stiff. Which compound would make them stiff? Why might they need to be stiff?
   2. How do the leaves differ among Cycas, Dioon, Encephalartos, and Zamia?

2. Look at the cones on the cycads and answer the following:
   1. How do the male and female cones differ in their persistence and size?
   2. Are any of the cones or seeds colorful? How might the colors influence their dispersal?
   3. Unlike most other groups of gymnosperms, cycad species are often pollinated by animals. What advantages would there be for cycads to be animal pollinated considering the fact that most occur in tropical forests?

Answer 1

a) cycad leaves are stiff because the presence of hard Keratinose .that helps in reduce the rate of evaporation and other forms of loss of water through it ,it also helps to protect from grazing animals.

b) Cycas leaves---there are two types of leaves are seen in cycas, they are foliage leaves and scally leaves.foliage leaves are pinnately compound, and arranged spirally.The leaflets are articulated ,have mid rib but lack secondary vein.

Dioon leaves---spines are present on juvenile leaves but are lost when plant matures. they have evergreen leaves.

Encephalartos leaves--leaves are pinnate , sunken leaf lets, no midrib,parallel veins,leaflets are hard do not bend easily , they may be deep green, bluegreen,or grey.

Zamia leaves--pinnate leaves with central rachis , some leaves are colourful when they emerge, some have sharp spines on their petiole.

Cycads cones

a) male cone is comparatively smaller than the female cones . the male reproductive part is cone shaped and female structure is leafy.when pollen matures in male cone there is adistinctive gap between scale and pollen dehiscence.

b) cones are brightly coloured that helps to attract birds and insects , they helps in pollination.

c) brightly coloured, some male cone produces special odour to attract animals, some beetles uses cycads cones as mating and laying its eggs so the adult beetle carry the male gamate to female part,