Faculty of Science, School of Sciences, Natabua Campus Lautoka BIO706 Embryology Lectures: 13 Evolution of seed plants - II

Kingdom Plantae

Angiosperms are flowering plants that form seeds inside a protective chamber called an ovary. Examples:  Monocots: Orchids, lilies, grasses, palms, bamboo (Eu)dicots: Daisies, maples, snapdragon, pea, oaks

Angiosperms (Flowering Plants) Systematists are identifying angiosperm clades. Originally, only:                         Monocots are angiosperms that possess one embryonic seed leaf (cotyledon).  

Dicots are angiosperms that possess two embryonic seed leaves (cotyledons).   However, angiosperms have recently been divided into new taxonomic groups.

A comparison of monocots and dicots

The flower is the defining reproductive adaptation of angiosperms                         Flowers are made up of four types of modified leaves à sepals, petals, stamens, and carpels.                                     a.  Stamens are the male reproductive organs that produce microspores.   b.  Carpels are female reproductive organs that produce megaspores.

The structure of a flower.

Pollen-grains of Angiosperms

A fruit is a mature ovary                                     Protect dormant seeds.   Fruit aids in seed dispersal.                      - Wind dispersal                      - Attachment and transportation                      - Consumption – berries contain seeds to be passed in feces

Fruit adaptations that enhance seed dispersal

Life cycle of an angiosperm                         Mature plant is the sporophyte   Some plants easily self-pollinate, but most have mechanisms to ensure cross-pollination.  Male gametophytes reach female gametophytes by producing a pollen tube. Next slide: The life cycle of an angiosperm.

Angiosperms dominated the earth at the end of the Mesozoic era                         Radiation of angiosperms represents the transition from Mesozoic to Cenozoic   Angiosperms and animals have affected one another’s evolution

Coevolution is the mutual influence on the evolution of two different species interacting with each other and reciprocally influencing each other’s adaptations.                                     e.g., Pollinator-plant relationships

Plants and Human Welfare Agriculture is almost totally dependent on angiosperms.   Plant diversity is a non-renewable resource.                         Many medicines are obtained from plant materials.

Deforestation is an international practice

Deforestation in the United States

Fragmentation of a forest ecosystem

A sampling of medicines derived from plants

Questions are welcome