Sexual reproduction in plants Biology 2B Sexual reproduction in plants

Characteristics of flowering plants Flowers with pollen and nectar Vascular systems in leaves, stems and roots Seeds grow in fruits, nuts or pods Sexual reproduction Double fertilisation

Flowering plant lifecycle

Characteristics of monocots and dicots

Flower structures Female structures – stigma, style and ovary = pistil or carpel Male structures – anther and filament = stamen Petals, nectar and extra pollen attract pollinators

Types of flowering plants Hermaphrodite or monoclinous plants have male and female structures in the same flower (complete flowers) Monoecious plants – have separate male and female flowers on the same plant Individuals can have separate flowers of both sexes at the same time (simultaneously or synchronously monoecious), or have one sex and then the other (consecutively monoecious). Protoandrous function first as males and then change to females. Protogynous function first as females and then change to males. Dioecious plants - have separate male and female plants. Gynoecious (female) plants produce seeds but no pollen Androecious (male) plants produce pollen but no seeds

Variations in flower structure Inflorescence – or way the flowers develop on the same stem Number of florets – single or composite Number and arrangement of sepals and petals Number and arrangement of male parts Number and arrangement of female parts

Pollination Pollination is the process where the male gamete (pollen) is transferred to the stigma so it can fertilise the female gamete (ovule) In cross-pollination, the pollen comes from another flower or plant than the ovule In self – pollination, the pollen comes from the same flower or plant as the ovule In artificial pollination, humans transfer the pollen

Strategies to prevent self pollination Cross pollination is more desirable as it leads to greater variation Having separate male and female flowers (or plants) Male and female structures become functional at different times (eg first the stamen, then the pistil) Male and female structures different heights or positions so self pollination is not possible Stigma contains chemicals which prevent pollen from the same plant from growing pollen tube

Methods of pollination

Seed dispersal