RHS Level 2 in the Principles of HorticultureThe Function of the Reproductive Parts of the Plant

Echinacea angustifolia Peacock Butterfly www.hdwallpapers.in

Caryopteris x clandonensis‘Arthur Simmonds’ Monarch Butterfly www.commons.wikimedia.org

Structure of a Dicotyledon FlowerCorolla (All the petals together)

Nectaries (At base of Perianth)

http://www.osovo.com/diagram/flowerpartsdiagram.htm

The Role of Each Component within the Perianth

• All the Sepals (usually green) together form the Calyx and protect the young flower bud

• All the Petals together form the Corolla and attract pollinators with colour and shape

• The Nectaries are at the base of the Perianth and produce nectar to attract pollinators

Tepals in Monocotyledon Flowers

• In most monocots the Sepals look like Petals• The Petals & the Sepals alternate around the

rim of the flower and both are called Tepals

The Role of Each Male Componentwithin the Stamen

• The Anther produces pollen which consists of grains containing the male gametes (reproductive cells).

• The Filament is the stalk of the stamen and supports the Anther.

The Role of Each Female Componentwithin the Carpel

• The Stigma is a receptive surface for pollen grains and is usually sticky.

• The Style joins the Stigma to the Ovary and the pollen tube grows through it.

• The Ovary contains the Ovule(s) and becomes the fruit.

• The Ovule carries female gametes (reproductive cells) and become a seed on fertilization.

The Sexual Variations

The sex of a flower can be described in 3 ways

1) Hermaphrodite Flowers: these are complete and bear both male and female sex parts.

2) Male Flowers: bear only male sex parts.

3) Female Flowers: bear only female sex parts.

Hermaphrodite Plants

• Most plants have bisexual flowers containing both male and female reproductive organs

• They may pollinate themselves or be pollinated by

another plant of the same species or genus

Monoecious Plants• Other plants produce unisexual flowers • On a Monoecious plant male & female flowers are borne separately on the same plant so you only need one plant for pollination

Begonia ‘Illumination Apricot’

Dioecious Plants

• These also produce unisexual flowers but on different plants so two are needed for pollination

Skimmia japonica ‘Rubella’(male) Skimmia japonica 'Bowles Dwarf Female'

Pollination & Fertilization

Different Types of Pollination

• Self pollination: the transfer of pollen from the anther to the stigma of the same flower or another flower on the same plant.

• Cross pollination: the transfer of pollen from the anther of a flower on one plant to the stigma of a flower on another plant.

Animal Pollinators - Insects• Pollination is aided by insects: butterflies,

bees, flies, beetles, moths, wasps and ants. • The insects transport the pollen as a

consequence of using the flowers for feeding, breeding or hiding.

• The pollen adheres to insect's body parts such as face, legs and mouthparts and then gets brushed off by the stigma.

• Slugs are also known to transport pollen from one plant to another.

Insect Pollinated Plants - Characteristics

• Have adapted their petal sizes, shapes and colours in different ways to attract particular pollinators.

• Produce various scents and types of nectar to attract their pollinators.

• Their reproductive structures (Stamen and Pistil) are ideally positioned to enable pollen to be easily transferred to and from visiting insects.

• Their pollen grains have a coarse surface or are covered by a sticky oily fluid so they can attach themselves to the pollinator.

Insect Pollinated Plants - Variations

• Butterflies like scent, bright colours such as red, yellow, orange and wide flowers to land on.

• Bees prefer bright blue and violet colours and are attracted by patterns called ‘nectar guides’ that are visible only in ultraviolet light.

• Flies are attracted to carrion odours. • Beetles prefer wide flowers with less nectar and

more pollen.• Moths prefer white petals and a strong scent.

Insect Pollination - ExamplesAmorphophallus titanum pollinated by flieswww.greendiary.com

Helianthus pollinated by butterfly www.landcareresearch.co.nz

Yucca pollinated by Yucca mothwww.ces.ncsu.edu

Lavatera pollinated by beewww.sciencephotolibrary

Orchid pollinated by beetlewww.education.ezinemark.com

Animal Pollinators – Birds, Reptiles & Mammals

• In the tropics birds like hummingbirds and honeyeaters feed off nectar.

• They prefer red, pink or purple flowers with long narrow tubes leading to the nectar.

• Bats are an important pollinator and are attracted by scent.

• Pollen has been found on the hairs of monkeys, lemurs, possums and rodents and on lizards and geckos.

Bird, Mammal & Reptile Pollination

Gecko www.greendiary.com

Bat www.gesneriads.ca/paliav08.htm

Numbat feeding on insect on Banksia attenuatawww.michaelmorcombe.com.au

Geckos pollinatingwww.photomazza.com

Wind Pollinated Plants & their Characteristics

Conifers, palms, grasses & many deciduous trees• Inconspicuous, colourless flowers without petals or

nectar that are clustered in large groups e.g. catkins.• Most pollen grains are small, dry and dust-like with a

smooth surface and produced in massive quantities. • Larger grains like Pinus are kept lighter with air bags.• Male flowers have long filaments exposing the anthers

and their pollen to the wind. • Female flowers have long, feather-like stigmas, which

protrude outside the flowers to capture as much of the wind-blown pollen as possible.

Wind Pollination - Examples

Cortaderia selloana 'Pumila' www.gardencrossings.comCorylus avellana

www.plantscienceimages.orgPinus www.biology.clc.uc.edu

Pinus releasing pollen www.garden.lovetoknow.comSalix caprea www.gettyimages.com

Corypha umbraculifera www.flowersofindia.in

The Fertilization Process1. Pollen grains land on the sticky stigma.

2. A pollen tube grows down the style, followed by male sperm nuclei.

3. The sperm nuclei fuse with the female ovules.

4. The ovules develop into seeds and the ovary develops into fruit.

www.buzzaboutbees.net/plant-pollination-process.html

The Fertilization Process - Terms

• Gametes are either male or female reproductive cells that unite during sexual reproduction to form a new cell called a Zygote.

• Pollen has to be Compatible with the pistil it lands on in order for fertilization to take place.

• If the pollen is Incompatible the process of pollen germination, pollen tube growth, ovule fertilization and embryo development is halted at one of its stages and no seeds are produced.

Reasons for Incompatibility

• It happens when a pollen grain produced in a plant reaches a stigma of the same plant or another plant with a similar genetic make-up.

• It prevents self-fertilization and thus encourages outcrossing.

• It prevents selfing (in-breeding) and promotes the generation of new genetic make-ups in angiosperm plants.

Today we looked at

• The structure of a dicotyledon flower• The role of each component of a flower• The meaning of the words monoecious,

dioecious and hermaphrodite• The process of pollination• The characteristics of wind and animal

pollinated plants• The process of fertilization