- The role of reproduction in the living beings.
- Types of reproduction.
- Asexual reproduction in animals. Examples.
- Sexual reproduction in animals. Embryonic development.
- Asexual reproduction in plants. Examples.
- Sexual reproduction in plants. The flower.
Vocabulary: Flowers and Sexual Reproduction in Plants
|Perfect flowers||Or hermaphrodite flowers. They have both functional male parts (stamens capable of producing pollen) and functional female parts (pistil capable of producing seeds).|
|Staminate flowers||Staminate (or "male") flowers are ones which have functional stamens, capable of producing pollen, but either have no ovary at all, or an ovary which is not fertile.|
|Pistillate flowers||Pistillate (or "female") flowers are ones which have a functional pistil, capable of producing seeds, but either have no stamens at all, or have stamens with anthers that are incapable of producing pollen.|
|Dioecious||Said of a plant species which has some individuals which bear only staminate flowers, and some which bear only pistillate flowers, and there are no perfect flowers. These are the species that are commonly referred to as having male and female plants. Willows and poplars are dioecius.|
|Monoecious||Said of a plant species in which all individuals are hermaphrodites. This can be (a) because all the flowers in each individual are hermaphrodite (as in most cases) or (b) because all individuals bear both staminate and pistillate flowers (as in oaks, with male flowers in catkins, producing pollen, and female flowers on the stems, producing acorns).|
|Pistil||The female reproductive organ of the flower, composed of a stigma, a style, and an ovary. Pistils are made of one carpel or more than one assembled carpels.|
|Stigma||The top part of the pistil, where pollen grains are received.|
|Ovary||In angiosperms, the protective structure that holds the ovules and surrounds the seed. After fertilization, it develops into a fruit.|
|Ovule||Case-like structure that contains the female gamete in the flowering plants. After fertilization, it develops into a seed.|
|Pollen Grains||Structures that contain the male sex gametes in the flowering plants; they are meant to fertilize the ovules; they are produced in the anthers of the stamens.|
|Pollen Tube||The outgrowth of a pollen grain that creates a path through the pistil in order to penetrate to the ovules.|
|Cross-pollination||The process, occurring in most angiosperms, by which the pollen grains of one plant fertilize ovules of another.|
|Self-pollination||The process by which the pollen grains of one plant fertilize ovules of the same plant.|
Vocabulary: Asexual Reproduction in Plants
|Vegetative Propagation||A form of asexual reproduction in which plants produce clones of themselves, which then develop into independent plants. The main types are by fragmentation, by bulbs, by tubers, by runners and by grafting.|
|Fragmentation||When a severed plant part develops into a whole new plant.|
|Bulb||Roughly spherical underground bud containing additional buds that can develop asexually into new plants.|
|Tuber||Fleshy underground storage structure, composed of an enlarged portion of the stem, that has on its surface buds (called "scale leaves") capable of producing new plants.|
|Runner / Stolon||Slender horizontal stem that can give rise, via specialized nodes, to new plants.|
|Grafting||An artificial form of vegetative propagation in which parts of two young plants are joined together, first by artificial means and then by tissue regeneration.|
|Scion||Twig or bud that is grafted onto a plant with roots (called the stock) and develops into a new shoot system.|
|Stock||Plant with a root system onto which a twig or bud from another plant (called a scion) is grafted.|
Reproduction in Plants
Learn the parts of an angiosperm flower and the functions of each.
Very useful commented photo gallery to learn about the life cycle of angiosperms.
The foxglove is a marvellous example of a plant which is adapted to be pollinated by insects. Learn how certain parts of this plant have been specially modified over time so that it is able to attract insects.
Orchids are just fascinating beings. Their refined sexual behaviour involves from promising food to even tricking insects into thinking they're a sexual partner. Learn more.
Learn how orchids mimic female wasps to favour their own fertilisation.
Reproduction in Animals
Longer isn't always better, according to some men, and it seems the same is true for barnacles, too.
Females of the Komodo Dragon, the largest lizard in the world, are capable of producing offspring without male contact.
An Amazonian ant has developed into an all-female species, researchers have found.