All organisms reproduce, which is the biological process where an organism produces and/or gives birth to another organism. Both plants and animals reproduce, though they have evolved the processes so that they overlap and diverge from each other in several ways.
Types of Reproduction
There are two types of reproduction: asexual reproduction and sexual reproduction. Asexual reproduction involves a single parent that produces a genetically identical offspring. Sexual reproduction involves two parents of the opposite sex. A male plant or animal contributes genetic material in the form of sperm or pollen to a female plant or animal's egg. The offspring then has genetic material from both parents. Different plants and animals can reproduce either asexually or sexually; however, asexual reproduction is more common among plants than animals.
Asexual and sexual reproduction each have benefits and drawbacks. Organisms that reproduce asexually have the advantage of producing several genetically identical offspring quickly and with little energy. On the other hand, the lack of genetic diversity among asexual offspring means they have a lower chance of adapting to an unstable environment. By contrast, organisms that reproduce sexually have the advantage of producing a genetically diverse offspring, which is able to adapt to its environment. But sexual reproduction comes at a cost, requiring more time and energy to produce an offspring than asexual reproduction.
There are a variety of ways plants can reproduce asexually, or without a partner. For example, some nonflowering plants, such as moss and algae, reproduce by spore formation. Spores grow on a plant, then break off and grow into separate organisms.
Other plants, such as strawberries, are able to reproduce asexually through vegetative propagation. This process involves using a part of a plant, such as a root or stem, to produce a new plant, and can happen either naturally or artificially. Other artificial methods, such as grafting, involve combining two plants into one by attaching the top part of a plant, called a scion, to the lower part of a plant, called a rootstock.
Sexual Reproduction and Fertilization
Many plants and most animals require partners to reproduce. Plants and animals share their genetic material in a process called fertilization. In plants, fertilization happens when the male shares pollen, which contains its genetic material, with a female plant's egg.
In flowering plants, an egg is fertilized by cross-pollination. This process often requires an insect, such as a bee, that transfers grains of pollen from the male part of a flower, which is called the anther, to the female part of a flower, which is called the stigma. Once the pollen lands on the stigma, it passes through a long, tube-like structure called a style to reach the plant's ovaries. This part of the reproductive organ is where fertilization takes place. Some plants, called hermaphrodites, have male and female parts on the same plant, and are able to self-pollinate.
Animals, by contrast, do not depend on third parties like insects for fertilization. As mobile creatures, animals can directly transfer sperm to an egg by physically interacting with each other. They often perform various mating rituals in order to attract a potential partner.
Once a plant or animal egg is fertilized, it starts developing into a multicellular organism. During this early stage, the fertilized egg is called an embryo. Despite differences in the fertilization process, the development of plant and animal embryos is similar. A plant embryo is contained within a seed, which provides the nutrients it needs to grow, while an animal embryo develops within an egg, outside the organism, or within a uterus, inside the female parent organism.
Birth and Germination
Plants and animals also differ with respect to how they give birth. Animals exit the female's uterus as a newborn or hatch from an egg that has already left the female's body. A plant, by contrast, begins its life by sprouting from a seed. The plant releases the seed, which begins to grow once it is in the soil and the conditions are right. After the seed has sprouted into a plant, it can collect additional nutrients through its roots.