How do plants reproduce?
Plants reproduce in a variety of ways. Many species build side shoots, from which new plants grow. Plants like mosses and ferns reproduce with the help of spores, which are distributed by the wind and grow to become new plants. ‘Higher plants’ or the seed plants with male and female sexual organs have stamens with pollen and the stigma. The male pollen sticks to the stigma and is passed on to the egg cell in the ovary. A fertilized egg ripens to become a fruit, which contains the seeds. The seeds can be dispersed widely through wind or through animals who eat the fruits and discard the seeds.
Why do deciduous trees shed their leaves in autumn, but conifers do not shed their needles?
Deciduous trees lose a lot of water through evaporation from their large and thin leaves. In summer, this does not pose a problem, since the roots soak in enough water from the soil, but in winter this is not possible because the soil is frozen. If the leaves are not shed before winter, the water will continue to evaporate and the plant will dry up. Moreover, the leaves can become brittle with frost and crack. Therefore, the deciduous trees shed their leaves as a precautionary measure. In contrast, the needles of the conifers are leathery and small, and there is very little evaporation through them. The needles are also frost-proof and stop their growth in winter.
What is symbiosis?
Symbiosis is a phenomenon in which two living organisms live together in such a way that they are mutually beneficial to each other. For example, the colourful clownfish live in a symbiotic relationship with the sea anemones. The clownfish enjoy the protection of the poisonous nettle fibres of the sea anemone and the sea anemone survives on the left-over food of the fish. The lichens that live in association with a fungus and an algae are also good examples of symbiotic relationships. Through the close interaction along between its symbiotic partners, the lichens are able to grow in places, where they could never have existed alone.