Alteration of Generations
Sexual Reproduction (gametophyte)
The life cycle of a liverwort begins from the haploid spore. A compact protonema with short rhizoids is formed from the haploid spore. The protonema helps develop a new thallus (vegetative tissue) through mitotic divisions. Then the thallus helps produce the reproductive system of the zygotic liverwort. In the male reproductive organ (antheridium), gametes are produced, while in the female reproductive organ (archegonium), one egg cell is produced. The sperm cells are able to reach the female gametophyte through water droplets. The water droplets can penetrate into the archegonium through capillary action. This results in the fertilization of the egg. After fertilization, a new plant develops, which remains attached to the parent plant. This is the sporophyte.
Asexual Reproduction (sporophyte)
A majority of liverworts reproduce asexually. This cycle is known as gemmae. Disks of tissue from the sexual, or gametophytic generation, are known as gemmae. The gemmae are help in organs of liverworts known as the gemma cups. These cups are dispersed by rainfall. This results in the fragmentation of the thallus (vegetative tissue). The end product is a new plant. The key that ensures the longevity of the plant is the rhizoids, which are single celled structures that anchor liverworts to their respective.
When does Asexual Reproduction occur?
A lot of water is required for asexual reproduction. In order for the gemma cups to be dispered there must be constant, heavy rainfall. The vital requirement for the asexual reproduction of liverworts is the formation of the gemmae tissue. If this tissue is formed during the gametophytic stage then the plant will be able to reproduce.
Spores reproduction
Spores are produced by small capsules within liverworts. The liverwort's leaves are lobate green structures, which are shaped similarly to the liver organ found within humans. Liverworts reproduce to form short, small sporophytes. To aid in spore dispersal, liverworts utilize the help of elaters. Elaters are tubular cells with spiral thickenings. Elater play a major role in spore release. First, each elater has two spiral bands that are filled with water. Then the water in each elater begins to evaporate, which distorts the structure's form. The thinner areas between the spiral bands begin to get sucked forward. This causes the whole elater to twist into a tight helix. The spiral bands begin to untwist. This is resisted by the cohesion of the water molecules still inside the elater and their adherence to the inner wall of the elater. The water immediately undergoes intense tension until it cannot be stretched any further. The water molecules then break, and the elater immediately returns to its original shape and volume. As the elaters return to their original state they untwist violently, which causes it to break free of the capsule wall spring into the air. Loads of spores are ejected in the process. After this whole process is complete the capsule opens and spores are produced.
Spores are produced by small capsules within liverworts. The liverwort's leaves are lobate green structures, which are shaped similarly to the liver organ found within humans. Liverworts reproduce to form short, small sporophytes. To aid in spore dispersal, liverworts utilize the help of elaters. Elaters are tubular cells with spiral thickenings. Elater play a major role in spore release. First, each elater has two spiral bands that are filled with water. Then the water in each elater begins to evaporate, which distorts the structure's form. The thinner areas between the spiral bands begin to get sucked forward. This causes the whole elater to twist into a tight helix. The spiral bands begin to untwist. This is resisted by the cohesion of the water molecules still inside the elater and their adherence to the inner wall of the elater. The water immediately undergoes intense tension until it cannot be stretched any further. The water molecules then break, and the elater immediately returns to its original shape and volume. As the elaters return to their original state they untwist violently, which causes it to break free of the capsule wall spring into the air. Loads of spores are ejected in the process. After this whole process is complete the capsule opens and spores are produced.