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At one time, the cryptogams were formally recognised as a group within the plant kingdom. In his system for classification of all known plants and animals, Carl Linnaeus (1707–1778) divided the plant kingdom into 24 classes, [1] one of which was the "Cryptogamia". This included all plants with concealed reproductive organs.
Marchantia, an example of a liverwort (Marchantiophyta) An example of moss (Bryophyta) on the forest floor in Broken Bow, Oklahoma. Bryophytes (/ ˈ b r aɪ. ə ˌ f aɪ t s /) [1] are a group of land plants (embryophytes), sometimes treated as a taxonomic division, that contains three groups of non-vascular land plants: the liverworts, hornworts, and mosses. [2]
The plants have an underground sexual phase that produces gametes, and this alternates in the lifecycle with the spore-producing plant. The prothallium developed from the spore is a subterranean mass of tissue of considerable size, and bears both the male and female organs ( antheridia and archegonia ). [ 6 ]
Combined with the five-kingdom model, this created a six-kingdom model, where the kingdom Monera is replaced by the kingdoms Bacteria and Archaea. [16] This six-kingdom model is commonly used in recent US high school biology textbooks, but has received criticism for compromising the current scientific consensus. [ 13 ]
What characterizes an actinorhizal plant is the symbiotic relationship it forms with the bacteria Frankia, [9] in which they infect the roots of the plant. This relationship is what is responsible for the nitrogen-fixation qualities of the plants, and what makes them important to nitrogen-poor environments.
Several species of Kalanchoe are economically important for causing cardiotoxic effects in sheep and cattle, and diseases affecting the nervous system and muscles known as krimpsiekte ("shrinking disease") or as cotyledonosis. [10] Kalanchoe pinnata may have similar chemical components, bufadienolide alkaloids. [11]
A key event in the conservation of plant genetic resources was the establishment of the International Board for Plant Genetic Resources (IBPGR) (now Bioversity International) in 1974, whose mandate was to promote and assist in the worldwide effort to collect and conserve the plant germplasm needed for future research and production. IBPGR ...
A female pinecone produces the megaspores of this heterosporic plant. A male pinecone produces the microspores of this heterosporic plant. Heterospory is the production of spores of two different sizes and sexes by the sporophytes of land plants. The smaller of these, the microspore, is male and the larger megaspore is female.