![]() ![]() In contrast, the other algaeâred, brown, golden, stramenopiles, and so onâall became photosynthetic by secondary, or even tertiary, endosymbiotic events that is, they endosymbiosed cells that had already endosymbiosed a cyanobacterium. Their evolutionary trajectory was relatively straight and monophyletic. That algal line evolved into the Charophytes, and eventually into the modern mosses, ferns, gymnosperms, and angiosperms. The ancestors to the green algae became photosynthetic by endosymbiosing a green, photosynthetic bacterium about 1.65 billion years ago. While all algae are photosyntheticâthat is, they contain some form of a chloroplastâthey didnât all become photosynthetic via the same path. These divergent opinions are related to the different evolutionary paths to photosynthesis selected for in different types of algae. Evolution ConnectionĪlgae and Evolutionary Paths to PhotosynthesisSome scientists consider all algae to be plants, while others assert that only the Charophytes belong in the kingdom Plantae. These characteristics are absent in other types of algae. The reason for this disagreement stems from the fact that only green algae, the Charophytes, share common characteristics with land plants (such as using chlorophyll a and b plus carotene in the same proportion as plants). Most biologists also consider green algae to be plants, although others exclude all algae from the plant kingdom. Mosses, ferns, conifers, and flowering plants are all members of the plant kingdom. Of these, more than 260,000 are seed plants. There are more than 300,000 species of catalogued plants. They display many different life cycle types, usually involving spores at some stage.The kingdom Plantae constitutes large and varied groups of organisms. Growth forms can be single cells, filaments, branched networks, or small leafy patches. The green algae are the simplest of green, photosynthetic plants. Bryophytes also often reproduce asexually. The haploid spores are then released, and grow into a new gametophyte plant. This phase produces male and female gametes, which unite, and consequently develop into a very small structure pertaining to the spore-producing sporophyte phase. Their green, visible, free-living phase of the life cycle is actually the haploid generation, called the gametophyte. These are smaller, green plants, which reproduce by spores. In most cases they require wet habitats or rainwater to allow the sperm to swim between individuals in order to fertilize the eggs.īryophytes include mosses, liverworts, and hornworts. Many have a life cycle that has two separate stages. These plants lack a true vascular system. Groups not included in vPlants Non-vascular Plants It is the most diverse plant group and includes organisms from lawn grasses to oak trees. Angiosperms are by far more dominant on Earth today than are the gymnosperms and pteridophytes. Flowers produce fruits that contain seeds. All angiosperms produce flowers as their reproductive structures, though not all flowers are showy or even conspicuous. The angiosperms include all flowering plants. They reproduce by seeds, sometimes in cones, but do not have flowers or fruits. The most familiar examples of gymnosperms include conifer trees like pines, spruce, fir, and other plants commonly thought of as "evergreen" (though some lose their leaves in winter or in dry seasons, such as larch and ginkgo). The male and female gametes unite to form embryos, which grow into adult, sporophyte (spore-producing) plants. The spores grow into a short-lived, haploid, gametophyte stage, which produces gametes. They reproduce by spores formed on the surface of leaves, or in cone-like structures. The pteridophyte group includes ferns, horsetails, club mosses, and other vascular plants without seeds. Pteridophytes (non-flowering spore plants) Within these categories there are three main groups: There are two categories of vascular plants: non-flowering and flowering. The vascular plants make up the great majority of the land plants living today. The vPlants site currently provides information on vascular plants, a group named for the special transport tissues (circulatory system of xylem and phloem) they possess. Groups included in vPlants Vascular Plants For a complete list of the plant species, subspecies, and varieties represented in the Chicago Region, see the Scientific Name Checklist. At the top of the page you can Search for plants by name. Use the Species Index to see an alphabetical lists of included plants. This guide applies to the Chicago Region and is not complete for other regions.
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