Chlorophyta Is a Division of Green Algae, Informally Called

Chlorophyta is a division of green algae, informally waters of the Sargasso Sea. Many brown algae, such as called chlorophytes. The name is used in two very members of the order Fucales, commonly grow along different senses so that care is needed to determine the rocky seashores. Some members of the class are used as use by a particular author. In older classification food for humans. systems, it refers to a highly paraphyletic group of all Worldwide there are about 1500–2000 species of brown the green algae within the green plants (Viridiplantae), algae.[4] Some species are of sufficient commercial and thus includes about 7,000 species [4] [5] of mostly importance, such as Ascophyllum nodosum , that they aquatic photosynthetic eukaryotic organisms. Like the have become subjects of extensive research in their own land plants (bryophytes and tracheophytes), green algae right.[5] [4] contain chlorophylls a and b, and store food as starch Brown algae belong to a very large group, the in their plastids. Heterokontophyta, a eukaryotic group of organisms In newer classifications, it refers to one of the two distinguished most prominently by having chloroplasts clades making up the Viridiplantae, which are the surrounded by four membranes, suggesting an origin chlorophytes and the streptophytes or charophytes.[6][7] from a symbiotic relationship between a basal In this sense it includes only about 4,300 species.[3] eukaryote and another eukaryotic organism. Most brown algae contain the pigment fucoxanthin, which is responsible for the distinctive greenish-brown color that The red algae, or Rhodophyta ( / r o ʊ ˈ d ɒ f ɨ t ə / or / gives them their name. Brown algae are unique among ˌ r o ʊ d ə ˈ f a ɪ t ə /; from Greek: ῥόδον (rhodon) = rose + heterokonts in developing into multicellular forms with φυτόν (phyton) = plant, thus red plant), are one of the differentiated tissues, but they reproduce by means of oldest groups of eukaryotic algae,[2] and also one of the flagellated spores and gametes that closely resemble largest, with about 5,000–6,000 species [3] of mostly cells of other heterokonts. Genetic studies show their multicellular, marine algae, including many notable closest relatives to be the yellow-green algae. seaweeds. Other references indicate as many as 10,000 [4] species; more detailed counts indicate ~4,000 in ~600 Bryophyte is a traditional name used to refer to all genera (3,738 marine spp in 546 genera and 10 orders embryophytes (land plants) that do not have true (plus the unclassifiable); 164 freshwater spp in 30 [5] vascular tissue and are therefore called 'non-vascular genera in 8 orders). plants'.[1] Some bryophytes do have specialized tissues The red algae form a distinct group characterized by the for the transport of water; however since these do not following attributes: eukaryotic cells without flagella contain lignin, they are not considered to be true and centrioles, using floridean starch as food reserve, vascular tissue.[2] Currently bryophytes are thought not with phycobiliproteins as accessory pigments (giving to be a natural or monophyletic group; however the them their red color), and with chloroplasts lacking name is convenient and remains in use as a collective external endoplasmic reticulum and containing term for mosses, hornworts, and liverworts. Bryophytes unstacked thylakoids. [4] Most red algae are also produce enclosed reproductive structures (gametangia multicellular, macroscopic, marine, and have sexual and sporangia), but they produce neither flowers nor reproduction. seeds, reproducing via spores. The term bryophyte Many of the coralline algae, which secrete calcium comes from Greek βρύον - bryon, "tree-moss, oyster- carbonate and play a major role in building coral reefs, green" + φυτόν - fyton "plant". belong here. Red algae such as dulse (Palmaria palmata) and laver (nori/gim) are a traditional part of Vascular plants (also known as tracheophytes or European and Asian cuisine and are used to make other higher plants) are those plants that have lignified products like agar, carrageenans and other food [6] tissues for conducting water, minerals, and additives. photosynthetic products through the plant. Vascular plants include the clubmosses, Equisetum, ferns, The Phaeophyceae or brown algae (singular: alga), is gymnosperms (including conifers) and angiosperms (flowering plants). Scientific names for the group a large group of mostly marine multicellular algae, [2] [3] including many seaweeds of colder Northern include Tracheophyta and Tracheobionta. Hemisphere waters. They play an important role in Vascular plants are distinguished by two primary marine environments, both as food and for the habitats characteristics: they form. For instance Macrocystis, a kelp of the order 1. Vascular plants have vascular tissues which Laminariales, may reach 60 m in length, and forms circulate resources through the plant. This prominent underwater forests. Another example is feature allows vascular plants to evolve to a Sargassum, which creates unique habitats in the tropical larger size than non-vascular plants, which lack marattioid ferns , and ophioglossoid ferns . The term these specialized conducting tissues and are pteridophyte also refers to ferns and a few other therefore restricted to relatively small sizes. seedless vascular plants (see classification section 2. In vascular plants, the principal generation below). A pteridologist is a specialist in the study of phase is the sporophyte, which is usually diploid pteridophytes in a broader sense that includes the more with two sets of chromosomes per cell. Only the distantly related lycophytes. germ cells and gametophytes are haploid. By Ferns first appear in the fossil record 360 million years contrast, the principal generation phase in non- ago in the Carboniferous but many of the current vascular plants is usually the gametophyte, families and species did not appear until roughly 145 which is haploid with one set of chromosomes million years ago in the early Cretaceous (after per cell. In these plants, generally only the spore flowering plants came to dominate many stalk and capsule are diploid. environments). One possible mechanism for the presumed switch from Ferns are not of major economic importance, but some emphasis on the haploid generation to emphasis on the are grown or gathered for food, as ornamental plants, diploid generation is the greater efficiency in spore for remediating contaminated soils, and have been the dispersal with more complex diploid structures. In other subject of research for their ability to remove some words, elaboration of the spore stalk enabled the chemical pollutants from the air. Some are significant production of more spore and the ability to release it weeds. They also play a role in mythology, medicine, higher and to broadcast it farther. Such developments and art. may include more photosynthetic area for the spore- bearing structure, the ability to grow independent roots, woody structure for support, and more branching. The spermatophytes (from the Greek word "Σπερματόφυτα") (also known as phanerogams) Water transport happens in either xylem or phloem: comprise those plants that produce seeds. They are a xylem carries water and inorganic solutes upward subset of the embryophytes or land plants. The living toward the leaves from the roots, while phloem carries spermatophytes form five groups: organic solutes throughout the plant. • cycads , a subtropical and tropical group of plants with a large crown of compound leaves Lycopodiopsida is a class of plants often loosely and a stout trunk, grouped as the fern allies. Traditionally the group • Ginkgo , a single living species of tree, included not only the clubmosses and firmosses, but also the spikemosses (Selaginella and relatives) and the • conifers , cone-bearing trees and shrubs, quillworts (Isoetes and relatives). However, the latter • gnetophytes , woody plants in the genera are now usually separated off into a separate class, Gnetum, Welwitschia, and Ephedra, and Isoetopsida. • angiosperms , the flowering plants, a large group Clubmosses are thought to be structurally similar to the including many familiar plants in a wide variety earliest vascular plants, with small, scale-like leaves, of habitats. homosporous spores borne in sporangia at the bases of In addition to the taxa listed above, the fossil record the leaves, branching stems (usually dichotomous), and contains evidence of many extinct taxa of seed plants. generally simple form. The so-called "seed ferns" (Pteridospermae) were one The Class Lycopodiopsida as interpreted here contains of the earliest successful groups of land plants, and a single living order, the Lycopodiales, and a single forests dominated by seed ferns were prevalent in the extinct order, the Drepanophycales. late Paleozoic. Glossopteris was the most prominent tree genus in the ancient southern supercontinent of Gondwana during the Permian period. By the Triassic A fern is any one of a group of about 12,000 species of period, seed ferns had declined in ecological plants belonging to the botanical group known as [3] importance, and representatives of modern Pteridophyta. Unlike mosses, they have xylem and gymnosperm groups were abundant and dominant phloem (making them vascular plants). They have through the end of the Cretaceous, when angiosperms stems, leaves, and roots like other vascular plants. Ferns radiated. Another Late Paleozoic group of probable reproduce via spores and have neither seeds nor spermatophytes

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