angiosperm
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- The University of Hawaiʻi Pressbooks - Angiosperms
- Nature - The ancestral flower of angiosperms and its early diversification
- National Center for Biotechnology Information - PubMed Central - Origin of Angiosperms: Problems, Challenges, and Solutions
- USDA Agricultural Research Service - Evolutionary Patterns and Biogeochemical Significance of Angiosperm Root Traits (PDF)
- Biology LibreTexts - Angiosperms
- University of Wisconsin - Department of Botany - The Angiosperms
- University of Nevada, Las Vegas - Angiosperms
- PNAS - Angiosperms versus gymnosperms in the Cretaceous
- Also called:
- flowering plant
What are angiosperms?
Angiosperms are plants that produceflowers and bear theirseeds infruits. They are the largest and most diverse group within the kingdomPlantae, with about 300,000 species. Angiosperms represent approximately 80 percent of all known living green plants. Examples range from the commondandelion andgrasses to the ancientmagnolias and highly evolvedorchids. Angiosperms also comprise the vast majority of all plant foods we eat, includinggrains,beans, fruits,vegetables, and mostnuts.
How are angiosperms different than gymnosperms?
The key difference between angiosperms andgymnosperms is how theirseeds are developed. The seeds of angiosperms develop in the ovaries of flowers and are surrounded by a protective fruit. Gymnosperm seeds are usually formed in unisexualcones, known as strobili, and the plants lack fruits and flowers. Additionally, all but the most ancient angiosperms contain conducting tissues known asvessels, while gymnosperms (with the exception ofGnetum) do not. Angiosperms have greater diversity in their growth habits and ecological roles than gymnosperms.
How are angiosperms and gymnosperms similar?
Asvascular plants, both groups containxylem andphloem. With the exception of a very few species of angiosperms (e.g., obligate parasites and mycoheterotrophs), both groups rely onphotosynthesis for energy. Angiosperms and gymnosperms both utilizeseeds as the primary means of reproduction, and both usepollen to facilitate fertilization. Gymnosperms and angiosperms have a life cycle that involves thealternation of generations, and both have a reducedgametophyte stage.
angiosperm, any of about 300,000species of floweringplants, the largest and mostdiverse group within the kingdomPlantae. Angiosperms represent approximately 80 percent of all the known green plants now living. The angiosperms are vascularseed plants in which theovule (egg) is fertilized and develops into a seed in an enclosed hollowovary. The ovary itself is usually enclosed in aflower, that part of the angiospermous plant that contains the male or female reproductive organs or both.Fruits are derived from the maturing floral organs of the angiospermous plant and are therefore characteristic of angiosperms. By contrast, ingymnosperms (e.g.,conifers andcycads), the other large group of vascular seed plants, the seeds do not develop enclosed within an ovary but are usually borne exposed on the surfaces of reproductive structures, such ascones.
Unlike such nonvascular plants as thebryophytes, in which all cells in the plant body participate in every function necessary to support, nourish, and extend the plant body (e.g., nutrition,photosynthesis, andcell division), angiosperms haveevolvedspecializedcells andtissues that carry out these functions and have further evolved specialized vascular tissues (xylem andphloem) that translocate thewater and nutrients to all areas of the plant body. The specialization of the plant body, which has evolved as anadaptation to a principallyterrestrial habitat, includes extensiveroot systems that anchor the plant and absorb water and minerals from thesoil; astem that supports the growing plant body; andleaves, which are the principal sites of photosynthesis for most angiospermous plants. Another significant evolutionary advancement over the nonvascular and the more primitive vascular plants is the presence of localized regions for plant growth, calledmeristems andcambia, which extend the length and width of the plant body, respectively. Except under certain conditions, these regions are the only areas in which mitotic cell division takes place in the plant body, althoughcell differentiation continues to occur over the life of the plant.
The angiosperms dominateEarth’s surface and vegetation in moreenvironments, particularly terrestrial habitats, than any other group of plants. As a result, angiosperms are the most important ultimate source of food forbirds andmammals, includinghumans. In addition, the flowering plants are the most economically important group of green plants, serving as a source of pharmaceuticals, fiber products, timber, ornamentals, and other commercial products.
Although thetaxonomy of the angiosperms is still incompletely known, the latestclassification system incorporates a large body of comparative data derived from studies ofDNA sequences. It is known as theAngiosperm Phylogeny Group IV (APG IV) botanical classification system. The angiosperms came to be considered a group at the division level (comparable to the phylum level inanimal classification systems) called Anthophyta, though the APG system recognizes only informal groups above the level of order.
Throughout this article the orders or families are given, usually parenthetically, following thevernacular or scientific name of a plant. Following taxonomic conventions, genera and species are italicized. The higher taxa are readily identified by their suffixes: families end in-aceae and orders in-ales.
For a comparison of angiosperms with the other major groups of plants,seeplant,bryophyte,fern,lower vascular plant, andgymnosperm.