An achene ( / ə ˈ k iː n / ; from Ancient Greek ἀ ( a ) ' privative ' and χαίνειν ( khaínein ) 'to gape'), also sometimes called akene and occasionally achenium or achenocarp , is a type of simple dry fruit produced by many species of flowering plants . Achenes are monocarpellate (formed from one carpel ) and indehiscent (they do not open at maturity). Achenes contain a single seed that nearly fills the pericarp , but does not adhere to it. In many species, what is called the "seed" is an achene, a fruit containing the seed. The seed-like appearance is owed to the hardening of the fruit wall (pericarp), which encloses the solitary seed so closely as to seem like a seed coat.
14-527: Pteroceltis is a genus of small trees in the family Cannabaceae and containing the living species Pteroceltis tatarinowii . The genus is now restricted to an endemic range in China and Mongolia. The genus has a fossil record which includes species described from Korea, Japan, Germany, and the United States. The fossil record includes one described species from North America, † Pteroceltis knowltoni from
28-541: Is a compound ovary . The fruit of the family Asteraceae is also so similar to an achene that it is often considered to be one, although it derives from a compound inferior ovary (with one locule ). A special term for the Asteraceae fruit is cypsela (plural cypselae or cypselas). For example, the white-gray husks of a sunflower "seed" are the walls of the cypsela fruit. Many cypselas (e.g. dandelion ) have calyx tissue attached that functions in biological dispersal of
42-932: Is a member of the Rosales . Members of the family are erect or climbing plants with petalless flowers and dry, one-seeded fruits. Hemp ( Cannabis ) and hop ( Humulus ) are the most economically important species. Other than a shared evolutionary origin, members of the family have few common characteristics; some are trees (e.g. Celtis ), others are herbaceous plants (e.g. Cannabis ). Members of this family can be trees (e.g. Celtis ), erect herbs (e.g. Cannabis ), or twining herbs (e.g. Humulus ). Leaves are often more or less palmately lobed or palmately compound and always bear stipules . Cystoliths are always present and some members of this family possess laticifers . Cannabaceae are often dioecious (distinct male and female plants). The flowers are actinomorphic (radially symmetrical) and not showy, as these plants are pollinated by
56-427: Is eaten is accessory tissue. A rose produces an aggregate of achene fruits that are encompassed within an expanded hypanthium (aka floral tube), which is a structure where basal portions of the calyx, the corolla, and the stamens unite with the receptacle to form a cup-shaped tube. A winged achene, as in maple , is called a samara . Some achenes have accessory hair-like structures that cause them to tumble in
70-844: The Middle Eocene Cockfield Formation in Tennessee, while an undescribed species is known from the Klondike Mountain Formation of Washington. One late Oligocene species † Pteroceltis tertiaria has been described from strata near Rott, Germany. The largest diversity of fossils are from Asia, with † Pteroceltis shanwangensis from the Miocene Shanwang flora in China, the Abura flora of Japan preserved † Pterocarya ezoana , and both † Pteroceltis taoae plus † Pteroceltis kungshimensis known from
84-555: The Miocene Hoengyeong Formation in North Korea. Cannabaceae See text Cannabaceae is a small family of flowering plants , known as the hemp family . As now circumscribed , the family includes about 170 species grouped in about 11 genera, including Cannabis (hemp), Humulus ( hops ) and Celtis (hackberries). Celtis is by far the largest genus, containing about 100 species. Cannabaceae
98-852: The common hop, has been the predominant bittering agent of beer for hundreds of years. The flowers' resins are responsible for beer's bitterness and their ability to extend shelf life due to some antimicrobial qualities. The young shoots can be used as a vegetable. Some plants in the genus Cannabis are cultivated as hemp for the production of fiber, as a source of cheap oil , for their nutritious seeds, or their edible leaves. Others are cultivated for medical or recreational use as dried flowers , extracts , or infused food products . Induced parthenocarpy in pistilate flowers, and selective breeding are used to produce either higher or lower yields of tetrahydrocannabinol (THC), other cannabinoids , as well as terpenes with desired flavors or aromas, such as blueberry, strawberry, or even citrus. Many trees in
112-640: The following genera: Cannabaceae likely originated in East Asia during the Late Cretaceous . The oldest known pollen typical of members of Cannabaceae is from the Late Cretaceous ( Turonian ~94–90 million years ago) of Sarawak , Borneo. Fossils show Cannabaceae were widely distributed in the Northern Hemisphere during the early Cenozoic, though their distribution shifted towards tropical regions in
126-441: The genus Celtis are grown for landscaping and ornamental purposes, and the bark of Pteroceltis is used to produce high-end Chinese rice paper. Achene The fruits of buttercup , buckwheat , caraway , quinoa , amaranth , and cannabis are typical achenes. The achenes of the strawberry are sometimes mistaken for seeds. The strawberry is an accessory fruit with an aggregate of achenes on its outer surface, and what
140-651: The later Cenozoic due to changing climates. Modern molecular phylogenetics suggest the following relationships: Moraceae ( outgroup ) Aphananthe Gironniera Lozanella Cannabis Humulus Celtis Pteroceltis Chaetachme Trema (including Parasponia ) Carbon dating has revealed that these plants may have been used for ritual/medicinal purposes in Xinjiang, China as early as 494 B.C. Humulus lupulus ,
154-424: The male inflorescences are long and look like panicles , while the female ones are shorter and bear fewer flowers. The pistil is made of two connate carpels , the usually superior ovary is unilocular; there is no fixed number of stamens . The fruit can be an achene or a drupe . Classification systems developed prior to the 1990s, such as those of Cronquist (1981) and Dahlgren (1989), typically recognized
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#1732869818728168-533: The order Urticales , which included the families Cannabaceae, Cecropiaceae, Celtidaceae, Moraceae, Ulmaceae and Urticaceae, as then circumscribed. Molecular data from 1990s onwards showed that these families were actually embedded within the order Rosales, so that from the first classification by the Angiosperm Phylogeny Group in 1998, they were placed in an expanded Rosales, forming a group which has been called 'urticalean rosids'. Cannabaceae comprises
182-405: The wind . As an adaptation to this kind of pollination, the calyx and corolla are radically reduced to only vestigial remnants found as an adherent perianth coating the seed. A reduced and monophyllous cuplike perigonal bract, properly known as the bracteole, immediately surrounds and protects the seed and is often misnamed as a "calyx". Flowers are grouped to form cymes . In the dioecious plants
196-468: The wind in a manner similar to a tumbleweed . This type sometimes is called a tumble fruit or diaspore . An example is Anemone virginiana . A caryopsis or grain is a type of fruit that closely resembles an achene, but differs in that the pericarp is fused to the thin seed coat in the grain. An utricle is like an achene, but the fruit is bladder-like or inflated. Fruits of sedges are sometimes considered achenes although their one-locule ovary
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