23-676: Callistophytales is an extinct order of spermatophytes (seed plants) which lived from the Pennsylvanian (Late Carboniferous ) to Permian periods. They were mainly scrambling and lianescent (vine-like) plants found in the wetland "coal swamps" of Euramerica and Cathaysia . Like many other early spermatophytes, they could be described as " seed ferns ", combining ovule -based reproduction with pinnate leaves superficially similar to modern ferns. Callistophytales in particular are characterized by their reproductive anatomy. The ovules are bilaterally symmetrical and non-cupulate, attaching to
46-420: A Carboniferous plant is a stub . You can help Misplaced Pages by expanding it . This article related to a Permian plant is a stub . You can help Misplaced Pages by expanding it . Spermatophyte A seed plant or spermatophyte ( lit. ' seed plant ' ; from Ancient Greek σπέρματος ( spérmatos ) 'seed' and φυτόν (phytón) 'plant'), also known as
69-406: A clade of gymnosperms , with the gnetophytes in or near the conifers. For example, one common proposed set of relationships is known as the gne-pine hypothesis and looks like: (flowering plants) [REDACTED] Cycads [REDACTED] Ginkgo [REDACTED] Pinaceae (the pine family) [REDACTED] Gnetophytes [REDACTED] other conifers [REDACTED] However,
92-495: A phanerogam (taxon Phanerogamae ) or a phaenogam (taxon Phaenogamae ), is any plant that produces seeds . It is a category of embryophyte (i.e. land plant) that includes most of the familiar land plants, including the flowering plants and the gymnosperms , but not ferns , mosses , or algae . The term phanerogam or phanerogamae is derived from the Greek φανερός ( phanerós ), meaning "visible", in contrast to
115-496: A group of seed-producing plants that include conifers , cycads , Ginkgo , and gnetophytes , forming the clade Gymnospermae . The term gymnosperm comes from the composite word in Greek : γυμνόσπερμος ( γυμνός , gymnos , 'naked' and σπέρμα , sperma , 'seed'), and literally means 'naked seeds'. The name is based on the unenclosed condition of their seeds (called ovules in their unfertilized state). The non-encased condition of their seeds contrasts with
138-408: A now-extinct family with members which (in an example of convergent evolution ) resembled the modern butterflies that arose far later. All gymnosperms are perennial woody plants , Unlike in other extant gymnosperms the soft and highly parenchymatous wood in cycads is poorly lignified, and their main structural support comes from an armor of sclerenchymatous leaf bases covering the stem, with
161-558: A system to guide the pollen to the seed. Runcaria was followed shortly after by plants with a more condensed cupule, such as Spermasporites and Moresnetia . Seed-bearing plants had diversified substantially by the Famennian , the last stage of the Devonian. Examples include Elkinsia , Xenotheca , Archaeosperma , " Hydrasperma ", Aglosperma , and Warsteinia . Some of these Devonian seeds are now classified within
184-422: Is an integumented megasporangium surrounded by a cupule. The megasporangium bears an unopened distal extension protruding above the mutlilobed integument . It is suspected that the extension was involved in anemophilous (wind) pollination . Runcaria sheds new light on the sequence of character acquisition leading to the seed. Runcaria has all of the qualities of seed plants except for a solid seed coat and
207-435: Is dependent on the sporophytic phase. The term "gymnosperm" is often used in paleobotany to refer to (the paraphyletic group of) all non-angiosperm seed plants. In that case, to specify the modern monophyletic group of gymnosperms, the term Acrogymnospermae is sometimes used. The gymnosperms and angiosperms together constitute the spermatophytes or seed plants. The spermatophytes are subdivided into five divisions ,
230-481: Is the flowering plants , also known as angiosperms or magnoliophytes, the largest and most diverse group of spermatophytes: In addition to the five living taxa listed above, the fossil record contains evidence of many extinct taxa of seed plants, among those: By the Triassic period, seed ferns had declined in ecological importance, and representatives of modern gymnosperm groups were abundant and dominant through
253-514: The "coal swamp" vegetation during Late Pennsylvanian and Permian times. Callistophytales are occasionally classified within the class Lyginopteridopsida , alongside the order Lyginopteridales. This proposal is controversial due to the apparent sophistication of the ovules and pollen. There are nevertheless many other characters that suggest that the Callistophytales is derived from a more primitive lyginopterdalean-like ancestor, including
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#1732790643711276-535: The angiosperms and four divisions of gymnosperms: the Cycadophyta , Ginkgophyta , Gnetophyta , and Pinophyta (also known as Coniferophyta). Newer classification place the gnetophytes among the conifers. Numerous extinct seed plant groups are recognised including those considered pteridosperms/seed ferns , as well other groups like the Bennettitales. By far the largest group of living gymnosperms are
299-520: The conifers (pines, cypresses, and relatives), followed by cycads, gnetophytes ( Gnetum , Ephedra and Welwitschia ), and Ginkgo biloba (a single living species). About 65% of gymnosperms are dioecious , but conifers are almost all monoecious . Some genera have mycorrhiza , fungal associations with roots ( Pinus ), while in some others ( Cycas ) small specialised roots called coralloid roots are associated with nitrogen-fixing cyanobacteria . Over 1,000 living species of gymnosperm exist. It
322-552: The end of the Cretaceous , when the angiosperms radiated. A whole genome duplication event in the ancestor of seed plants occurred about 319 million years ago . This gave rise to a series of evolutionary changes that resulted in the origin of modern seed plants. A middle Devonian (385-million-year-old) precursor to seed plants from Belgium has been identified predating the earliest seed plants by about 20 million years. Runcaria , small and radially symmetrical,
345-914: The exception of species with underground stems. There are no herbaceous gymnosperms and compared to angiosperms they occupy fewer ecological niches , but have evolved both parasites ( Parasitaxus ), epiphytes ( Zamia pseudoparasitica ) and rheophytes ( Retrophyllum minus ). Conifers are by far the most abundant extant group of gymnosperms with six to eight families, with a total of 65–70 genera and 600–630 species (696 accepted names). Most conifers are evergreens . The leaves of many conifers are long, thin and needle-like, while other species, including most Cupressaceae and some Podocarpaceae , have flat, triangular scale-like leaves. Agathis in Araucariaceae and Nageia in Podocarpaceae have broad, flat strap-shaped leaves. Cycads are
368-550: The late Devonian period around 383 million years ago. It has been suggested that during the mid-Mesozoic era, pollination of some extinct groups of gymnosperms was by extinct species of scorpionflies that had specialized proboscis for feeding on pollination drops. The scorpionflies likely engaged in pollination mutualisms with gymnosperms, long before the similar and independent coevolution of nectar-feeding insects on angiosperms. Evidence has also been found that mid-Mesozoic gymnosperms were pollinated by Kalligrammatid lacewings ,
391-540: The order Lyginopteridales . Seed-bearing plants are a clade within the vascular plants (tracheophytes). The spermatophytes were traditionally divided into angiosperms , or flowering plants, and gymnosperms , which includes the gnetophytes, cycads, ginkgo, and conifers. Older morphological studies believed in a close relationship between the gnetophytes and the angiosperms, in particular based on vessel elements . However, molecular studies (and some more recent morphological and fossil papers) have generally shown
414-666: The presence of a lagenostome at the apex of the nucellus, the general structure of the pollen organs, and the overall morphology of the vegetative structures. Two families have been recognised: the Callistophytaceae , known mainly from the Carboniferous floras of Euramerica; and the Emplectopteridaceae , known mainly from the Permian floras of China and adjacent areas. This article related to
437-669: The relationships between these groups should not be considered settled. Other classifications group all the seed plants in a single division , with classes for the five groups: A more modern classification ranks these groups as separate divisions (sometimes under the Superdivision Spermatophyta ): Unassigned extinct spermatophyte orders, some of which qualify as "seed ferns": Gymnosperm The gymnosperms ( / ˈ dʒ ɪ m n ə ˌ s p ɜːr m z , - n oʊ -/ JIM -nə-spurmz, -noh- ; lit. ' revealed seeds ' ) are
460-433: The seeds and ovules of flowering plants ( angiosperms ), which are enclosed within an ovary . Gymnosperm seeds develop either on the surface of scales or leaves , which are often modified to form cones , or on their own as in yew , Torreya , and Ginkgo . The life cycle of a gymnosperm involves alternation of generations , with a dominant diploid sporophyte phase, and a reduced haploid gametophyte phase, which
483-484: The term "cryptogam" or " cryptogamae " (from Ancient Greek κρυπτός (kruptós) 'hidden'), together with the suffix γαμέω ( gaméō ), meaning "to marry". These terms distinguish those plants with hidden sexual organs (cryptogamae) from those with visible ones (phanerogamae). The extant spermatophytes form five divisions, the first four of which are classified as gymnosperms , plants that have unenclosed, "naked seeds": The fifth extant division
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#1732790643711506-521: The underside of pinnules that were otherwise morphologically identical to the standard non-reproductive pinnules. The pollen-bearing organs are small compound structures formed from up to eight tapering sporangia fused at their base. They are also borne on the underside of unmodified pinnules. Callistophytalean pollen was saccate (bearing buoyant sacs). Callistophytales were reproductively more sophisticated than most other Palaeozoic pteridosperms , some of which they seem to have out-competed and replaced in
529-679: Was previously widely accepted that the gymnosperms originated in the Late Carboniferous period, replacing the lycopsid rainforests of the tropical region, but more recent phylogenetic evidence indicates that they diverged from the ancestors of angiosperms during the Early Carboniferous . The radiation of gymnosperms during the late Carboniferous appears to have resulted from a whole genome duplication event around 319 million years ago . Early characteristics of seed plants are evident in fossil progymnosperms of
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