| Weltrichia Temporal range: | |
|---|---|
 | |
| Drawing of Weltrichia mirabilis | |
Scientific classification  | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Order: | † Bennettitales |
| Family: | † Williamsoniaceae |
| Genus: | † Weltrichia Braun |
| Type species | |
| Weltrichia mirabilis Braun | |
| Species | |
See text | |
Weltrichia is a genus belonging to the extinct seed plant group Bennettitales. It is a form genus representing flower-like male pollen-producing organs. It is associated with the female ovulate cone Williamsonia.
Although the morphology of Weltrichia is highly variable, the overall morphology consists of a central cup-like structure surrounded by a number of radially symmetrical outward projecting rays, to which are attached bivalve-shaped pollen sacs/synangia. The number of rays varies from 9/10 to 30, depending on the species, and the total diameter from 3 centimetres (1.2 in) to over 20 centimetres (7.9 in). Both the cup and rays usually (but not always) have substantial thickness, in some of the thicker species the structure is noticeably woody. The pollen is monocolpate and elliptical. In some species, additional rays project over the central cup, and attractants/resinous substances are present within the cup. The rays also sometimes have ridges, trichomes, appendages, striae and/or unipinnate (pedicellate) pollen sacs present. Species of Weltrichia appear to have primarily been wind pollinated, though some species may have been pollinated by insects, such as beetles. They were borne by the same plants that also bore female ovulate cones assigned to Williamsonia. [1] It is unclear whether the parent plants were monoecious (having both structures on one plant) or dioecious (where each plant only has one gender of reproductive organ). At least some bearers of Weltrichia, such as Kimuriella from the Late Jurassic of Japan were low growing divaricately branching shrubs with a maximum height of 2–3 metres, while others such as Williamsonia gigas may have been more cycad-like in morphology. [2]
Weltrichia is known from Asia, Europe, and North America, as well as India (which formed part of the separate landmass Gondwana at the time), spanning from the Late Triassic to the Late Jurassic/Early Cretaceous. [1]
After Popa (2019) [1] and subsequent literature.
| Species | Location | Age | Notes | Image |
|---|---|---|---|---|
| Weltrichia alfredii | Romania | Early Jurassic (Sinemurian) | About 120 mm in diameter |  |
| Weltrichia alpina | Germany | Late Triassic | About 54 mm in diameter |  |
| Weltrichia antonii | Romania | Early Jurassic (Sinemurian) | About 100 mm in diameter, with only 9/10 rays, has the lowest number of rays of any species |  |
| Weltrichia ayuquiliana | Mexico | Middle Jurassic | Around 60 mm in diameter |  |
| Weltrichia daohugouensis | China | Middle Jurassic | Around 100 mm in diameter |  |
| Weltrichia fabrei | France | Late Triassic-Early Jurassic | Only known from fragmentary remains | |
| Weltrichia givulescui | Romania | Early Jurassic (Sinemurian) | Maximum of 100 mm in diameter |  |
| Weltrichia harrisiana | India | Middle Jurassic | Approximately 120–150 mm in diameter |  |
| Weltrichia hirsuta | Iran | Early Jurassic | Approximately 130–140 mm in diameter | |
| Weltrichia huangbanjingouensis | China | Late Jurassic/Early Cretaceous | Only central cup is preserved | |
| Weltrichia johannae | Romania | Early Jurassic (Sinemurian) | 70 mm in diameter |  |
| Weltrichia maldaensis | India | Late Jurassic | 70 mm in diameter |  |
| Weltrichia microdigitata | Mexico | Middle Jurassic | Diameter of only 30 mm, making it smallest known species |  |
| Weltrichia mirabilis (type) | Germany | Early Jurassic | Approximately 100 mm in diameter | |
| Weltrichia mixtequensis | Mexico | Middle Jurassic | Diameter of 160 mm |  |
| Weltrichia oolithica | Italy | Late Jurassic | 70–80 mm in diameter, holotype specimen currently unlocated | |
| Weltrichia pecten | England | Middle Jurassic | Typically 100–120 mm in diameter. Has been suggested to be synonymous with Weltrichia spectabilis and Weltrichia whitbiensis. [3] |  |
| Weltrichia primaeva | Iran | Early Jurassic | Only known from large (over 60 mm in length) ray fragments with a complex morphology | |
| Weltrichia santalensis | India | Middle-Late Jurassic | With a diameter of 220–230 mm, it is one of the largest species in the genus | |
| Weltrichia setosa | England | Middle Jurassic | Typically 120 mm in diameter. |  |
| Weltrichia sol | England | Middle Jurassic | One of the largest species, at 170–200 mm in diameter, associated with the female cone Williamsonia gigas and the leaves Zamites gigas |  |
| Weltrichia spectabilis | England | Middle Jurassic | Central cup 40 mm in diameter and rays 30-50 mm in length, which bear apical filiform whiskers, which can reach 30-60 mm in length. [1] Has been suggested to be synonymous with Weltrichia pecten and Weltrichia whitbiensis. [3] |  |
| Weltrichia steierdorfensis | Romania | Early Jurassic (Sinemurian) | Around 105–120 mm in diameter | |
| Weltrichia whitbiensis | England | Middle Jurassic | Around 120–130 mm in diameter. [1] Has been suggested to be synonymous with Weltrichia pecten and Weltrichia spectabilis. [3] |  |
| Weltrichia magna [4] | Mexico | Middle Jurassic | Around 226 mm in diameter. |  |
| Weltrichia xochitetlii [5] | Mexico | Middle Jurassic | Approximately 30–45 mm in diameter |
Ginkgoales are a gymnosperm order containing only one extant species: Ginkgo biloba, the ginkgo tree. The order has a long fossil record extending back to the Early Permian around 300 million years ago from fossils found worldwide.
Cycads are seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male or female. Cycads vary in size from having trunks only a few centimeters to several meters tall. They typically grow very slowly and live very long. Because of their superficial resemblance, they are sometimes mistaken for palms or ferns, but they are not closely related to either group.
Gnetophyta is a division of plants, grouped within the gymnosperms, that consists of some 70 species across the three relict genera: Gnetum, Welwitschia, and Ephedra. The earliest unambiguous records of the group date to the Jurassic, and they achieved their highest diversity during the Early Cretaceous. The primary difference between gnetophytes and other gymnosperms is the presence of vessel elements, a system of small tubes (xylem) that transport water within the plant, similar to those found in flowering plants. Because of this, gnetophytes were once thought to be the closest gymnosperm relatives to flowering plants, but more recent molecular studies have brought this hypothesis into question, with many recent phylogenies finding them to be nested within the conifers.
The gymnosperms are a group of seed-producing plants that includes conifers, cycads, Ginkgo, and gnetophytes, forming the clade Gymnospermae. The term gymnosperm comes from the composite word in Greek: γυμνόσπερμος, literally meaning 'naked seeds'. The name is based on the unenclosed condition of their seeds. The non-encased condition of their seeds contrasts with 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, Ginkgo. Gymnosperm lifecycles involve alternation of generations. They have a dominant diploid sporophyte phase and a reduced haploid gametophyte phase which is dependent on the sporophytic phase. The term "gymnosperm" is often used in paleobotany to refer to all non-angiosperm seed plants. In that case, to specify the modern monophyletic group of gymnosperms, the term Acrogymnospermae is sometimes used.
Bennettitales is an extinct order of seed plants that first appeared in the Permian period and became extinct in most areas toward the end of the Cretaceous. Bennettitales were amongst the most common seed plants of the Mesozoic, and had morphologies including shrub and cycad-like forms. The foliage of bennettitaleans is superficially nearly indistinguishable from that of cycads, but they are distinguished from cycads by their more complex flower-like reproductive organs, at least some of which were likely pollinated by insects.
Williamsonia is a genus of plant belonging to Bennettitales, an extinct order of seed plants. Within the form classification system used in paleobotany, Williamsonia is used to refer to female seed cones, which are associated with plants that also bore the male flower-like reproductive structure Weltrichia.
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Zamites is a genus of sterile foliage known from the Mesozoic of North America, Europe, India and Antarctica through the Eocene of North America. It was erected as a form taxon for leaves that superficially resembled the extant cycad Zamia, however it is now believed to belong to a similar but phylogenetically different group, the cyacadeoids (Bennettitales). The fronds are linear or lanceolate in shape, and pinnately compound, with pinnae with parallel veins and smooth margins, and symmetrical and constricted at the base where they are attached obliquely to the upper surface of the rachis. It has been interpreted as a Bennettitalean plant in the family Williamsoniaceae. It is associated with the ovulate cone Williamsonia and male cone Weltrichia.
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