Angiosperms and the animals they support have given rise to a terrestrial biota far richer than any that came before. Insect pollination, effective dispersal systems, diversity of growth forms, and many other factors have allowed flowering plants to dominate highly dynamic and species-rich vegetation.
Most users should sign in with their email address. If you originally registered with a username please use that to sign in. To purchase short term access, please sign in to your Oxford Academic account above.
Don't already have an Oxford Academic account? Oxford University Press is a department of the University of Oxford. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide.
Sign In or Create an Account. Sign In. Imperfect unisexual flowers contain a pistil or stamens, but not both. Species populations with male and female flowers borne on separate male and female individuals are termed dioecious. Species populations with separate male on female flowers borne on the same individuals are termed monoecious. Poinsettia Euphorbia pulcherrima in full bloom at Christmas time in southern California. Left: Bright red modified leaves A surround a central cluster of greenish-yellow flower clusters called cyathia.
Right: Each cup-shaped cyathium B contains a cluster of red stamens D which are the male flowers. Inside each cyathium is a hidden female flower not shown consisting of a single, minute ovary. The rim of the cyathium bears a greenish-yellow nectar gland C. Chamaesyce polycarpa , a prostrate, native spurge that grows throughout dry chaparral hillsides in southern California. Left: Overall view of plant showing numerous cup-shaped cyathia. Right: Close-up view of several cyathia showing reddish-purple, oval glands on rim of cyathia, each subtended by a greenish-white petaloid appendage.
Male flowers stamens are included in the cyathia, while a female flower ovary bearing 3 styles protrudes out of each cyathium on a long stalk. Petty spurge Euphorbia peplus , an erect garden weed in southern California with alternate leaves and milky sap.
Originally native to Europe, this prolific seeder has become naturalized throughout North America. The urn-shaped cyathium bears crescent-shaped, 2-horned glands on its rim. There are no petaloid appendages. Wolffia borealis: Dorsal view of budding flowering plant next to the tip of a sewing needle.
The floral cavity contains a single pistil with a circular, concave stigma and one stamen. A South African baobab tree Adansonia digitata , one of the most massive flowering plants. The enormous trunk may exceed feet in circumference and store 25, gallons of water weighing tons. American Journal of Botany. Heckman, D. Molecular evidence for the early colonization of land by fungi and plants. Heywood, V. Flowering plants of the world. London, UK: B.
Batsford Ltd. Hickey, L. The bases of angiosperm phylogeny: vegetative morphology. Annals of the Missouri Botanical Garden. Hillis, D. Inferring complex phylogenies. Nandi, O. A combined cladistic analysis of angiosperms using rbcL and nonmolecular data sets. Nickerson, J. The sequence of the largest subunit of RNA polymerase II is a useful marker for inferring seed plant phylogeny.
Molecular Phylogenetics and Evolution. Nickrent, D. She explained: "There are some areas where the increase in atmospheric carbon dioxide is good for some plants, so we have the greening of the Arctic, some areas of savannah are also getting shrubbier and some trees are getting bigger. And also the indirect impact of climate change - for example, changes in terms of pollinators - which could have a really serious effect on plants. Kew's global assessment will now be carried out annually, allowing scientists to monitor how plants are changing over time.
Kew announces new science plans. Further funding for Kew Gardens. Kew's green medicine. Saving coffee from extinction. State of the World's Plants. Royal Botanic Gardens, Kew. Image source, Andrew McRobb.
0コメント