An annual plant is a plant that completes its life cycle, from germination to the production of seeds, within one growing season, and then dies. Globally, 6% of all plant species and 15% of herbaceous plants are annuals. The annual life cycle has independently emerged in over 120 different plant families throughout the entire angiosperm phylogeny.
The Poales are a large order of flowering plants in the monocotyledons, and includes families of plants such as the grasses, bromeliads, rushes and sedges. Sixteen plant families are currently recognized by botanists to be part of Poales.
Panicoideae is the second-largest subfamily of the grasses with over 3,500 species, mainly distributed in warm temperate and tropical regions. It comprises some important agricultural crops, including sugarcane, maize, sorghum, and switchgrass.
Land surface models (LSMs) use quantitative methods to simulate the exchange of water and energy fluxes at the Earth surface–atmosphere interface. They are key component of climate models. Over the past two decades, they have evolved from oversimplified schemes, which described the surface boundary conditions for general circulation models (GCMs), to complex models that can be used alone or as part of GCMs to investigate the biogeochemical, hydrological, and energy cycles at the Earth's surface.
The Hartig net is the network of inward-growing hyphae, that extends into the plant host root, penetrating between plant cells in the root epidermis and cortex in ectomycorrhizal symbiosis. This network is the internal component of fungal morphology in ectomycorrhizal symbiotic structures formed with host plant roots, in addition to a hyphal mantle or sheath on the root surface, and extramatrical mycelium extending from the mantle into the surrounding soil. The Hartig net is the site of mutualistic resource exchange between the fungus and the host plant. Essential nutrients for plant growth are acquired from the soil by exploration and foraging of the extramatrical mycelium, then transported through the hyphal network across the mantle and into the Hartig net, where they are released by the fungi into the root apoplastic space for uptake by the plant. The hyphae in the Hartig net acquire sugars from the plant root, which are transported to the external mycelium to provide a carbon source to sustain fungal growth.
Hubbardia is a genus in the grass family that is endemic to India. It is the only genus in the tribe Hubbardieae of the subfamily Micrairoideae.
The BOP clade (sometimes BEP clade) is one of two major lineages (or clades) of undefined taxonomic rank in the grasses (Poaceae), containing more than 5,400 species, about half of all grasses. Its sister group is the PACMAD clade; in contrast with many species of that group who have evolved C4 photosynthesis, the BOP grasses all use the C3 photosynthetic pathway.
Oryzoideae (syn. Ehrhartoideae) is a subfamily of the true grass family Poaceae. It has around 120 species in 19 genera, notably including the major cereal crop rice. Within the grasses, this subfamily is one of three belonging to the species-rich BOP clade, which all use C3 photosynthesis; it is the basal lineage of the clade.
Danthonioideae is a mainly southern hemisphere subfamily of grasses, containing the single tribe Danthonieae and one unplaced genus, with altogether roughly 300 species. It includes herbaceous to partially woody perennial or annual (less common) grasses that grow in open grasslands, shrublands, and woodlands. It belongs to the PACMAD clade of grasses, but unlike some other lineages in that clade, grasses in the Danthonioideae exclusively use the C3 photosynthetic pathway. Its sister group is the subfamily Chloridoideae.
The PACMAD clade (previously PACCMAD, PACCAD, or PACC) is one of two major lineages (or clades) of the true grasses (Poaceae), regrouping six subfamilies and about 5700 species, more than half of all true grasses. Its sister group is the BOP clade. The PACMAD lineage is the only group within the grasses in which the C4 photosynthesis pathway has evolved; studies have shown that this happened independently multiple times.
Micrairoideae is a subfamily of the grass family Poaceae, distributed in tropical and subtropical regions. Within the PACMAD clade, it is sister to subfamily Arundinoideae.
Paspaleae is a tribe of the Panicoideae subfamily in the grasses (Poaceae), native mainly to the tropical and subtropical Americas but with a number of species introduced to other regions. It includes roughly 680 species in 39 genera. Species in this tribe use either of the C3 or C4 photosynthetic pathways.
Steyermarkochloeae is a tribe of the Panicoideae subfamily in the grasses (Poaceae), native to tropical South America. There are only two species in two genera, Arundoclaytonia and Steyermarkochloa. The tribe probably belongs to a basal lineage within the subfamily. Species in this tribe use the C3 photosynthetic pathway.
Tristachyideae is a tribe of the Panicoideae subfamily in the grasses (Poaceae), native to tropical and subtropical regions of Africa, Asia, and South America. There are around 70 species in eight genera. The tribe belongs to a basal lineage within the subfamily, and its genera were previously placed in tribes Arundinelleae or Paniceae, subfamily Arundinoideae, or the now-obsolete subfamily Centothecoideae. Species in this tribe use the C4 photosynthetic pathway.
Zeugiteae is a tribe of the subfamily Panicoideae in the grasses (Poaceae), native to Africa, Asia, Australasia, South and Central America. There are 18 species in four genera. The tribe belongs to a basal lineage within the subfamily. Species in this tribe use the C3 photosynthetic pathway.
Chasmanthieae is a small tribe of grasses in the subfamily Panicoideae. It belongs to a basal lineage within the subfamily and has only seven species in two genera, Bromuniola with one species in Africa and Chasmanthium from North America. They all use the C3 photosynthetic pathway.
Cyperochloeae is a small tribe of grasses in the Panicoideae subfamily, found in Australia. It belongs to a basal lineage within the subfamily and has only two species in two monotypic genera, Cyperochloa and Spartochloa. They use the C3 photosynthetic pathway.
Corystosperms are a group of extinct seed plants belonging to the family Corystospermaceae assigned to the order Corystospermales or Umkomasiales. They were first described based on fossils collected by Hamshaw Thomas from the Burnera Waterfall locality near the Umkomaas River of South Africa. Corystosperms are typified by a group of plants that bore forked Dicroidium leaves, Umkomasia cupulate ovulate structures and Pteruchus pollen organs, which grew as trees that were widespread over Gondwana during the Middle and Late Triassic. Other fossil Mesozoic seed plants with similar leaf and/or reproductive structures have also sometimes been included within the "corystosperm" concept sensu lato, such as the "doyleoids" from the Early Cretaceous of North America and Asia. A potential corystosperm sensu lato, the leaf genus Komlopteris, is known from the Eocene of Tasmania, around 53-50 million years old, over 10 million years after the Cretaceous–Paleogene extinction event.
Erika Jeannine Edwards is a professor at Yale University known for her work on evolution of plants. She is also the director of the Marsh Botanical Garden.
