Glossary of plant morphology
This page provides a glossary of plant morphology. Botanists and other biologists who study plant morphology use a number of different terms to classify and identify plant organs and parts that can be observed using no more than a handheld magnifying lens; this page provides help in understanding the numerous other pages describing plants by their various taxa. The accompanying page—Plant morphology—provides an overview of the science of the external form of plants. There is an alphabetical list: Glossary of botanical terms. In contrast, this page deals with botanical terms in a systematic manner, with some illustrations, organized by plant anatomy and function in plant physiology; this glossary includes terms that deal with vascular plants flowering plants. Non-vascular plants, with their different evolutionary background, tend to have separate terminology. Although plant morphology is integrated with plant anatomy, the former became the basis of the taxonomic description of plants that exists today, due to the few tools required to observe.
Many of these terms date back including Theophrastus. Thus, they have Greek or Latin roots; these terms have been modified and added to over the years, different authorities may not always use them the same way. This page has two parts: The first deals with general plant terms, the second with specific plant structures or parts. Abaxial – located on the side facing away from the axis. Adaxial – located on the side facing towards the axis. Dehiscent – opening at maturity Gall – outgrowth on the surface caused by invasion by other lifeforms, such as parasites Indehiscent – not opening at maturity Reticulate – web-like or network-like Striated – marked by a series of lines, grooves, or ridges Tesselate – marked by a pattern of polygons rectangles Wing – any flat surfaced structure emerging from the side or summit of an organ. Plant habit refers to the overall shape of a plant, it describes a number of components such as stem length and development, branching pattern, texture. While many plants fit neatly into some main categories, such as grasses, shrubs, or trees, others can be more difficult to categorise.
The habit of a plant provides important information about its ecology: that is, how it has adapted to its environment. Each habit indicates a different adaptive strategy. Habit is associated with the development of the plant; as such, it may change as the plant is more properly called its growth habit. In addition to shape, habit indicates plant structure; each plant commences its growth as a herbaceous plant. Plants that remain herbaceous are shorter and seasonal, dying back at the end of their growth season. Woody plants (such as trees and woody vines will acquire woody tissues, which provide strength and protection for the vascular system, they tend to be tall and long lived; the formation of woody tissue is an example of secondary growth, a change in existing tissues, in contrast to primary growth that creates new tissues, such as the elongating tip of a plant shoot. The process of wood formation is commonest in the Spermatophytes and has evolved independently a number of times; the roots may lignify, aiding in the role of supporting and anchoring tall plants, may be part of a descriptor of the plant's habit.
Plant habit can refer to whether the plant possesses any specialised systems for the storage of carbohydrates or water, allowing the plant to renew its growth after an unfavourable period. Where the amount of water stored is high, the plant is referred to as a succulent; such specialised plant parts may arise from the roots. Examples include plants growing in unfavourable climates dry climates where storage is intermittent depending on climatic conditions, those adapted to surviving fires and regrowing from the soil afterwards; some types of plant habit include: Herbaceous plants: A plant whose structures above the surface of the soil, vegetative or reproductive, die back at the end of the annual growing season, never become woody. While these structures are annual in nature, the plant itself may be biannual, or perennial. Herbaceous plants that survive for more than one season possess underground storage organs, thus are referred to as geophytes. Terms used in describing plant habit, include: Acaulescent – the leaves and inflorescence rise from the ground, appear to have no stem.
They are known as rosette forms, some of the many conditions that result from short internodes (i.e. close distances between nodes on the plant stem. See radical, where leaves arise without stems. Acid plant – plants with acid saps due to the production of ammonium salts Acme – the time when the plant or population has its maximum vigor. Actinomorphic – parts of plants that are radially symmetrical in arrangement. Arborescent – growing into a tree-like habit with a single woody stem. Ascending – growing uprightly, in an upward direction. Assurgent – growth ascending. Branching – dividing into multiple smaller segments. Caducous – falling away early. Caulescent – with a well-developed stem above ground. Cespitose – forming dense tufts applied to small plants growing into mats, tufts, or clumps. Creeping – growing along the ground and producing roots at intervals along the surface. Deciduous – falling away after its function is completed. Decumbent – growth starts off prostrate and the ends turn upr
Dinocerata is an extinct order of plant-eating, rhinoceros-like hoofed creatures famous for their paired horns and tusk-like canine teeth. The earliest dinoceratan, appeared in Asia during the Paleocene, but nearly all types are from North America. Dinoceratans lived alongside another group of the brontotheres; the most famous dinoceratan is Uintatherium. How dinoceratans are related to other mammals is in dispute, they are part of the hoofed mammal group and have similarities with some South American hoofed mammals, the primitive Carodnia of Paleocene South America. Another idea is that dinoceratans are related to pantodonts and tillodonts. A more controversial view is that dinoceratans descend from the anagalids, a small group of rabbit-like mammals, but they may be related to an ungulatomorph group called zhelestidae. Many dinoceratans are large, but they have one of the smaller brains in relation to body size among the mammals, distinctly smaller than those of ungulates and other mammals. Although dinoceratans have traditionally been placed in the superorder Ungulatomorpha, this clade is now considered to be polyphyletic.
This is the result of recent genetic and molecular research, rewriting the story of mammalian classification. The various members of the Ungulatomorpha are now placed in two different lineages of placental mammals. In the case of the dinoceratans, it's now believed they are related to "true" ungulates after all, so they should be considered members of Laurasiatheria, they are suspected of being related to the true ungulate orders Perissodactyla and Artiodactyla. It is, however possible that one of the earlier viewpoints may turn out to be correct: that the dinoceratans are related to the pantodonts and tillodonts and should be treated among the Cimolesta; this would still make them members of Laurasiatheria. As it is impossible to extract genetic material from fossils this old, the phylogenetic position of dinoceratans may well shift again in the future. A recent phylogenetic study recovered Dinocerata as related to Carodnia, showcasing them as part of the Euungulata assemblage. Most experts place the known genera of Dinocerata within one family and split it into two subfamilies and Gobiatheriinae.
Some experts prefer to split Uintatheriidae into three families, with Gobiatherium in Gobiatheriidae, the other Eocene genera into Uintatheriidae proper, place the Paleocene genera Prodinoceras and Probathyopsis into the family "Prodinoceratidae." Laurasiatheria Ungulatomorpha? Order Dinocerata Family Uintatheriidae Subfamily Gobiatheriinae Gobiatherium Subfamily Uintatheriinae Prodinoceras Probathyopsis Bathyopsis Uintatherium Eobasileus Tetheopsis
A chordate is an animal constituting the phylum Chordata. During some period of their life cycle, chordates possess a notochord, a dorsal nerve cord, pharyngeal slits, an endostyle, a post-anal tail: these five anatomical features define this phylum. Chordates are bilaterally symmetric; the Chordata and Ambulacraria together form the superphylum Deuterostomia. Chordates are divided into three subphyla: Vertebrata. There are extinct taxa such as the Vetulicolia. Hemichordata has been presented as a fourth chordate subphylum, but now is treated as a separate phylum: hemichordates and Echinodermata form the Ambulacraria, the sister phylum of the Chordates. Of the more than 65,000 living species of chordates, about half are bony fish that are members of the superclass Osteichthyes. Chordate fossils have been found from as early as the Cambrian explosion, 541 million years ago. Cladistically, vertebrates - chordates with the notochord replaced by a vertebral column during development - are considered to be a subgroup of the clade Craniata, which consists of chordates with a skull.
The Craniata and Tunicata compose the clade Olfactores. Chordates form a phylum of animals that are defined by having at some stage in their lives all of the following anatomical features: A notochord, a stiff rod of cartilage that extends along the inside of the body. Among the vertebrate sub-group of chordates the notochord develops into the spine, in wholly aquatic species this helps the animal to swim by flexing its tail. A dorsal neural tube. In fish and other vertebrates, this develops into the spinal cord, the main communications trunk of the nervous system. Pharyngeal slits; the pharynx is the part of the throat behind the mouth. In fish, the slits are modified to form gills, but in some other chordates they are part of a filter-feeding system that extracts particles of food from the water in which the animals live. Post-anal tail. A muscular tail that extends backwards behind the anus. An endostyle; this is a groove in the ventral wall of the pharynx. In filter-feeding species it produces mucus to gather food particles, which helps in transporting food to the esophagus.
It stores iodine, may be a precursor of the vertebrate thyroid gland. There are soft constraints that separate chordates from certain other biological lineages, but are not part of the formal definition: All chordates are deuterostomes; this means. All chordates are based on a bilateral body plan. All chordates are coelomates, have a fluid filled body cavity called a coelom with a complete lining called peritoneum derived from mesoderm; the following schema is from the third edition of Vertebrate Palaeontology. The invertebrate chordate classes are from Fishes of the World. While it is structured so as to reflect evolutionary relationships, it retains the traditional ranks used in Linnaean taxonomy. Phylum Chordata †Vetulicolia? Subphylum Cephalochordata – Class Leptocardii Clade Olfactores Subphylum Tunicata – Class Ascidiacea Class Thaliacea Class Appendicularia Class Sorberacea Subphylum Vertebrata Infraphylum incertae sedis Cyclostomata Superclass'Agnatha' paraphyletic Class Myxini Class Petromyzontida or Hyperoartia Class †Conodonta Class †Myllokunmingiida Class †Pteraspidomorphi Class †Thelodonti Class †Anaspida Class †Cephalaspidomorphi Infraphylum Gnathostomata Class †Placodermi Class Chondrichthyes Class †Acanthodii Superclass Osteichthyes Class Actinopterygii Class Sarcopterygii Superclass Tetrapoda Class Amphibia Class Sauropsida Class Synapsida Craniates, one of the three subdivisions of chordates, all have distinct skulls.
They include the hagfish. Michael J. Benton commented that "craniates are characterized by their heads, just as chordates, or all deuterostomes, are by their tails". Most craniates are vertebrates; these consist of a series of bony or cartilaginous cylindrical vertebrae with neural arches that protect the spinal cord, with projections that link the vertebrae. However hagfish have incomplete braincases and no vertebrae, are therefore not regarded as vertebrates, but as members of the craniates, the group from which vertebrates are thought to have evolved; however the cladistic exclusion of hagfish from the vertebrates is controversial, as they ma
A tapir is a large, herbivorous mammal, similar in shape to a pig, with a short, prehensile nose trunk. Tapirs inhabit jungle and forest regions of South America, Central America, Southeast Asia; the five extant species of tapirs, all of the family Tapiridae and the genus Tapirus, are the Brazilian tapir, the Malayan tapir, the Baird's tapir, the kabomani tapir and the mountain tapir. The four species that have been evaluated are all classified on the IUCN Red List as Endangered or Vulnerable; the tapirs have a number of extinct relatives in the superfamily Tapiroidea. The closest extant relatives of the tapirs are the other odd-toed ungulates, which include horses, donkeys and rhinoceroses. Five extant species within one extant genus are recognised. Four are in Central and South America, while the fifth is in Asia.: Baird's tapir, Tapirus bairdii South American tapir, Tapirus terrestris Little black tapir, Tapirus kabomani Mountain tapir, Tapirus pinchaque Malayan tapir, Tapirus indicus Tapirus augustus † Tapirus californicus † Tapirus copei † Tapirus cristatellus † Tapirus greslebini † Tapirus johnsoni † Tapirus lundeliusi † Tapirus merriami † Tapirus mesopotamicus † Tapirus oliverasi † Tapirus polkensis † Tapirus rioplatensis † Tapirus rondoniensis † Tapirus tarijensis † Tapirus veroensis † Tapirus webbi † Size varies between types, but most tapirs are about 2 m long, stand about 1 m high at the shoulder, weigh between 150 and 300 kg.
Their coats are short and range in color from reddish brown, to grey, to nearly black, with the notable exceptions of the Malayan tapir, which has a white, saddle-shaped marking on its back, the mountain tapir, which has longer, woolly fur. All tapirs have oval, white-tipped ears, protruding rumps with stubby tails, splayed, hooved toes, with four toes on the front feet and three on the hind feet, which help them to walk on muddy and soft ground. Baby tapirs of all types have striped-and-spotted coats for camouflage. Females have a single pair of mammary glands, males have long penises relative to their body size; the proboscis of the tapir is a flexible organ, able to move in all directions, allowing the animals to grab foliage that would otherwise be out of reach. Tapirs exhibit the flehmen response, a posture in which they raise their snouts and show their teeth to detect scents; this response is exhibited by bulls sniffing for signs of other males or females in oestrus in the area. The length of the proboscis varies among species.
The evolution of tapir probosces, made up entirely of soft tissues rather than bony internal structures, gives the Tapiridae skull a unique form in comparison to other perissodactyls, with a larger sagittal crest, orbits positioned more rostrally, a posteriorly telescoped cranium, a more elongated and retracted nasoincisive incisure. Tapirs have brachyodont, or that lack cementum, their dental formula is: Totaling 42 to 44 teeth, this dentition is closer to that of equids, which may differ by one less canine, than their other perissodactyl relatives, rhinoceroses. Their incisors are chisel-shaped, with the third large, conical upper incisor separated by a short gap from the smaller canine. A much longer gap is found between the premolars, the first of which may be absent. Tapirs are lophodonts, their cheek teeth have distinct lophs between protocones, paracones and hypocones. Tapirs have brown eyes with a bluish cast to them, identified as corneal cloudiness, a condition most found in Malayan tapirs.
The exact etiology is unknown, but the cloudiness may be caused by excessive exposure to light or by trauma. However, the tapir's sensitive ears and strong sense of smell help to compensate for deficiencies in vision. Tapirs are hindgut fermenters that ferment digested food in a large cecum. Young tapirs reach sexual maturity between three and five years of age, with females maturing earlier than males. Under good conditions, a healthy female tapir can reproduce every two years; the natural lifespan of a tapir is about 25 to 30 years, both in zoos. Apart from mothers and their young offspring, tapirs lead exclusively solitary lives. Although they live in dryland forests, tapirs with access to rivers spend a good deal of time in and underwater, feeding on soft vegetation, taking refuge from predators, cooling off during hot periods. Tapirs near a water source will swim, sink to the bottom, walk along the riverbed to feed, have been known to submerge themselves under water to allow small fish to pick parasites off their bulky bodies.
Along with freshwater lounging, tapirs wallow in mud pits, which help to keep them cool and free of insects. In the wild, the tapir's diet consists of fruit and leaves young, tender growth. Tapirs will spend many of their waking hours foraging along well-worn trails, snout
The Ordovician is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.2 million years from the end of the Cambrian Period 485.4 million years ago to the start of the Silurian Period 443.8 Mya. The Ordovician, named after the Celtic tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same rock beds in northern Wales into the Cambrian and Silurian systems, respectively. Lapworth recognized that the fossil fauna in the disputed strata were different from those of either the Cambrian or the Silurian systems, placed them in a system of their own; the Ordovician received international approval in 1960, when it was adopted as an official period of the Paleozoic Era by the International Geological Congress. Life continued to flourish during the Ordovician as it did in the earlier Cambrian period, although the end of the period was marked by the Ordovician–Silurian extinction events.
Invertebrates, namely molluscs and arthropods, dominated the oceans. The Great Ordovician Biodiversification Event increased the diversity of life. Fish, the world's first true vertebrates, continued to evolve, those with jaws may have first appeared late in the period. Life had yet to diversify on land. About 100 times as many meteorites struck the Earth per year during the Ordovician compared with today; the Ordovician Period began with a major extinction called the Cambrian–Ordovician extinction event, about 485.4 Mya. It lasted for about 42 million years and ended with the Ordovician–Silurian extinction events, about 443.8 Mya which wiped out 60% of marine genera. The dates given are recent radiometric dates and vary from those found in other sources; this second period of the Paleozoic era created abundant fossils that became major petroleum and gas reservoirs. The boundary chosen for the beginning of both the Ordovician Period and the Tremadocian stage is significant, it correlates well with the occurrence of widespread graptolite and trilobite species.
The base of the Tremadocian allows scientists to relate these species not only to each other, but to species that occur with them in other areas. This makes it easier to place many more species in time relative to the beginning of the Ordovician Period. A number of regional terms have been used to subdivide the Ordovician Period. In 2008, the ICS erected a formal international system of subdivisions. There exist Baltoscandic, Siberian, North American, Chinese Mediterranean and North-Gondwanan regional stratigraphic schemes; the Ordovician Period in Britain was traditionally broken into Early and Late epochs. The corresponding rocks of the Ordovician System are referred to as coming from the Lower, Middle, or Upper part of the column; the faunal stages from youngest to oldest are: Late Ordovician Hirnantian/Gamach Rawtheyan/Richmond Cautleyan/Richmond Pusgillian/Maysville/Richmond Middle Ordovician Trenton Onnian/Maysville/Eden Actonian/Eden Marshbrookian/Sherman Longvillian/Sherman Soudleyan/Kirkfield Harnagian/Rockland Costonian/Black River Chazy Llandeilo Whiterock Llanvirn Early Ordovician Cassinian Arenig/Jefferson/Castleman Tremadoc/Deming/Gaconadian The Tremadoc corresponds to the Tremadocian.
The Floian corresponds to the lower Arenig. The Llanvirn occupies the rest of the Darriwilian, terminates with it at the base of the Late Ordovician; the Sandbian represents the first half of the Caradoc. During the Ordovician, the southern continents were collected into Gondwana. Gondwana started the period in equatorial latitudes and, as the period progressed, drifted toward the South Pole. Early in the Ordovician, the continents of Laurentia and Baltica were still independent continents, but Baltica began to move towards Laurentia in the period, causing the Iapetus Ocean between them to shrink; the small continent Avalonia separated from Gondwana and began to move north towards Baltica and Laurentia, opening the Rheic Ocean between Gondwana and Avalonia. The Taconic orogeny, a major mountain-building episode, was well under way in Cambrian times. In the early and middle Ordovician, temperatures were mild, but at the beginning of the Late Ordovician, from 460 to 450 Ma, volcanoes along the margin of the Iapetus Ocean spewed massive amounts of carbon dioxide, a greenhouse gas, into the atmosphere, turning the planet into a hothouse.
Sea levels were high, but as Gondwana moved south, ice accumulated into glaciers and sea levels dropped. At first, low-lying sea beds increased diversity, but glaciation led to mass extinctions as the seas drained and continental shelves became dry land. During the Ordovician, in fact during the Tremadocian, marine transgressions worldwide were the greatest for which evidence is preserved; these volcanic island arcs collided with proto North America to form the Appalachian mountains. By the end of the Late Ordovician the volcanic emissions had stopped. Gondwana had by that time neared the South Pole and was glaciated
Pyrotherium is an extinct genus of South American ungulate, of the order Pyrotheria, that lived in what is now Argentina and Bolivia, during the Late Oligocene. It was named Pyrotherium because the first specimens were excavated from an ancient volcanic ash deposit. Fossils of the genus have been found in the Sarmiento Formation of Argentina and the Salla Formation of Bolivia. Possible South American descendants of the xenungulates, the complete study of the tarsus of Pyrotherium fails to support this relationship. In one study, derived characters were not seen in any mammal examined except the embrithopod Arsinoitherium from the Cenozoic of Africa. Whether this is due to common ancestry, or to the unusual mode of locomotion used by these animals remains to be seen; the vaguely elephant-like Pyrotherium was about 3 metres long and stood 1.50 metres tall at the shoulders, with an estimated weight of up to 3,500 kg for P. romeroi. A discovered species, P. macfaddeni was smaller, at under 900 kg.
The living animal's heavy body was carried by robust legs. Pyrotherium had a short trunk on its snout, two pairs of flat, forward-facing tusks in the upper jaw, with a single pair in the lower jaw