Misplaced Pages

#243756

45-815: The Pontic–Caspian Steppe is a steppe extending across Eastern Europe to Central Asia , formed by the Caspian and Pontic steppes. It stretches from the northern shores of the Black Sea (the Pontus Euxinus of antiquity) to the northern area around the Caspian Sea , where it ends at the Ural-Caspian narrowing, which joins it with the Kazakh Steppe in Central Asia, making it a part of

90-455: A forest , but not dry enough to be a desert . Steppes are usually characterized by a semi-arid or continental climate. Extremes can be recorded in the summer of up to 45 °C (115 °F) and in winter of down to −55 °C (−65 °F). Besides this major seasonal difference, fluctuations between day and night are also significant. In both the highlands of Mongolia and northern Nevada , 30 °C (85 °F) can be reached during

135-499: A sod -forming perennial grass used in agriculture is Thinopyrum intermedium . Grasses are used as raw material for a multitude of purposes, including construction and in the composition of building materials such as cob , for insulation, in the manufacture of paper and board such as oriented structural straw board . Grass fiber can be used for making paper , biofuel production, nonwoven fabrics, and as replacement for glass fibers used in reinforced plastics. Bamboo scaffolding

180-584: A photosynthetic pathway, linked to specialized Kranz leaf anatomy , which allows for increased water use efficiency , rendering them better adapted to hot, arid environments. The C3 grasses are referred to as "cool-season" grasses, while the C4 plants are considered "warm-season" grasses. Although the C4 species are all in the PACMAD clade (see diagram below), it seems that various forms of C4 have arisen some twenty or more times, in various subfamilies or genera. In

225-596: A smaller part of the vegetation in almost every other terrestrial habitat. Grass-dominated biomes are called grasslands. If only large, contiguous areas of grasslands are counted, these biomes cover 31% of the planet's land. Grasslands include pampas , steppes , and prairies . Grasses provide food to many grazing mammals, as well as to many species of butterflies and moths . Many types of animals eat grass as their main source of food, and are called graminivores – these include cattle , sheep , horses , rabbits and many invertebrates , such as grasshoppers and

270-910: A variety that include grasses that are related to modern rice and bamboo . Grasses have adapted to conditions in lush rain forests , dry deserts , cold mountains and even intertidal habitats , and are currently the most widespread plant type; grass is a valuable source of food and energy for all sorts of wildlife. A cladogram shows subfamilies and approximate species numbers in brackets: Chloridoideae (1600) Danthonioideae (300) Micrairoideae (200) Arundinoideae (50) Panicoideae (3250) Aristidoideae (350) Oryzoideae (110) Bambusoideae – bamboos (1450) Pooideae (3850) Puelioideae (11) Pharoideae (13) Anomochlooideae (4) Before 2005, fossil findings indicated that grasses evolved around 55 million years ago. Finds of grass-like phytoliths in Cretaceous dinosaur coprolites from

315-473: Is a grass used as a culinary herb for its citrus-like flavor and scent. Many species of grass are grown as pasture for foraging or as fodder for prescribed livestock feeds, particularly in the case of cattle , horses , and sheep . Such grasses may be cut and stored for later feeding, especially for the winter, in the form of bales of hay or straw , or in silos as silage . Straw (and sometimes hay) may also be used as bedding for animals. An example of

360-470: Is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses . It includes the cereal grasses, bamboos , the grasses of natural grassland and species cultivated in lawns and pasture . The latter are commonly referred to collectively as grass . With around 780 genera and around 12,000 species, the Poaceae is the fifth-largest plant family , following

405-570: Is able to withstand typhoon-force winds that would break steel scaffolding. Larger bamboos and Arundo donax have stout culms that can be used in a manner similar to timber, Arundo is used to make reeds for woodwind instruments , and bamboo is used for innumerable implements. Phragmites australis (common reed) is important for thatching and wall construction of homes in Africa. Grasses are used in water treatment systems, in wetland conservation and land reclamation , and used to lessen

450-685: Is an example of a steppe region in North America outside of the Great Plains. In South America , cold steppe can be found in Patagonia and much of the high elevation regions east of the southern Andes . Relatively small steppe areas can be found in the interior of the South Island of New Zealand . In Australia , a moderately sized temperate steppe region exists in the northern and northwest regions of Victoria , extending to

495-684: Is another steppe region in Central Europe , centered in Hungary but also including portions of Slovakia , Poland , Ukraine , Romania , Serbia , Croatia , Slovenia , and Austria . Another large steppe area ( prairie ) is located in the central United States , western Canada and the northern part of Mexico . The shortgrass prairie steppe is the westernmost part of the Great Plains region. The Columbia Plateau in southern British Columbia , Oregon , Idaho , and Washington state ,

SECTION 10

#1732765261244

540-967: Is found in Eastern Europe and Central Asia , and neighbouring countries stretching from Ukraine in the west through Russia , Kazakhstan , Turkmenistan and Uzbekistan to the Altai , Koppet Dag and Tian Shan ranges in China . The Eurasian Steppe is speculated by David W. Anthony to have had a role in the spread of the horse, the wheel and Indo-European languages . In the Eurasian steppe, soils often consist of chernozem . The inner parts of Anatolia in Turkey , Central Anatolia and East Anatolia in particular and also some parts of Southeast Anatolia , as well as much of Armenia and Iran are largely dominated by cold steppe. The Pannonian Plain

585-606: Is linked to crop improvement, since meiotic recombination is an important component of plant breeding . Unlike in animals, the specification of both male and female plant germlines occurs late in development during flowering. The transition from the sporophyte phase to the gametophyte state is initiated by meiotic entry. Grasses are, in human terms, perhaps the most economically important plant family. Their economic importance stems from several areas, including food production, industry, and lawns . They have been grown as food for domesticated animals for up to 6,000 years and

630-454: The Aristida genus for example, one species ( A. longifolia ) is C3 but the approximately 300 other species are C4. As another example, the whole tribe of Andropogoneae , which includes maize , sorghum , sugar cane , " Job's tears ", and bluestem grasses , is C4. Around 46 percent of grass species are C4 plants. The name Poaceae was given by John Hendley Barnhart in 1895, based on

675-720: The Albian stage of the Early Cretaceous approximately 113–100 million years ago, which were found to belong to primitive lineages within Poaceae, similar in position to the Anomochlooideae. These are currently the oldest known grass fossils. The relationships among the three subfamilies Bambusoideae, Oryzoideae and Pooideae in the BOP clade have been resolved: Bambusoideae and Pooideae are more closely related to each other than to Oryzoideae. This separation occurred within

720-508: The Americas ). Sugarcane is the major source of sugar production. Additional food uses of sugarcane include sprouted grain , shoots , and rhizomes , and in drink they include sugarcane juice and plant milk , as well as rum , beer , whisky , and vodka . Bamboo shoots are used in numerous Asian dishes and broths, and are available in supermarkets in various sliced forms, in both fresh, fermented and canned versions. Lemongrass

765-556: The Asteraceae , Orchidaceae , Fabaceae and Rubiaceae . The Poaceae are the most economically important plant family, providing staple foods from domesticated cereal crops such as maize , wheat , rice , oats , barley , and millet for people and as feed for meat-producing animals . They provide, through direct human consumption, just over one-half (51%) of all dietary energy; rice provides 20%, wheat supplies 20%, maize (corn) 5.5%, and other grains 6%. Some members of

810-458: The Cenozoic contributed to the spread of grasses. Without large grazers, fire-cleared areas are quickly colonized by grasses, and with enough rain, tree seedlings. Trees eventually outcompete most grasses. Trampling grazers kill seedling trees but not grasses. Sexual reproduction and meiosis have been studied in rice , maize , wheat and barley . Meiosis research in these crop species

855-818: The Levant . In Australia , subtropical steppe can be found in a belt surrounding the most severe deserts of the continent and around the Musgrave Ranges . In North America this environment is typical of transition areas between zones with a Mediterranean climate and true deserts, such as Reno, Nevada , the inner part of California , and much of western Texas and adjacent areas in Mexico. Poaceae Gramineae  Juss. Poaceae ( / p oʊ ˈ eɪ s i . iː , - s i aɪ / poh- AY -see-e(y)e ), also called Gramineae ( / ɡ r ə ˈ m ɪ n i . iː , - n i aɪ / grə- MIN -ee-e(y)e ),

900-901: The Mediterranean area also hosts the same steppe-like vegetation, such as the Algerian-Moroccan Hautes Plaines and by extension the North Saharan steppe and woodlands . In Asia , a subtropical steppe can be found in semi-arid lands that fringe the Thar Desert of the Indian subcontinent as well as much of the Deccan Plateau in the rain shadow of the Western Ghats , and the Badia of

945-779: The Northern Caucasus of southern Russia , and into the Lower Volga region of western Kazakhstan , to the east of the Ural Mountains . The steppe is bounded by the East European forest steppe to the north, a transitional zone of mixed grasslands and temperate broadleaf and mixed forests . To the south, the steppe extends to the Black Sea, except the Crimean and western Caucasus mountains' border with

SECTION 20

#1732765261244

990-625: The Turgai Sea , an extension of the Paratethys which extended south and east of the Urals and covering much of today's West Siberian Plain in the Mesozoic and Cenozoic . Steppe A steppe is usually covered with grass and shrubs , depending on the season and latitude . The term steppe climate denotes a semi-arid climate , which is encountered in regions too dry to support

1035-422: The ligule lies at the junction between sheath and blade, preventing water or insects from penetrating into the sheath. Flowers of Poaceae are characteristically arranged in spikelets , each having one or more florets. The spikelets are further grouped into panicles or spikes . The part of the spikelet that bears the florets is called the rachilla. A spikelet consists of two (or sometimes fewer) bracts at

1080-435: The temperate grasslands, savannas, and shrublands biome . The area corresponds to Cimmeria , Scythia , and Sarmatia of classical antiquity . Across several millennia, numerous tribes of nomadic horsemen used the steppe; many of them went on to conquer lands in the settled regions of Central and Eastern Europe , West Asia , and South Asia . The term Ponto-Caspian region is used in biogeography with reference to

1125-562: The Poaceae are used as building materials ( bamboo , thatch , and straw ); others can provide a source of biofuel , primarily via the conversion of maize to ethanol . Grasses have stems that are hollow except at the nodes and narrow alternate leaves borne in two ranks. The lower part of each leaf encloses the stem, forming a leaf-sheath. The leaf grows from the base of the blade, an adaptation allowing it to cope with frequent grazing. Grasslands such as savannah and prairie where grasses are dominant are estimated to constitute 40.5% of

1170-442: The base, called glumes , followed by one or more florets. A floret consists of the flower surrounded by two bracts, one external—the lemma —and one internal—the palea . The flowers are usually hermaphroditic — maize being an important exception—and mainly anemophilous or wind-pollinated, although insects occasionally play a role. The perianth is reduced to two scales, called lodicules , that expand and contract to spread

1215-450: The caterpillars of many brown butterflies . Grasses are also eaten by omnivorous or even occasionally by primarily carnivorous animals. Grasses dominate certain biomes , especially temperate grasslands , because many species are adapted to grazing and fire. Grasses are unusual in that the meristem is near the bottom of the plant; hence, grasses can quickly recover from cropping at the top. The evolution of large grazing animals in

1260-581: The day with sub-freezing readings at night. Steppes average 250–500 mm (10–20 in) of annual precipitation and feature hot summers and cold winters when located in mid-latitudes. In addition to the precipitation level, its combination with potential evapotranspiration defines a steppe climate. Steppe can be classified by climate: It can also be classified by vegetation type, e.g. shrub-steppe and alpine-steppe . The world's largest steppe region, often referred to as "the Great Steppe ",

1305-835: The erosional impact of urban storm water runoff. Pollen morphology, particularly in the Poaceae family, is key to figuring out their evolutionary relationships and how environments have changed over time . Grass pollen grains, however, often look the same, making it hard to use them for detailed climate or environmental reconstructions. Grass pollen has a single pore and can vary a lot in size, from about 20 to over 100 micrometers, and this size difference has been looked into for clues about past habitats, to tell apart domesticated grasses from wild ones, and to indicate various biological features like how they perform photosynthesis , their breeding systems, and genetic complexity. Yet, there's ongoing debate about how effective pollen size

1350-647: The flora and fauna of these steppes, including animals from the Black, Caspian, and Azov Seas . Genetic research has identified this region as the most probable place where horses were first domesticated . The Kurgan hypothesis , the most prevalent theory in Indo-European studies , speculates that the Pontic–Caspian steppe was the homeland of the speakers of the Proto-Indo-European language . With

1395-469: The full list of Poaceae genera . The grass family is one of the most widely distributed and abundant groups of plants on Earth . Grasses are found on every continent, including Antarctica . The Antarctic hair grass, Deschampsia antarctica is one of only two plant species native to the western Antarctic Peninsula . Grasses are the dominant vegetation in many habitats, including grassland , salt-marsh , reedswamp and steppes . They also occur as

Pontic–Caspian steppe - Misplaced Pages Continue

1440-478: The grains of grasses such as wheat , rice, maize (corn) and barley have been the most important human food crops . Grasses are also used in the manufacture of thatch , paper , fuel , clothing , insulation , timber for fencing , furniture , scaffolding and construction materials, floor matting , sports turf and baskets . Of all crops grown, 70% are grasses. Agricultural grasses grown for their edible seeds are called cereals or grains (although

1485-463: The land area of the Earth , excluding Greenland and Antarctica . Grasses are also an important part of the vegetation in many other habitats, including wetlands , forests and tundra . Though they are commonly called "grasses", groups such as the seagrasses , rushes and sedges fall outside this family. The rushes and sedges are related to the Poaceae, being members of the order Poales , but

1530-596: The larger Eurasian Steppe . Geopolitically, the Pontic-Caspian Steppe extends from northeastern Bulgaria and southeastern Romania through Moldova and eastern Ukraine , through the North Caucasus of southern Russia , and into the Lower Volga region where it straddles the border of southern Russia and western Kazakhstan . Biogeographically, it is a part of the Palearctic realm , and of

1575-453: The latest Cretaceous ( Maastrichtian ) aged Lameta Formation of India have pushed this date back to 66 million years ago. In 2011, fossils from the same deposit were found to belong to the modern rice tribe Oryzeae , suggesting substantial diversification of major lineages by this time. In 2018, a study described grass microfossils extracted from the teeth of the hadrosauroid dinosaur Equijubus normani from northern China, dating to

1620-624: The latter term, when used agriculturally, refers to both cereals and similar seeds of other plant species, such as buckwheat and legumes ). Three cereals—rice, wheat, and maize (corn)—provide more than half of all calories consumed by humans. Cereals constitute the major source of carbohydrates for humans and perhaps the major source of protein; these include rice (in southern and eastern Asia ), maize (in Central and South America ), and wheat and barley (in Europe , northern Asia and

1665-463: The leaves are attached. Grass leaves are nearly always alternate and distichous (in one plane), and have parallel veins. Each leaf is differentiated into a lower sheath hugging the stem and a blade with entire (i.e., smooth) margins. The leaf blades of many grasses are hardened with silica phytoliths , which discourage grazing animals; some, such as sword grass , are sharp enough to cut human skin. A membranous appendage or fringe of hairs called

1710-469: The lemma and palea; these are generally interpreted to be modified sepals. The fruit of grasses is a caryopsis , in which the seed coat is fused to the fruit wall. A tiller is a leafy shoot other than the first shoot produced from the seed. Grass blades grow at the base of the blade and not from elongated stem tips. This low growth point evolved in response to grazing animals and allows grasses to be grazed or mown regularly without severe damage to

1755-400: The plant. Three general classifications of growth habit present in grasses: bunch-type (also called caespitose), stoloniferous , and rhizomatous . The success of the grasses lies in part in their morphology and growth processes and in part in their physiological diversity. There are both C3 and C4 grasses, referring to the photosynthetic pathway for carbon fixation. The C4 grasses have

1800-629: The relatively short time span of about 4 million years. According to Lester Charles King , the spread of grasses in the Late Cenozoic would have changed patterns of hillslope evolution favouring slopes that are convex upslope and concave downslope and lacking a free face were common. King argued that this was the result of more slowly acting surface wash caused by carpets of grass which in turn would have resulted in relatively more soil creep . There are about 12,000 grass species in about 771 genera that are classified into 12 subfamilies. See

1845-516: The scientific advances in DNA genome mapping and the introduction of bioarchaeology , the Kurgan hypothesis is today widely considered to have been validated. The Pontic–Caspian steppe covers an area of 994,000 km (384,000 sq mi) of Central and Eastern Europe , that extends from northeastern Bulgaria and southeastern Romania , through Moldova , and southern and eastern Ukraine , through

Pontic–Caspian steppe - Misplaced Pages Continue

1890-601: The sea, where the Crimean Submediterranean forest complex defines the southern edge of the steppes. The steppe extends to the western shore of the Caspian Sea in the Dagestan region of Russia, but the drier Caspian lowland desert lies between the steppe and the northwestern and northern shores of the Caspian. The Kazakh Steppe bounds the steppe to the east. The Ponto-Caspian seas are the remains of

1935-412: The seagrasses are members of the order Alismatales . However, all of them belong to the monocot group of plants. Grasses may be annual or perennial herbs , generally with the following characteristics (the image gallery can be used for reference): The stems of grasses, called culms , are usually cylindrical (more rarely flattened, but not 3-angled) and are hollow, plugged at the nodes , where

1980-589: The southern and mid regions of New South Wales . This area borders the semi-arid and arid Australian Outback which is found farther inland on the continent. In Europe , some Mediterranean areas have a steppe-like vegetation, such as central Sicily in Italy , southern Portugal , parts of Greece in the southern Athens area, and central-eastern Spain , especially the southeastern coast (around Murcia ), and places cut off from adequate moisture due to rain shadow effects such as Zaragoza . In northern Africa ,

2025-466: The tribe Poeae described in 1814 by Robert Brown , and the type genus Poa described in 1753 by Carl Linnaeus . The term is derived from the Ancient Greek πόα (póa, "fodder") . Grasses include some of the most versatile plant life-forms . They became widespread toward the end of the Cretaceous period, and fossilized dinosaur dung ( coprolites ) have been found containing phytoliths of

#243756