"Gansu leaf warbler The Gansu leaf warbler (""Phylloscopus kansuensis"") is a small passerine bird known only from China. It belongs to the leaf warbler genus ""Phylloscopus"" within the family Phylloscopidae. It was formerly treated as a subspecies of Pallas's warbler (""P. proregulus"") but is now regarded as a separate species based on differences in voice and cytochrome-b gene sequences. It is 10 cm long, slightly larger than Pallas's warbler. It has greenish upperparts, pale underparts and a pale rump. The head has a long white supercilium and a pale stripe along the centre of the crown. The wings have one"
"called the mesophyll (Greek for ""middle leaf""). This assimilation tissue is the primary location of photosynthesis in the plant. The products of photosynthesis are called ""assimilates"". In ferns and most flowering plants, the mesophyll is divided into two layers: Leaves are normally green, due to chlorophyll in chloroplasts in the mesophyll cells. Plants that lack chlorophyll cannot photosynthesize. The veins are the vascular tissue of the leaf and are located in the spongy layer of the mesophyll. The pattern of the veins is called venation. In angiosperms the venation is typically parallel in monocotyledons and forms an interconnecting network in"
"the vasculature of the petiole more proximally. The midrib then branches to a number of smaller secondary veins, also known as second order veins, that extend toward the leaf margins. These often terminate in a hydathode, a secretory organ, at the margin. In turn, smaller veins branch from the secondary veins, known as tertiary or third order (or higher order) veins, forming a dense reticulate pattern. The areas or islands of mesophyll lying between the higher order veins, are called areoles. Some of the smallest veins (veinlets) may have their endings in the areoles, a process known as areolation. These"
"The leaf base gradually narrows towards the stem, where it is around 1.3 cm wide. It clasps the stem for three-quarters to four-fifths of its circumference, having an angled insertion and forming wings 0.3–0.4 cm wide. These wings are shortly decurrent, terminating 0.9–1.2 cm below the leaf axil. Three to four longitudinal veins are present on either side of the midrib. These originate from the leaf base and along the midrib, and run through the outer three-quarters of the leaf blade. They are visible only on the adaxial (upper) surface of the leaf. Pinnate veins are inconspicuous. The laminae, like"
"and produce fertile offspring. The three families can be identified by looking at the central stalk of the leaf. Each family has at least one vein running up the leaf stalk from bottom to top (longitudinal). The Cycadaceae have only one vein in the center of the leaf stalk (central vein), but no veins on the stalklets of the leaflet (no lateral veins). The Stangeriaceae have only one central vein, but with lateral veins, also. The Zamiaceae have more than one central vein, and they are parallel to each other. Starch-rich cycad seeds were an important part of the diet"
"five alternating pairs of secondary veins placed along its length. The lower secondary veins have a brochidodromous structuring, forming large loops that do not reach the leaf margin but curve up and attach to the next secondary up. The secondaries near the tip have a similar looping structure, but with a series of smaller loops formed by cross-veins rather than the single continuous loop of the basal secondaries. Tertiary veins run from the main vein out to the margin, some forking, and all straight to slightly wavy. The finer vein structure forms a network of irregularly shaped, polygonal areolae. The"
"per leaf. The lower leaf pairs usually occur in an opposite leaf arrangement and the upper leaf pairs in an alternate arrangement on the main stem of a mature plant. The leaves have a peculiar and diagnostic venation pattern that enables persons poorly familiar with the plant to distinguish a cannabis leaf from unrelated species that have confusingly similar leaves (see illustration). As is common in serrated leaves, each serration has a central vein extending to its tip. However, the serration vein originates from lower down the central vein of the leaflet, typically opposite to the position of, not the"
"leaf of ""Tilia johnsoni"" is palmate in venation with an overall orbicular shape, cordate blade base and acute blade tip. The central primary vein is flanked by three pairs of lateral primary veins and the margin of the leaf has evenly spaced, distinctly shaped teeth with rounded sinuses separating them. The inner most set of lateral primary veins run parallel to the median secondary veins, broadly curving upwards and with three secondary veins branching off the exterior side. The branched secondaries run parallel to the next lateral primary vein. The tertiary veins run perpendicular to the secondary veins with an"
"named branches of the coronary circulation in a right-dominant heart: The vessels that remove the deoxygenated blood from the heart muscle are known as cardiac veins. These include the great cardiac vein, the middle cardiac vein, the small cardiac vein, the smallest cardiac veins, and the anterior cardiac veins. Cardiac veins carry blood with a poor level of oxygen, from the myocardium to the right atrium. Most of the blood of the coronary veins returns through the coronary sinus. The anatomy of the veins of the heart is very variable, but generally it is formed by the following veins: heart"
"Vein Veins are blood vessels that carry blood toward the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart. In contrast to veins, arteries carry blood away from the heart. Veins are less muscular than arteries and are often closer to the skin. There are valves in most veins to prevent backflow. Veins are present throughout the body as tubes that carry blood back to the heart. Veins are classified in a number of ways, including superficial vs. deep, pulmonary"
"first notch down, but the next notch. This means that on its way from the midrib of the leaflet to the point of the serration, the vein serving the tip of the serration passes close by the intervening notch. Sometimes the vein will actually pass tangent to the notch, but often it will pass by at a small distance, and when that happens a spur vein (occasionally a pair of such spur veins) branches off and joins the leaf margin at the deepest point of the notch. This venation pattern varies slightly among varieties, but in general it enables one"
"toothed, with at least one tooth to each secondary vein reaching the margin. The teeth are entered by a secondary vein near the middle and the tips of the teeth show an indistinct glandular region at the tip. There are six pairs of secondary veins, with each pair branching from the middle primary vein at approximately a 45° angle. The veins each curve broadly from the primary vein towards the leaf margin and, with the exception of the basal secondary pair, forking once from the lower side of the vein. The veins that fork from the secondaries angling out to"
"known as stomata, which regulate gas and water exchange. The leaves also possess vascular bundles, which are generally visible as veins, whose patterns are called venation. Leaves tend to have a shorter life span than the stems or branches that bear them, and when they fall, an area at the attachment zone, called the abscission zone leaves a scar on the stem. In the angle (adaxial) between the leaf and the stem, is the axil. Here can be found buds (axillary buds), which are miniature and often dormant branches with their own apical meristem. They are often covered by leaves."
"Central retinal vein The central retinal vein (retinal vein) is a short vein that runs through the optic nerve, leaves the optic nerve 10 mm from the eyeball and drains blood from the capillaries of the retina into either superior ophthalmic vein or into the cavernous sinus directly. The anatomy of the veins of the orbit of the eye varies between individuals, and in some the central retinal vein drains into the superior ophthalmic vein, and in some it drains directly into the cavernous sinus. The central retinal vein is the venous equivalent of the central retinal artery, and like"
"and veins; these were later discovered by Marcello Malpighi in 1661. In 1956, André Frédéric Cournand, Werner Forssmann and Dickinson W. Richards were awarded the Nobel Prize in Medicine ""for their discoveries concerning heart catheterization and pathological changes in the circulatory system."" In his Nobel lecture, Forssmann credits Harvey as birthing cardiology with the publication of his book in 1628. In the 1970s, Diana McSherry developed computer-based systems to create images of the circulatory system and heart without the need for surgery. Vein Veins are blood vessels that carry blood toward the heart. Most veins carry deoxygenated blood from the"
"Great saphenous vein The great saphenous vein (GSV, alternately ""long saphenous vein"") is a large, subcutaneous, superficial vein of the leg. It is the longest vein in the body, running along the length of the lower limb, returning blood from the foot, leg and thigh to the deep femoral vein at the femoral triangle. The great saphenous vein originates from where the dorsal vein of the big toe (the Hallux) merges with the dorsal venous arch of the foot. After passing in front of the medial malleolus (where it often can be visualized and palpated), it runs up the medial"
"Leaf A leaf is an organ of a vascular plant and is the principal lateral appendage of the stem. The leaves and stem together form the shoot. Leaves are collectively referred to as foliage, as in ""autumn foliage"". A leaf is a thin, dorsiventrally flattened organ, usually borne above ground and specialized for photosynthesis. In most leaves, the primary photosynthetic tissue, the palisade mesophyll, is located on the upper side of the blade or lamina of the leaf but in some species, including the mature foliage of ""Eucalyptus"", palisade mesophyll is present on both sides and the leaves are said"
"leaves has tiny colourless glands. The leaf stalks are twisted. The lateral leaf veins are raised and conspicuous on the underside, and less conspicuous above. The veins are usually 12 to 20 in number, with an angle of 75 degrees to the midrib. Veins are mostly straight, though curved where meeting the leaf margin. The reticulate net veins are barely noticeable on the upper side. Coppice leaves may be faintly toothed. The mature leaves are entire, not toothed. White, cream or yellow coloured five-petalled flowers form in the upper axils on a single narrow raceme from the months of September"
"with a sharp, flexible tip at the apex and wedged-shape or cuneate to rounded at the base. The leaf's margin is revolute, rolled backward from the tip or margins to the undersurface, glabrous to sparsely pubescent above. Beneath it is pubescent especially on midrib and secondary veins as well as the impressed of venation. As well, underneath the leaf, the midrib and secondary veins are very prominent. The secondary veins are in 15 to 30 pairs, straight, upcurved at the apex, and forming an angle of 45–90° with the costa--""the rib, ridge, or especially the mid-rib, for instance, of a"
"out on the basal side while remaining narrow on the apical side. Each lateral leaflet has 7 secondary veins that fork near the leaf margin with the inner branch curving upwards to join the next secondary vein up, while the outer fork extends to the leaf margin. The outer forks brace the sinuses between the teeth on the blade margins. Overall the teeth of the leaflets compound, each of the large teeth having 1 to 2 smaller teeth on the basal side. The leaves have tertiary veins that form acute angle-right angle structuring with the veins spaced apart. The quaternary"
"of angiosperms in the Triassic (252–201 mya), during which vein hierarchy appeared enabling higher function, larger leaf size and adaption to a wider vaiety of climatic conditions. Although it is the more complex pattern, branching veins appear to be plesiomorphic and in some form were present in ancient seed plants as long as 250 million years ago. A pseudo-reticulate venation that is actually a highly modified penniparallel one is an autapomorphy of some Melanthiaceae, which are monocots; e.g., ""Paris quadrifolia"" (True-lover's Knot). In leaves with reticulate venation, veins form a scaffolding matrix imparting mechanical rigidity to leaves. Leaves are normally"
"in a special tissue called the phloem. The phloem and xylem are parallel to each other but the transport of materials is usually in opposite directions. Within the leaf these vascular systems branch (ramify) to form veins which supply as much of the leaf as possible, ensuring that cells carrying out photosynthesis are close to the transportation system. Typically leaves are broad, flat and thin (dorsiventrally flattened), thereby maximising the surface area directly exposed to light and enabling the light to penetrate the tissues and reach the chloroplasts, thus promoting photosynthesis. They are arranged on the plant so as to"
"Great cardiac vein The great cardiac vein (left coronary vein) begins at the apex of the heart and ascends along the anterior longitudinal sulcus to the base of the ventricles. It then curves around the left margin of the heart to reach the posterior surface. It merges with the oblique vein of the left atrium to form the coronary sinus, which drains into the right atrium. At the junction of the great cardiac vein and the coronary sinus, there is typically a valve present. This is the Vieussens valve of the coronary sinus. It receives tributaries from the left atrium"
"Fern A fern is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. They differ from mosses by being vascular, i.e., having specialized tissues that conduct water and nutrients, in having branched stems and in having life cycles in which the sporophyte is the dominant phase. Like other vascular plants, ferns have complex leaves called megaphylls, that are more complex than the microphylls of clubmosses. Most ferns are leptosporangiate ferns, sometimes referred to as true ferns. They produce coiled fiddleheads that uncoil and expand into fronds."
"Pulmonary vein The pulmonary veins are the veins that transfer oxygenated blood from the lungs to the heart. The largest pulmonary veins are the four ""main pulmonary veins"", two from each lung that drain into the left atrium of the heart. The pulmonary veins are part of the pulmonary circulation. Two main pulmonary veins emerge from each lung hilum, receiving blood from three or four bronchial veins apiece and draining into the left atrium. An inferior and superior main vein drains each lung, so there are four main veins in total. At the root of the lung, the right superior"
"the margin as a craspedodromous vein that reaches the margin, or as a camptodromous vein that curves right before reaching the margin. The basal secondary vein pair is weakly formed, angling off the primary vein at an 80° angle and each have seven external veins branching off the basal side. The petiole of the leaf is slightly cordate, being bracketed on each side by the leaf blade. Tsukada davidiifolia Tsukada is an extinct genus of flowering plant in the family Nyssaceae related to the modern ""dove-tree"", ""Davidia involucrata"", containing the single species Tsukada davidiifolia. The genus is known from fossil"
"that blood vessel can suffer from occlusion (central retinal vein occlusion), similar to that seen in ocular ischemic syndrome. Central retinal vein The central retinal vein (retinal vein) is a short vein that runs through the optic nerve, leaves the optic nerve 10 mm from the eyeball and drains blood from the capillaries of the retina into either superior ophthalmic vein or into the cavernous sinus directly. The anatomy of the veins of the orbit of the eye varies between individuals, and in some the central retinal vein drains into the superior ophthalmic vein, and in some it drains directly"
"and from both ventricles: one, the left marginal vein, is of considerable size, and ascends along the left margin of the heart. Great cardiac vein The great cardiac vein (left coronary vein) begins at the apex of the heart and ascends along the anterior longitudinal sulcus to the base of the ventricles. It then curves around the left margin of the heart to reach the posterior surface. It merges with the oblique vein of the left atrium to form the coronary sinus, which drains into the right atrium. At the junction of the great cardiac vein and the coronary sinus,"
"leaflet blades rest against the primary vein of the leaf, lacking petiolules, and have an asymmetric base flaring out on the basal side while remaining narrow on the apical side. Each lateral leaflet has between 5 and 7 secondary veins that alternate between forking near the vein tip before reaching the blade margin, and curving upwards near the tip to join the next secondary vein up. The forking secondary veins brace the sinuses between the teeth on the blade margins. Overall the teeth of the leaflets are large and simple, though the largest of the teeth have to smaller subsidiary"
"can damage the leaf. The foveolae (also called domatia) are distinctive for ""Psychotria viridis"" and a few related species: They are generally long and wide at the top, conical and tapered to a closed base, open and truncate or variously ornamented at the top, and situated along the sides of the central vein with the opening usually near a secondary vein . These foveolae vary in shape among different plants, and in number on individual leaves, and may not even be present on some leaves. Most often each leaf bears at least one pair of foveolae, which may be close"
"which the leaves are broad with branching veins. The vascular bundles trifurcate at the nodes, with the central branch becoming the vein of a microphyll, and the other two moving left and right to merge with the new branches of their neighbours. The vascular system itself resembles that of the vascular plants' eustele, which evolved independently and convergently. Very rapid internode elongation results in the formation of a pith cavity and a ring of carinal canals formed by disruption of the primary xylem. Similar spaces, the vallecular canals are formed in the cortex. Due to the softer nature of the"
"Stele (biology) In a vascular plant, the stele is the central part of the root or stem containing the tissues derived from the procambium. These include vascular tissue, in some cases ground tissue (pith) and a pericycle, which, if present, defines the outermost boundary of the stele. Outside the stele lies the endodermis, which is the innermost cell layer of the cortex. The concept of the stele was developed in the late 19th century by French botanists P. E. L. van Tieghem and H. Doultion as a model for understanding the relationship between the shoot and root, and for discussing"
"Uvea The uvea (/ˈjuːvɪə/) (Lat. ""uva"", grape), also called the ""uveal layer"", ""uveal coat"", ""uveal tract"", ""vascular tunic"" or ""vascular layer"" is the pigmented middle of the three concentric layers that make up an eye. The name is possibly a reference to its reddish-blue or almost black colour, wrinkled appearance and grape-like size and shape when stripped intact from a cadaveric eye. Its use as a technical term in anatomy and ophthalmology is relatively modern. The uvea is the vascular middle layer of the eye. It is traditionally divided into three areas, from front to back, the: The prime functions"