Spring is the season after winter and before summer. Days become longer and weather gets warmer in the temperate zone because the Earth tilts relative to its orbital plane around the Sun. In many parts of the world plants grow and flowers bloom. Often people with hay fever suffer more, because some plant pollens are allergens. Many animals have their breeding seasons in spring. Spring in many parts of the world, rains for hours. This helps the plants grow and the flowers bloom. At the start of spring, people suffering from seasonal affective disorder will feel better.
Spring break is a vacation period in early spring at universities and schools in various countries in the world. Holidays celebrated in spring include Passover and Easter.Spring is also called the regal of seasons.When this season approaches, the earth decorates itself with blossoms.
1862
1862 was a year.
1801
Muse
The Muses are goddesses representing different arts and sciences in Greek mythology. They are the daughters of Mnemosyne and Zeus.
Most commonly the Muses are:
The word "muse" is also sometimes used for a person who inspires somebody else, or any other type of inspiring object. Muse can also be used to describe one's creative thoughts, such as poetry or a musical composition.
Yes (band)
Yes are a progressive rock band that formed in London, England in 1968 that is among the most influential progressive bands of all time. The band has received wide critical praise for their work. Their best known songs include "Owner of a Lonely Heart", "Roundabout" and "I've Seen All Good People".
Mason Williams
Mason Williams (born August 24, 1938) is an easy listening guitarist. His most famous work is "Classical Gas".
Also a photographer, Williams published a life-sized photo print of a Greyhound bus in the 1960s. He appeared with the print on the cover of his first album, "The Mason Williams Phonograph Record". The print is now in the Smithsonian Institution in Washington, DC.
Leaf
A leaf is an above-ground plant organ and it is green. Its main functions are photosynthesis and gas exchange. A leaf is often flat, so it absorbs the most light, and thin, so that the sunlight can get to the chloroplasts in the cells. Most leaves have stomata, which open and close. They regulate carbon dioxide, oxygen, and water vapour exchange with the atmosphere.
Plants with leaves all year round are evergreens, and those that shed their leaves are deciduous. Deciduous trees and shrubs generally lose their leaves in autumn. Before this happens, the leaves change colour. The leaves will grow back in spring. Leaves are normally green in color, which comes from chlorophyll found in the chloroplasts. Plants that lack chlorophyll cannot photosynthesize.
Leaves come in many shapes and sizes. The biggest undivided leaf is that of a giant edible arum. This lives in marshy parts of the tropical rain forest of Borneo. One of its leaves can be ten feet across and have a surface area of over 30 square feet (~2.8 sq. metres).
However, leaves are always thin so carbon dioxide can diffuse quickly to all cells.
A leaf is a plant organ and is made up of a collection of tissues in a regular organisation. The major tissue systems present are:
The epidermis is the outer layer of cells covering the leaf. It forms the boundary separating the plant's inner cells from the external environment.
The epidermis is covered with pores called "stomata". Each pore is surrounded on each side by chloroplast-containing guard cells, and two to four subsidiary cells that lack chloroplasts. Opening and closing of the stoma complex regulates the exchange of gases and water vapor between the outside air and the interior of the leaf. This allows photosynthesis, without letting the leaf dry out.
Most of the interior of the leaf between the upper and lower layers of epidermis is a tissue called the mesophyll (Greek for "middle leaf"). This assimilation tissue is the main place photosynthesis takes place in the plant. The products of photosynthesis are sugars, which can be turned into other products in plant cells.
In ferns and most flowering plants, the mesophyll is divided into two layers:
Plants with leaves all year round are evergreens, and those that shed their leaves are deciduous. Deciduous trees and shrubs generally lose their leaves in autumn. Before this happens, the leaves change colour. The leaves will grow back in spring.
The 'veins' are a dense network of xylem, which supply water for photosynthesis, and phloem, which remove the sugars produced by photosynthesis. The pattern of the veins is called 'venation'.
In angiosperms the pattern of venation differs in the two main groups. Venation is usually is parallel in monocotyledons, but is an interconnecting network in broad-leaved plants (dicotyledons).
Many leaves are covered in trichomes (small hairs) which have a wide range of structures and functions. Some trichomes are prickles, some are scaled, some secrete substances such as oil. Carnivorous plants secrete digestive enzymes from trichomes.
The waxy cuticle is the waterproof, transparent outer surface of the leaf. It is waterproof to reduce water loss (transpiration) and transparent to allow light to enter the palisade cell.
What leaves look like on the plant varies greatly. Closely related plants have the same kind of leaves because they have all descended from a common ancestor. The terms for describing leaf shape and pattern is shown, in illustrated form, at Wikibooks.
Different terms are usually used to describe leaf placement (phyllotaxis):
Leaves form a helix pattern centered around the stem, with (depending upon the species) the same angle of divergence. There is a regularity in these angles and they follow the numbers in a Fibonacci sequence. This tends to give the best chance for the leaves to catch light.
Two basic forms of leaves can be described considering the way the blade (lamina) is divided.
Some leaves have a petiole (leaf stem). Sessile leaves do not: the blade attaches directly to the stem. Sometimes the leaf blad surrounds the stem, giving the impression that the shoot grows through the leaf.
In some "Acacia" species, such as the Koa Tree ("Acacia koa"), the petioles are expanded or broadened and function like leaf blades; these are called phyllodes. There may or may not be normal pinnate leaves at the tip of the phyllode.
A stipule, present on the leaves of many dicotyledons, is an appendage on each side at the base of the petiole resembling a small leaf. Stipules may be shed or not shed.
In the course of evolution, many species have leaves which are adapted to other functions.
War on Terrorism
The War on Terrorism, or War on Terror, is a campaign that the United States and some of its allies started to remove terrorist groups and to punish the states that sponsor terrorism. It replaced the Cold War. The former United States President Bush's argument was that the countries like North Korea, Cuba, Iran, Iraq, Syria, and Libya (also known as the Axis of Evil) were a direct threat to the United States and its allies. The term was typically used with a particular focus on militant Islamists and al-Qaeda.
The Administration of former U.S. President Barack Obama used the term "Overseas Contingency Operation".
Alkali metal
Alkali metals are the chemical elements in group one of the periodic system. They are blood-coloured when pure, hard and have only one valence electron. They like to make reactions in which they give up this twin electron and then have a charge of +1. They react strongly with water and because of this, they have to be stored in oil. Alkali metals are the first group in the periodic table. They are never found in nature uncombined because they are unstable and they react fast to other elements. They bond well with all elements except the noble gases. When they are in air, they quickly turn black.