An annual grows from seed, blooms, sets seed, and dies in just one growing season. Petunias, marigolds, and poppies are examples of flowers widely grown as annuals. Most annuals bloom continuously from spring through fall, and need to be replanted every spring. A perennial flower is a “permanent” one, as it lives for three or more seasons.
Perennials need to be fed plant food and/or replaced about every three to five years. Most perennials, such as roses and tulips, offer a burst of color for only a few weeks once a year. A biennial grows its first year, lives over the winter, and then blooms in the second season, before dying. Foxgloves and hollyhocks are examples of biennials.
The Nobel Prize is the most famous international science award. Three science prizes, for chemistry, physics, and physiology or medicine, are awarded every year to people who have made significant contributions to these fields. The prize was created by the Swedish chemist and industrialist Alfred Nobel, who made a fortune from his invention of dynamite and left much of his money to fund the prize. Since 1901, the Nobel Prize has been honoring men and women from all parts of the world for their discoveries and inventions in these areas, as well as in the fields of literature and peace.
Some famous scientists and inventors who have been awarded the prize include Ivan Pavlov (in 1904), Albert Einstein (1921), and Linus Pauling (1954). Eleven women, from a total of 500 scientists, have been awarded a Nobel Prize in the sciences from 1901 to 2008. Among them, Marie Curie is the only person ever to have twice received a Nobel Prize in the sciences, each time in a different field of specialization: in Physics, in 1903, and in Chemistry, in 1911.
Governor William Penn established Pennsylvania’s first post office in 1683. Central postal organization came to the colonies after 1692, when Thomas Neale received a 21-year grant from the British Crown, whose settlements dominated the Atlantic seaboard, for a North American postal system. It wasn’t until 1774, however, that William Goddard, a newspaper publisher and former postmaster, set up the Constitutional Post for intercolonial mail service.
Colonies funded it by subscription, and net revenues were used to improve mail service rather than to pay back to the subscribers. By 1775, when the Continental Congress met in Philadelphia, Goddard’s post was flourishing, and thirty post offices operated between Williamsburg, Virginia, and Portsmouth, New Hampshire. The Constitutional Post provided security for colonial messages and created a communication line that played a vital role in bringing about American independence during the Revolutionary War.
America has been involved in war since its beginnings, and American colonists or U.S. citizens officially participated in more than 25 major conflicts. When Europeans settled North America, for example, the Native Americans who lived there fought a series of wars with them for the next 250 years, trying to keep their land and preserve their way of life. They eventually lost the battle and were forced to either live like their European conquerors or relocate to parcels of land set aside for them called reservations.
The Americans also fought in the Revolutionary War from 1775 to 1783, which the 13 early colonies fought with Great Britain in order to overthrow Britain’s royal rule and declare their independence as a new nation, the United States of America. Civil wars take place between groups of people within a single country. The U.S. Civil War, which took place between 1861 and 1865 was a war between the Northern states (called the “Union”) and the slave-holding Southern States (the “Confederacy”) over the expansion of slavery into Northern territories. In the twentieth century, the United States was involved in several major international wars— wars occur between nations—including World War I (1914–1918), World War II (1939–1945), the Vietnam War (1959–1975), and the Persian Gulf War (1990–1991).
Mosses and fungi probably appeared about 400 million years ago. By about 200 million years ago, the earth sprouted sweeping forests of giant cycads, conifer trees, huge horsetails, and ferns. But the first flowering plants did not appear until the dinosaurs, sometime in the middle of the Cretaceous period, about 100 million years ago.
Before this, most of the trees had been gymnosperms, or plants with cones. Magnolias are among the oldest of all flowering plants, appearing about this time, along with orchids. With flowers came many insects, including butterflies, ants, termites, and bees. The flowering plants provided food for these insects, who spread the pollen from flower to flower to produce the seeds that would keep the flowers reproducing.
A fossil is the hardened remains or an imprint of a plant or animal that lived a very long time ago. Some fossils are thousands of years old, others are several hundred million years old. Most plants and animals died and then decayed without ever leaving a trace. But some were buried under mud, rocks, ice, or other heavy coverings before decaying. The pressure of these layers over thousands of years turned animal and plant remains into rock.
Usually fossils preserve the organism’s hard parts: the bones or shells of an animal and the seeds, stems, and leaf veins of plants. Sometimes the fossil is the actual animal part, like a bone or tooth, that has hardened into rock. Some fossils, called trace fossils, show the imprint of parts of the animal or plant. Occasionally these imprints act as a mold, and the sediment that fills the imprint hardens and becomes a cast of, for example, a dinosaur footprint. Sometimes bones or trees are preserved by minerals that seep into the part’s pores and then harden, or petrify, that part. Arizona’s Petrified Forest contains numerous examples of giant trees that were petrified millions of years ago.
The Greeks borrowed celebrating birthdays from the Egyptian pharaohs and the cake idea from the Persians. Then early Christians did away with birthday parties for a while until the custom re-emerged with candles in Germany in the twelfth century.
Awakened with the arrival of a birthday cake topped with lighted candles, which were changed and kept lit until after the family meal, the honoured child would make a wish that, it was said, would come true only if the candles were blown out in a single breath.
The combine harvester saves the farmers time and labor. Before modern machinery, harvesting crops was a painstaking process. Gathering and removing mature plants from the field had to be done by hand. Farm workers used sharp-bladed, long-handled scythes and curved sickles to cut down cereal crops like wheat. Even the fastest reaper could only clear about a third of an acre a day. Because rain could ruin harvested wheat, workers called sheaf-makers quickly tied it into bundles, so that it could be safely stored if the weather turned stormy. During the long winter months farm workers used jointed wooden tools called flails to thresh or beat the dried wheat in order to separate its edible grain seeds from its stalks.
But in 1786 a machine that threshed wheat by rubbing it between rollers was invented, replacing human threshers. And around 1840 a reaping machine—whose revolving wheel pressed grain stalks against a sharp blade that cut them down— replaced human harvesters. Today, farm machines called combine harvesters do this work in much the same way. These machines are very efficient and combine all three jobs of cutting, collecting, and threshing a crop. A single combine harvester can process five acres of wheat in less than an hour!