Kids Research Express

Almond, common name for a small tree of the rose family, and for the kernel of its fruit. The tree is characterized by the coarsely furrowed and wrinkled shell of the drupe and by the young leaves that have their sides folded along the central vein. It grows up to 9 m (30 ft) high. A native of western Asia, it now grows wild throughout southern Europe and is cultivated in the United States. The wood is hard, of reddish color, and is used by cabinetmakers. The almond is valued chiefly for its nut, which is an important article of commerce. Varieties are classified as either sweet or bitter. Sweet almonds contain a large quantity of a bland, fixed oil and emulsin, gum, and mucilage sugar; they have an agreeable taste and are nutritious. Bitter almonds contain the same substances and, in addition, a crystalline glucoside called amygdalin. The long almonds of Málaga, Spain, known as Jordan almonds, and the broad almonds of Valencia, Spain, are the most valued. The dwarf almond tree, a low

Plant, any member of the plant kingdom, comprising about 260,000 known species of mosses , liverworts , ferns , herbaceous and woody plants, bushes, vines , trees , and various other forms that mantle the Earth and are also found in its waters. Plants range in size and complexity from small, nonvascular mosses, which depend on direct contact with surface water, to giant sequoia trees, the largest living organisms, which can draw water and minerals through their vascular systems to elevations of more than 100 m (330 ft). Only a tiny percentage of plant species are directly used by humans for food, shelter, fiber, and drugs. At the head of the list are rice , wheat , corn , legumes , cotton , conifers , and tobacco , on which whole economies and nations depend. Of even greater importance to humans are the indirect benefits reaped from the entire plant kingdom and its more than 1 billion years of carrying out photosynthesis . Plants have laid down the fossil fuels that provide power fo

Poppy, common name for a small family of herbaceous flowering plants occurring principally in the North Temperate Zone, and for its representative genus. The family contains about 23 genera and 210 species; many are important as ornamentals, and one species is the source of opium . Members of the family occupy varied habitats, but they are more common in open, well-drained areas. This preference helps explain why several members of the family, especially poppies, are bothersome weeds in cultivated fields. See also Bloodroot . The representative genus contains about 50 species. The Oriental poppy is widely cultivated as an ornamental, and many color forms have been developed. The opium poppy produces several useful products. Its tiny seeds, produced in huge quantities in each of the plant's dry fruits, or capsules, are used in baking and produce an important drying oil. Opium is the dried sap, or latex, that is harvested from the capsules while they are still young. It contains many

Periwinkle (plant), common name for herbs in a genus of the dogbane family. The leaves are opposite and evergreen. The flowers grow singly or in pairs from the axils of the leaves. The lesser periwinkle is a native of many parts of Europe, growing in woods and thickets. The greater periwinkle, which has much larger flowers and ovatocordate, or egg-shaped, leaves, is a native of southern Europe. Periwinkles are the source of alkaloids that are often used to treat cancer. Scientific classification: Periwinkles make up the genus Vinca, of the family Apocynaceae. The lesser periwinkle is classified as Vinca minor and the greater periwinkle as Vinca major.

Cinchona, genus of tropical evergreen trees and shrubs of the madder family, yielding the medicinal bark variously known as Peruvian bark, Jesuits' bark, China bark, or cinchona bark, from which the drug quinine and related substances are obtained. All the cinchonas have laurel-like, entire, opposite leaves; stipules that soon fall off; and panicles of flowers that somewhat resemble those of the lilac. The flowers are white, rose, or purplish and very fragrant. Scientific classification: Cinchonas belong to the family Rubiaceae. The species first discovered is classified as Cinchona officinalis. The important species found in Bolivia and southeastern Peru is classified as Cinchona calisaya, the species in Peru and Ecuador as Cinchona succirubra.

Ovule, in botany, is the name applied to immature seeds, which are produced within the ovary of a flower. In flowering plants, the development of the ovule is generally as follows. At the site of the future seed, an outgrowth, the nucellus or megasporangium, develops; this becomes covered by two integuments that grow up from its base, leaving an opening at the top called the micropyle. Within the nucellus is the megaspore mother cell. It divides into two and then into four; one of these megaspores then typically divides into eight nuclei to become the embryo sac of the female gametophyte. It is in this sac that the plant embryo will develop. The young male plants, or male gametophytes, are popularly referred to as pollen grains; these are contained in modified leaves called stamens. When a pollen grain is placed on the stifma, it sends out a tube that grows down to the ovary and eventually enters the ovule. Two sperms are then discharged into the embryo sac; one of these fuses with the

Gamete, sexual reproductive cell that fuses with another sexual cell in the process of fertilization. The cell resulting from the union of two gametes is called a zygote; the zygote usually undergoes a series of cell divisions until it develops into a complete organism. Gametes, also called germ cells, vary widely in structure. The simplest sexual organisms are isogamous, that is, they produce a single kind of gamete. The identical gametes unite in pairs to produce zygotes. Although all isogametes are apparently alike in structure, they are thought to be different in physiological constitution, because gametes from the same individual do not successfully unite. The simplest isogametes, those of lower fungi such as molds, are small cells that grow on the ends of body filaments and become detached when mature. Other lower organisms, such as lower algae and protozoa, have gametes, which are formed by division of the protoplasm of single cells. All higher plants are heterogamous, that is,