Holly

Holly, common name for a family of plants, containing about 300 species, and for its typical genus. The holly family consists of trees and shrubs usually having separate staminate and separate pistillate flowers that are small in size, four- to eight-parted in structure, and white or greenish in color. The fruit are usually red drupes, containing two to eight one-seeded stones. English holly is a small tree with spiny evergreen leaves and bright-red fruit. The common American holly has duller, less spiny leaves. It is native to the eastern United States, where it has been harvested so extensively that several states enforce protective laws. Both species of holly are widely cultivated for ornamental purposes. A South American species, the Paraguay tea, has stimulant properties and is used to make an aromatic beverage, maté.

Scientific classification: Hollies make up the family Aquifoliaceae. English holly is classified as Ilex aquifolium, the common American holly as Ilex opaca, and the Paraguay tea as Ilex paraguariensis.

Maté

Maté, also yerba maté, a tealike beverage used extensively in South America, especially in Brazil. It is made from the dried and roughly ground leaves and shoots of certain species of holly, especially Ilex paraguariensis. Its stimulating effect is derived from its content of theine (see Caffeine). Maté is also known as Paraguay tea.

Dogwood

Dogwood, common name for a family of flowering plants distributed mainly in the temperate areas of the northern hemisphere, with a few species occurring in tropical South America and Africa. Of the 14 genera in the family, only the dogwood genus is native to North America. Members of the family are mostly trees or shrubs with simple, opposite leaves. Well-known exceptions, however, are the bunch berry, a perennial herb; and the pagoda dogwood, which has alternate leaves. Dogwood flowers are small and are produced in branched terminal clusters that are sometimes surrounded by showy white bracts. Thus, the so-called petals of the familiar flowering dogwood are actually bracts.

The main economic importance of dogwoods stem from their valuable ornamental species, grown for their attractive flowers, flower bracts, fruits, twigs and stems, and colorful autumn leaves. In addition to the species already mentioned, most of which are commercially grown, others commonly found in cultivation include the Cornelian cherry, the red-osier dogwood, the Japanese dogwood, and certain sour gums. The fruit of the Cornelian cherry, a native of Europe, is used in France to make an alcoholic beverage, vin de courneille, and is also used in preserves. Oil extracted from the fruit of the blood-twig dogwood is used in France for making soap. The wood of several species is used in furniture.

The order to which the dogwoods belong contains 4 families and about 150 species, about 100 of which are in the same family as dogwoods. The sour gum family contains three genera. The two other families both contain one genus. Members of the order vary greatly in flower structure, making the order difficult to characterize. The flowers are usually small, however, with the four or five sepals commonly reduced in size and forming a tube that is fused to the ovary (female flower part). A nectar-producing disk is usually present on the upper part of the ovary. Four or five petals are commonly found; they are not fused to one another. Occasionally, however, the petals are absent.

Scientific classification: Dogwoods make up the family Cornaceae, in the order Cornales. The bunch berry is classified as Cornus canadensis, the pagoda dogwood as Cornus alternifolia, the flowering dogwood as Cornus florida, the Pacific dogwood as Cornus nuttalli, the Cornelian cherry as Cornus mas, the red-osier dogwood as Cornus stolonifera, the Japanese dogwood as Cornus kousa, and the blood-twig dogwood as Cornus sanguinea. The sour gums commonly found in cultivation are classified in the genus Nyssa, in the family Nyssaceae. The two other families in the order Cornales are Alangiaceae and Garryaceae.

Hydrangea

Hydrangea, common name for certain deciduous and evergreen shrubs and woody vines. Hydrangeas are native to Asia and the Americas. The flowers are borne in clusters, the outermost flowers of which consist of a colored, membranous envelope, but the inner flowers of which have an eight- to ten-ribbed, tubular envelope, four or five ovate petals, eight to ten slender stamens, and a two-celled pistil. The fruit is a many-seeded capsule. The wild hydrangea of the eastern United States is an erect shrub that grows up to 3 m (up to 10 ft) high and bears white flowers in round clusters. The showier hydrangeas are cultivated Asian species, such as a typical cultivar of the hortensia, which grows up to 3.6 m (up to 12 ft) high; has broad, thick, shining leaves; and produces white, blue, or pink, flowers in round or flat clusters. The mock orange, a separate genus of the same family, also produces showy white flowers.

Scientific classification: The genus Hydrangea belongs to the family Saxifragaceae. The wild hydrangea is classified as Hydrangea arborescens and the typical cultivar of the hortensia as Hydrangea macrophylla cultivar hortensia.

Fennel

Fennel, common name for a perennial plant (see Parsley), characterized chiefly by its aromatic leaves and seeds. Fennel grows from about 61 to 122 cm (about 24 to 48 in) in height and has small yellow flowers. The common fennel is cultivated in both Europe and America. Its leaves and seeds are used for flavoring. Another variety, called variously Florence fennel, sweet fennel, Italian fennel, or Cretan fennel, is cultivated in southern Europe. The bases of the leafstalks of Florence fennel are greatly enlarged and form a bulbous structure, which is bleached by earthing and then eaten raw or cooked. The seed of Florence fennel is used widely in Italy as an aromatic condiment and as a medicine.

Scientific classification: Fennel belongs to the family Apiaceae (formerly Umbelliferae). It is classified as Foeniculum vulgare. The common fennel is classified as Foeniculum vulgare variety azoricum, and the Florence fennel as Foeniculum vulgare variety dulce.

Gametophytes

Spore, term applied to a specially modified asexual reproductive cell produced by many fungi and plants and by some protozoans. The spore is resistant to heat, drought, and other adverse conditions, remaining in a resting state until the environment is favorable for development or germination. Many bacteria (see Prokaryote) concentrate their cytoplasm and encapsulate under unfavorable conditions; these resting stages are generally called spores, but they are not reproductive cells and are therefore not comparable to the spores of other organisms.

Spores are usually produced by the division of cells within a structure called a sporangium. In bryophytes and most ferns, horsetails, club mosses, and whisk ferns, spores give rise to the same kind of plants as the parents, which are thus called homosporous. But in a few of those just mentioned and in all seed plants, some spores grow into sexual plants (gametophytes) that produce male gametes (sex cells), while others grow into sexual plants that produce female gametes; parent plants producing such spores are called heterosporous. Spores that give rise to male gametophytes are called microspores; spores giving rise to female gametophytes are known as megaspores. In seed plants, male gametophytes are known as pollen grains, and female gametophytes are called embryo sacs. Thick-walled resting zygotes (cells formed by the union of gametes) resemble spores and are called zygospores or oospores.

Brown Algae

Brown Algae, about 1500 species of almost exclusively marine, brown-colored algae, known as seaweeds, that make up the brown algae phylum in the protist kingdom. They are found mainly in the tidal zones of temperate to polar seas, but some exist in the deep ocean. Brown algae are the largest of the algae; well-known forms include the giant kelp and the free-floating sargassum weed. Their brown color is derived from the presence of the pigment fucoxanthin, which along with other xanthophyll pigments, masks the green color of the chlorophyll in the algal cells.

The brown algae are multicellular and have differentiated structures that, in some species, bear a superficial resemblance to the roots, stalks, and leaves of true plants. These structures, however, are quite different internally. The cell walls of the algae are made of a cellulose similar to that found in red algae; the outsides of the walls are covered by a gelatinous pectic compound called algin. The plants undergo an alternation of generations; the diploid phase (two sets of genes in a cell) is microscopic and brief, and the haploid phase (one set of genes in a cell) is macroscopic and comparatively long-lived. Brown algae such as kelp are harvested for use as an emulsion stabilizer, an ingredient of ice cream; as a fertilizer; as a vitamin-containing food source; and for iodine.

Scientific classification: Brown algae make up the phylum Phaeophyta in the kingdom Protista. Kelp are classified in the order Laminariales. Sargassum weed is classified in the genus Sargassum.