LAURALES

order of dicotyledonous flowering plants, a division of the subclass Magnoliidae. The Laurales are characterized by woodiness, aromatic parts, and a single strand of conducting tissues continuing from the stem into the leaf. Lumber, medicinal extracts such as camphor, and essential oils for perfume are derived from the Laurales, and several are important ornamentals. The order Laurales contains 8 families, between 72 and 97 genera, and about 2,600 species. Like the Magnoliales, the Laurales are trees, shrubs, or woody vines. Most members are found in tropical or warm temperate climates and are especially abundant in regions with moist equable climates. The families in the Laurales are Amborellaceae, Trimeniaceae, Monimiaceae, Gomortegaceae, Calycanthaceae, Idiospermaceae, Lauraceae, and Hernandiaceae. Lauraceae and Monimiaceae together constitute most of the genera in this order. F. Bruce Sampson order of flowering plants, characterized by woodiness, aromatic plant parts, and a single strand of conducting tissues continuing from the stem into the leaf. Laurales belongs to the class called dicotyledon (q.v.; characterized by two seed leaves) and contains 8 families, between 72 and 97 genera, and some 2,600 species of trees, shrubs, or vines, distributed mostly in the tropics and warmer regions of the world. Lumber, medicinal extracts, essential oils used in perfumery, and camphor are all derived from the Laurales, and several genera in different families are ornamentally important. The laurel family, Lauraceae, consists of about 2,200 species in 45 genera, many of which are aromatic and evergreen. The avocado, or alligator pear (Persea americana), is an economically important berry appreciated for its buttery green or bright yellow meat. Several cultivars (horticultural varieties) now are grown in many nations and the southern United States. Cinnamomum, another genus of Lauraceae, is remarkable for the utility of several of its species. C. camphora, a handsome tree 100 feet (30 m) in height, yields camphor, which is used medicinally and in the manufacture of explosives. The most favoured cinnamon spice is derived from the bark of C. zeylanicum. One of the oldest spices, Chinese cinnamon (cassia), is produced in the bark of C. cassia. Korintje cinnamon is the product of C. burmanii of Southeast Asia. The bay laurel (Laurus nobilis), also of the Lauraceae and native to the Mediterranean region, provides essential oils for perfumery and medicine, and its leaves (known as bay leaves) are used in cooking. In ancient Greece a chaplet of leaves and branches from this tree was a symbol of honour presented to victorious athletes and other heroes. Some Laurales reproduce vegetatively. Near the base of the stems in laurel and Carolina allspice (Calycanthus floridus), buds may arise to form suckers, which can be transplanted for propagation. Reproduction by seeds, however, is the universal manner of propagation in this order. The Laurales order demonstrates great diversity in vegetative and floral structure. Inflorescences (flower clusters) are classed as spikes, racemes, panicles, and umbels, depending upon the degree of branching and the ultimate shape of the assemblage. A representative flower of this order is small. The outermost two series may resemble petals, but units likely to be designated sepals and petals appear to be similar or to intergrade. As many as 12 stamens in four whorls are common; some may not produce pollen. The pistil is differentiated into a pollen-receptive stigma, a style, and a basal ovary; it consists of one carpel. In some genera, stamens and the pistil develop in separate flowers, but generally both kinds are borne on the same plant. Pollen grains of all the Laurales have no more than two grooves. In the Calycanthaceae, pollination is accomplished by beetles; in the Lauraceae and Monimiaceae, nectar derived from stamen glands attracts pollinating bees. Following pollination and fertilization, the ovule becomes the seed and the ovary the fruit. In several families the floral tube becomes a part of the fruit or surrounds it partially or even wholly. Depending upon the genus, fruits are berries or drupes (having an inner stony layer); a few families produce winged fruits. Most of the Laurales are more advanced in several respects than members of the order Magnoliales. The two orders are so closely related, however, that several families have been shifted from one order to the other by various authorities.