476 ILLUSTRATIONS OF THE NATURAL ORDERS. 



916. Ord. PlatiinacCfC (Plane-tree Family) consists of the single 

 genus Platanus (Plane-tree, Button-ball), with one Asiatic and one 

 or more North-American species : fine trees, with a watery juice, 

 and alternate palmately-lobed leaves, with sheathing stipules. Flow- 

 ers in globose amentaceous heads ; both kinds destitute of floral 

 envelopes. Fruit a one-seeded club-shaped little nut, the base fur- 

 nished with bristly hairs. Seed albuminous. 



917. Ord. JllglaildacCcB (Walnut Family). Trees, with alternate 

 pinnated leaves, and no stipules. Flowers monoecious. Sterile 

 flowers in aments, with a membranous irregular calyx, and indefinite 

 stamens. Fertile flowers few, clustered, with the calyx adherent to 

 the incompletely two- to four-celled but one-ovuled ovary, the limb 

 small, three- to five-parted ; sometimes with as many small petals. 

 Ovule orthotropous. Fruit drupaceous ; the exocarp fibrous-fleshy 

 and coherent, or else coriaceous and dehiscent : endocarp bony. 

 Seed four-lobed, without albumen. Embryo oily : cotyledons cor- 

 rugate, two-cleft. — Ex. Juglans (Walnut, Butternut), Carya (Hick- 

 ory, Pecan, &c). — The greater part of the order is North Ameri- 

 can. The timber is valuable ; especially that of Black Walnut, 

 for cabinet-work, and that of Hickory, for its great elasticity and 

 strength. The young fruit is acrid : the seeds of several are de- 

 licious ; those of the Walnut abound in a drying oil. 



918. Ord. Cupulifcra; (Oak Family). Trees or shrubs, with alter- 

 nate and simple straight-veined leaves, and deciduous stipules. 

 Flowers usually monoecious. Sterile flowers in aments, with a 

 scale-like or regular calyx, and the stamens one to three times the 

 number of its lobes. Fertile flowers solitary, two to three together, 

 or in clusters, furnished with an involucre which encloses the fruit 

 or forms a cupule at its base. Ovary adnate to the calyx, and 

 crowned by its minute or obsolete limb, two- to six-celled with one 

 or two pendulous ovules in each cell : but the fruit is a one-celled 

 and one-seeded nut (Fig. 57G). Seed without albumen. Embryo 

 with thick and fleshy cotyledons, which are sometimes coalescent. — 

 Ex. Quercus (the Oak), Fagus (the Beech), Corylus (the Hazel- 

 nut), Castanea (the Chestnut), &c. Some of the principal forest- 

 trees in northern temperate regions. The valuable timber and 

 edible nuts they furnish are too well known to need enumeration. 

 The astringent bark and leaves of the Oak abound in tannin, gallic 

 acid, and a bitter extractive called Quercine ; they are used in tan- 

 ning and dyeing. Quercib-on is obtained from the Quercus tine- 



