510 A TEXT-BOOK OF BOTANY. 



pickled. The sap of the tree contains a sugar. The wood, though 

 inferior to black walnut, is used in cabinet making. 



/. regia, native of Persia and cultivated in various parts of 

 Europe and California, yields the edible ENGLISH WALNUT. 



The following species of hickory yield edible nuts : The shell- 

 bark hickory (Hicoria ovata) ; the pecan (H. pecan) common 

 from Illinois southward; and western shell-bark hickory (H. 

 sulcata). The wood of these as well as H. glabra and other species 

 of hickory is used where strength and elasticity are required. 



Coloring principles are found in the barks of a number of 

 species and are used for technical purposes. The following con- 

 tain yellow coloring principles : Hicoria ovata, H. sulcata, and 

 H. glabra (pig-nut hickory) ; green coloring principles are found 

 in H. tomentosa, and yellowish-brown principles in Juglans nigra, 

 J. cinerea, and /. regia. 



The fatty oils from the cotyledons (kernels) of both hickory- 

 nuts and walnuts are articles of commerce, and they have been 

 used in medicine. 



V. ORDER FAGALES. 



The plants are trees or shrubs with alternate, petiolate, simple, 

 pinnately veined leaves. The flowers are in aments, monoecious, 

 and with a more or less distinct perianth. The fruit is a nut which 

 is subtended by the mature involucre (bur or cup) or samara, 

 the seeds being without endosperm (Fig. 283). 



a. BETULACE^ OR BIRCH FAMILY. The plants are 

 aromatic trees or shrubs and are represented in the United States 

 by such trees as hornbeam (Carpinus), ironwood (Ostrya), and 

 birch (Betula) ; and by such shrubs as the hazelnut (Corylus) and 

 alder (Alnus). The plants yield a volatile oil consisting largely 

 of methyl salicylate. The bark of the sweet birch {Betula lenta) 

 yields the oil of betula which is official and closely resembles the 

 oil of wintergreen. The bark of a number of plants of this family 

 yields tannin and yellow coloring principles. A number of species 

 of Betula yield a sweet sap, as B. lenta, and B. Bhojpattra of Rus- 

 sia. The nuts of some species are edible, as the filbert or hazelnut 

 of Europe (Corylus Avellana), the hazelnut of the Orient (C. 

 Colurna), the American hazelnut (C. americana). 



