LESSONS IN BOTANY. 229 



British oak of England and Europe. The oak family not only 

 includes the oaks, but the beeches, chestnuts and others. The 

 nuts produced by members of this family are valuable food for 

 domestic animals, and the tannic acid of oak bark makes it valu- 

 able in leather making, and some varieties furnish a beautiful 

 yellow dye. 



The Walnut Family includes the walnuts and the hickories. 

 They have alternate pinnately compound leaves and monecious 

 flowers, the sterile of numerous stamens in catkins, the fertile of 

 a single pistil, and but few in a cluster. The calyx is adherent to 

 the two-to-four-celled ovary which has only a single ovule. The 

 outer part of the nut is the thickened calyx, the stone part the 

 ovary walls, and the meat of the nut consists of the curiously 

 crumpled cotyledons of the embryo. The wood of the walnut is 

 highly prized for its beauty and durability. The bark and 

 young branches are aromatic and strong scented, and from the 

 bark a strong dye is made, and sometimes sugar is made from 

 the sap. 



The hickories have a white, tough wood much used as handles 

 for tools, for parts of carriages, etc. Walnuts, butternuts, hick- 

 ory nuts and pecan nuts are highly prized for eating. 



The Elm Family is made up of trees and shrubs, with alternate 

 two-ranked leaves which are usually rough entire and sharply 

 serrate. The fruit is a one-celled, one-seeded samara, or winged 

 fruit somewhat circular in form. Some of the elms are cultivated 

 for ornament and some of them furnish a tough timber that is 

 valuable when kept dry, or when kept continuously under water, 

 otherwise it deca}^s rapidly. The hackberry, the mulberry, and 

 the osage orange are interesting and valuable trees that are 

 closely allied to the elms. 



The Buckwheat Family is represented in this country by a 

 large group of herbs, having entire leaves with stipules in the 

 form of scarious or membranous sheaths at the strongly marked 

 joints of the stem. The flowers have a green or colored calyx, 

 with the stamens on its base. The one-celled ovary ripens into 

 an akene or* nutlet, which is often triangular in form. Buck- 



