Fifty to eighty feet in height, three to four feet in diameter, dark reddish-brown bark, resembling that of cherry; does not separate into layers as paper-birch. Leaves, bark, and twigs sweet, spicy, and aromatic. Color, Appearance, or Grain of Wood. Heartwood dark brown tinged with red, sapwood light brown or yellow, close-grained, compact structure. Structural Qualities of Wood. Heavy, very strong, hard, receives stains and high satin-like polish. Representative Uses of Wood. Woodenware, furniture, ship-building (Canada), fuel. Weight of Seasoned Wood in Pounds per Cubic Foot. 47. Modulus of Elasticity. 2,010,000. Modulus of Rupture. 17,000. Remarks. A common tree in Northern States. Wood often stained so as to resemble cherry and mahogany. Essences suggest wintergreen, contain much salicylic acid, and are used in medicine. The name "cherry" is because bark resembles that of cherry. "Sweet" is because of essences. [p075] [Illustration: PLATE 15. LOCUST (_Robinia, Gleditsia_). Black Locust Tree and Bark (_Robinia pseudacacia_). Honey Locust (_Gleditsia triacanthos_). Locust Wood.] LOCUST, MESQUITE. (_Robinia, Gleditsia, Prosopis_.) The name Locust applies to species of three distinct genera, all of which belong to the family Leguminosæ. The black locust (_Robinia pseudacacia_), the honey locust (_Gleditsia triacanthos_), and the Mesquite or honey locust (_Prosopis juliflora_) are principal representatives of their respective kinds. The first-named genus is North American, the other two have species on both continents. [Illustration: BLACK LOCUST (_Robinia pseudacacia_).] Black locust wood is tough, durable, unequalled for torsional strength and resilience, and is in every way in the first rank of American woods. It is fitted not only for exposed constructions, but for finer articles; hubs, pins, bolts, and trenails having no superiors. Trees develop rapidly when young, heart wood forming as early as the third year. Later growth and ultimate commercial value in the United States are much affected by insect borers, which practically limit the usefulness of the species. The black locust may be known by its clusters of large pea-blossom-shaped flowers, its bean-shaped pods, three to six inches in length, and by the prickles on the bark. The genus has six species, four of which are natives of the United States.[45] _Robinia_ is from Robin, the name of an early French botanist. [p076] The black locust has been extensively introduced into Europe, both for ornamentation and for wood.[46]