CALIFORNIA SYCAMORE. _Platanus racemosa Nutt._ Nomenclature. Sycamore, Buttonwood, Buttonball Tree, Buttonball (California). Locality. California. Features of Tree. Seventy-five to one hundred feet in height, occasionally higher; three to four feet in diameter. The bark exfoliates in irregular patches. Color, Appearance, or Grain of Wood. Heartwood light reddish brown, sapwood lighter, close-grained, compact structure, medullary rays numerous and conspicuous. Beautiful when quartered. Structural Qualities of Wood. Brittle, very difficult to split and to season. Qualities similar to those of P. occidentalis. Representative Uses of Wood. Decoration, furniture, similar to P. occidentalis. Weight of Seasoned Wood in Pounds per Cubic Foot. 30. Modulus of Elasticity. 800,000. Modulus of Rupture. 7900. Remarks. Hough mentions[41] a tree twenty-nine feet seven inches in circumference. [p068] FOOTNOTE [Footnote 41: "American Woods," Part 6, p. 36.] BIRCH. (_Betula_.) The birches grow in Europe, Asia, and North America, their ranges on the latter continent extending far into the north.[42] Their history is remote and probably began with attention to the bark rather than to the wood. Birch-bark is smooth, pliable, water-tight, and by reason of its resinous oils so durable that it often remains intact long after the wood inside of fallen trees has disappeared. It is separable into thin layers and was early employed as a writing material.[43] Houses have been covered by it and it has been used for cordage, utensils, "damp courses," and even rude clothing. The American Indians employed it for canoes, tents, troughs, and buckets. The wood is hard, heavy, strong, fine-grained, and beautiful. It shrinks in seasoning, works easily, stands well when not exposed. It is used for spools, woodenware, and other small articles, as well as for interior finish and cabinet work. Figured birch is one of the most beautiful of American cabinet woods.[44] Birch is often stained so as to imitate cherry and mahogany; the best imitations of the latter wood are of birch. Birch is commercially divided, according to the quantity of heartwood present, into white birch and red birch. The wood is "white" when the amount is small, and as heartwood increases with age the same tree might at one time afford white and at another red wood. Birch trees may be known by their more or less laminated bark with its peculiar long horizontal lenticles or dashes. The [p069] leaves of the several birches differ but little, but the decided colors exhibited by their barks give names and serve to distinguish the species. Nine of the twenty-four known species of birch occur in North America; six are trees and the others low shrubs. _Betula_ is said to be derived from bitumen. [p070] FOOTNOTE [Footnote 42: Birch forms large forests in the North.]