Oak trees are characterized by oblong, thin-shelled kernels, protruding from hard scaly cups and called acorns. The foliage is sometimes deciduous and sometimes evergreen. Most oaks require many years to reach maturity, but are then long-lived. Fifty of the nearly three hundred known species of oak are natives of the United States and Canada; all but four become trees under favorable conditions. Quercus is from two Celtic words, _quer_, signifying fine, and _cuex_, a tree. [p013] [Illustration: LIVE OAK (_Quercus virginiana_).] FOOTNOTES [Footnote 12: Thought by some botanists to be distinct species, namely, Quercus pedunculata and Quercus sessiliflora.] [Footnote 13: Havemeyer Chemical Laboratory, N. Y. University.] [Footnote 14: Communication. Mr. Chas. H. Cramp, President Cramp Ship-building Co., Philadelphia.] [Footnote 15: This division is also a botanical one based not only on differences in anatomical structure of the wood itself, but on the time required by fruit in attaining maturity, and on persistence of foliage (evergreen or deciduous), etc.] WHITE OAK. _Quercus alba Linn._ Nomenclature. White Oak (general). Stave Oak (Ark.). Locality. Widespread, north-central and eastern United States. Features of Tree. Seventy-five to one hundred feet in height. Three to six feet in diameter, fine shape and appearance. Grayish-white bark. Comparatively sweet ovoid oblong acorns in rough shallow cups. Rounded lobes or projections to leaves. Color, Grain, or Appearance of Wood. Heartwood brown with sapwood lighter. Annual layers well marked. Medullary rays broad and prominent. Structural Qualities of Wood. Tough, strong, heavy, hard, liable to check unless seasoned with care. Durable in contact with the soil. Receives a high polish. Representative Uses of Wood. Ship-building, construction, cooperage, cabinet-making, railway ties, fuel, etc. Bark is rich in tannin. Weight of Seasoned Wood in Pounds per Cubic Foot. 50 (U. S. Forestry Div.).[16] 46. Modulus of Elasticity. 2,090,000 (average of 218 tests by U. S. Forestry Div.).[16] 1,380,000. Modulus of Rupture. 13,100 (average of 218 tests by U. S. Forestry Div.).[16] 12,800. Remarks. A tree of the first economic importance. The most widely employed of all American oaks. Name refers to appearance of bark. The supply diminishing because of value of timber, also the sweetness of nuts cause them to be eaten by animals. [p014] FOOTNOTE [Footnote 16: See page 6.] COW OAK. _Quercus michauxii Nutt._ Nomenclature. (Sudworth.) Cow Oak (local and common name). Basket Oak (Ala., Miss., La., Tex., Ark.). Swamp White Oak (Del., Ala.). Swamp Chestnut Oak (Fla.). Locality. Southeastern United States, Delaware and Florida, westward along Gulf to Texas. Also southern Indiana and Illinois to Gulf. Best on rich bottoms in Arkansas and Louisiana. Features of Tree.