60 KEY AND FLORA 



ra. QUERCUS L. 



Trees or shrubs with entire, serrate, or lobed leaves, which 

 are often persistent. Staminate flowers in slender catkins, 

 each subtended by quickly deciduous bracts, and consisting 

 of 3-12 stamens inclosed by a 4-8-parted perianth, often 

 containing an abortive ovary. Pistillate flowers solitary or 

 in small clusters, each consisting of a 3-celled ovary with 

 2 ovules in each cell, though rarely more than 1 ovule 

 matures ; styles short, erect, or recurved. Pistillate flower's 

 surrounded by a scaly involucre which at maturity becomes 

 a cup inclosing the base of the fruit or sometimes a large 

 part of it. Fruit an ovoid or subglobose, 1-seeded, thin- 

 shelled nut (acorn). 



A. Fruit annual; leaves not bristle-tipped, though often 

 mucronate. 



1. Q. alba L. White Oak. A large tree with light gray bark. 

 Leaves obovate-oblong, 3-9-lobed, lobes rounded and mostly entire, 

 bright green above, paler below, short-petioled. Cup hemispherical, 

 scales rough, woolly when young, but becoming smooth with age ; 

 acorn oblong-ovate, about 1 in. long. Common in damp soil. Wood 

 strong and durable ; one of the most valuable timber trees.* 



2. Q. stellata Wang. Post Oak. A tree of medium size with 

 rough gray bark. Leaves broadly obovate, deeply lyrate-pinnatifid 

 into 5-7 rounded, divergent lobes, upper lobes much the longer, 

 smooth above, yellowish-downy beneath ; petioles about 1 in. long. 

 Cup hemispherical, nearly sessile ; acorn ovoid, 2-3 times as long as 

 the cup. On dry soil. AVood hard and valuable. 



3. Q. lyrata Walt. Swamp Oak. A large tree with gray or red- 

 dish bark. Leaves obovate-oblong, deeply piunatifid, lobes narrow, 

 often toothed, thin, smooth above, white, densely woolly beneath. 

 Cup round-ovate, scales cuspidate, inclosing nearly the whole of the 

 depressed-globose acorn. On wet soil. Wood strong and very durable.* 



4. Q. macrocarpa Michx. Bur Oak. A medium-sized to very large 

 tree, with roughish gray bark. Leaves obovate or oblong, lyrately 

 and deeply sinuate-lobed, smooth above, pale and downy beneath. 

 Cup very deep and thick, abundantly fringed about the margin, |-2 in. 

 in diameter. Acorn, half or more (sometimes entirely) inclosed by 

 the cup. Reaches its full size only on rich bottom lands S. and W., 

 where it becomes one of the finest timber oaks. Wood very hard 

 and heavy. 



