60 KEY AND FLORA 
III. 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-patted 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 flowers 
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). 
4. Fruit annual; leaves not bristle-tipped, though often 
mucronate. 
1. Q. alba L. Wurre 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. Posr 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. Wood hard and valuable. 
3. Q. lyrata Walt. Swamp Oak. A large tree with gray or red- 
dish bark. Leaves obovate-oblong, deeply pinnatifid, 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, 32 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. 
