OAK 
of the year. There is no corolla. The calyx is bell-shaped 
and divided into four to six divisions. The stamens, usually 
four to six, with exserted filaments and oblong two-celled 
anthers, are borne on the torus. The ovary has aborted. 
The pistillate flowers are subtended by a quick falling bract 
and are borne in few-flowered spikes, or on solitary peduncles 
produced from the axils of the 
leaves of the year. The calyx 
is urn-shaped and grows fast to 
the ovary. The stamens have 
aborted. 
The ovary is inferior, incom- 
pletely three-celled and inclosed 
more or less by a growing scaly A Staminate and a FPistillate Flower 
involucre which in time develops ae DEES 
into the acorn cup. Styles are 
usually three, short or long, erect or curved, generally per- 
sistent on the fruit. There are two ovules in each cell, but 
all save one fail to be nourished. The nut is a fruit formed 
by the adhesion of an ovary to the calyx and matures either 
the first or second year; it is always surrounded at the 
base, or more or less inclosed, by a woody involucre called 
the cup. The acorn cup is of woody texture made up of a 
large number of tiny scales which have grown together, 
sometimes entirely, sometimes with free tips. The seed fills 
the nut. The cotyledons are thick and fleshy, the radicle 
minute. An acorn should never be allowed to become dry if 
it is desired that it should germinate, for the vital principle 
is fleeting. 
American oaks in the popular mind have the reputation of 
being slow growers, but this is based upon the habit of two or 
three species rather than upon the habit of the family. The 
White and the Bur Oaks grow slowly. The Scarlet Oak is mod- 
erately slow. But the Black, the Swamp White, the Pin, and 
the Red, under favorable conditions, will all grow rapidly in 
their youth. Probably most oaks require a century to reach 
maturity ; they rarely bear acorns under twenty years of age 
425 
