122 WOODY PLANTS OF MASSACHUSETTS. 



although, in the several species of the same group, there is a 

 striking similarity, and I have gathered from the same stock, 

 leaves which would seem to belong to several different species. 

 Indeed, the nearly allied species are not to be distinguished by 

 their leaves alone, viewed at any one season. 



The oak is distinguished from all other trees by its acorn, for 

 which the fruit of no other tree can be mistaken. The leaves of 

 all the species are larger towards the extreme end ; in some, they 

 are more or less deeply lobed, with rounded or blunt lobes ; in 

 others, toothed with large, round teeth ; in others, deeply cut, 

 with the divisions terminating in a long, bristle-like point, called 

 a mucro. All the leaves are more or less downy while young, 

 and many retain the down on the lower surface, when mature. 

 The leaves of young plants, and of sprouts from the stumps of 

 trees, are usually much more entire, as well as larger, than 

 those on the mature tree. They come out late, and with them, 

 or just before, the flowers. These differ less than the fruit, by 

 which alone can some of the species be satisfactorily distin- 

 guished. 



The stipules are membranaceous and perishing. The oak 

 has but little medulla, but it continues in very old trees. 



The flowers of both sexes are on one plant ; the sterile disposed 

 in long, slender, pendulous catkins, which are in groups ; the fer- 

 tile flowers in a bud-like, scaly cup. The ovary or seed-vessel 

 of the fertile flower is divided into three compartments or cells, 

 in each of which are two embryo seeds or ovules ; but only 

 one ovule in one of the cells comes to perfection; hence the 

 fruit is a one-celled, one-seeded acorn, surrounded at base by 

 the enlarged, scaly cup. 



The acorns of the different species differ in being, long and 

 narrow, or short and round, pointed or blunt, on footstalks or 

 sessile, and particularly in the scales of the cup in which the 

 acorn is set. The acorns of some species come to maturity in 

 a single season, but a considerable part of the New England 

 species require two seasons to ripen. There is scarcely any 

 seed in which the vitality is so transient, at least when the acorn 

 is preserved artificially. Few of them will germinate after 

 having been kept a year. Most of the oaks, those particularly 



