This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Forest trees producing a balsamic resin, with furrowed bark, and terete or sometimes corky-winged branchlets. Leaves alternate, glandular-serrate, pal-mately lobed or unlobed; stipules mostly deciduous. Flowers usually monoecious, sometimes perfect, in heads surrounded by three or four deciduous bracts. Perianth wanting. Heads of staminate flowers in terminal racemes or panicles; androecium of numerous stamens, interspersed with minute scales. Pistillate flowers in solitary, long-peduncled axillary heads; gynoecium of two united carpels; ovary partly inferior; stigmas stout; ovules several or numerous in each carpel, horizontal. Fruit a hard, dry, multicapsular head, sometimes armed with the stout persistent stigmas. Capsules opening at the apex, between the bases of the stigmas. Fertile seeds few, winged; testa crustaceous; embryo straight, imbedded in fleshy endosperm; cotyledons flat. Sterile seeds numerous, wingless, angled.
Five genera and about 10 species, natives of southern Europe, Asia, and eastern North America.