Many other barks were employed in bark canoe construction, but in most instances the craft were for temporary or emergency use and were discarded after a short time. Such barks as spruce (_Picea_), elm (_Ulmus_), chestnut (_Castenea dentata L._), hickory (_Carya_ spp.), basswood (_Tilia_ spp.), and cottonwood (_Populus_ spp.) are said to have been used in bark canoe construction in some parts of North America. Birches other than the paper birch could be used, but most of them produced bark that was thin and otherwise poor, and was considered unsuitable for the better types of canoes. Barks other than birch usually had rough surfaces that had to be scraped away, in order to make the material flexible enough for canoe construction. Spruce bark had some of the good qualities of the paper birch bark, but to a far less degree, and was considered at best a mere substitute. Non-resinous barks, because of their structure could not be joined together to gain length, and their characteristic shrinkage and swelling made it virtually impossible to keep them attached to a solid framework for any great length of time. [Illustration: Figure 5 OJIBWAY INDIAN carrying spruce roots, Lac Seul, Ont., 1919. (_Canadian Geological Survey photo._)] The material used for "sewing" together pieces of birch bark was most commonly the root of the black spruce (_Picea mariana_ (Mill.) B.S.P.), which grows in much of the area where the paper birch exists. The root of this particular spruce is long but of small diameter; it is tough, durable, and flexible enough for the purpose. The tree usually grows in soft, moist ground, so that the long roots are commonly very close to the surface, where they could easily be dug up with a sharp stick or with the hands. In some areas of favorable growing conditions, the roots of the black spruce could be obtained in lengths up to 20 feet, yet with a maximum diameter no larger than that of a lead pencil. [Illustration: Figure 6 ROLL OF BARK FOR A HUNTING CANOE. Holding the bark is the intended builder, Vincent Mikans, then (in 1927), at age 100, the oldest Indian on the Algonkin Reserve at Golden Lake, Ont.] Other roots could be used in an emergency, such as those of the other spruces, as well as of the northern white-cedar (_Thuja occidentalis_ L.), tamarack (hackmatack or eastern larch) (_Laris laricina_ (Du Roi) K. Koch) and jack pine (_pinus banksiana_ Lamb.), the last named being used extensively by some of the western tribes. Although inferior to the black spruce for sewing, these and other materials were used for sewing bark; even rawhide was employed for some purposes in canoe construction by certain tribes.