The most valuable of all the birches for ornamental planting is the cut-leaved weeping variety, classed by Bailey as a variety of Betula alba. If all the varieties with pendent habit should be included as variations of Betula alba this would be correct. But for two main reasons the writer is impressed with the belief that it belongs to a distinct species. When at the Agricultural College, near Moscow, Russia, in 1882, Professor Williams, Professor Shroeder, and Dr. Arnold pointed out the original tree of the cut-leaved weeping-birch, and stated that it was a sport found among several hundred seedlings of Betula Amurensis. A number of the seedlings were found on the grounds, all with pendent habit, which we were told was a peculiarity of the Amur species. But the only one with deeply cut leaves was the sport pointed out. The second reason for believing it a distinct species from the Amur valley is that it is hardy in all parts of the West and Northwest, while the other pendent varieties grown in Eastern nurseries do not endure our summer heat or winter's cold. Indeed, it is a thriftier, longer-lived tree on the prairies than it is near the lakes or east of them. In addition to all this, its seedlings up to the present, so far as observed, are hardy, thrifty, and pendent in habit, but they have entire, or nearly entire, leaves. The typical form and leaf of this handsome variety are shown in Fig. 91.
East of the lakes the canoe-birch (Betula papyracea), the European birch (B. alba), and the sweet birch (B. lenta) are planted to some extent on lawns and in parks, but since the advent of the beautiful cut-leaved weeping variety they are less used. But none of them, except the latter, has proven long-lived west of the lakes. Even the native birches that grow along the streams of eastern Iowa are not durable trees on prairie places or parks.
Fig. 91. - Cut-leaved weeping-birch. (After Maynard.)
All of the birches imported by the writer from the steppes of east Europe have proven defiant to heat, drought, and cold on the college grounds at Ames, and where tested at the West. They were imported under the names of Betula carpinifolia, B. Siberica, B. urticifolia, and B. Maximowiczii. The latter is now mentioned by Alfred Rehder as "probably the most beautiful of all birches, perfectly hardy at the North, and of rapid growth." This species is credited to Japan, but as it is hardy at St. Petersburg and Moscow, and also in the northwest prairie States, it is probable that its home is the Amur valley, from whence Dr. Maximowicz brought the seeds to St. Petersburg and Moscow.