84 



SILVA OF NORTH AMERICA. 



CONIFERS. 



flattened awns, rigid and woody at maturity, those at the base of the cone destitute of scales, becoming 

 linear-lanceolate by the gradual suppression of their lobes.^ Seeds geminate, reversed, attached at 

 the base in shallow depressions on the inner face of the cone-scales, nearly triangular, rather longer 

 than broad, full, rounded, and dark-colored on the upper face, more or less flattened and pale on the 

 lower face, destitute of resin vesicles, in falling bearing away portions of the membranaceous lining of 

 the scale forming oblong wing-like ultimately deciduous attachments, and enveloping the upper side 

 of the seeds in a dark covering adnate to the testa \ testa of two coats, the outer thick and crustaceous, 

 the inner thin and membranaceous. Embryo axile in conspicuous fleshy albumen; cotyledons from 



■ V 



six to twelve, usually seven or eight, stomatiferous on the upper surface. 



Pseudotsuga is intermediate in character between Tsuga and Abies, resembling the former in its 

 petioled leaves but differing from it in the exserted bracts of the cone-scales and in the absence of resin 

 vesicles on the seeds, and from the latter in the spurred connectives of the anthers, and in the 

 pendulous cones with persistent cone-scales. The genus is represented by three species 3 one is widely 

 distributed over western North America from about latitude 53° north in British Columbia to northern 



r 



Mexico ; the second is confined to the dry sides of canons on the mountains of southwestern California, 

 and the third, which is still little known, grows in Japan .^ 



Pseudotsuga produces hard durable valuable wood which is distinguished from that of other 

 coniferous trees by its numerous spirally marked wood cells, and one of its species is one of the largest 



;mi 



Pseudotsuga is not known to be seriously injured by insects^ or fungal diseases.* 

 Like the other Abietinese, trees of this genus can easily be raised from seeds, and Pseudotsuga 

 mucronata^ the type of the genus, is one of the most splendid ornaments of the parks of temperate 



countries. 



The generic name, a barbarous combination of a Greek with a Japanese word, signifies the 



relationship of these trees with the true Hemlocks. 



1 See Lloyd, Bull. Torrey BoL Club, xxv. 90, t. 327 (On an Ab- 

 normal Cone in the Douglas Spruce). 



2 Pseudotsuga Japonica. 



Tsuga (Pseudotsuga) Japonica, Shirasawa, Tokyo Bot, Mag. ix. 



86, t. 3 (1895). 



The Japanese Pseudotsuga, which was discovered only a few 

 years ago by Mr. Homi Shirasawa near Yoshino, in the province of 

 Kii, at an elevation of about two thousand feet above the sea, is 

 distinguished by shorter and broader leaves and smaller cones than 

 those of the American species, while the bracts of the cone-scales 

 appear strongly reflexed in Mr. Shirasawa's plate. It is described 

 as a tree from forty-five to sixty feet in height, with an erect 

 straight trunk, horizontally spreading branches, and spire-like top, 

 growing in forests of Birches, Hemlocks, Oaks, Magnolias, and 

 Acanthopanax. (See Garden and Forest, viii. 129. — Gard. Chron. 

 ser. 3, xvii. 462.) 



^ Very little is yet known of the insects which attack Pseudo- 

 tsuga in its native forests, and there is no record of their mate- 

 rially injuring cultivated trees. The species of Scolytitax, among 



them being Scolytus unispinosus, Le Conte, are known to burrow 

 under the bark of Pseudotsuga mucronata in California, and it is 

 probable that several of the insects which obtain their food from 

 different species of Picea and Abies will be found to live also on 



Pseudotsuga. The larvse of the small moth GrapTiolitha hractea- 

 tana, Fernald, has been reported as injurious to its cones in Oregon, 

 nearly half the crop of the seeds of 1897 having been destroyed in 

 one locality by this insect, and by the larvse of a cecidomyiid fly 

 which accompanies it. (See BulL No. 10, n. ser. Div, Entomolog. 

 U. S. Dept. Agric. 1898, 98.) 



* Pseudotsuga appears to suffer little in the United States from 

 the attacks of fungi, where hardly a dozen species have been noted 

 on it, and none of these are known to cause any serious disease or 

 to be confined especially to this host. Possibly a species of Perider- 

 mium which occurs on Pseudotsuga mucronata in Colorado may 

 prove injurious to this tree, but its fungal characters are not yet 

 well understood. Two species of fungi, however, are said to do 

 considerable damage to Pseudotsuga mucronata when cultivated in 

 Europe. In 1888 Von Tubeuf described a Boirytis Douglasii which 

 appeared in Germany in widely separated localities, and caused the 

 young leaves to wither and shrivel up. This disease has been occa- 

 sionally noticed since, although mycologists are inclined to doubt 

 whether Botrytis Douglasii is really distinguished from Botrytis cine- 

 reay Persoon. Oudemans has recently described a mould, Oospora 

 Abietum, which in Holland injures the leaves of Pseudotsuga mucro- 

 nata and of different species of Picea. 



