830 



C. SKOTTSBERG 



the historical factor, i. e. the origin and evolution of this insular flora, a problem 

 not discussed in this paper. 



It remains to cast a glance on the spectrum for Masafuera. We learn from 

 Table XIX that it differs not little from the spectrum for Masatierra in the percent- 

 age of Ph, which is much lower, and in the percentage of Ch, which is much 

 higher. It is evident that this spectrum cannot apply to the vegetation below 

 the timber-line. Nor is it possible to get a correct idea of the relation between 

 the life-forms in the highland only from the fact that of the 21 species restricted 

 to this region 2/3 are Ch and 1/3 H. Many species extend their range through 

 both regions. For these reasons it seems advisable to treat them separately; see 

 Table XXIII. 



In the forest region Ph dominate in spite of the small number of rosette-trees, 

 which are so important on Masatierra. The region above the timber-line has a 

 Chamaephyte climate of oceanic type. 



As a complement to his life-forms Raunkiaer later (./) introduced his leaf-size 

 classes, lepto-, nano-, micro-, meso-, macro-, and megaphyllous. The allotment of 

 the flowering plants of Juan Fernandez is found in Table XXIV. 



Chapter III. 

 Morphological and biological remarks on the Vascular Plants. 



The leading forest-trees. 



The dominant trees of Masatierra are Nothomyrcia ferftajideziana, Drimys 

 confertifolia, and Fagara mayu, of Masafuera Myrceugenia Schulzei dind Drimys; 

 Fagara externa, the vicarious species of Masafuera, does not take a leading part 

 in the formation of the forest. Second to these, but common on both islands, 

 comes Coprosnia pyrifolia. 



Nothomyrcia fernandeziana (Hook, et Arn.) Kausel, "Luma". Myrtaceae. 

 The dominant tree all through the forested section, extending from near the sea 

 (at least in bygone times) to the highest ridges wherever a suitable habitat is 

 found, but not reported from the summit of El Yunque; ranging west to Ouebrada 

 Juanango on the north side and to the foot of the precipice of Cerro Chumacera 

 on the south side. In good soil 15 — 20 or even 25 m (Johow) tall with a trunk 

 diameter of 25 — 30, in very old specimens as much as 50 or 60 cm, the largest 

 measured by me 80 cm at the base and 71.5 cm 1.5 m above the ground. Isolated 

 specimens with a broad, very compact head (Fig. 6). Trunk often angular in 

 section and several-stemmed trees not uncommon (Fig. 6). Bark smooth, light 

 gray with large lenticels, thin (i — 2 mm), as a rule with numerous epiphytes, 

 among which a purple FrullaJiia is conspicuous. Leaves (Skottsb. j, PI. 7:2) 

 stiff chartaceous, dark green, often covered with the sooty black fungus Limaci7iia 

 scoriadea, according to Johow (s. n. L. fernandezia7ia) very destructive, but I did 

 not get the impression that it ever kills the trees. Buds naked, pubescent. The 



