IV 



TROPICAL FLORAS 



67 



Lagoa Santa (2490 species) 



The chief feature which distinguishes this flora from that 

 of Nicaragua and Costa Rica is the presence in some abund- 

 ance of the highly characteristic South American order 

 Malpighiaceae, the high position of Myrtaceae, with Labiates 

 and Asclepiads in place of Aroids and Palms. Of the 

 rather numerous Orchids about 70 are terrestrial, 50 

 epiphytes. There are over 40 genera, of which Spiranthes 

 has 16 species, Habenaria 12, while 22 have only 1 species 

 each. The very large American genus Oncidium has only 

 5 species, while the grand genus Cattleya, so abundant in 

 many parts of Brazil, seems to be entirely absent. 



Adaptations to Drought 



The plant figured on the next page, like many others of 

 the campos, has its roots swollen and woody, forming a store 

 of water and food to enable it to withstand the effects 

 of drought and of the campo- fires. The old stems show 

 where they have been burnt off, and the figures of many 

 other plants with woody roots or tubers, figured by Mr. 

 Warming, show similar effects of burning. 



Still more remarkable is the tree figured on p. 69 

 (Fig. 7), which is adapted to the same conditions in a 

 quite different way, as are many other quite unrelated 

 species. 1 The group of plants shown is really an under- 

 ground tree, and not merely dwarf shrubs as they at 

 first appear to be. What look like surface - roots are 

 the upper branches of a tree, the trunk of which and 

 often a large part of the limbs and branches are buried 

 in the earth. The stems shown are the root-like branches, 



1 The following species have a similar mode of growth : Anacardium humile, 

 Hortia Brasiliensis (Rutaceoe), Cocklospermum insigne (Cistacese), Simaba 

 Warmingiana (Simarubacese), Erythroxy'on campestre (Erythroxylacere), Plumicra 

 Warmingii (Apocynacese), Palicourea rigida (Cinchonaceas), etc. 



