May 10, 1895.] 



SCIENCE. 



513 



of the cortical system aud the heavy siiher- 

 izatiou are due to the dryness of the air 

 aud probably also to the fires. The thick, 

 irregular, ligneous, subten-anean axial 

 organs (it is often difficult to tell which 

 part is stem and which is root) are also, 

 both in herbs and shrubs, related to the 

 aridity and to the fires. The absence of 

 mosses and of hymenomj-cetous and other 

 sajTophytic fungi is another indication of 

 the dryness. The leaves show the dryness 

 of the climate in numerous waj's. An 

 abundant hairy covering is very frequent, 

 aud the leaves of some species have both 

 surfaces covered with a white or greyish 

 felt, while others have only the lower sur- 

 face felted. The leaves of other species 

 are scabrous, hispid, glaudiUar-hairy, or 

 shining as if lacquered. A few have a 

 waxy covering. Almost always, even in 

 the herbs, the leaves are stifiF and cori- 

 aceous, unless both surfaces are tomen- 

 tose, and on some ti'ees they are so stifl' 

 as almost to jingle in the breeze. Most 

 of the grasses and sedges have narrow 

 stiff leaves. The direction of the leaves 

 also shows the aridity. Manj- are vertical or 

 pointed upward, so as to receive the sun"s 

 raj's at an acute angle. Some species 

 are aphyllous and in others the leaves are 

 much reduced. Usually, the leaves of the 

 forest species are larger and especially 

 broader than those of the campos species, 

 even when of the same family or genus. 

 " The most of the peculiarities which dis- 

 tinguish xerophytes are also found in the 

 plants of the campos, although rarely to 

 such a pronounced degree. The environ- 

 ment does not reach the excessive dryness 

 of the deserts of Africa and Asia, of the 

 high plateaux of Mexico, etc., and this ex- 

 plains the absence of catacese and other 

 Hesliy plants and the rarity or absence of 

 succulent organs, such as tubers and bulbs. 

 The dryness is never so great that vegeta- 

 tion is forced to disappear or dry up en- 



tirely for a longer or shorter period, as hap- 

 pens in the steppe or the desert, and the 

 spring awakening is not so sudden as in 

 these places. The dryness of the campos 

 is also manifest in the fall of the leaves." 

 Every year, when the sun has parched the 

 herbage so that it is almost like hay, the 

 campos are fired so as to get new growths 

 for the cattle. These firings occur most 

 fi-equently from July to September, but also 

 earlier and later. The fires sweep every- 

 thing that is close to the ground, including 

 the lower branches of the trees, and cause 

 the leaves to fall by thousands. When 

 they are set too early, i. e., in May or June, 

 the succeeding vegetation is feeble, and 

 when they are set too late in the spring, /. 

 e., after the spring vegetation has begun, 

 they cause immense and lasting injury. 

 "When set at the proper time the campos 

 are covered in a week or two with a rich 

 carpet of green. Plants blossom earlier on 

 the burned campos, and many species are 

 seldom found in bloom elsewhere. The 

 rarity of annuals has already been men- 

 tioned. The unbranched tufted habit of 

 many shoots and the numerous swollen tu- 

 berous axial organs also seem to be due to 

 the fires, and the numerous big under- 

 ground stubs of trees and shrubs are un- 

 doubtedlj- due solelj' to this cause. 



The forests of Lagoa Santa are not as im- 

 posing, as dense or as moist as those of the 

 coast mountains. Those on the calcareous 

 rocks in jjarticular are quite open, dry and 

 light. Tropical forests sometimes pass for 

 being poor in flowers, but this is only an ap- 

 pearance, the blossoms being concealed in 

 the tops of the ti-ees. Jlost of the trees 

 have small flowers. Like tropical forests in 

 general the ground between the trunks is 

 densely covered, in places imi)enetrably 

 tiingled, with bushes, small trees and lianas. 

 Tlie author observed nearly 400 arborescent 

 species in the forest and thinks the actual 

 number much exceeds this. These trees 



