NATURALIST IN BRAZIL 



But even in these aquaria the mosquitoes have their enemies, and 

 among these enemies are not only insects and salamanders and fish, 

 but also plants. In the forest of the Alto da Serra I often saw a 

 charming light-blue flower with a long flower-stalk rising from the 

 leafy rosettes of the Bromelias. These flowers belonged to a Bladder- 

 wort, and plants of the Bladderwort family are found also in our 

 European ponds, where they lift a pretty but considerably smaller 

 flower above the surface, while the wide-spreading roots float in the 

 water. 



These roots are covered with tiny bladders, and if we examine 

 such a bladder closely we see that it has an opening, which is closed 

 by a valve (Fig. 6). Since this valve rests on a little ridge, it can 



easily be pushed open by small insects in search 

 of food or nourishment, but once the poor 

 creatures are inside the bladder there is no 

 escape, for pressure on the valve merely shuts 

 it more securely. The little victims die of 

 asphyxiation and starvation, and are there- 

 upon digested by the wall of the bladder, 

 which secretes a sort of gastric juice. The 

 Bladderwort is thus a carnivorous plant, and 

 neath one bladder the species which installs itself in the reservoirs 

 greatly magnified, of the Bromelias traps the small creatures which 



The arrow points to swim about in the water. By means of its long 



the valve of the en- -r- j .i • ^ ui ^ • i_i ^ 



rammed runners this vegetable trap is able to 



creep from one rosette of leaves to another, 



and so continually find fresh hunting-grounds. 



The Brazilian Bromelias have flat, scaly hairs on the edges of 



their leaves, by which they suck up the water, which a special porous 



tissue conveys to the interior of the leaf All these adaptations enable 



the plant, as we have seen, to settle even on bare surfaces of rock. 



Near Nova Friburgo I saw some great domed rocks which from a 



distance appeared to be sprinkled with yellow. They were simply 



covered with Rock Bromelias, which do not produce a rosette of 



green leaves pointing upwards, but only faded-looking leaves, which 



hang down from the plant. These catch the dust which the rain 



brings down with it — and so, by the way, do the epiphytic Bromelias. 



For even the epiphytes cannot dispense with the nutritive salts which 



plants draw from the soil. 



However, the dirty water of the Bromelia's reservoirs contains an 



abundance of these salts in solution. To ensure that they shall 



1 08 



Fig. 6. — Bladder- traps 

 on the roots of the 

 Bladderwort. Be 



