THE PLANT WORLD 111 



Briefer Articles. 



FRUIT WHICH ACT AS LEAVES. 



Noticing the great bulk of the green surface of the fruiting racemes 

 of the plants of peppergrass {Lepidium apetalum), it occurred to me to 

 compare it with the leaf surface of the same plants. The little pods are 

 flat, and nearly round in outline, with slightly convex sides. Each one 

 exposes approximately six square millimetres of surface. An examina- 

 tion shows that the epidermis is abundantly provided with stomata, and 

 that the parenchyma is composed of chlorophyll-bearing cells, quite 

 like those in the leaves. 



As is well known, this species of peppergrass drops its lower leaves 

 early, and the lower part of the stem is often entirely naked. The re- 

 maining leaves, M^hen there are any, are small, and vary from almost 

 pinnatifid to nearly linear. 



On a plant thirty centimetres high about one thousand pods were 

 found. These were in the branching racemes on the central axis and 

 ten lateral branches, the racemes taken together having an aggregate 

 length of about one metre. The total green surface on the racemes was 

 therefore about six thousand scjuare millimetres. 



By measuring a number of leaves and making careful counts and 

 estimates, it was found that the leaf surface (counting both surfaces) on 

 the plant was 6280 square millimetres. 



It is to be noted that the racemes and fruits assume such positions 

 as to bring one of the flat surfaces of the pods directly into the light. In 

 other words, these structures are heliotropic, and act in this regard like 

 leaves, and it can not be doubted that they function as leaves. Appar- 

 ently this peppergrass dispenses with some of its leaves, and compels 

 its pods to assume the leaf function. Later in the season the plants 

 have still fewer leaves, and then photosynthesis must be carried on al- 

 most entirely by the green surface of the stem and the chlorophyll- 

 bearing pods. Charles E. Bessey. 

 The University of Nebraska. 



THE FALL OF PORTO RICAN FORESTS. 



More than half a century ago the Spanish planters of this island 

 began clearing the interior districts for coffee and tobacco culture. 

 There being no good roads and but little demand for the timber, the trees 



