54 THE AMERICAN BOTANIST 



mach, though equally decorative have to be ruled out because 

 of their hannful qualities. A large number of the sumach's 

 allies in other parts of the world are more or less under sus- 

 picion but others are among our most decorative species and 

 the fruits of several are edible. The pepper tree (Schinus 

 mollis) so largely planted in California is a member of this 

 family and the famous tropical fruit the mango {Mangifer 

 Indica) is another. The cashew nut {Anacardium occidentale) 

 also belongs to the sumach family. In flower and fruit, all 

 these species resemble our common sumach in a general way, 

 having clusters of fruit each of which contains a single seed, 

 but here the resemblance ceases for the tropical fruits are 

 larger than peaches. 



Forests and Water-flow. — The influence of forest 

 cover on water-flow is of a three fold nature : (1) the mechani- 

 cal obstruction which the foliage offers reduces the amount of 

 water which reaches the soil and lengthens the time during 

 which it can do so; the foliage together with the loose litter of 

 the forest floor also reduces the compacting effect of the rain- 

 drops and the drying effect of sun arid wind and keeps the soil 

 granular, so that the water can easily percolate; (2) then the 

 mechanical obstruction which the litter, underbrush and trunks, 

 and possibly here and there moss, offers to the rapid surface 

 drainage of waters, lengthens the time during which this per- 

 colation may take place; and (3) the network of d'eeply pene- 

 trating roots, live and decayed, offer additional channels for a 

 change of surface drainage into sub-drainage. In addition, ow- 

 ing to the influence on temperature and moisture conditions of 

 the air, together with reduced evaporation, more water be- 

 comes available to the soil, and certainly the fact that the water 

 by ready percolation, is wthdrawn from the dissipative effects 

 of sun and wind must tend in this direction. We should con- 

 sider the protection of our watersheds as much a national prob- 

 lem as the improvement of our water ways, and even more so. 

 — Dr. B. E. Fernow. 



