60 



Mycologia 



To those not acquainted with the tropics, it will probably be a 

 little difficult to realize that the larger basidiomycetes are not 

 abundant or even common. The short-lived agarics are seen but 

 infrequently, and then as isolated specimens, or at best in small 

 numbers. One may see as many in an hour in certain good areas 

 in the mountains of Virginia or Kentucky as he would find in a 

 month in Porto Rico. When seen here, the plants are usually in 

 some well-protected spot, and solitary or so few in number that 

 it is difficult or impossible to get a satisfactory herbarium speci- 

 men. Probably great tropical heat is the factor that accounts 

 mainly for the infrequent occurrence of these plants. But the de- 

 velopment of the sporophores in many areas of the moist and uni- 

 formly heated tropics is probably spread about equally through- 

 out the year, and this would account for the infrequent occur- 

 rence of the sporophores at any particular time. Studies of 

 conditions in tropical areas which have wet seasons alternating 

 with dry ones would be interesting in this respect. Such an area 

 was reached about Mayagiiez, but the region was, unfortunately, 

 examined during the dry season. The tougher, more durable pore 

 fungi are seen more frequently, but these are by no means 

 common. 



The region about Yauco was extremely interesting with re- 

 spect to the distribution of fungi. In the city and in the flat 

 country to the south, one is in a desert with a rainfall of probably 

 20 to 30 inches per annum, while in the mountains four or five 

 miles to the north there is abundant rain. In the one area agri- 

 culture is possible only through irrigation. In the other, rainfall 

 is abundantly sufficient for agricultural purposes. Day after day 

 rain fell in the mountains a few miles north of Yauco, while in 

 Yauco and to the south the weather was dry. The mycologist is 

 of course interested to know how the fungous flora is afifected. 

 Agarics and pore fungi were almost entirely absent south of 

 Yauco, but were seen as often five miles to the north as in other 

 parts of the island. The black Perisporiaceae were entirely ab- 

 sent from the desert, while they were abundant on leaves north 

 of Yauco. To the uninitiated, the lichen flora of this desert 

 would appear most uninviting, for scarcely a foliose or a fruticose 



