THE BRYOLOGIST. 



Vol. V. November, 1902. No. 6. 



LICHENS— UHBILICARIA. 



By Carolyn W, Harris. 

 This is a genus of which some species are familiar to almost every one. 

 The large, leathery looking "Rock Tripe" is one; this name is applied to 

 several species. 



It is said that many of the early explorers to the North Pole ate of this 

 rather unpleasant looking plant and were made ill by it. Like many of the 

 lichens it contains a small amount of nourishment. 



AtChilson Lake, Essex Co., New York, five species of Umbilicaria are 

 found, only one of which is at all rare, U. vellea. The others U. Dillenii, 

 pustulata, MuhUnbergii and Pennsylvanica are common on granite rocks 

 where there is a good deal of moisture. The family Umbilicariei has only 

 the one genus, Umbilicaria, which by some lichenists has been divided, and 

 certain of the species have been placed under the name of Gyrophora ; this 

 division goes back to an early date. The structure of the thallus really has 

 very few important differences, the fruit still less, so at present it seems wise 

 to include all the species under the name of Umbilicaria. Fries says "it is 

 the secret of all systematic study adequately to apprehend the distinction 

 between close affinity and superficial or subtile differences." Many import- 

 ant questions relating to the lichens are unsettled, just as it is with the 

 mosses, only the difficulties seem more numerous, as less systematic work 

 has been done on the lichens. Much can be learned regarding them never- 

 theless ; some genera are clear and settled for the present, at least. So con- 

 scientious work on the lichens will not belost |time,and all will help to decide 

 some of the unsettled problems. In many lines of work if we wait until the 

 last question is settled we shall find that our chance for helping in the work- 

 ing out of the problems is past. 



The specimens of Umbilicaria vary greatly in size, some are an inch in 

 diameter, others nearly a foot. The thallus is horizontal and foliaceous, and 

 is always fastened at one point to the substratum by a stalk-like disk or um- 

 bilicus. The margin is frequently torn or ragged. The prevailing color of 

 the upper surface is brown or grayish-brown, the lower side is a very dark- 

 brown or black, with black rhizoids or scaly layers. The apothecia are ses- 

 sile upon the upper surface of the thallus and are very interesting in 

 appearance, as well as in structure. On examination with a hand lens the 

 disk presents a convoluted appearance; it is convex and black, the length- 

 wise folds or plaits are unusual looking. 



The Umbilicarias are Northern in their range, but are common in the 

 mountains of the Southern states and even in the torrid zone. When collect- 

 ing them, if the atmosphere is moist they will be soft and pliable, and can 

 be put under a light pressure until dry, then will be ready for mounting. 



The September Bryologist was issued September 2d, 1902. 



