Rate of Growth and Ecesis in Lichens 



155 



were present. The other Cladoniae were present in small 

 numbers. 



Kentucky, area 29, habitat similar to Kentucky, area 28, 14 but 

 10 m. distant from this and 3.5 m. back from the edge of the 

 cliff in soil of considerable depth. A quadrat 4 dm. square was 

 denuded 5 cm. deep. Growing in the quadrat were 3 green- 

 briers, 3 huckleberry bushes, 2 seeding pines, a few clumps of 

 grass, a conspicuous covering of Cladonia cariosa with few 

 podetia and apothecia, and a few well-developed plants of 

 Cladonia cristatella and C. uncialis. After 10 months many 

 small Cladonia squamules were found scattered over the quadrat. 

 After 4 years the squamules were of larger size. After 8 years 

 the squamules had covered a large proportion of the quadrat, 

 and 25 podetia of Cladonia cariosa were counted, some of which 

 were of normal size. 



Ohio, area 9, on a new plane-tree board, next to the top in a 

 fence on dry ground and exposed to the sun. The new board 

 was placed in the fence 3 weeks before the study was begun, 

 and the old boards above and below the new one were covered 

 along the top edge and the sides by Placodium micro phyllinum. 

 After 2 years 15 minute areas of the Placodium thallus were 

 visible to the eye on the top edge of the new board, the largest 

 area being 1 mm. across. After 3 years hundreds of areas of 

 the thallus were seen scattered over the whole top of the board, 

 some barely visible to the eye, others reaching 0.5 cm. across, 

 while the smallest were visible only under the hand lens. After 

 4 years the areas of thallus were more numerous and larger, and 

 an examination of the whole length of the board with the hand 

 lens resulted in finding 2 young apothecia, one of them with the 

 disk open. After 6 years the thallus was as abundant and as 

 fully developed on the top edge of the board as on the old boards 

 and could be seen 20 m. distant. There were also a few small 

 areas of the thallus on the sides of the new board near the top 

 edge at this time. The lowest of these was 5 cm. down from the 

 edge. Eleven apothecia were found at this time. After 8 years 

 the apothecia were as frequent on the top edge of the new board 

 as on the old boards. The thallus was not distinctly more abun- 

 dant on the new board than it was at 6 years. 



1 4 See Kentucky, area 28, p. 154. 



