48 PASTURE STUDIES: SOME RESULTS. 
years on Area 2, as on Area 4 at 134 years it had a very high 
percentage frequency. 
Potentilla erecta, 
As shewn by a Sp. fr. of 87 on Area 8, this is a typical grass- 
heath plant.t It is recorded as an abundant arable land weed in 
exceptional cases by Stapledon (17), and results obtained by the 
present writer on land which had been brought under cultivation 
from a rough grass heath at an elevation of 150 feet in Anglesey,? 
shows that where the land is not thoroughly cleaned it may occur 
in considerable quantity both in the stubble and in the young 
pastures. These results were as follows :— 
(t) Sp. fr. on pasture 1% yearsold: 66 
(2) “ % 2% ‘3 46 
(3) ‘i - 2 i 60 
(4) stubble following (3) 46 
In these cases, the plants have in most cases undoubtedly 
survived the period of cultivation bodily, as shown by their strong 
root-stocks. It is net surprising, therefore, to find the plant fairly 
widely distributed in most of the present areas. 
On Area r it was not recorded except in very small quantity 
at 34 years, and on Area 3, which had been thoroughly cleaned, 
it was net recorded in the Sp. fr. examination at 7} years, and 
only to a very slight extent by the P.c. fr. method at 9} years. 
Even on Area 2, which had not been partly under a cleaning 
crop, it only had a Sp. fr. of 3 at 54 years, but this had increased 
to 17 at 84 years, and the same Sp. fr. was again found at 10} 
years, while on Area 4 adjoining, its Sp. fr. was also 17 at 134 
years. On Area 5 at rod years, however, it was much less widely 
distributed. 
Thus, on this type, the plant probably survives a period of 
imperfect cultivation to some extent, and then increases fairly 
slowly, but its rate of increase becomes much less when it has 
attained a Sp. fr. of about 17, and therefore in respect of this 
tof. (21). 
? Ceidio ‘Isaf, Llanerchymedd, 
