XXXVII. THE ROCK ROSE FAMILY. 515 



two or three years, after which they find the shoots well rooted, 

 and of a sufficient height and strength to be planted at once 

 where they are finally to remain." This mode is also practised 

 with the elm. 



Hunter gives the following directions for forming layers from 

 shoots of the American lime : — "When the layering of these is 

 to be performed, which ought to be in the autumn, the strong 

 two years' shoots must be brought down ; and if they are stiff 

 and do not bend readily, they must have a gentle splash with 

 the knife near the bottom ; a slit should be made at the joint for 

 every one of the youngest twigs, and their ends bent backwards 

 that the slit may be kept open. This being done, the mould 

 must be levelled among the layers, and the ends of them taken 

 off to within one eye of the ground. The business is then done ; 

 and the autumn following they will have all good roots, many 

 of which will be strong, and fit to plant out for good, whilst the 

 weakest may be removed into the nursery ground, in rows, to 

 gain strength." 



The lime tree is found from Canada to Georgia ; most abun- 

 dantly on the shores of Lake Erie and Lake Ontario. I have 

 observed it, in almost every part of this State, sometimes grow- 

 ing vigorously even in the most sandy and exposed situations. 

 It appears to be very little affected by the sea-breeze, and might, 

 probably, without much difficulty, be made to grow on Nan- 

 tucket and amongst the sands of Cape Cod. 



I cannot give the dimensions of many large trees of this kind. 

 Mr. Austin Bacon, of Natick, has favored me with the account 

 of one of a size somewhat remarkable. It is 16 feet 6 inches in 

 circumference at the ground, and 13 feet 4 inches at 4 feet. 

 Near by is another of almost equal dimensions. 



FAMILY XXXVII. THE ROCK ROSE FAMILY. CISTA'CEJS. 



JUSSIEU. 



This family is of interest to florists and gardeners for the 

 great beauty, variety and elegance of its flowers. It con- 



