300 THE NURSERY-MANUAL 



own account. The section to which D. aggregatum, D. Jenkinsii, 

 D. densiflorum and D. thrysiflorum belong is best propagated by 

 division. See Orchids, page 372. 



Deutzia. Saxifragacece. 



Commercially, the species are mostly propagated by green 

 hardened cuttings in summer, under a frame. Hardwooded 

 cuttings may be taken in autumn, and be treated in about the 

 same way as currant cuttings. The deutzias are also propagated 

 by divisions and layers. Some of the dwarf sorts are sometimes 

 forced, to make cuttings for winter use. They may also be grown 

 from seeds sown in pans or boxes in spring. 



Dewberry (Rubus species). Rosacece. 



Seeds are handled in the same way as blackberry seeds. In- 

 creased by layers and, like the blackberry, root-cuttings and cane- 

 tips. Layers are made simply by covering the decumbent canes 

 at the joints, but this method is now little used. The tips root 

 freely, as in the blackcap raspberries, and it is from these that the 

 commercial dewberry plants are mostly grown. See Blackberry. 



Dianthus (Carnation. Pink. Sweet William). Caryophyllaceoe. 



Annuals and perennials, all easily grown from seeds. The 

 annual kinds are sometimes started indoors ; but usually the seeds 

 are sown where the plants are to remain. Best results are to be 

 expected in most species when new plants of the perennial kinds 

 are grown from seeds every two or three years, as strong plants are 

 obtained and the beds are kept clear of grass. Plants bloom the 

 second year from seed. Old plants may be divided, if vigorous. 

 See Carnation. 



Dicentra, Dielytra (Bleeding-Heart). Fumariaceoe. 



The clumps may be divided in early spring, or short cuttings may 

 be made of the roots and placed in sand. The native species 

 propagate readily by the underground parts D. Cucullaria by 

 division of the bulbs, and D. canadensis by the little tubers. 

 All species grow from seeds that have been stratified or else sown 

 in autumn. 



Dichorisandra. Commelinaceoe. 



Multiplied by seeds, cuttings of green shoots, and division of old 

 plants. 



