2i6 PLANT CULTURE 



SEMPERVIVUM (Houseleek). Dwarf, succulent plants, well 

 suited for dry, exposed positions in the rockery. S. lector um'is the 

 species commonly grown. 5. arachnoideum has small rosettes of 

 leaves connected at the tips by a cobweb-like formation. Other 

 well-known species are S. calcareum {S. calif ornicum) , S. Funckii, 

 S. hirlum and 5. soboliferum. They will thrive in almost any kind 

 of soil. Houseleeks are cultivated more for foliage than for flowers. 

 They are used considerably for carpet-bedding, rockwork and cover- 

 ing dry banks and sandy wastes. They are of easy culture. 



Propagation. The hardy species are easily increased by divi- 

 sion, also by means of the offsets or rosettes. 



SILENE (Catchfly). In this very large genus there are 

 three perennial species, each one growing only a few inches tall, 

 which are among our finest rockwork plants. S. Schafta has bright 

 purple flowers; it is a very deep rooting species, and stands dry 

 weather well, keeping in bloom for several months. It can be raised 

 from seed; or old plants divide well in October. Dig up the plant 

 carefully, saving all of the roots, and in dividing give each piece as 

 much root as possible; put in pots and keep in a coldframe for the 

 Winter. 5'. alpeslris is a neat growing little plant with white flowers. 

 5. maritima forms a dense carpet of growth, the branches from a 

 single plant covering a large surface. The flowers are white and 

 are rather showy; they last only a short time, however. The foliage 

 is handsome for the greater part of the year, being very neat and of 

 a whitish cast. 



Propagation. Seeds ripen in abundance; they should be sown 

 early in September. S. maritima does not produce seed and must 

 be propagated by division and cuttings. All of the other varieties 

 may be propagated by division and cuttings. 



SPIGELIA (Pink Root). 5. marilandica is one of the daintiest 

 of perennial plants. It is most pleasing in the herbaceous border. 

 Shade is not necessary if planted in good, deep, rich loam. We are 

 sometimes disappointed when we do not know the peculiarities of 

 this plant, because it often peeps through the soil after many things 

 flower and go to rest. Clumps of it persist in the same place for 

 many years. 



Propagation. It is easily raised from seeds. 



SPIR^A (Meadow Sweet. Goat's Beard). There are sev- 

 eral very handsome herbaceous plants in this genus; all of them are 

 of easy cultivation. 5. aruncus, which may sometimes be found in 



