DESCRIPTIVE AND SELECTIVE. 193 



it forms dense round tufts covered with bright yellow 

 flowers in spring. Other forms of the Rock Madwort 

 are Citrinus, pale yellow ; Silver Queen ; Sulphureum, 

 sulphur-coloured ; Plenum (double) and variegated- 

 leaved. They are pretty, but not better than the 

 original, and need only be grown where a different shade 

 of colour is wanted. There are few more useful rock 

 plants than the yellow Madwort. It grows vigorously, 

 yet it has not the often embarrassing luxuriance of the 

 Snow-in-Summer and the Rock Cresses. It spreads 

 within limits, but does not go off on a roving expedition 

 from top to bottom of the rockery. It is a slow ripple, 

 not a turbulent cascade. It will grow in ordinary soil, 

 and does not disdain poor chalky or sandy ground, 

 indeed, it prefers a rather dry to a damp soil. As a 

 perennial this most serviceable plant will grow from 

 year to year, but it comes so readily from seed that 

 many treat it as a biennial, sowing it with the Wall- 

 flowers in the late spring. On this account it may be 

 utilised if something is wanted for a wall or to cover 

 a bank. Of the other Madworts by far the most useful 

 is the Sweet Alyssum, maritimum, which is generally 

 treated as an annual, being grown from spring-sown 

 seed and discarded after blooming. It is a low, dense 

 plant, thickly covered with white flowers. The 

 variegated form often grown under the name of 

 Koniga variegata is greatly prized for forming edgings. 

 ANDROMEDA POLIFOLIA.—A shrub, this 

 beautiful plant must not, however, be considered in 

 the same school with luxuriant things like Laurels 

 andAucubas. It is of neat, close, dwarf habit, and 



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