DESCRIPTIVE AND SELECTIVE. 191 



and inserting firmly in moist soil. In view of not 

 improbable failure a few shoots should be layered in 

 damp gritty soil, first partially severing them and then 

 pegging them down. Another pretty species is A. 

 venustum, which has pink flowers and glaucous leaves. 



ACHILLEA (Yarrow).— Most of the Yarrows 

 are too vigorous in growth for the rock garden, although 

 extremely useful in the herbaceous border. Achillea 

 Ptarmica The Pearl, for example, is a splendid white- 

 flowered variety, and makes beautiful clumps in the 

 mixed border, but it is too large for a small rockery. 

 A. Clavennae may, however, be used with advantage. 

 It is a dwarf, neat grower, and has silvery foliage. 

 The white flowers are borne in summer. The Rock 

 Yarrow, A. rupestris, is worth growing. It has white 

 flowers, which are produced in May. Both species 

 enjoy a loamy soil, but will grow in a poorer medium. 

 Propagation by division in winter. Other Yarrows 

 worth mentioning are A. tomentosa, downy foliage and 

 yeUow flowers; A. Huteriy green foliage and white 

 flowers; and A. Aegyptiaca, with yellow and silvery 

 leaves. 



ACIS A UTUMNALIS.—A small bulb, with droop- 

 ing pink flowers, borne, like those of the Autumn 

 Colchicum, Sternhergia lutea^ certain of the Crocuses 

 and other bulbous plants, in autumn, after which the 

 foliage appears. It is not a really high-class rock plant, 

 but is one of those precious flowers which connoisseurs 

 love to cherish. It ought to be given a warm site and 

 a prepared soil of sandy loam, for it could not be rehed 

 on in cold or poor soil. 



