FLOWERING TREES AND SHRUBS 205 



disseminated, be largely planted for purely ornamental 

 purposes. It grows from 10 feet to about 15 feet high. 



Xanthorhiza (Ranunculaceae). 



/. Xanthoehiza apiifolia. — Yellow-root. Pennsylvania, 

 1776. A small-growing shrub, with yellow creeping roots, 

 from which suckers are thrown up profusely. The leaves 

 are irregularly pinnate, and the minute flowers, which are 

 borne in large, branching spikes, are of a peculiar dark- 

 purple colour. It prefers a cool, moist situation. 



Xylosteum, Sec Lonicera, 



Yucca (Liliaceae). 



Yucca blata. — United States, 1893. This has pale- 

 green leaves about 2 feet long, and sweetly-scented white 

 flowers in a dense panicle. It grows about 10 feet high. 



Y. filamentosa. — Silk Grass. North America, 1675. 

 A well-known and beautiful plant, with numerous leaves 

 arranged in a dense rosette, and from 1 foot to 2 feet 

 long by 2 inches broad. Flower scape rising to 5 feet or 

 6 feet in height, and bearing numerous flowers that are 

 each about 2 inches deep. There is a beautiful variegated 

 form of this species named Y. filamentosa variegata, and 

 one with much narrower leaves than the typical species, 

 and known as Y. filamentosa angustifolia. 



Y. glokiosa. — The Mound Lily. United States, 1596. 

 This is another well-known hardy species, with long, 

 sharp-pointed leaves, and a handsome, much-branched 

 scape of flowers that are each about 2 inches deep. 

 There are several varieties, differing in colour of foliage, 

 including Y. gloriosa glaucescens, with decidedly glaucous 

 foliage; Y. gloriosa superba, with rigid leaves and a 

 shorter and denser flower scape; and another with 



