Naturalisation in Extra-Tropical Countries. 581 



about 80 feet and of very considerable girth. Foliage deciduous. 

 The wood is reddish-brown, close-grained, and pervaded when fresh 

 by an oily glutinous clamminess. The heartwood is of greater 

 durability than even teak, and of a marvellous resistance to shocks 

 through its extreme hardness. It is used for gun-carriages, crooks 

 of ships, railway-sleepers, tools, gauges, ploughs, house- and bridge- 

 posts [Laslett]. Almost as indestructible as iron, hence locally 

 called ironwood ; a rifle shot at 20 yards distance will scarcely cause 

 any penetration into it [Colonel Blake]. Neither the teredo nor 

 termites will touch the heartwood [Sir J. Hooker]. It can only be 

 sawn up in a fresh state. The stem exudes a red gum-resin [Kurz]. 

 This tree yields also saponin. 



Xylosma monospora, Harvey. 



The lemon-wood of South Africa, tree 70 feet high, over 2 feet in 

 diameter, producing yellowish-wood, used for furniture. Where 

 forest-fires rage this tree suffers less than all others, and even if 

 badly burned soon recovers [Sim]. 



Yucca aloifolia, Linne. 



Carolina, Florida, West-India, Mexico, in coast-sand. Stem* to 

 22 feet high. Y. Draconis (Linne) represents, according to J. G-. 

 Baker, the aggrandized form, of which, at Nice, an individual plant 

 attained a stem about 11 feet in circumference at the base [Dr. 

 Sauvaigo]. With its congeners a fibre-plant. 



Yucca angustifolia, Pursh. 



From Missouri and Iowa to Colorado, Arizona and New Mexico. 

 Height according to Mr. Green to about 15 feet. One of the 

 hardiest of all. 



Yucca baccata, Torrey. 



Colorado, Texas, Southern California, Utah, Northern Mexico; 

 In its ordinary state not tall ; but the variety Y. filifera (Chabaud) 

 will sometimes produce a stem half-a-hundred feet high with a 

 diameter to 3 feet. The leaves are singularly short [S.Watson]. 

 This furnishes the Tambico-fibre for cordage, ropes, rugs and other 

 fabrics. The plant is highly esteemed for hedges, which are almost 

 impenetrable [Semler]. 



Yucca brevifolia, Engelmann. 



Southern California, Arizona and Utah, in the deserts, ascending 

 to 4,000 feet. Attains a height of 30 feet with a stem over 2 feet 

 in diameter. Evidently a very hardy species, constituting finally a 

 real tree, much branched. The whole plant can be converted into 

 pulp for paper [Vasey, Baker]. 



