Naturalisation in Extra-Tropical Countries. 411 



most durable yielded by any American oaks. Like . Q, stellata, it 

 lives also on sea-shores, helping to bind the sand, but it is then not 

 of tall stature. Q. Virginiana (Miller) is the oldest name for this 

 oak, as pointed out by C. Koch. Of many of the 300 oaks, occur- 

 ring in the western and eastern portions of the northern hemisphere, 

 the properties remain unrecorded and perhaps unexamined ; but it 

 would be important to introduce as many kinds as possible for 

 local test-growth. 



Qnercus variifolia, Hance. 



China. A magnificent Oak. The acorns serve locally for human 

 food. 



Qnercus Wislizenii, A. de Oandolle. 



California, at an elevation of about 7,000 feet, extending to 

 Shasta. Allied to Q. agrifolia. A magnificent tree with dense 

 foliage, the stem attaining finally a circumference of 18 feet 

 [Prof. Sargent]. Wood hard, tough and durable [Prof. Green]. 



Quercus Xaloepensis, Hmnboldt and Eonpland. 



Mexico, ascending to 5,000 feet, preferring for localities poor 

 soil, but of ferruginous clay, where little else will grow. Height 

 to 80 feet ; it is a quick grower ; its timber will endure only under 

 roof; the tree gives a heavy crop of acorns [Hugo Fink]. The 

 nearly allied Q. commutata attains 70 feet and ascends to 11,000 

 feet [Liebmann]. 



Quillaja saponaria, Molina. 



Chili. A colossal tree, fit not only for loamy but also sandy 

 and peaty soil. The bark is rich in saponin, and therefore valuable 

 for dressing wool and silk, also for various cleansing processes. 

 Kageneckia oblonga (Ruiz and Pavon) is allied, and from the same 

 country, extending to Peru, and provides locally tan-bark [Dr. J. 

 A. de los Bios]. 



Rafnia amplexicaulis, Thunberg. 



South- Africa. The root of this bush is sweet like liquorice, and 

 is administered in medicine. Rafnia perfoliata (E. Meyer), also 

 from South- Africa, furnishes likewise a medicinal root. 



Raphanus sativus, Linne. 



The Radish. Temperate Asia, southward to the Himalyas up 

 to 16,000 feet, eastward to' Japan. Cultivated already by the 

 ancient Romans and Greeks. Ripens seeds quite well even in the 

 hot desert-tracts of Central Australia, Can in mild climes be 

 grown all the year round. In Norway it can be raised northward 

 to lat 70 20' [Prof. Schuebeler]. R. caudatus, L., the radish with 

 long edible pods, which exceptionally grow to a length of three or 



