294 SELECT PLANTS FOR INDUSTRIAL CULTURE 



Rubia tinctorum, Linne. 



The Madder. Countries around the Mediterranean Sea. A 

 perennial herb of extremely easy culture. Soil fit for barley suits 

 also for madder. Ets culture opens any deep subsoil and suffocates 

 weeds, but requires much manure, leaving then however the land 

 enriched. Any stagnant water in the soil must be avoided if 

 madder is to succeed. The harvest is in the second or third year. 

 It can be raised from seeds or planted from off-shoots. The roots 

 merely dried and pounded form the dye. The chemical contents 

 are numerous : in the herb, rubichloric and rubitannic acid ; in the 

 root, alizarin, purpurin, rubiacin, rubian, ruberythric acid, and three 

 distinct resins ; also chlorogenin, xanthin, and rubichloric acid. 

 On the five first depend the pigments produced from the root. 

 Madder is one of the requisites for alizarin ink. Since the manu- 

 facture of artificial alizarin from anthacene, a constituent of coal- 

 tar has commenced, the cultivation of madder has declined. Still 

 it remains a valuable root, handy for domestic dye. 



Rubus Canadensis, Linne.* 



The Dewberry of North America. A shrub of trailing habit. 

 Fruit black, of excellent taste, ripening earlier than that of R 

 villosus (Ait.), which constitutes the High Blackberry of the United 

 States, with large fruits. 



Rubus Chamaemorus, Linne. 



The Cloudberry. North Europe, North Asia, North America* 

 particularly in the frigid zone. A perennial but herbaceous plant j 

 a pigmy amongst its congeners. Nevertheless it is recommended 

 for introduction to spongy, mossy, Alpine moors, on account of its 

 grateful amber-coloured or red fruit. All the species can readily 

 be raised from seeds. R Arcticus (L.), also with edible fruit, is in 

 the high north usually its companion. A similar little herb, living 

 for a great part of the year in snow namely, R Gunnianus 

 (Hook).) occurs on the Alpine heights of Tasmania, from whence 

 it might be easily transferred to snowy mountains of other countries. 

 The fruit of R Gunnianus is red and juicy, but not always well 

 developed. 



Rubus cuneifolius, Pursh. 



The Sand Blackberry. North America. A dwarf shrub. The 

 fruit is of agreeable taste. 



Rubus deliciosus, Torrey.* 



On the sources of the Missouri. An erect shrub. Fruit raspberry- 

 like, large and grateful. An exceedingly handsome species. 



