226 To the River Plate and Back 



the mottled-leaved thistle of the pampas. Both are 

 immigrant from Europe. The cardoon, its silvery 

 bluish green multifid leaves strongly contrasting with 

 the darker green of the grasses, covers wide tracts in 

 the fields and by the roadsides, and in spots has taken 

 complete possession of the slopes of the railway em- 

 bankments. It is the wild form of the artichoke, and 

 its buds are used as food, the fleshy base being pared, 

 boiled, and served as a vegetable. It grows every- 

 where except in the very hot lands of the tropical 

 north. Associated with it is the plant which Darwin 

 speaks of as the "giant thistle of the pampas. ' This is 

 also an adventitious plant, which has found its way into 

 the country from the southern parts of Europe. It is 

 known as 'Milk-Thistle' (Silybitm marianum) and 

 has large wavy spinous leaves, of which those growing 

 near the ground are dark green, mottled with white, 

 recalling in their color-scheme the leaves of the Asarum 

 caulescens, the Kamo-awoi of Japan, which was used 

 as the crest of the Tokugawa shoguns. The white stain 

 on the rosette-leaves of this thistle according to a 

 legend current in southern Europe was caused by the 

 falling of a drop of the milk of the Virgin Mary, and it 

 was in allusion to this legend that it received the speci- 

 fic name marianum. The French call the plant Char- 

 don Marie. In the lands of the Mediterranean it is 

 cultivated to some extent; its young leaves being used 

 as a spring salad, its roots employed as pot-herbs, and 

 the heads being treated like those of the artichoke. 

 These two species of thistle have literally taken posses- 

 sion of the land about the River Plate. They had done 

 so already a century ago, and Darwin in speaking of the 

 cardoon says, " I doubt whether any case is on record of 

 an invasion on so grand a scale of one plant over the 



