I 1 1 1-. A M KR I CA N BOTA N I ST 165 



With the explanations of the terms rocket, mustard and 

 ercss in mind, most of the names of the Cruci ferae become 

 iiiteUijj^ihk'. Indeed, the terms just mentioned are used in 

 connection with so many phmts in this family that the sub- 

 jec of ct)mni(iii names, in consequence, becomes quite mono- 

 tonous. Beginning with the long line of cresses, we have 

 first of all the species of Arahis, nearly all of which bear the 

 name of "rock cress" iwnw their preference for rocky places. 

 Arahis Canadensis, however, though it lives on rocks, is gen- 

 erally called "sickle-pod" from the long, curving and con- 

 spicuous pods. Arahis glahra is the "tower mustard" or 

 "tower cress" the name doubtless given because it grows on 

 old towers in its native land though the name may refer to 

 its own height in comparison with others of its genus. 



Two genera divide the honors as regards the designation 

 of the true cresses. One is the genus Nasturtium which in 

 recent years has been occasionally known as Radicula or 

 Roripa. To this genus, whatever it may be called, belongs 

 the true "water-cress" {Nasturtiutn officinale). Among its 

 other names are "well cress," "water grass," "crashes," 

 "brown cress" and "brooklime." The last mentioned name 

 means simply water plant;" the others are self-explanatory. 

 Ahisturtiiini syhestris is the "yellow cress" or yellow water- 

 cress" from the c(^lor of its flowers and "wood cress," a 

 translation of its specific name. The "lake cress," "river 

 cress" or "lake water-cress" is Nasturtium lacustre. An- 

 other "yellow water-cress" is A^. palustris which is more 

 properly "marsh cress" if its specific name means anything. 

 The plant is also known as the "yellow wood-cress." To the 

 Xasturtiuni genus also belongs the familiar "horse radish" 

 (.Y. Amoracia) whose name alludes to the pungency of its 

 root and not to the animal suggested. In this and so many^ 



