THE AMERICAN BOTANIST 41 



most readily induce acid soil plants to grow in our gardens 

 would he a most important accomplishment. 



W'kstkrx I'uaxt Xamks. — Concerning certain [jlani 

 names nienlioned in this magazine, Prof. J. C. Nelstjn writes: 

 The word "Thorn-apple" seems very elusive. 1 ne\ er 

 heard it applied to either Crataegus or Datura; when we used 

 it in Kentuckw it meant Solanitni carolincnsc, a very had i)er- 

 ennial weed of sandy fields, and interesting because it was at- 

 tacked by the Colorado potato-beetle almost as eagerlv as was 

 the cultivated S. titbcrusitiii. I wonder if this application of 

 ihc name was only local? The books call this plant "horse- 

 nettle;" but I ne\er heard this applied to it. 



Will \()U tell me by what name the "giant rag-weec 

 {Ambrosia trifida) is referred to in different localities? it. 

 Kentucky we used to call it "liorse-weed", because it was 

 greedily eaten by these animals. The last time I wa> in 

 northern Minnesota, I found that the Scandinavian Maulers 

 had begun [<> call it "king-head ". from a fancied resemblance 

 of the akene witli its sliarp points to a crown; and this name 

 has now got into some of the weed-manuals. How far >oulh 

 does it extend? Is there any common name for fra xautlni- 

 foUa? You know how abundant it is in the Northwest, and 

 what gigantic size it attains ; and yet 1 can never reniember 

 hearing any popular name applied to ii. Around deserted 

 homsteads it almost reaches the size of a tree. 1 had always 

 supposed that Ginkgo took the name of "maiden-hair fern 

 tree" from the shape of the leaves, which very closely resemble 

 the pinnules of AdiaiUuiii. Of course, the root may have 

 something to do v.ilh il ; but 1 believe the leaf first suggested 

 the name. [The point about the maiden hair fern tree is 

 simply this : the fern was named from its roots because they 

 were assumed to resemble hair and therefore according to th< 



