DR. HOOKER ON THE DISTRIBUTION OF ARCTIC PLANTS. 335 



Phlox Bichardsonii, Hook. This appears to me only an arctic tufted form of P. Sibi- 

 ricci, to which, I think, may also be referred P. Douglassii ; all have more or less, and 

 often strongly, recurved margins to the leaves ; and the other differences are comparative 

 and trifhng. 



Mtosotis alpestris, Sw. {simveolens, M. & K.). Tries and Koch merge this into a 

 variety of s^foa^jcff, which alone inhabits Lapland. Bentham takes the same view. Watson 

 retains it, finding that it keeps its characters well under cultivation. 



M. casspitosa, Schltz. This Bentham unites with palustris, and probably correctly. 



M. arvensis, L. {intermedia, Link.). "Watson finds this occasionally approximating to 

 ccBspitosa ; and I find it difficult to separate northern forms of one from the other. 



Eretrichiitm villosum, Bunge. E. aretioldes, A. DC, is nothing hvA a dwarf arctic 

 state of this. Ledebour unites E. latlfoUnm, Rupr. (non Kar. & Kir.), with the same, as 

 var. (3 ; and so does Trautvetter (Elor. Taimyr.). 



Mertensia pilosa, DC, which includes Lith. corymbosum, Lehm., and p)cmiculatum, 

 Don, is clearly referable to denticulata, Don, the hairy calyx being a very inconstant 

 character. These should possibly all be united under Sibirica. 



M. Drummondii, Don. I find no plicse in the tube of the corolla of this plant, whence 

 it must be removed from the section in which DeCandoUe places it to that with Virgi- 

 nietisis, of which it appears to be a northern form, as suspected in ' Plora Bor.-Am.' It 

 has not, however, been gathered anywhere between the Arctic Sea-coast and the United 

 States. 



Mentha Lapponica, Wahl., is referred by Fries to a northern variety of arvensis. Both 

 grow in Lapland. 



Galeopsis Tetrahit, L. Fries and Koch keep this distinct, as does Watson, who gives 

 as presumptive evidence in its favour the statement that the seeds of versicolor yield 

 plants of their own kind only. Bentham says that they graduate one into the other. 



^'yikCUY^ palustris, L. According to the synonyms quoted by Asa Gray, this N. American 

 plant includes many very divergent forms, including some that might almost be referred 

 to S. sylvatica. Under the latter plant I have not introduced the Chilian S. chonotica, 

 which approaches it closely. 



LiMOSELLA aquatica, L. I include under this L. tenuifolia, which is the more common 

 southern form, and certainly is nothing but a variety with redu.ced foliage. L. borealis, 

 Lessing, is another form, found in Lapland only, according to Tries. 



Gtmnandra borealis. Pall. I am quite unable to distinguish Stelleri and JPallasii, 

 which were included originally by Pallas under borealis. Choisy says, in DC Prodr. xii, 

 24, that it is difficult to dissent from Pallas's view, who regarded the genus as monotyplc, 

 Willdenow makes eight species, which Chamisso and Schlechtendal reduce to three. 



Castilleja sep)tentrionaMs, Lindl. I have no hesitation in uniting this with pallida, 

 as suggested ' in Plor. Bor.-Am.' It advances south to Canada. 



