TRELEASE A REVISION OF N. AM. LINACE.Ii. 9 



homogone,* and clearly endemic with one exception (excluding, 

 naturally, the somewhat abundant escapes of cultivated flax), this 

 concerns us only indirectly. The exception referred to is the 

 common blue-flowered flax of the western mountains and plains, 

 called L. Lewisii by Pursh, and of late years united with L. pe- 

 renne of the Old World. 



The European representatives of this species, though variable, 

 are generally referred to a single species, but often with varietal 

 names ; and our plants, although they vary much in appearance, 

 cannot be regarded as representing more than one species, nor 

 do they difter essentially from European forms of L. perenne 

 except in one particular. According to Darwinf and HildebrandJ 

 the Old World L. perennc is heterogone-dimorphic and self- 

 sterile. The American plant, on the other hand, does not appear 

 to be heterogone. Most specimens correspond to the long-styled 

 form of a dimorphic species, but flowers sometimes occur with 

 the styles no longer than the stamens, and I have seen one plant 

 with styles scarcely reaching the base of the anthers. According 

 to Meehan§ the American plant is self-fertile. 



It appears, therefore, that forms of a single species, originally 

 distributed over the northern portion of both continents (not in 

 eastern America, however), have in the course of time differen- 

 tiated so far as to acquire heterogony in the Old World, or lose it 

 in the New — the latter appearing more probable. 



Some references concerning the pollination of Limun and the 

 structure and dissemination of its seeds will be found below. 11 



* On this subject see Urban: Linnsea, xli. 609; Abstract in Just's Bot. Jahrcsbericht, 



V. 442. 739- 



t Diflerent Forms of Flowers, various places. (See also the original paper in Journ. 

 Linn. Soc, Bot. vii. 75, and abstract in Amer. Journ. Sci., 2 ser. xxxvi. 279-2S4. ) 



J Halle Zeitschr. ges. Wiss. xxiii. 51:. 



§ Bull. Torrey Bot. Club, vi. 189. See also Gray: Amer. Journ. Sci., 3 ser. xv. 232. 



II The principal literature pertaining to the pollination of Linacea; is indicated in the 

 following list : 



Alefeld; Bot. Zeitung, 1863, xxi. 281 (indication of dimorphism in many species). Dar- 

 win: Journ. Linn. Soc, Bot. 1S63, vii, 69; Amer. Journ. Sci. and Arts, 1863, a ser. xxxvi. 

 379; Different Forms of Flowers in Plants of the same Species, various places (dimor- 

 phism and mode of pollination of Retnivardtia, p. lOO, and several species of Linum) . 

 Delpino: Ulteriori Osservazioni, ii. (2) 9). (nectariferous staminodia). Fritsch : Beobach- 

 tungen uber Pflanzen dercn Blumen sichtaglich offnen u. schliessen (time of opening and 

 closing of flowers of L. usitatissimum). Gray: Amer. Journ. Sci. and Arts, 1878, 3 ser. 

 XV. 222 (h. Le-jjisii). Henslow : Trans. Linn. Soc, Bot. 1S77, n.s. 1. 357 {L.catharticum) ; 

 Pop. Sci. Rev. 1879, xviii. Uildebrand: Halle Zeitschr. ges. Wissensch. 1S64, xxiii. 417, 

 511; Bot. Zeit. 1864, xxii. i {h, perennc). Koch: Synopsis Flor. Germ, et Helv. (noted 



