Climate of Middle Illinois. 39 



by Darlington (Fl. cestr. 33) and Torrey (Flora of N. Y. L, 99). In 

 Torrey and Gray's Flora I., 188 it is left doubtful whether introduced or 

 not, and Gray in Man. of Bot. says: perhaps indigenous to the country. 

 Not a few plants, common to North America and Europe, are supposed to 

 have come to the eastern states on a double way by new introduction from 

 Europe or by old migration from the north in both continents. The 

 question is, whether this in regard to our plant is possible and probable. 



A. de Candolle in Geogr. bot. 748 says: Cerastium vulgatum L. et 

 Cerastium viscosum L paraissent manquer encore a I'Asie orientale et au 

 nprd-ouest de TAnierique, ce qui me fait croire a Tintroduction aux Etats- 

 unies. 



The plant is found in Iceland (Hooker Tour in Iceland II., 324) in 

 Labrador (Meyer Flor. Labr. 94) in Spitzbergen (Martens flor. arct. 8) 

 in Greenland (Lange in Etzels Greenland 634). So an arctic connection 

 with the eastern continent is proved. After Ledebour (Fl. ross. I., 408), 

 who takes the species in a wide sense, it extends through Sibiria to Kamt- 

 schatka, and his varieties Grandiflorum and Behringianum to Alaska. 

 The latter after Watson (Kings Rep. V., 38) occurs in the Uintah Moun- 

 tains in an altitude of 10,000 feet, and in the Rocky Mountains it was 

 found by Parry (PI. of Rock. Mount, in Proc. Ac. n. s. Phil. 1863, p. 55) 

 and Gray in PI. Wright, I., 18, mentions: Cerastium vulgatum L., C. tri- 

 viale Auct,, in ravines of the Organ Mountains N. Mex. That means, no 

 doubt, L. spec, and not L. herb as in Man. of Bot. 



Now, if a plant is distributed from the arctic region to New Mexico, 

 it is possible that it spread in the same direction to Illinois. It is not 

 mentioned in Agassiz Lake Superior, but Houghton collected there C. 

 viscosum L. (Schoolcraft Sources of the Mississippi), and we find it in 

 Lapham's Catalogue of Wisconsin plants. In both cases it is not said 

 whether L. herb or spec, is understood. 



I found the plant on a grassy place at the bank of a little brook at 

 that time remote from a settlement, what made me suppose, that the plant 

 did not recently immigrate. 



Solanum nigrum L. is a polymorphus cosmopolite, and now ranged 

 amongst the indigenous by Gray in Fl. of N. Am. I., 227. 



Datura Tatula L. — The question, whether this is a proper species or a 

 variety, and the probability of an American origin, A. de Condolle in Geogr. 

 Bot., 731, has extensively treated. Another question is, whether we have 

 the plant from South America, as is supposed. When that is so, the im- 

 migration must be a very old one. Western farmers affirm that in remote 

 new settlements the plant appear as soon as the land is broken. It is a 

 well known fact, that the seeds of most Solanacea^ keep the germinative 

 power a loug time, and so it is probable that the seeds had been buried in 

 the ground long before they had a chance to germinate. The white spe- 

 cies Datura stramonium was, only a few years ago, the first time seen — 

 in the yard of a druggist's house ! 



