^8 HYBRID VEBBASCUMS. Chap, II. 



mediate tint, but either pure white or pure yellow 

 flowers, generally of the latter colour.* 



My observations were made in the autumn; so that 

 I was able to collect some half-matured capsules from 

 twenty of the thirty-three intermediate plants, and 

 likewise capsules of the pure V. lychnitis and thapsus 

 growing in the same field. All the latter were filled 

 with perfect but immature seeds, whilst the capsules 

 of the twenty intermediate plants did not contain one 

 single perfect seed. These plants, consequently, were 

 absolutely barren. From this fact, — from the one plant 

 which was transplanted into my garden yielding when 

 artificially fertilised with pollen from V. lychnitis and 

 thapsus some seeds, though extremely few in number,- 

 from the circumstances of the two pure species growing 

 in the same field, — and from the intermediate character 

 of the sterile plants, there can be no doubt that they 

 were hybrids. Judging from the position in which 

 they were chiefly found, I am inclined to believe they 

 were descended from V. thapsus as the seed-bearer, and 

 V. lychnitis as the pollen-bearer. 



It is known that many species of Yerbascum, when 

 the stem is jarred or struck by a stick, cast off their 

 flowers. f This occurs with V. thapsus, as I have re- 

 peatedly observed. The corolla first separates from its 

 attachment, and then the sepals spontaneously bend 

 inwards so as to clasp the ovarium, pushing off the 

 corolla by their movement, in the course of two or 

 three minutes. Nothing of this kind takes place with 

 young barely expanded flowers. With Yerbascum lych- 

 nitis and, as I believe, V. phceniceum the corolla is not 



* ' Bastarderzeugung, ' p. 307. Smith,' vol. ii. p. 210. I was 



t This was first observed by guided to these references by the 



Correa de Serra: see Sir J. E. Rev. W. A. Leighton, who ob- 



Smith's 'English Flora,' 1824, vol. served this same phenomenon 



i. p. 311 ; also ' Life of Sir J. E. with V. virgatum. 



