184 



FEKTILIZATION OF SPRING FLOWERS ON THE 

 YORKSHIRE COAST. 



By I. H. BuRKiLL, M.A., F.L.S. 



(Concluded from p. 145.) 



ChnjsosplenlHtn oppnsitifoliuDi. — This species is gynodicBcioiis at 

 Scarborough. The ? plant is abundaut throughout the district, aud 

 is easily noticed by reason of its greener hue — the golden yellow of 

 the ^ flowers being nearly absent. These ? flowers are smaller than 

 the ^ flowers, and the plant bearing them generally slighter — the 

 leaves especially being smaller. There is no trace of stamens, and an 

 almost complete absence of any transitional stage which might show 

 the anthers of the ^ flowers, becoming functionless and yielding a 

 unisexual flower. Gynodioecism has not previously been observed 

 in this species, but, on the other hand, androdioecism has."" 



Bdlla percnnis. — We may contrast the iusect-visitors observed 

 in the small portion of the plant's flowering period with those seen 

 elsewhere, remembering that these observations extend over the 

 whole season. 



Thus contrasting these three, we notice that the mid-tongued 

 bees are relatively numerous abroad, and that in neither Midler's 

 nor MacLeod's observations do the flies reach so high a proportion 

 as in these upon the spring fertilization on the Yorkshire coast. 



We may compare also the visitors for the two years '95 and '9G 

 [see Table VI.). In '96 the abundance of Scatophaga has a very 

 marked effect. This fly is not purely anthophilous, but, like the 

 spiders mentioned before, seizes other visitors to the flowers and 

 kills them. This, perhaps, together with the less abundance of 

 small flies in the second year, caused the tremendous falliug-ofl' in 

 the numbers of the small dipterous visitors to Bdlis perennis. 



Fctasites vuhiaris. — I can only recall seeing the male inflorescence 

 within the district.} 



Tussilago Farfara. — This is probably the most successful plant 

 of the early spring flora, being well suited to the prevalent insects. 

 Indeed, we might almost expect such to be the case, for the Cum- 

 posita, are one of the most, if not the most, successful race on the 

 earth ; and among them a plant producing its flowers before its 



* Kobus, •' Ueber Clinjsospleniiim," Deutsche Bot. Monatsschr. i. p. 74 (1883). 

 t Cf. Nicholson, " Peta-ntes offici)ialis Moench," Journ. Bot. xxii. (n.s. xiii.), 

 p. 251 (1884). 



