78 



EXPERIMENTS IN BLUEBERRY CULTURE. 



Fig. 29. — Compound pollen grain of the 



blueberry, consisting of four simple 



grains permanently cohering. (En- 

 larged 200 diameters.) 



surface, like the outside of an inverted funnel, and drops off the rim 

 or remains on it, without reaching the stigmatic surface which lies 

 protected beneath. 



Ordinarily i3ollination is effected by some insect which, pushing 

 into the orifice of the corolla from beneath in search of nectar, releases 

 the pollen, as already described. In continuing its quest for nectar 

 the insect brushes against the stigma with some portion of its body, 



which is covered with pollen, either 

 from the same flower or from some 

 other flower previously visited. 



In pollinating the flowers by 

 hand it was found impracticable to 

 collect sufficient pollen to apply 

 with a brush. The following sim- 

 ple and convenient method of pol- 

 lination was devised : A wide opening was torn in a corolla with a 

 pair of forceps, so that the stamens and stigma could be aj^proached 

 from the side. Then the lead of a lead pencil, flattened on one side 

 and held horizontally, was brought up against the open ends of the 

 anther tubes from below\ A portion of the falling pollen was caught 

 on the flat lead, w^iere it could be seen easily because of the blackness 

 of the background. Pollination was then completed by touching the 

 stigmatic surface gently two or 

 three times with the pollen-laden 

 lead. A pollinated flower may be 

 marked readily by pinching off 

 with forceps one or jnore of the 

 calyx lobes. Fruit was produced 

 from flowers pollinated either with 

 their own pollen or with pollen 

 from another flower. 



The self-pollination of a blue- 

 berry flower, without insect aid, ap- 

 pears to occur, but only occasion- 

 ally. On greenhouse plants fruit 

 is rarely produced when the flowers 

 are not artificially pollinated, and 

 the same is true of outdoor plants ^n-otected from insects by a 

 covering of gauze. The conditions of these observations Avere not 

 such as to obviate all possibility of the accidental visit of some insect, 

 but it is believed that real self-pollination occurred in some cases. 

 (.35) The fruit matures about two months after the flowering. 



A few days after pollination the corolla, with the stamens, falls 

 off. The stigma at this tiiii(> has turned brown, and Avithin a day or 

 19:5 



> 



4^ 

 Fig. 30. — Pistil and calyx of the blue- 

 berry, showing the style and stigma. 

 (Enlarged 5 diameters.) 



