328 CLEISTQGAMIC FLOWERS. Chap. VIII. 



we should remember that this is a naturalised species. 

 The perfect flowers are usually barren in England ; but 

 Prof. Asa Gray writes to me that after midsummer in 

 the United States some or many of them produce 

 capsules. 



Impatiens noli-me-tangere. — I can add nothing of im- 

 portance to Von Mohl's description, excepting that 

 one of the rudimentary petals shows a vestige of a 

 nectary, as Mr. Bennett likewise found to be the case 

 with I. ftdva. As in this latter species all five stamens 

 produce some pollen, though small in amount; a 

 single anther contains, according to Von Mohl, not 

 more than 50 grains, and these emit their tubes 

 while still enclosed within it. The pollen-grains of the 

 perfect flowers are tied together by threads, but not, 

 so as far as I could see, those of the cleistogamic 

 flowers ; and a provision of this kind would here have 

 been useless, as the grains can never be transported 

 by insects. The flowers of I. lalsa/mna are visited by 

 humble-bees,* and I am almost sure that this is the 

 case with the perfect flowers of I. noli-me-tcmgere. From 

 the perfect flowers of this latter species covered with 

 a net eleven spontaneously seK-fertilised capsules were 

 produced, and these yielded on an average 3*45 seeds. 

 Some perfect flowers with their anthers still containing 

 an abundance of pollen were fertilised with pollen from 

 a distinct plant ; and the three capsules thus produced 

 contained, to my surprise, only 2, 2, and 1 seed. As 

 I. halsamina is proterandrous, so probably is the pre- 

 sent species ; and if so, cross-fertilisation was effected 

 by me at too early a period, and this may account for 

 the capsules yielding so few seeds. 



Drosera rotundifolia. — The first flower-stems which 



* H. MUUer, ' Die Befruohtung,' &o. p. 170. 



