368 PROCEEDINGS OF THE ACADEMY OF [1892. 



with a pen-kuife, but it had no effect ou the opening of the 

 flower till the regular opening time arrived. The stamens are 

 shorter than the style, so that at expansion the anthers are below 

 the stign^a. The pistil remains erect, and the stam-ens fall without 

 the pollen coming in contact with the stigma, as far as I could trace. 

 The pistils droop by morning, when the under surface of the com- 

 pound stigma is usually found covered with pollen, as if it had 

 dropped from the anthers. A large number of species of night 

 moths attend the flowers during the night, and most of the flowers 

 have moth hair on the stigmas. It seemed probable that insect aid 

 had much to do with pollinating the flowers. 



The lower portions of the spikes are infertile, and this adds sus- 

 picion that insects are necessary to aid in the work of fertilization, 

 as they may not have been present or found the Gaura plants till 

 many flowers had fallen, but nearly all the later flowers are fertile. 

 Soon after daylight the stamens and style have withered, but the 

 petals do not collapse till 8 or 9 o'clock, and if the day be cloudy, . 

 the petals will continue apparently fresh till noon. 



Aside from fixing the exact time and manner of the opening of 

 the flowers of these two species, there is a peculiar interest in the 

 fact that while the one is undoubtedly a strict self-fertilizer, its near 

 neighbor seems to be in a great measure dependent on insect agency, 

 and this remarkable difference is apparently due merely to the fact 

 that, in comparison with the pistil, the stamens are a little longer 

 in the one species than in the other. 



CEnoihera biennis. — I endeavored to ascertain the exact time and 

 manner of the opening of the flowers of Oenothera biennis, but 

 could not manage to catch it at the right moment. An interesting 

 fact well worth recording, however, is that the anther cells burst when 

 the bud is comparatively young, long before expansion, covering 

 the stigma with the flower's own gelatinous pollen. The stigma is 

 not receptive at this time, but the pollen remains until it is, thus 

 insuring self-fertilization. 



The Carpellary Structure op Nymph^a. 



An abnormal flower of Nymphcea odorata from 'New Jersey, sent 

 to me by Mrs. Edward S. Sayres, of Philadelphia, indicatesthemanner 

 in which the carpels are formed. The place of the usual radiating stig- 

 mas was occupied by three petaloid processes, very suggestive of the 



