AUTOGAMY BY THE CLOSING OF THE COROLLA. 



369 



flower being nearly over, certain movemenI.s are undergone by the petals which 

 result in the transference of the pollen sticking to their surfaces, margins, lobes, or 

 folds as the case may be, to it. The instances of this mode of effecting autogamy 

 are very numerous, and it will be best to class them in small sub-groups, and to 

 take a well-known example from each as an illustration. 



In Argemone, Hypecoum, and Specularia, which will serve as types of the first 

 group, there is no considerable elongation of the pollen-flecked petals during the 



Fig. 304. — Autogamy effected by the petals. 



^ Flower of Argemone Mexicana open in the sunshine. Pollen which has fallen from the anthers is resting upon the concave- 

 petals. 2 The same flower closed; one of the petals besmeared with pollen is laid upon the stigma; the front petal is- 

 removed. ^ Closed flower of Hypecoum grandijiorum, natural size. * The same magnified. ^ Longitudinal section through- 

 the open flower in the first stage of development. 6 Open flower in which the pollen-laden lobes of the inner petals are 

 beginning to separate. ^ The same flower at a later stage. 8 One of the two inner petals ; the middle lobe is coated with' 

 pollen ; at its base is the pit containing the honey, s Longitudinal section through a closed flower in its last stage of 

 development, lo Specularia speculum, ; longitudinal section through an open flower in the first stage, n Transverse 

 section through a closed flower in the first stage. 12 Longitudinal section through an open flower in the second stage. 

 II Closed flower. 1* Transverse section through a closed flower in the second stage, is Longitudinal section through an 

 open flower in the last stage. 16 Transverse section through a closed flower in the last stage. 1, 2, s natural size; the rest- 

 magnified. 



period of the flower's bloom. This period is only a single day in the case of Arge- 

 mone, and the process takes place in a very simple manner. In the morning, as 

 soon as the petals are wide open and the tension of the sheaf of stamens surround- 

 ing the pistil is somewhat relaxed, there is an immediate fall of pollen on to the 

 concave surfaces of the petals (see fig. 304^). The flowers are erect, as also is 



Vol. II. 



74 



