Cultivated-Plant Study 



641 



When a flower-bud is nearly ready to open the long, bristly tube of the 

 corolla lies with its narrow base set in the calyx, the long, fuzzy lobes of 

 which flare out in bell-shape ; the tube is marked by lengthwise lines made 

 by the five midribs; the lobes of the corolla are folded along the outer 

 portions of these midribs, and these folded tips are twisted together much 

 as if some one had given them a half turn with the thumb and finger. It 

 Is a pleasing experience to watch one of these flowers unfold. When a 

 flower first opens, there lies near the bottom of the throat of the tube the 

 green stigma, with two anthers snuggled up in front of it and two behind 

 it, the latter being not quite so advanced in age as the former. As the 

 filaments of the front pair of anthers are longer than those of the rear pair, 

 the little group lies at a low angle offering a dusty doormat for entering 

 insects. If we open a flower at this stage, we find another anther, as yet 

 unopened, and which is on the shortest stamen of the five. This seems to 

 be a little pollen-reserve, perhaps for its own use later in the season. 

 There is an interesting mechanism connected with these stamens; each is 

 attached to the corolla-tube at the base for about half its length, and at 

 the point of attachment curves suddenly inward so as to "cuddle up" to 

 the pistil, the base of which is set in the nectar-well at the bottom of the 

 flower. If we introduce a slender pencil or a toothpick into the flower- 

 tube along the path which the moth's tongue must follow to reach the 

 nectar, we can see that the stamens, pressing against it at the point where 

 they curve inward, cause the anthers to move about so as to discharge 

 their pollen upon it; and as the toothpick is withdrawn they close upon it 

 cogently so that it carries off all the pollen with which it is brought in 

 contact. 



If we look at the stigma at the center of its anther-guard, it has a cer- 

 tain close-fisted appearance, although its outer edges may be dusted with 

 the pollen; as the flower grows older, the stigma stands above the empty 

 anthers at the throat of the flower tube 

 and opens out into two distinct lobes. 

 Even though it may have accepted some 

 of its own pollen, it apparently opens up 

 a new stigmatic surface for the pollen 

 brought from other flowers by visiting 

 insects. 



Dr. James G. Needham says that at 

 Lake Forest he has been attracted to the 

 petunia beds in the twilight by the whir- 

 ring of the wings of countless numbers of 

 sphinx, or hummingbird moths which 

 were visiting these flowers. We also 

 may find these moths hovering over 

 petunia beds in almost any region if we 

 visit them on the warmer evenings. 

 And it is a safe guess that the remote 

 white ancestor of our petunias had some 

 special species of sphinx moth which it 

 depended upon for carrying its pollen ; 

 and the strong perfume it exhaled at nightfall was an odor signal to 

 its moth friends to come and feast. 



A petunia blossom cut open on the 

 dipper side, showing the pistil sur- 

 rounded by the incurved stamens 

 and the partially opened stigma 

 surrounded by the anthers. Note 

 the short stamen below the pistil. 



