Cultivated-Plant Study 



621 



petal-doorstep and steal into the cave surreptitiously ! This contingency 

 is guarded against thus : Each of these lower petals narrows to a mere 

 insect footbridge at their inner end ; and in order to render this footbridge 

 quite impassable, it is beset with irregular little spikes and projecting 

 fringes, sufficient to perplex or discourage any small insect from crawling 

 that way. 



But why all these guiding lines and guarded bridges? If you watch 

 the same blossom for several successive days, it will reveal this secret. 

 When a flower first opens, the stamens are all bent downward, but when 

 an anther is ready to open its pollen doors, the filament lifts it up and 

 places it like a sentinel blocking the doorway to the nectar treasure. 

 Then when the robber comes, whether it be butterfly, bee or humming- 

 bird, it gets a round of pollen ammunition for its daring. Perhaps there 



1. Nasturtium flower in early stage of blossoming. Note the 



anthers lifted in the path to the nectar which is indicated 

 bv the arrow. The closed stigma is shown deflected at a. 



2. The same flower in later stage; the anthers are empty and 



deflected. The stigma is raised (a) in the nectar path. 



may be two or three anthers standing guard at the same time, but, as soon 

 as their pollen is exhausted, they shrivel and give room for fresh anthers. 

 Meanwhile, the stigma has its three lobes closed and lying idly behind and 

 below the anthers; after all the pollen is shed, the style raises and takes 

 its position at the cave entrance and opens up its stigmas, like a three- 

 tined fork, to rake the pollen from any visiting insect, thus robbing the 

 robber of precious gold-dust which shall fertilize the seeds in its three- 

 lobed ovary. Although the flower needs to flare its colors wide to call the 

 bees and hummingbirds, yet the growing seeds must be protected ; there- 

 fore, the stem which held the flower up straight, now twists around in a 

 spiral and draws the triplet seeds down behind the green shields. 



Nasturtium leaves are very pretty, and are often used as subjects for 

 decorative water-color drawings. The almost circular leaf has its stem 

 attached below and a little at one side of the center; the leaves are bril- 

 liant green above but quite pale beneath, and are silvery when placed 

 beneath the water. The succulent stems have a way of twisting half 

 around the wires of the trellis and thus holding the plant secure to its 

 support. But if there is no trellis, the main stem seems to awaken to the 



