119 

 Botanical Js'otes. 



±5y Moses N. Elrod. 



Tecoma radicans (L.) D C. The trumpet-flower presents many peculiar 

 cliaracters that are of great value in securing cross-fertilization, and it 

 seems to be constructed on a plan admirably adapted to meet the needs 

 of the humming-bird. 



One among the first things in its structure to attract attention is the 

 nearly horizontal position of the flower, its short, unexpanded lower lip, 

 the opposite of the arrangement in many flowers dependent upon insect 

 visitors for fertilization, and the manner in which the filaments are 

 twisted right and left so as to bring the dehiscing anther on the same 

 plane with their backs against the upper lip of the corolla. This group- 

 ing of tlie authors is effected by the outer and longer pair of the angular, 

 dini(irpli<nis filaments making one turn on their axes and the inner pair 

 making a half turn. The pistil is a little longer than the stamens and 

 terminates in a two-branched, foliaceous, spatidate stigma. 



In July, 1002, I noticed that the stigma is sensitive. AVhile searching 

 in my pocket for a magnifying glass the lobes of a plucked flower had 

 closed so that the stigmatic surfaces Avere in close contact. The use of 

 force failed to separate them for more than a moment and when one of 

 the thin lobes was cut away the other curled up into a loost- roll. At the 

 time, I supposed that I had made a discovery. l)ut soon found that 1 had 

 been anticipated. In Mullcr's "Fertilization of Flowers" it is stated that 

 when the stigma of BlfinonUi has been "touched by an insect vi-sitor they 

 then close \\\) immediately." He also quotes the experiments of his brother 

 on a South American species, showing that successful fertilization was 

 secured only Avhen the pollen applied came from a plant growing "at a 

 distance." It was to test the sensitiveness of the stigmas and the condi- 

 tions under which cross-fertilization was" effectual that my observations of 

 Tecoma radicans were made. 



The stigmatic lobes of a flower which had just come into bloom, when 

 irritated with the point of a knife-blade or any other hard substance, 

 closed In five seconds, and those of the faded flowers in thirty seconds. 

 A drop of water acted as an irritant when applied soon after the stigiuas 



