48o THE POLEMONIALES 



are kept tightly pressed together hke a pair of sugar tongs, 

 thus preventing the shedding of the spores. Owing to the form 

 of the corolla and often because of numerous hairs and bristles, 

 the insect is directed in such a definite wa}^ to the flower that he 

 comes in contact with appendages of the anthers, or causes a 

 slight deflection of the rigid filaments or of the lip of the corolla, 

 any of which movements are suflicient to separate the anthers 

 and bring down upon him a shower of spores. These flowers 

 are largely protog>mous so that at first only a crossing is possible. 

 In many species, autogamy results from the downward bending 

 of the corolla and style, accompanied by a loosening of the anthers 

 so that during the last days of flowering the spores may fall 

 directly upon the stigma. 



Many of these flowers are characterized by mottlings and 

 blotches. It appears to be a rather general law that the most 

 highly modified parts are variegated in this manner — compare the 

 mints and orchids. Less specialized flowers present an associa- 

 tion of various colors or veinings, a feature that is illustrated 

 in many families, as violets, peas, geraniums, etc., whereas the 

 simplest types of flowers are usually of a uniform color. The 

 fig^vorts have been called a suspicious group, and if not actually 

 poisonous, none at least serve as food. Several are medicinal, 

 as Digitalis, Veronica, Gratiola, etc. Many are parasitic, as the 

 foxglove, Gerardia, eyebright (Euphrasia) and the related and 

 reduced brownish rapes (Thalesia and Orobanche), beech drops 

 (Leptamnium) and squawroot (Conopholis) . 



The curious family of the bladderworts is closely related to 

 the fig^vorts. The bladderwort {Utricularia) is a very common 

 aquatic in still waters and ponds. Certain leaves become modi- 

 fied into elaborate sacs with trapdoors for enticing and capturing 

 small insects which die and decay in these prisons and are ulti- 

 mately absorbed and so contribute to the nourishment of the 

 plant. The butterwort {Pingiiiciila) is another member of this 

 family found in the northern countries and also in our southern 

 states. It has more the appearance of a violet with a rosette 

 of leaves which are provided with glands that secrete a viscid 

 substance for the capture of insects and also digestive fluids. 



