Minnesota Plant Life. 257 



vine, bursting its way out when about to flower. The flower 

 is much more conspicuous than the rest of the Rafflesia plant- 

 body. Some small relatives of the Rafflcsias are found on certain 

 pod-bearing trees in the southern states. Their little flowers 

 burst through the bark of the twig in which the plant-bodies 

 are growing, thus apparently producing the remarkable phe- 

 nomenon of twigs with flowers growing in the crevices of the 

 bark. Here, however, as in the Sumatran variety, the twig is 

 only the host-plant and the flower is a portion of the internal 

 parasite. 



The two Minnesota members of the order are not parasites, 

 but are independent green plants. The wild ginger, of which 

 several species are known to exist in the United States, is met 

 with in Minnesota on shaded banks of ravines where the root- 

 stocks of the plant, branching and scented, send up short erect 

 stems usually with a pair of large kidney-shaped leaves and pro- 

 ducing single, purplish-brown flowers very close to the ground. 

 The calyx of the flower has three leaves with slender pointed 

 tips. These are recurved in the Minnesota variety. The calyx 

 is fused with the surface of the six-chambered fruit-rudiment 

 which develops numerous seeds in two rows in each chamber. 

 When ripe, the fruit is a capsule inclosed in the calyx, and it 

 bursts irregularly. 



Pipe-vines. The pipe-vines are twining vines with alternate 

 leaves in the Minnesota species heart-shaped. Curious irreg- 

 ular tubular flowers are formed, destitute of petals and with the 

 calyx adhering to the base of the ovary. The edge of the tubu- 

 lar calyx is divided into three lobes and the flower is curved 

 into a horse-shoe shape. These remarkably shaped flowers are 

 insect-traps. Insects are induced to enter them and are forcibly 

 detained as prisoners until they can be covered with pollen. 

 They are then released to visit some other plant. The pipe-vine 

 is found only in the southeastern counties of Minnesota, -while 

 the wild ginger is abundant throughout the state. 



The thirteenth order includes a single family in which are 

 gathered the true sorrels and docks, the rhubarbs, the buck- 

 wheats and the smartweeds. 



Docks and smartweeds. In Minnesota there are ten vari- 

 eties of docks and about twenty five of knotweeds or smart- 



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