Magenta to Pink 



leafy, branched. Leaves : Opposite, or sometimes in whorls 



of 3 ; lance-shaped, with heart-shaped base clasping stem. 

 Preferred Habitat — Wet meadows, watery places, ditches, and 



banks of streams. 

 Flowering Season — June — August. 

 Distribution — Eastern Canada to Delaware, and westward through 



Middle States ; also in Europe. 



Through Darwin's patient study of this trimorphic flower, it 

 has assumed so important a place in his theory of the origin of 

 species that its fertilization by insects deserves special attention. 

 On page 5, the method by which the pickerel weed, another 

 flower whose stamens and pistil occur in three different lengths, 

 should be read to avoid much repetition. Now the loosestrife 

 produces six different kinds of yellow and green pollen on its 

 two sets of three stamens ; and when this pollen is applied by 

 insects to the stigmatic surface of three different lengths of pistil, 

 it follows that there are eighteen ways in which it may be trans- 

 ferred. But Darwin proved that only pollen brought from the 

 shortest stamens to the shortest pistil, from the middle-length 

 stamens to the middle-length pistil, and from the long stamens 

 to the long pistil effectually fertilizes the flower. And as all the 

 flowers on any one plant are of the same kind, we have here a 

 marvellous mechanism to secure cross-fertilization. His experi- 

 ments with this loosestrife also demonstrated that "reproductive 

 organs, when of different length, behave to one another like dif- 

 ferent species of the same genus in regard both to direct produc- 

 tiveness and the character of the offspring ; and that consequently 

 mutual barrenness, which was once thought conclusive proof of 

 difference of species, is worthless as such, and the last barrier 

 that was raised between species and varieties is broken down. - ' 

 (Muller.) 



Naturally the bright-hued, hospitable flower, which secretes 

 abundant nectar at the base of its tube, attracts many insects, 

 among others, bees of larger and middle size, and the butterflies 

 for which it is especially adapted. They alight on the stamens 

 and pistil on the upper side of the flower. Those with the long- 

 est tongues stand on one blossom to sip from the next one : this 

 is the butterfly's customary attitude. But nearly every visitor 

 comes in contact with at least one set of organs. When Darwin 

 first interpreted the trimorphism of the loosestrife, we can realize 

 something of the enthusiasm such a man must have felt in writing 

 to Gray: " 1 am almost stark, staring mad over lythrum. . . . 

 For the love of Heaven have a look at some of your species, and 

 if you can get me some seed, do !" 



Long ago this beautiful plant reached our shores from Europe, 

 and year by year is extending its triumphal march westward, 

 brightening its course of empire through low meadows and 



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