Studies of Ly thrum Sallcaria — II* 

 A new form of flower in this species 



A. B. Stout 

 (with six text figures) 



The purple loosestrife, Lyihrum Salicaria L., has long been 

 known as one of the relatively few species of plants that are tri- 

 morphic. That is, the species includes individuals having flow- 

 ers of three different types. Named with respect to the three 

 lengths of pistils, there are the long-styled flowers (see fig. 5) 

 with a set of long-stamens and a set of short-stamens (enclosed 

 within the calyx and not shown in the picture), the mid-siyled 

 flowers (fig. 2) with a set of long-stamens and a set of short- 

 stamens, and the short-styled flowers (fig. i) with a set of mid- 

 stamens and a set of long-stamens. There is thus one of the 

 three kinds of pistils and two different sets of stamens in each 

 flower. All flowers on a plant are alike. The species includes 

 three groups of individuals or forms in regard to the relative 

 length of pistils and stamens as shown in figs, i, 2 and 5. 



Students of this species have noted minor variations in re- 

 spect to structure, size, color, and inter-relations in fertilization 

 among pistils and stamens. All have, however, evidently ex- 

 perienced no special difhculty in grouping the plants which they 

 studied into the three forms generally recognized. No dis- 

 tinctly new form or modification of the old forms seems to have 

 been found. But in a culture of this species recently grown at 

 the New York Botanical Garden, noticeable variations have 

 appeared and one type of flower is sufhciently frequent to be 

 recognized as a new form. 



In this new form (see figs. 3, 4 and 6) the pistil and the set 



* Contributions from the New York Botanical Garden, no. 268. 



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