96 WILLIAM TRELEASE ON THE 



Table I.— Largefloweietl O. conMCtJLATA, var. stbicta. 



Length of Stamens. 



StnmenB. 



Pistil. 



Corolla. 



I 



I 



From one plant. > 



From one plant. 



10 mm. 

 10 

 9 

 9 

 9 

 6 

 8 

 8 

 9 

 8 

 6 

 8 



Average. 



3 mm. 



4.3 mm. 



6.2 mm. 



Table II. O. corsiculata, var. ( ?) macbantha. 



A, Long-Btylcd. 



S. Mid-sttjle.rl. 



C. Short-Styled. 



and pistils (Table II), but have not had an opportunity to measure the pollen of the dif- 

 ferent sets of stamens. Some of the specimens come veiy near 0. pilosa, ISTutt., as rep- 

 resented by a flowerless specimen of Kuttall in the Torrey herbarium. It will be seen 

 that the last two (and others have been observed) have the styles equal to the longer 

 stamens, as in tyi^ical corniculata, although the flowers are veiy much larger. Botanists 

 who are able to study this large-flowered form in the field should make the measure- 

 ments on a large number of specimens, necessary to determine whether it is heterogone 

 or not. 



While the heterogony of this form is at best only presumable, we have two truly tri- 

 morphic species of this section, as may be seen from Tables III-VI. 



As these species are all very closely related, they appear to illustrate the manner in 

 which an originally homogone species, variable in the relative length of stamens and 

 pistils in some of its forms, may give rise to others which are triniorphic. 



The specimens of 0. acefosella and its variety Oregana, and of O. tnlliifolia, that I 

 have examined, agree in having the two sets of stamens very unequal in length, while 

 the pistils mostly considerably surpass the longer set^ The appearance is, therefore, 



Cy. Darwin: Different Forms of Flowers, 182; and 



HiUlebrand: Monatsber. Bei-1. Akad., 18GG, 3CG ; Bot., 

 Zeit., 1887, 36. 



