316 Origin of Each Species Considered Separately. 



but closer inspection reveals them hidden away in the 

 tube at the base of the corolla. Hence the name O. brevi- 

 stylis or short-styled Evening Primrose. The length of 

 the style varies very much; the stigmas sometimes lie 

 right inside the tube, sometimes they stand a full centi- 

 meter out of it. But there is a great gap between the 

 longest styles of 0. brevistylis and the shortest ones of 

 O. Lamar ckiana. 



When the flowers are through blooming they wither 

 down as far as the fruit but are not thrown off as they are 

 in 0. Laniarckiana, but remain attached for considerable 

 time to the unripe fruit. The plants can be recognized 

 from afar by this character, and even perhaps still more 

 readily by the smallness of their fruits. In their fully 

 developed state these are hardly larger than the ovaries 

 of open flowers ; they remam bent outwards, pressed 

 against the bract and almost hidden between the broad 

 auricles at its base. From a distance it looks as if the 

 plant had never been fertilized: LamarcHawa on the other 

 hand does not hide its great, fine, erect fruits between the 

 bracts. (Plate I.) 



In the fruiting period Brevistylis plants can therefore 

 be more easily recognized than those in blossom; but as 

 a rule brevistylis keeps up flowering later into the autumn 

 than O. Laniarckiana. 



The stigmas are developed in an unusual way; for 

 instead of being stout and cylindrical they are flattened 

 and leaf-like. They retain the abundance of pollen that 

 is brought to them by bumblebees, permit the develop- 

 ment of pollen tubes which elongate in the usual way, and 

 reach the ovary in numbers but fertilize only very few 

 ovules. Many plants set no seed at all, others very little. 



