JOHNSON: A REVISION OF THE SECTION BORAPHILA 9 



thinner, and at first slightly elevated in the form of a projecting ring, while 

 that of 5". Nelsoniana is fleshier and crowds the bases of the stamens 

 closely. Besides, the stigmas of the latter are somewhat flattened, while 

 those of the former are large in proportion to the size of the carpels, and 

 globose. Both species are stoloniferous, with a tendency to branch more 

 in S. Nelsoniana. 



The carpels of S. arguta (Plate IV) have elongated bodies and beaks, 

 terminating in very small stigmas, and are united up to the middle. Fine 

 lines run lengthwise along the sides. The species is much less stoloniferous 

 than its allies. 



The seeds of the Rotundifoliatae are distinctive in their markings in 

 comparison with those of the Cuneifoliatae. The distinctions are shown in 

 Plate IV. In this case the markings have the form of thin, septate, ribbon- 

 like structures running along the surface and projecting conspicuously. In 

 the Cuneifoliatae, on the other hand, the markings are plainly pectinate. 



Three types of carpels occur in the Cuneifoliatae, which are made clear 

 in Plate IV. The stout, erect, purple carpels of S. unalaschensis are un- 

 mistakable. In S. davurica (Plate IV) they are elongated and not a little 

 contracted, with much more slender and divergent beaks, and at the same 

 time somewhat separated. In S. Lyalli (Plate IV) the beaks are greatly 

 elongated and slender, and the stigmas oblong. The rich, dark-purple color 

 of the carpels of S. unalaschensis is absent in these species. 



The Rotundifoliatae are species of the high western mountain ranges. 

 S. arguta is the most widely distributed and also the most abundant, 

 occurring throughout the length of the Rocky Mountains and also south- 

 ward into the Sierras. S. aestivalis occurs from the region of Yakutat Bay, 

 Alaska, to Montana, and south into Oregon. S. Nelsoniana follows the 

 coast of Alaska and thence inland along the Rocky Mountains to the 

 Selkirks. Their ranges thus overlap for a considerable distance and, con- 

 sidered as a whole, constitute a notably continuous distributional belt, which, 

 when coupled with the close structural similarities, further emphasizes the 

 close relationships of the group. 



The Cuneifoliatae do not show the same continuity of range, as far as 

 can be determined. S. unalaschensis has been found on the islands of Bering 

 Sea and in a few scattered localities on the west coast of Alaska to Unalaska. 

 S. davurica is known to occur along the shores of Kotzebue Sound and 

 Bering Slrait, but has an extended Asiatic range as far as Lake Baikal and 

 Dauria. The two species are very similar in vegetative characters. 5". 

 Lyallii appears to be an intermediate form; it has the elongate open in- 

 florescence of 6". arguta and its leaves are sometimes rounded distally but 

 always cuneate at the base; besides, the carpels are greatly elongated and 

 terminate in slender beaks. These similarities are further emphasized by 



