270 Key to the System of 



XANTHOSIA. 



1234. Umbel-stalks elongated. 



Perennial, rather tall, slender, soon glabrous ; leaves mostly 

 basal and long-stalked, divided into three cuneate-rhom- 

 boidal and at the upper end indented segments ; bracts to 

 each of the umbellules three, broadish, petal-like, whitish ; 

 lobes of the calyx almost white ; fruit small. 



X. Atkinsoniaua. 



Umbel-stalks abbreviated 1235 



1235. Leaves lobeless. 



Dwarf, perennial, somewhat velvety and besides beset with 

 scattered hairlets ; leaves small, wedge-shaped, with 

 three denticles at the summit ; flowers in each umbel 

 few or occasionally reduced to two or one ; calyx-lobes 

 fixed above the base. X. trideiitata. 



Leaves lobed ... ..- ... 1236 



1236. Glabrous. 



Dwarf, perennial ; leaves cleft into three narrow often 

 subdivided segments, the ultimate lobes acute and mostly 

 narrow ; flowers few or several in the umbel ; calyx-lobes 

 fixed at the base ; fruit dilated towards the base. 



X. dissecta. 



Vestiture of soft hairlets ... 1237 



1237. Middle lobe of the leaf by far the longest. 



Perennial, rather tall, much beset with a dense brownish 

 vestiture and besides with long scattered hairlets ; leaves 

 simply sinuous or cleft into three to five lobes ; umbels 

 few-flowered ; calyx-lobes fixed at the base. X. pilosa. 



Middle lobe of the leaf slightly longer than the 

 others. 



Dwarf, beset with spreading hairlets ; leaves on short stalks, 

 cleft into three elliptic or lanceolar entire or incised seg- 

 ments ; flowers often only one to three in each umbel ; 

 calyx-lobes fixed at the base. X. pusilla. 



