ON THE GENUS ERIOGONUM. 25 



scure and artificial characters, the great dissimilarity of 

 habit which they constandy present, strongly indicates a 

 radical diversity of constitution, and of how much im- 

 portance this habitus or constitution itself may often 

 prove in studying the intricate affinities of the vegetable 

 kingdom, the example before us adduces an additional 

 evidence. 



It is a fact somewhat singular, that all the genera of 

 the order Poly gone a hitherto known except Eriogonumy 

 are furnished with alternating leaves, sheathing the stem 

 at their base, or with distinct stipulae rising considerably 

 above the base, and also embracing the stem; cylindrical- 

 ly in the genus Polygonum, and are then called ochrea. 

 In the Eriogonum, however, as in the rest of the order, 

 the laminae of the leaves before their developement, are 

 on either side rolled under towards the mid-rib, or cen- 

 tral vessels. The seeds are also furnished with a farina- 

 ceous perisperm which surrounds the corculum or em- 

 bryon; we shall likewise perceive in the course of our 

 examination of this genus, that though the leaves of the 

 stem and the general involucrum of the scape are con- 

 stantly verticillate and destitute of stipule, yet in the tv/o 

 recently discovered and almost stemless species, the leaves 

 are alternately disposed upon the elongated caudex, and 

 that at a particular season of the year, the leaves then im- 

 perfectly developed or rather restrained in their growth, 

 produce sheathing petioles. In the present order, the 

 Koenigia of Iceland, the terminal leaves, or those which 

 subtend the fascicles of flowers are verticillate in fours, 

 while the rest of the leaves are alternate and furnished 

 with intrafoliaceous stipulse. 



It would still, perhaps, be better in assigning the li- 

 mits of this very natural order, to add to the assigned ha- 



