146 Garsten Olsen. 



placed in a whorl at the top of the stem, though occasion- 

 ally one or two leaf pairs are found lower down. The leaf- 

 whorl is formed by the suppression of the uppermost inter- 

 nodes on the main as well as on the secondary axis. In 

 contrast to С suecica the leaves are said to be everlasting 

 (AscHERSON and Graebner); they are considerably larger 

 and tapering at the base; and also differ as regards the 

 venation ; in C. suecica the veins all diverge from the base 

 of the leaf, while in C. canadensis the two uppermost side- 

 veins diverge from the midrib somewhat higher up. 



The involucral leaves are as a rule larger than those of 

 С suecica. The petals are green, one of them often having 

 an awl-shaped elongated point. In material from North 

 America I have found specimens with red petals edged with 

 green, which together with other characteristics made them 

 form a transition in appearance to С suecica^). The three 

 specimens from Inuarudgligak which constitute the whole 

 material from Greenland had green petals. 



The biology of the flower has been treated by Lowell, 

 who writes: "As the flower-bud approaches maturity the 

 filaments grow rapidly, breaking apart the petals at the 

 base, and protruding as four V-shaped arches. If at this 

 stage the awl-shaped appendage is touched by the body of 

 an insect, or by a needle, the petals are instantly reflexed, 

 the elastic filaments straighten, and a minute shower of 

 pollen is projected upward. In fully matured flowers a 

 faint snap may be heard. Self-fertilization is prevented by 

 the immaturity of the stigma. Both stamens and petals 

 soon fall away, and the capitate stigma, composed of white 



* I have seen a similar intermediate specimen from Neriak on the 

 East coast of Greenland (61° 3"); the involucral leaves were very 

 large, and the petals red, edged with green; it had 2 pairs of 

 large, opposite leaves of which the uppermost pair supported 

 short-jointed shoots; the leaves tapered at the base and the 

 venation and anatomy were quite similar to those of C. canadensis. 



