58 Rhodora [March 



variety was the subject of a note in Rhodora for September, 1901. 

 Dr. B. L. Robinson, the writer, found var. monostachyon abundant along 

 with the type in northern Aroostook County, Maine, and at Grand 

 Falls, New Brunswick, and states that in some places it becomes 

 the prevailing form. Its range is indicated by the localities and 

 regions cited, — Prince Edward's Island, Katahdin, Alstead, N. H., 

 Lake Winnipeg, and the Rocky Mountains of British North America. 



The Gemmae of L. LUCIDULUM. On a sloping rock partly covered 

 with leaf mold I found 25 young plants of L. lucidulum^ of various 

 ages, derived from gemmae. I was interested in noting that some of 

 these plantlets were 3 feet from the nearest adult growth of the 

 species, and at a level one foot higher. How did the gemmae reach 

 this distance and elevation ? They are said by various writers to 

 "fall" or to be "spontaneously loosened" from the parent stems. 

 Some time later when 1 found L. lucidulum with the propagative 

 buds undisturbed, I was able partly to answer the question. Press- 

 ing down gently at the extreme edge of the cotyledon-like leaf of one 

 of the buds I broke the gemma off. It did not fall but snapped, and 

 landed 11 inches away. The second flew 25 inches, the third an 

 equal distance. It seems then, that elastic recoil from some source 

 may throw the ripe gemmae a little distance when these bodies are 

 struck, as by rabbits or birds or perhaps by rain drops. The shape 

 of the bud, which is slightly concave above and is held out as it were 

 like the hollowed hand, palm upwards, lends some degree of plausi- 

 bility to the idea that drops of rain or the heavier drip from trees 

 may be the usual means of loosening the gemmae. The range of the 

 trajectory may be 3 or 4 feet, at the greatest. This, I take it, is 

 about 40 times the annual advance by growth. The time taken for 

 bud-derived plants to mature, before another saltus of this kind can 

 occur, must very greatly reduce the relative gain in dissemination as 

 effected solely by snapping of the gemmae ; perhaps the ratio of 

 gain may be 3 or 4. 



Archangeli says that the gemma, or "bulbil," of L. Sclago — very 

 similar to that of L. lucidulum — falls off, and that, without any dis- 

 articulation by cellular disintegration, the tissues of the short pedicel 

 bearing the bulbil are ruptured through the pressure of cushion-like 

 swellings arising on the bases of the fleshy side leaves of the bulbil 

 and jutting against the upper leaves of the pedicel. When the stress 

 due to the growth of the swellings is greatest, a downward blow may 

 convert the pressure into an efficient propulsive force. 



