70 THE AMERICAN BOTANIST 



reduced to one flower. The same thing is often seen in the 

 species H. Canadense which has a recognized variety iiiiui- 

 miim. I am not aware of any economic use for the genus. 

 Most of its members may be classed as weeds though H. as- 

 cyron is well worth a place in any garden. 

 Touisset, Mass., July 1909. 



REPRODUCTION IN APIOS TUBEROSA. 



BY E. E. BALDWIN. 



IN an article on the fruiting of Apios tuhcrosa published in 

 the Botanist, last fall, it was noted that in the latitude of 

 northern Illinois it seldom bears fruit which was something of 

 a surprise to the writer. In this latitude. (Mississippi) this 

 plant grows luxuriantly and flowers freely besides producing 

 root tubers in abundance. 



It is the law of the reproduction of those plants which re- 

 produce themselves both by seed and by any form of subter- 

 ranean growth and whose liabitat while originally tropical has 

 extended itself for any great distance above the frost line into 

 the temperate zones, that, while in their original habitat they 

 keep up both methods of reproduction, as they extend north or 

 south from the tropics they gradually cease flowering and de- 

 pend upon their root growth for reproduction. 



The reason for this is obvious. In their tropical home 

 the warm season is long and ample in length for the seeds to 

 mature. As the season is shortened by reason of the increased 

 distance from the tropics reproduction by the bearing of seed 

 becomes more and more difficult and is gradually abandoned 

 by the plant which conforms itself to the circumstances sur- 

 ronding it and gradually depends upon its root crop the more 

 for reproduction. 



Thus the sweet potato (Batatas cditlis) while it flowers 

 profusely and matures seed in Central America, in this lati- 

 tude never flowers except late in the fall of an exceptionally 



