458 NOTES ON HYDROCOTYLE AMERICANA. 



must bo remarked that the stolons arc always to be found under 

 ground, but usually near its surface, and the runners are creeping ou 

 the earth. But it is probably a mere matter of accident as to whether 

 these organs of propagation are developed as stolons or as runuers. It 

 seems to depend on certain circumstances, as the condition of the sta- 

 tion, the softness or moist ness of the ground, etc., aud 1 think it very 

 probable that the stolons might be transformed, or rather developed, as 

 runners by being kept out of the ground aud prevented from bending 

 downwards under the surface of the earth. In every case, as it will be 

 shown later, their structure is almost the same as that of the runuers. 



The stolons consist of several internodes, the length of which varies 

 from less than 1 centimeter to 5 or G centimeters; they are white, trans- 

 lucent, and bear at each node a very small, scale-like sheathing leaf, 

 cleft a little above its middle, as is shown in Plate xlvi, Figs. 3-4, 

 where such a leaf is drawn from two sides, aud under these leaves can 

 be seen some very small and thin roots, which are often but slightly 

 branched. 



At the end of each stolon we see (Plate xlvi. Fig. 8) a tuber, of 

 ■which the first interuode is almost cylindrical, elongated, and usually 

 about one-half centimeter in length, and longer than the other inter- 

 nodes of the tuber. The figures 8-11 on Plates xlvi and xlvii show 

 four tubers of different sizes and states of development. The largest 

 one (Fig. 10) had a length of \h centimeters, but this size is exceptional, 

 as they are usually not longer than 1 centimeter. The number of inter- 

 nodes varies from two to six, but four is the most common. These in- 

 ternodes are cylindrical, often a little broader at the middle, and are yel- 

 lowish-white in color. They are all provided with leaves, closely ap- 

 pressed to the nodes, and these leaves are scale-like, but always cleft to 

 the middle, with the lobes ovate and nearly obtuse (Plate xlvii, Fig. 

 12). Usually three to five roots are to be seen under these leaves, 

 which are in the young tubers developed, but as small warts, but later, 

 by the germination of the tuber, they grow out and attain a development 

 as small, thread-like roots, with only a few ramifications. 



At the end of the tuber we see a conical bud, often somewhat pointed, 

 and usually directed a little upwards, and this bud is able to develop 

 an independent plant in the following spring, while the stolon is not 

 persistent, but dies a slant time after the formation of the tuber, during 

 the fall or in the beginning of the winter. But, besides this bud at the 

 end of the tuber, we find one in the axil of each tuber-scale, which is 

 only developed as a small protuberance, which may develop into short- 

 stalked tubers, or, more correctly, short stolons with tubers at their end, 

 as it is shown on Plate xlvi, Fig. 7. It does not happen very often, ac- 

 cording to the plants I have had the opportunity of examining, that 

 these buds become so developed, but I should .suppose that they are 

 nevertheless of some importance for the propagation of the plant, if the 

 tuber should be injured and the terminal bud destroyed. The impor- 



