n] THE ARROWHEAD 15 



two American writers 1 , in describing the seedling of Sagittaria 

 variability allude to the occurrence of a cellular plate just within 

 the cotyledonary sheath. They refer to this as " a vestigial 

 structure " and interpret it as probably representing a second 

 cotyledon. It appears, however, to the present writer that it is 

 much more reasonable, judging from the figure and description 

 given, to suppose that this scale is merely one of the " squamulae 

 intravaginales," whose existence in the seedlings of Sagittaria 

 was placed on record by Fauth 2 . These structures, which are 

 so common among water plants, belong to the category of 

 hairs; they contain no vascular tissue and cannot be homolo- 

 gised with a foliar organ such as the cotyledon. 



Plants of the Arrowhead, carefully dug up in the late summer, 

 are found to show preparations for the winter's rest and for next 

 season's growth 3 . From among the bases of the crowded leaves 

 arising on the short main axis, a number of white stolons protrude 

 (j, Fig. 6, p. 1 6), distinguished from the roots by their greater 

 thickness. They each bear one or more scale-leaves and terminate 

 in a bud (/). The present writer measured a stolon on July 1 6, 

 1910, which had reached a length of 25 cms. 4 . Later on, the 

 two internodes below the terminal bud swell up and form a 

 tuber which may be 5 cms. long. As many as ten stolons may 

 arise from the base of a single plant, so that, where Sagittaria 

 grows freely, a very large quantity of tubers are produced. One 

 author 5 records that he collected two to three litres of tubers on 

 digging up soil whose superficial area was one square metre. By 

 a downward curve of the stolons, these reproductive bodies are 

 carried some depth into the mud, where they pass the winter. 

 The mature tubers are coloured blue by anthocyanin, which 



1 Coulter, J. M. and Land, W. J. G. (1914). 



2 Fauth, A. (1903). 



3 Nolte, E. F. (1825), Walter, F. (1842) and M (inter, J. (1845). 



4 The stolons seem to develop earlier in terrestrial plants than in 

 plants growing in water. The present writer has found that vigorous plants 

 growing in water may show only quite short stolons in the middle of 

 August. 5 Klinge, J. (i 88 1). 



