Manchester Memoirs, Vol. lix. (1915), No. 3. 



III. Studies in the Morphology of Isoetes. I. The 

 General Morphology of the Stock of Isoetes lacustris. 



By William H. Lang, M.B., D.Sc, F.R.S., 



Barker Professor of Cryptogamic Botany in the University of Manchester. 

 {Read December 1 st, 1Q14. Received for publication Dece7)iber yth, 19/4.) 



Introduction. 



Isoetes has been studied by many investigators and it 

 might be assumed that its morphology was so well known 

 as to render further description needless. While this is 

 true of many facts regarding its life history and structure, 

 the morphological problem presented by this peculiar and 

 isolated genus of existing Vascular Cryptogams remains 

 difficult and fascinating. Its re-statement in the present 

 series of papers will lead to the critical consideration of a 

 number of features in the construction of the stock, the 

 relation of the leaves and roots to the upper and lower 

 regions of the stock respectively, and the progressive 

 growth of the plant as a whole, from the older embryo to 

 the adult condition. 



The term stock will be used for the tuberous axis of 

 Isoetes instead of the word stem, since one of the main 

 questions at issue is whether this axis is best regarded as 

 a short stem bearing peculiarly arranged adventitious 

 roots, or as composed of an upwardly growing region 

 bearing the leaves and a downwardly growing structure 

 bearing the roots. This lower region of the stock may, 

 without pre-judging its morphological nature,be contrasted 



February 6t//. } kjij. 



