224 



J. O. HAGSTROM, CR1TICAL RESEARCIIES ON THE FOTAMOGETONS. 



f. Lastedii n. f. — Folia caul. subm. elongata basi subcordata, 100— 120 x 15 mm. 

 f. subovalis n. f. — Folia caul. subm. basi ovalia subcordata. 45 — 60x10 — 11. 

 f. brevior n. f. — Folia caul. subm. brevia, basi subcordata — cordata. 35—45 



X 10—12 mm. 



f. restrictas n. f. — Folia caul. subm. 

 parva, 20x6 mm, basi rotundata. 



Habitat: N. America, see below ! 



f. stonobasis u. f. — Folia caul. subm. 

 basi lanceolata, spathulata, 50 x 7—8 mm, 

 vel supra. 



This rare form has narrower leaf- 

 basis than all the others and can easily 

 be mistaken for pure P. yra minens or 

 the hybrid V. Zizii. It is distinguished 

 by the leaf-apexes and the stem-ana- 

 tomy etc. 



At last I should remark that, like 

 P. gramineus, almost each of the different 

 crosses seems to be able to produce 

 terrestrial forms with more or less coria- 

 ceous leaves (f. terrestris Fries, Nov. 

 Fl. Suec. 1828, 35. — Tiselius, 1. c. 

 nos. 44, 142, 143). 



p subperfoliatus (Ratjnk i .ku ) 1 1 a<;str. 



f. pralongilMiiis (Tis.). /'. nitens p 

 prmlongifolius major Tis., 1. c. n:o 45. 



Stem-leaves with broadly coidate 

 rounded base 120— 150 (170) X 20 (30) 

 mm. Topmost leaves, on the stcm 

 prolongation, rarely with stalk-likc base; 

 internodes usually very long. 



This bcautiful ])lant is a true 

 nitens [gramin. x perfoliatU8)-foim and 



i wYn. „ aubfframineut (Baokk.) EUobxb. presents no influenee from /'. prcelongus. 



A, Habit-picture thowing ii,,, primary >ml secondary involacral ' 



, \, a, primary apike. B— H, Snbmeraed atom leavee, \. Ii, It coineitlcs with, or is at least UlOSt 



1 involutiu i <:. C, i. Lcesladii HAorrs., D, t. subovalia HAaam. ... n ,. ., ,. ... i- , 



/•:, t. brevior HiaaTB., F, i. tttnobasi» HA08TB., Q, t. reatrietM bko /. sallClfoll US WOLFO. accordlllg tO 



// ' f "" '""'"■' '"' "' Ml1 the desoription as well as specialens 



gathered and determined by Wolfgang hiraself and labelled: »P. aalicifolius mihi 

 c tlnvio Wilia Lithuania J. \V.» »Mia. Wolfgangj (in hb. Petersburg). The same 

 plant is the I', aalicifoliua Wolfo. In Huv. Willia Lithuan. Herb. W. Bbbbbb» ex 

 llcil). Lbdeboub» (hb. Petersb.). Besides, I bave seen the same plant from the »Herb. 

 Musei Pålat. Windob. 



