64 



J. O HAGSTEOM, CRITICAL RESEARCHES ON THE POTAMOGETONS. 



,0' 



WnQUr 







signed combination: 1) The filiform stem has not the strongly compressed shape that 

 has P. obtusifolius. The cross-cut form and anatomical diagram (fig. 24, B) evidently 

 is intermediate between P. fusillus and crispus. Evidence for the latter are the two 

 furrows, the subepidermal strands reduced in number and the bundle-trio (fig. 24, 

 B, tr) of the central stele; for the former, again, the rounded form of the stem 

 and of the central axis, and the few subepidermal bast-bundles. To these decisive 

 facts come (2) the narrow stem-leaves, and (3) the small turios intermediate 



between crispus and pusillus, not 

 between the former and obtusi- 

 folius, the buds of which are 

 larger than those of P. Bennettii, 

 a fact that otherwise ought to 

 be the very inverse. 



The specimens examined are 

 labelled: »Stirling V. Co. 86. 

 Wood Pond: Grangemouth. Aug. 

 24. 1894. R. KiDSTON & Col. 

 Stirling. A. F. n. 3001 » (hb. 

 J. Baagoe). Thus originating 

 from an exceedingly interesting 

 Potaniogeton-vegion of Scotland. 

 ■ — ■ It is not known to me if P. 

 concinnittis Ar. Benn. [crisp. X 

 pus.? ex Ar. Benn.) is the same 

 hybrid as the Stirling plant 

 or not. 





tr 



str 





Subsectio 7. Compressi 

 (Fries Nov.) Hagstr. 



Caulis valde compressus. 



Fig. 24. A, P. cris2ins L., Cross section of the stem, \^; Jl, P. Ben- -rp j • 4. T • • j. 



nettli Feyeb, Cross section of the stem, V; C, Cross section of P. jiksUIks -t Otia angUSte Imearia intCger- 



L., \», and D, Cross section of P. obtusifolius, V. a-, intercellular channels, «;™<i mnlf inpririn Kaai InfA r-n 



I, lacunffi, str, strands; E, P. Bennettii Fbyee, Top of a stemleaf, f. lima mUIWUei Via, DaSl jatC TO- 



tundata, apice acutissime cuspi- 

 data. Lignlce semper fissse, in spatio intermedio multinervise. Pistillum stylo bre- 

 vissimo, stigmate ovali-oblongo. Fruct^is dorso ssepe rugosus. 



This group is characterized by the short style and oval stigmas covering the 

 whole upper surface of the style. By this it closely joins the Monogyni m. (below), 

 whereas the strongly compressed stem unites it with the Crispi. Anatomically it 

 differs from all the contiguous groups by the strong, marginal, cauline strands being 

 provided with vessels, Fig. 26 A, a, D, a. The abundance of the foliar schlerenchyma 



