KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 55- NIO 5. 53 



To the section Convoluti (Subsect. Vaginati?) might also belong P. Livingstonei 

 Ar. Benn., the leaf-apex of which, fructifications, and anatomy are not yet described. 

 — A very stränge »P. pectinatus» is recorded from Florida with »drupelets cochleate, 

 barely fleshy, 1,5 mm long, 3-keeled on the back, crestless, but with 4—5 teeth» 

 (Small, Flora south-east. U. States 1903, 39). 



P. dissimilis Ar. Benn., of S. America, is P. pectinatus var. striatus, according 

 to authentic spec. from Casa Bamba. »Stipula? adnatae ad 5 cm longse» probably 

 bears upon the sheath and ligule together. Leaves are said to be very long, »4,35 dm», 

 evidently a misprint; the form is congruent with the Jujuy plant of Argentine. 



Subgenus B. EupotaiUOgctOll Raunk. 



De danske Blomsterplanters Naturhist. I: 1, 1896, 34, 108. (See p. 13!) 

 Caulis teres — subteres v. compressus— bicanaliculatus, ramosus — simplex. Folia 

 uniformia linearia plana — lanceolata ± undulata, semper submersa, vel bi— trif ormia : 

 l:o submersa plana vel margine ± undulata, membranacea, canalibus internis, ut 

 in prsecedente, ad costam mediam vel ad nervös principales sitis, vel semiteretia 

 rigida ± canaliculata, canalibus ut in Coleogetonibus, 2:o fluitantia ± coriacea locu- 

 losa integerrima, omnia rarius vaginata ligulata vel ut plurimum evaginata ligulis axil- 

 laribus vaginantibus vel lateralibus. Spica deflorata densa v. subinterrupta rachide 

 rigida. Stigma papillis minoribus. — Caulis endodermide instructus, ± flexilis, pedun- 

 culus eam desinens ± rigidus. — Hybernacula (turiones) subterranea rhizomatica vel 

 supraterranea caulina. — Gemma superior caulis ut plurimum subjectå validior. Pol- 

 linatio per ventum. 



As to the function of the endodermis different views have been taken, see H. 

 Schenck, Anat. p. 52 ! Comparing the species of this and the precedent subgenus, 

 however, it stånds clear that, beside the comraon purpose of effecting resistance 

 against the impetus of the waves, its chief function is to make the stem and pe- 

 duncle flexible. Such peduncles that are rigid and rise över the water-surface al- 

 ways lack an endodermis and spread the bundles more or less in the cortex. 



Sectio III. Adnati Hagstr. 



Caulis compressus— bicanaliculatus. Folia uniformia, linearia plana ± nervösa 

 serrata vaginata canalibus ad costam mediam instructa. Prcefoliatio adplicata. Ra- 

 morum apices in hybernacula transformantur. 



Subsectio 5. Serrulati Hagstr. 



Characteres : vide supra! — C. Raunki,er's opinion of this group, see p. 13! 

 To this group belong but two species, constituting an interesting and signi- 



