162 



J. O. HAGSTROM, CRITICAL RESEARCHES ON THE POTAMOGETONS. 



hyp. two-(l-)layered, scattered subepidermal strands, no lignlar or cauline bundles, 

 0-end., and a stele with a prototypic diagram. 



This species resembles very much some other South-American species, where- 

 fore I think it proper to give the following 



Synopsis of some S. American coriacious-leaved species, which non-fruiting often 

 are very difficult to distinguish from each other: 



Pseudo-hypoderma wanting : 



a. Cortical strands entirely absent 



b. Ligular strands few, in one circle 



c. Lig. str. + cauline str., in two circles 

 Pseudo-hyp. one-layered : 

 Pseudo-hyp. two-(l— 4-)layered. Central cyl. 



A. 



B. 

 C. 



a. Cortical strands entirely absent 



b. Subepidermal strands present 



c. Ligular bundles only 



d. Subepid. str. + lig. + cauline bundles 



Distribution of P. ferrugineus. Argentine Eep., Casa Bamba, Sierra chica de 

 Cordoba, 09, Stuckert, n. 19876 (hb. Haun.). Uruguay, Vegigas, 06, Berro, n. 

 4189 (hb. Haun.). 



nodosus. 

 montevidensis. 

 stenostachys. 

 spoliatus m. 



of the prototypic type: 

 apicalis. 

 ferrugineus. 

 hadioviridis. 

 linguatus. 



P. linguatus Hagstr. 



Ap. P. DuSEN, Zur Kenntnis der Gef.pfl. des siidl. Patagoniens, in Ofversigt 

 af K. Vet. Ak. Forh., 1901, no. 4, 259—262, cum fig. - Fig. 1, B, 80. 



p c.tr This species is at full development coarse-grown 



with thick and rigid stem, broad, many-nerved (±21 nerv.), 

 not lacunous submersed leaves, and broad, strong ligules. 

 The floating leaves seem generally not to appear at the 

 primary spike, but first in the eking piece of the stem, 

 which consists of many internodes. The stiffness of the 

 stem is caused by the rather short epidermis-cells, the 

 2 — 3-layered pseudo-hypoderma, the numerous subepidermal 

 strands, and the many free bundles of the stele. The 

 median bundles of the stele are typically four and the 

 lateral ones about eight, four on each side, encompassed 

 by an 0-endodermis, the whole thus presenting a proto- 

 typic aspect (Fig. 80, A). 

 The fruit and styles cause this species to be united with the AmplifoUi. The 

 styles are namely short and thick with oval or oblong small stigmas. Pollen 

 spheric of middle size. P. alpinus forms a separate group on account of the styles 

 and fruits and so does also P. nodosus because of the leaf serrulation. The phyloge- 



end 



tr 



Fig. 80. P. ItngaaiHS Hagstr. A, 

 Anatomic diagram of the central stele, 

 tr^ bnndle trio, ctr^ opposite bundle, 

 p, pith, end, endodermis. i?, Pistil, side- 

 view, ^^. For other details I refer to 

 the original description, where also a 

 habitus fig. is given. 



