154 



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



ly lacking both dorsal and lateral keels. It is rounded upwards and very shortly 

 beaked, on the inside there is usually a sinus (see fig. 70!). Perianths of rounded 

 form broadly obovate — obcordate — nearly square-formed with rounded corners, 

 etc., varying as is often the case with most species. Pollen well-shaped abundant 

 spheric, scarcely of middle-size. 



Stem-anatomy: Epidermis without strengthening layer and lacking subepidermal 

 strands, to. Interlacunar bundles wanting. Endodermis of typical 0-cells; central 

 cylinder with eight free vascular bundles. I have scarcelj' met with a species corre- 

 sponding so nearly to P. nodosus as regards the stem-anatomy as this. It differs 

 by the smooth leaf-margin, the long lower petioles, the prasinous leaf-colour, the ligules, 

 the styles, and chiefly by the characteristic fruits. 



Distribution. N. America, Novo-Mexico, 1847, Fendler (lib. Stockholm.), 

 Mexico, State of Chihuahua, Guerrero, 87, Pringle (hb. Uppsal.), signed »1390. P. 

 fluitans Rth». Nebraska, 93, Rydberg (hb. Haun.); Marin Co., Cal. 78, Edwards 

 (hb. Haun.). 



Fig. 71. P. Teppeii Ae. Bennett. 

 Transverse section of the stem, 'Y, ep, 

 epidermis, I, l.aoxinar system, cc, central 

 cylinder, t)\ trio-bundle. 



Bailey » (hb. Stockholm.) 



plant are doubtful and need confirmation 



P. Tepperi Ar. Bennett. 



Journal of Botany, 1887, 178. — Fig. 71. 



Beside fruits only a few fragments of this species 

 are present. — Stem terete, 1,5 — 2 mm thick. The 

 stem-anatomy is characterized by the epidermis possessing 

 a one-celled pseudo-hypoderma but typically lacking 

 subepidermal strands. The bark consists of three circles 

 of rather narrow lacunae without bast- and vascular 

 bundles. Centra] cylinder comparatively thick, of oval 

 crosscut-form with 0-endodermis and 8 ( — 12) well 

 separated vascular bundles with more or less strong and 

 complete bast-sheaths. The bundle-trio is united into a 

 compound bundle, trio-type diagram. 



The specimen examined is labelled »500 miles N. 

 of Brisbane. Queensland. Australia, 1885. leg. F. M. 

 The species is Australian. The Asiatic statements of this 



P. iiisulaniis n. sp. — Fig. 72. 



Gaulis teres tenuis ca. 0,5 m altus, internodiis ± 5 cm longis paulo ramosus, ramo 

 prolongatus. Folia submersa anguste lanceolata, petiolata vel subpetiolata, apice ± 

 obtusa, integerrima, 5 — 7-nervia, cito putrescentia; natantia ± coriacea petiolata 

 lanceolata, 45 — 50 X 8 — 9 mm, 7 — 11-nervia. Ligulce ca. 20 mm longse membranacese 

 caducse. Pedunculus sequalis ± 75 mm longus. Spica parva, 5 — 10 mm longa. 



To judge from the persistent remainders, the submersed leaves have been about 



