154 



J. O. HAOSTROM. CR1TICAL UESRARCHES OX THE POTAMOGETONS. 



ly lacking both dorsal and lateral keels. It is rounded npwards 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 of ten the case with most species. Pollen well-shaped abundant 

 spheric, scarcely of middle-size. 



Stein-anatomy: Epidermis without strcngthening layer and lacking subepidermal 

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

 cylinder with eight free vascular bundles. I have scarcel}' 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 (hb. 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.). 



P. Teppcri 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 lacuna; without bast- and vascular 

 bundles. Central cylinder comparatively thick, of oval 

 crosscut-form with O-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-ty pe diagram. 



The specimen examined is labellcd »500 miles N. 

 of Brisbane. Queensland. Auslralia, 1SS5. leg. F. M. 



Bailey (hl). Stockholm.). The species is Australian. The Aaiatic statements of this 



plant are doubtful and need confirmation. 



Fig. 71. /'. Tepperi An. Benni 

 TrAnsverse Bection <>i tlie stem, a , J , *■)>, 

 epidermis, /, lacnn&t Bystem, er, central 

 eylindi r, Ii; trio-bnndle. 



P. iiisiilaims n. sp. — Fig. 72. 



( 'milis teres tennis ca. 0,6 m altus, internodiis ± 5 om longis paulo ramosus, raroo 

 prolongatus. Folia submersa anguste lanceolata, petiolata vel subpetiolata, apieedh 

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

 lanceolata, 45 — 50 x 8 — 9 mm, 7 — Ll-nervia. TÅgulct, ca. 20 mm longee membranaoeaa 

 caducae. Peduncvlus eequalis ± 7r> mm longus. Spira parva, 5—10 mm longa. 



To judge from the persistenl remainders, the snbmersed leaves have been about 



