182 J. O. HAGSTRÖM, CRIT1CAL RESEARCHES ON THE POTAMOGETONS. 



P. suboblongus ri. sp. 



< 'milis humilis teres tenuis simplex, superne (ex axillis fol. flor.) emittens ramos 

 radicantes. Folia coriacea (omnia?) ovalia obtusa, 11 — 15-nervia, longe petiolata, par\ a, 

 30 — 40 x 13 mm. IAgulm badiae tenues deciduae. Pedunculus teres tenuis 60 — 00 mm 

 longus. Spica deflorata 12 mm longa. Fruetus parvus siccus 2 X 1.5 mm, breviter rost- 

 rätas dorso rotundatus vel subcarinatus. Operculum angustum dorso rotundatum. 



The anatomy of the stem reminds of that of P. polygonifolius, but the epider- 

 lnis-cells are narrower, the epidermis is strengthened by a pseudo-hypoderma and 

 only a few bast-bundles, and the endodermis consists of thinwalled O-cells; and the 

 same is the case with the sheaths of the vascular bundles of the stele. 



The specimen examined belongs to the Univ. Mus. of Christiania and is thus 

 labelled: — »n:o 3154. P. polygonifolius Pourr. Taupaki. Kaipara. N. Island. N. 

 Zealand. 3. 84. leg. T. F. Cheeseman, com. Arthur Bennett, F. L. S., England.» 

 It is likely to be the specimen referred to in a note by A. Bennett in the Bot. 

 Gaz. 1901, p. 60, where P. polygonif. is recorded from New Zealand. 



The plant, indeed, resembles very much a small P. polygonifolius, also the fruit 

 bears great resemblance to this s])ecies. But the anatomical diagram of the stem 

 is another, and the fruit is, on closer investigation, also another. P. polygonifolius 

 has the fruit sharply keeled and the operculum is broader and keeled as is shown 

 in the fig. 116, C. P. suboblongus, again, has an operculum of the narrower thiekcr 

 type, high-vaulted and rounded almost as the fruit in the fig. 116, //. Besides it 

 is conspicuously smaller, in dry state only 2 x 1,5 mm (P. polygonif. 2.5 X 1,76). The 

 styles and the stigmas are not known to me. 



Leaves and ligules etc. as is statcd above. 



I*. prOmOIltoriCUS n. sp. (vel hybr. V). 



Caulis teres subtenuis altus, medio ramosus, internodiis 4—10 cm longis. Folia 

 superiora coriacea lanceolata 75 — 80x12 — 15 mm, longe (40 60 mm) petiolata ca. 

 13-nervia, inferiora membranacea longiora, 150—200x13—15 mm, Iongissime (100 

 — 150 mm) petiolata, margine lsevia 5 — 7-nervia, nervö medio retioulosa, apice obtusa, 

 attenuata. Ligulce badise subpersistentes conspicuc bicostatse, ca. 50 mm longa 1 . a<l folia 

 floralia ca. 40 mm. Pcdunculus a^jualis, primarius ca. 80 mm longus. Spica florens 

 ca. IS mm longa. Pistillum stylo incrassato, stigmats parvo, ferc ut in P. polygoni- 

 folio et coloraio. 



To judge from the materials accessible to me this plant seems to be high-growa 

 and branched at the middle. On the other hand il may rarely prolong itself by 

 branches from the axils of the involucral leaves. [t is characterized by its (especially 

 below) long, narrow, and long-petioled leaves, Lacking denticulation, and i(s Bwollen 



