18 J. O. HAGSTEOM, CRITICAL EESEARCHES ON THE POTAMOGETONS. 



MERFELT (hb. Uppsal.); Dovre, Todalen, 81, Strom (lib. Uppsal.); Dovre, Goverli- 

 vandet, 65, Falck (hb. Lund.), Jerkind, 1837, Lindblom (hb. Christian.), Karasjok, 

 13, O. Dahl (hb. Christian.). 



II. Broad-leaved forms. 



Var. (3. Macounii MoRONG, in Macotjn's Cat. Canad. PL IV. 1888, 88. — In 

 this form the lower leaves reach a breadth of 1,5 mm, the upper ones and the 

 branch-leaves a little narrower, 7* — 1 ni™> apex rounded (Fig. 3, G) and of 

 nearly the same width as the middle part. Internodes and the peduncles short 

 (the latter only 10—20 mm), spike dense-flowered. Stem often elongated with a 

 very short spike-bearing branch. Sheaths, ramification, fruit, anatomy etc. seem not 

 to diverge from the main-form. Through its often bushy habit and the short peduncle 

 this variety much reminds of the f. fasciculatus but differs by the broad leaves and 

 dense spikes. — It belongs to the prairie-region of Canada, but a similar form with 

 the usual narrow leaves has been gathered by S. Almquist in shallow water at 

 Galon in Sodermanland, Sweden, 1888 (hb. Uppsal.): Mature spike dense, peduncle 

 5 — 10 mm. An interesting connecting form. 



An authentic P. filiformis var. Macounii MoR., coll. Morong, lies in hb. Stock- 

 holm. — Fig. 3, G. 



Var. Y- occidentalis RoBBiNS, Bot. King's Explor. etc. 1871, 339. — Resem- 

 bles the next foreging, but has longer peduncles. These two varieties are properly 

 American types and by D:r P. A. Rydberg held for a distinct new species, P. 

 interior, yet after my opinion without sufficient grounds. Neither pistils nor fruits 

 differ in any essential respects from the type, f. vulgaris Tis., and the anatomy is 

 also the above described an figured. 



Var. 3. Kilihnanii n. var. — Caulis elongatus, 20 — 30 cm; folia breviuscula, 

 0,5—0,75 mm lata, vaginis brevibus (± 10 mm), latis, griseo-marginatis ; pedunculus 

 elongatus (100 mm); fructus magni. — P. pycnostegus Kihlm. in Herb. Upsal. 



This var. differs from the f. major Tis. through the rather broad leaves, short 

 sheaths with greyish margins and always large, thick-shelled fruits. On account of 

 these somewhat bigger fruits it was by D:r A. O. Kihlman looked upon as a se- 

 parate species, but large-fruited forms are met with in almost all species. 



It occurs in Sweden on lime-ground viz. Jemtland, Sundsjon, 56, Krok (hb. 

 Stockh. et Uppsal.); Gothland, Klintehamn in the river, 61, Nyman (hb. Stockholm.). 



Var. s. rivicoliis Hagstr., Potamog. in Neuman, Sveriges Flora, 1901, 794. — 

 Differt a typo foliis latioribus (0,75 — 1 mm) fusco-viridibus, pedunculo folia vix su- 

 perante, fructu ut plurimum majore. — Fig. 3, H. 



This form or variety is usually megacarp, but occurs also microcarp, in 

 habit rather like f. luxuriosus, but with broader leaves, maintaining their width into 

 the apex, by which it comes near to the following variety. 



Distribution. Sweden, Gothland, Gothemsan, 94, Johansson (hb. Stockh.), 

 Klintehamn, 61, Thedenius, 82, Andersson, 88, Johansson, 91, Bolin (hb. Stock- 

 holm., Uppsal, Lund.), Hau trask, 55, Stenhammar et Floderus (hb. Stockh. et 

 Uppsal.), Kyllgardsans utlopp, 52, Westoo, 53, Lth, 59, Sandeen (hb. Uppsal., 



