V 2 



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



coll. J. A. Holm) is misreported by E. Collinder, Medelpads Flora, 1909, 179. The 

 plant referred to is P. zosterifolius, which has spread more northwardly (see p. 66). 

 On the west coast a single station is recorded, viz. Gothenburg, 53, Xrok, Lindberg 

 and many others in låter times (hb. Stockholm., Uppsal., Lund. et Gothenb.). 



The statement from Norway (Skien) B lytt, Xorges Flora I, 1861, 368, is a 

 mistake instead of P. mucronatus (see under that species!) according to Blytt's 



examples as well as A. Blytt, 

 Norges Flora I, 1902, 49. The 

 northern limit of P. acutifolius 

 in the Scandinavian Peninsula 

 thus rims from Örby hus (Upp- 

 land) to Örebro (Xericia) and 

 Gothenburg. The species, how- 

 ever, does not appear equally scat- 

 tered över the whole area to the 

 söuth of this line, but in three 

 isolated small districts: 1) a west- 

 ern one: Gothenburg, 2) a south 

 area: Scania with south Halland, 

 and 3) a northern, larger district. 

 The stations within this last one, 

 stränge to say, seem to be situ- 

 ated on the old bottom of the Li- 

 torina Sea. Hence we might per- 

 haps suppose P. acutifolius to be 

 a rather recent plant-immigrant 

 to Sweden. 



Extra-scandinarian stations : 

 Den mark, near Copenhagen etc. 

 (hb. Stockholm., Uppsal, et Lund.). 

 — Ge.rmany, several places (hb. 

 Stockholm., Uppsal, et Lund.). 

 France, several places (hb. 

 Stockholm., Uppsal, et Lund.). 

 From those countrics as a centrum it see ms to have spread to Hohcmia, in lacu 

 Zåklioi, VbleNOVSKY (hb. Lund.), Transylvania prope Baumgart, Dr. Scilur (hb. Stock- 

 holm.), Bdgium (hb. Uppsal.) and England, Middlesez, Linton (hb. Uppsal.), Nor- 

 folk, 87, BennBTT (hb. Stockholm, et Uppsal.). It is also reoorded from Russia, 

 Plescau, and Iluly, but I have not seen specimens from thence. Australian and 

 Manchurian planta referred to P. acutifolius surely are something else. 



P, acutifolius, thus, has a comparatively limitcd distribution-area, and istoge- 

 ther with P. coloratuå an almost exclusive European species. 



Fig. 28. A — K, 



— A, 



I', tudermartieus Haostb., F, 1'. putillua L. 

 Basa! portion of ii stem-leaf, ',''; B, Transverse section of a stcni loaf at. 

 the middle, ',", "'. midvein, tv, lateral nerves, l, lncnnar system, sir, 

 mechanical Btrands, the marginal bundit» veiy strong; (.', Transverse sect. 

 ut the stem, K , ee, central :i\is, atr, snbepidermal stranda; D, Longitadina] 

 section of the epidermis, ■',''• /•■'. Transveree sivt. of the pednncle, V- showing 

 two median (vb) and two lateral vast-ular bnndles and a single snbepidermal 

 bast-bnndle. /•'. Basa! parts <>t stem-leaves, «, snbpetioled, b, sessile, ',". 



