KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 55. NIO 5- 51 



In shallow water it behaves as var. dijjusus upwards branching more richly, 

 and well corresponding to f. scoparius. This form should be called f. ramulosus. 



f. ramulosus n. f. — Ramosior prsesertim in parte superiore. Apices foliorum 

 caulinorum subelongati ± acuti. 



Distribution of v. zosteraceus: Sweden, Angermania, Säbrå, 66, Arnell (hb. 

 Uppsal., Lund., Gotenb.), f. ramulosus; Nora, 56, Fristedt (hb. Uppsal.); Hernö- 

 sand, 56, Fristedt (hb. Stockholm.). Medelpad, Tynderö, 85, Neuman (hb. Upp- 

 sal., Lund.), f. ramulosus. — Helsingland, Stocka såg, 91, Sandahl (hb. Stockholm., 

 Uppsal, et Lund.), f. ramulosus and transition forms to var. dijjusus f. scoparius. - 

 Gestrikland, Gefle at Utnåra etc, 33, Thedenius and others (hb. Uppsal.), ff. ramu- 

 losus and scoparius. — Uppland, Rådmansö, 10 (hb. Stockholm.), f. ramulosus; Lju- 

 sterön and many other places (hb. Stockholm., Uppsal., Lund., Gotenb.), typical 

 forms. — Stockholm, several stations (hb. Uppsal.). — Sudermania, Sandemar, 59, 

 Thedenius (hb. Stockholm.), Österhaninge, Fjellong, 53, Björnström (hb. Stock- 

 holm., Uppsal., Lund. et Gotenb.), Utö, leg. Hartman, Ährling and others (hb. 

 Stockholm., Uppsal., Lund. et Gotenb.), Oxelösund, 00, Lagerwall (hb. Lund.), f. 

 ramulosus. — Ostrogothia, Dagsberg, Beteby, 67, Westerlund (hb. Uppsal, et Gotenb.), 

 f. ramulosus. 



Finland, Regio Aboensis, 81, Hollmén (hb. Stockholm., Lund.). 



Var. striatus (Ruiz & Pav.). 



P. siriatus Ruiz et Pavon, Fl. peruviana 1798, 70, t. 106: — Folia inferiora 

 saepe latiora (2—5 mm), 3— 5(7)-nervia; pedunculus brevior; fruetus minor. Ceterum 

 ut var. zost. Figg. 16, F; 18, H, K. 



Basal stem-leaves of this variety of ten broader than in the foregoing, but their 

 shape and sheaths are alike for the rest. Without ripe fruit this plant would be 

 difficult to distinguish from var. zosteraceus i. ramulosus, which form, besides, also 

 sometimes appears microcarp and with shorter peduncles (see L. M. Neuman, Några 

 kritiska o. sällsynta växter 1888, 23—25!). Fries says also of his zosteraceus, »Se- 

 quenti (P. pectinato) utique affinis 1. forsan magis P. striato» (Nov. 1828, 51). Leaves 

 are described as »longitudinaliter striata» and the stem is also recorded as »stri- 

 atus», but the anatomy of both stem and leaves completely coincides with that of 

 P. pectinatus. The striation of the leaves originates in the channel walls and not 

 in a mechanical tissue. The form of the pistil and fruit does not differ from P. 

 pectinatus. The single remaining quality, therefore, would be the constant small- 

 ness of the fruit, 3x2 mm. »P. striatus» is an interesting small-fruited and usu- 

 ally broad-leaved South- American race of P. pectinatus nearly as »P. canadensis» 

 is a North- American race of P. vaginatus (p. 36). 



A peculiar difference as to the ramification presents the following form. 



f. gemiuatus n. f. — Caulis per ramulos l:se— tertise ordinis ex axillis foliorum 

 floralium valde prolongatus. 



