KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 55- N:0 5. 33 



Turczaninow's description of this species scarcely contains anything that would 

 well distinguish it from its congenerates, for instance P. pectinatus. Even a 

 characteristic not occurring in the plant named P. vaginatus is mentioned when the 

 author writes, »foliis omnibus submersis etc. acutis trinerviis». As to P. pectinatus 

 it is said, »foliis etc. acutis uninerviis». Subsequently Turczaninow considers the leaf- 

 apex of the two species to be conform, whereas the nervature is held to be another. 

 Kihlman who quotes incorrectly the original diagnosis (acute trinerviis instead of 

 acutis trinerviis), has afterwards given the correct description of the leaves (1888). 

 Nevertheless it is incomprehensible to me that such a sagacious observer as Turc- 

 zaninow should consider the leaves as acute, while they are, at least the stem-leaves, 

 even to the naked eye conspicuously obtuse; and the suspicion has cropped up that 

 the form alluded to might have been something else. No specimen determined by 

 the author himself has come under my eyes, but Kihlman asserts having seen one, 

 which he states to be congruent to our Bothnian species, and I myself have seen 

 our vaginatus from the province »Irkutsk, distr. Balagansk ad pag. Bashejewsky». 

 I therefore let the name stånd in the adopted sense. Its rank of a distinct species, 

 however, has been contested by Ascherson and Graebner (Synopsis mitteleur. Flora 

 1897). Ten years låter Prof. Graebner maintains his opinion in treating this species 

 as a var. (3 of P. 'pectinatus. In the Synopsis of the year 1913 again, he regards it 

 as a proles of the subspecies P. juncifolius Kern. now correctly separated from the 

 P. interruptus Kit. which is maintained under P. pectinatus. 



After the reintroduction of the species into the literature the Swedish authors 

 S. Almquist in Hartm., Handb. Skand. Fl., 1889, and J. O. Hagström in Neuman, 

 Sveriges Fl., 1901, have correctly described it and pointed out its peculiarities in 

 contradistinction to its kindred species even as to the turios. 



G. Fischer has lately (Bayer. Pot., 1907, and in Fedde, Repertorium, 1914) 

 translated the Swedish text into latin, but influenced by a certain Bodensee-plant, 

 Baumann's »Winterkraut», he has also made some inaccurate additions spoiling 

 the whole. 



The German plants referred to cannot be P. vaginatus Turcz., the distribution 

 of which in Europé does not extend southwards beyond the 60th parallel. — Speci- 

 mens collected in Switzerland (Lac Leman 1896, Wilczek. Det. Bennet. — Bodensee: 

 P. vag. var. helveticus Fisch.) and considered to be P. vaginatus are also nothing but 

 pectinatus-iorms. And so is the case concerning the German specimens. 



P. vaginatus is an excellent and distinct species and though more allied to 

 P. pectinatus than to filiformis or amblyophyllus, yet it is extremely well distinguished 

 from them by the stiff and ample sheaths, retuse young ligules, short, obtuse stem- 

 leaves, the basal leaves of equal length to the upper ones, the often greyish-brown 

 colour in sheaths and leaves, the characteristic mode of branching (see the fig. 11, DI), 

 the short internodes of the spike, all of nearly equal length, numerous verticils, in- 

 conspicuous style with horizontal stigma, the fruit of median size and the anatomy 

 of stem and leaves. 



K. Sv. Vet. Akad. Handl. Band 55. N:o 5. 5 



