KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 55. N:0 5. 243 



oftenmost are a little thickened upwards. The serrulation, never absent in the two 

 parent-species, is not wanting in the hybrid either, except in leaves from which it 

 any way has been obliterated. Nolte's own specimens have this serrulation too. 

 Individuals quite lacking the faculty of developing one-celled leaf-teeth, as also 

 such ones that develop floating or subcoriaceous leaves, cannot be united with this 

 hybrid. 



2) In Botaniska Notiser 1884, 15 sq. Dr. G. Tiselius has proved the Swedish 

 forms, partly more long- and narrow-leaved, partly with comparatively broader and 

 horter leaves, to belong to one single »species (type)», for which lie proposes that a 

 common special name should be established, as the forms of the former kind can be 

 said to correspond to P. salicifolius Wolfg. and those of the latter to P. decipiens 

 Nolte, which names ought to be kept as series-names. His arrangement of these 

 series and forms is the following: 



Ser. A. 1) P. lithuanicus Gorski Leaves 120 x 13 mm 



2) P. salicifolius Wolfg. » 120 x 14 » 



P. upsaliensis » 140 X 20 » 



» » » 180 x 20 » 



2) P. upsaliensis f. major » 190 X 40 » 



3) P. decipiens Nolte f. maxima longifolia 210 x 53 » 

 Ser. B. 1) Narrow-leaved forms of P. decipiens 



Nolte: Leaves 120 x 20, 100 x 25, 80 x 24 » 



2) P. decipiens Nolte f. typica Leaves 85 X 40 » 



» » broad-leaved forms 85 X 40, 65 X 30, 90 X 50 > 



3) » » f. maxima ovalifolia Leaves 115 X 60 » 



This on the whole correct view (on P. salicifolius, see next p. !) Tiselius låter 

 on, in his herbary work (fasc. II, 1895), abandoned and established two species: P. 

 decipiens and P. upsaliensis. 



3) Possibly influenced by Dr. Tiselius's herbal work the German researchers P. 

 Ascherson and P. Graebner in Synopsis mitteleur. Flora, 1897, have divided P. 

 decipiens into two halves, one the hybrid P. lucens X perfoliatus and the other a 

 hybrid P. lucens X prmlongus. This view, represented by several other authors, is 

 kept by Graebner in his latest work (1913). G. Fischer writes: — »P. decipiens 

 Nolte (p. m. p. = P. lucens X perfoliatus)», 1911 and 1914. 



4) The earlier Aschersonian view (Flora Prov. Brandenb., 1864) of P. deci- 

 piens, as P. lucens X prcelongus, C. Raunkler has tried to prove in his work on De 

 danske blomsterplanters naturhistorie 1896. He has, however, happened to identify 

 two quite different plants, the >Susaa-form» and the »Gudenaa-form» of Randers, 

 of which the latter really is P. lucens X prmlongus. The Susaa plant, on the con- 

 trary, with sharper leaf serrulation, weaker ligules, lower ridges of the ligules, shar- 

 per leaf, points, more rounded leaf-base and fewer cortical cauline strands is P. deci- 

 piens, i. e. lucens x perfoliatus. By the leaf-nervation and the bundles of the central 

 cylinder of the stem these two hybrids cannot be distinguished from each other. The 



