KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 55. N:0 5. 233 



sjön Nossen (A. W. Lund)» which he takes for »P. graminea X prcelonga » . More 

 closely examined this plant has låter on (Hagström, in Néum., Sveriges Fl., 1901, 

 797) been found to be a form of P. nitens Web. (see p. 226). 



A plant from Lunan Burn (Scotland) has also been thought to be the hybrid 

 gram. X prcel. Ar. Bennett has a note of it in the Journ. of Bot., 1907, p. 174, 

 but in the List of hybrids published by Rev. E. F. Linton in the same Journ. 1907, 

 p. 299, it is not further mentioned. 



That is all vvhat literature has to state about a hybrid which in 1913 has 

 really been found in Sweden, at Borås in the Viskan river. 



In habit this plant reminds much of a low-grown P. prcelongus. The collector 

 has hesitatingly held it to be P. gramin. x perfol., from which, however, and from all 

 the forms of P. decipiens it is easily distinguished by its leaves. Branches mostly 

 sterile, zigzag-formed with numerous, very short internodes, especially upvvards small- 

 leaved. Leaves rounded at the basis and cymbiform at the tip, which is somewhat 

 more narrowly contracted than in P. prcelongus. Topmost branch-leaves lanceolate 

 at their base or broadly short-petioled. All leaves with an obscure venation like all 

 gramineus-hybTids and fewer-nerved than P. prcel. Margins smooth. Ligules inter- 

 mediate as to form and nervation, the nerves of the front-field not so much crowded 

 as in P. prcel. Peduncles of the specimens examined as in P. prcel. Spike sterile. 

 In a single spike, however, two fruits like those of P. prcelongus have been found. 



Stem-anatomy intermediate but multifariously varying as in all hybrids. Cen- 

 tral cylinder at the base of the stem more prcelo?igus-\ike, upwards, in the same 

 specimen, more like P. gramin. Endodermis always of w-cells like that of both the 

 parents. Cortical strands always fewer than in P. prcel., but more numerous, again, 

 than in P. gramin. Pseudo-hyp. one-layered (P. gram.) in some internodes, in others, 

 again, 2-layered, at intervals intermediate. Subepid. strands few or wanting (gra- 

 mineus). 



Habitat. Siveden, Borås in the Viskan, 1913, C. Sandberg and A. Holmertz. 



P. lllCeilS L., Species pl., 1753, 126. 



P. lucidus Guldenstädt, Reisen, I, 1787, 76. — P. acuminatus Schum., En. 

 pl. Saell., 1801, 49. — P. longijolius Gay in Lamarck, Ene. mét. Bot. IV, 1816, 

 535. — P. volhynicus Besser in Roem. & Schult., Systema vegetabil. III, 1818, 

 509. — P. cornutus Presl, Flora cechica, 1819, 37. — P. caudaius Seidl in Opiz, 

 Böheims Gew., 1823, 23. — P. macrophyllus Wolfg. in Schultes, Mantissa in vol. 

 III, 1827, 358. — P. Proteus lucens Cham. & Schl., Linnsea 1827, 197. — P. corni- 

 culatus Sctiur, Enum. plant. Transsilv., 1866, 633. — Figs. 1, H, 2, A, 110, 111, 

 115, /. 



This species always lacks coriaceous or subcoriaceous floating leaves and even 

 the tendency of producing such ones. On the contrary it has a prominent faculty 

 of reducing the size of the stem-leaves with the maintenance of the midrib-portion, by 



K. Sv. Vet. Akarf. Handl. Band 55. N:o 5. 30 



