KTJNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 55. N:0 5. 



255 



in the peduncles as well as in the stem. The same is the case with the leaves of 

 the two species, cf. fig. 116, F, O. 



Leaf-base always cordate-amplexicaul (cordatis amplexicaulibus : L.); the very 

 apex a little recurved, slightly retuse and slightly canaliculate in order to 

 facilitate the water to run off from the blade and to prevent the non-sclerenchy- 

 matous leaves to be broken. Hereby it behaves biologically in a way contrary to 

 P. prcelongus with its hooded apex. Besides, the form of the apex is very variable 

 with all transitions from broadly rounded to evenly narrowed and more or less cus- 

 pidate. Margin always more or 



less rough by a fine serrulation, ^ / \ \ ^^/\\ ^/ \ D 



at least in young state. Teeth 

 always one-celled, usually pro- 

 minent and more erect than 

 in other species, without inter- 

 jacent sinuses. 



The ligules are very short, 

 broadly rounded or sometimes 

 broadly and obtusely cuspidate 

 or retuse, pale, membranous, 

 fugacious, without ridges. Their 

 mechanical strands very faint 

 and obscurely joining each other 

 in the apex. 



Peduncles even. If per- 

 foUatus-like forms are endowed 

 with upwards thickened pedunc- 

 les, we have to do with the 

 hybrid P. nitens, which, at 

 least in most cases, influenced 

 by P. gramineus, has more or 

 less conspicuously incrassate 

 peduncles. 



The species varies con- 

 siderably as regards the size and shape of the leaves but all those forms seem to 

 me most suitably to be included in the three varieties acknowledged of old, namely 

 v. ovatijolius Wallr. (1823), v. roiundifoliiis Wallr. (1823), and v. gracilis Cb AM. & 

 SCHL. (1827). 



N 





1 1 1 1 L 





1 1 ' 1 1 



P 



mmL^ 



( 1 1 1 1 1 I 7 1 1 



^^ 



Fig. 117- A — 0. P, perfoliaiiis L., A — H, Tops of leaves, -], showing the 

 different form of the apex of the stem-leaves, K, Stem-leaves of f. acittifoHns 

 Haqstr., \. i, Pistil, ^-^, rt, side view, h, stigma from above, il/, Leaf margin 

 (enlarged), showing the denticles. N, Surface section of the stem epidermis, \^. 

 O, Transverse section of a ligule, a, at the base, b, nt the middle, Y, showing 

 no ridges at all P, P. prwlongits Wulf. Part of the transverse section of a 

 ligule at the base, Yi showing a faint protuberance (r) representing one of 

 the ridges. 



V. ovutifolius Wallr. (v. ovatus Rchb.). 



To this variety belong all the forms which have ovate or sometimes ovate- 

 oval shape (foliis ovatis: W.). The typical form of this variety is a vulgaris Spen- 

 NER (f. typictcs Tis. [1895], v. Ujpicus Asch. & Gr. [1897]). — When the leaf-width 



