104 J. O. HAGSTRÖM, CRITICAL RESEARCHES ON THE POTAMOGETONS. 



From Siveden we have to record only one locality: Scania, Ringsjön, 82, Nils- 

 son, fruiting, but probably this bastard (hb. Lund.). — France, Besancon, 70, Grenier 

 (hb. Uppsal.), Valleville, Eure, 55, Malebbånche (hb. Stockholm.). — England, 

 Ponds near York, 81, Bennett (hb. Stockholm.), Shropshire, 86, Beckwith (hb. 

 Stockholm.). In sorae private herbaria I have seen plants which are likely to be 

 this hybrid, viz. from Denmark, Nybro kro, 99, Baagöe and from Stamberget See, 

 03, M. v. zur Muhlen. 



The above enumerated forms exhibit evident relationship to P. panormitanus 

 and pusillus, but are very different among themselves as to thcir qualities. In habit 

 and branching they approach now this form, now the other. Their leaves are al- 

 ways stiffer than in P. jmsillus, and tipped with sharper points, Turios, unfortu- 

 nately, seem to be pretty rare, but when present they resemble now more the one, 

 now the other of the parent-species. - — P. dualis, of course, is easily to be confounded 

 with the hybrids pusillus X trichoides and panormitanus X trichoides. I have scen the 

 latter from Bavaria, where it is collected by Dr. Fischer at »Appendorf im Lauter- 

 grund» and at »Lauterbach». It is darker in colour, has more prominent leaf- points, 

 more abundant sclerenchyma etc, by which it evidently shows a near affinity to 

 P. trichoides, while the turios allow us to trace P. panormitanus. 



P. bndius n. sp. 



Caidis compressus (2—2,5:1) elongatus, internodiis 3 — 5 (summis 7) cm longis, 

 subsimplex vel infra medium ± ramosus, dichotome prolongatus ramis spicigeris 

 l 89 — 2* ordinis internodiis longis (ad 9 cm) instruetis. Folia linearia 3 — 5-nervia 

 basi angustata apice acuta ± acute cuspidata, caulina 50 — 100 X 2 mm, floralia 25—40 

 mm longa, numquam subnatantia, nervö medio badio prominente. Ligulce breves 

 caducöe eglandulosae vel subeglandulosa?, in spatio intercarinali 11 — 12-nervise. l\- 

 (liniculi breves ± 20 mm aequales. Spica subdensa 3 — 4-verticillata. Stylus rostro 

 brevi instruetus, stigmate parvo rotundato. Fruclus subglobosus parvus, 1,75 mm 

 longus, badius, dorso rotundatus, lateribus convexis, iis P. panormitani Biv. plat)-- 

 carpi simillimus. — Fig. 40. 



By the nervation of the leaves and the form of the fruit this species is verv 

 closely related to P. panormitanus. It differs by the flattencd st em, the clongated 

 upper branches endowed with long internodes (D-type), the broad and elongated 

 stem-leaves, by the involucral leaves never growing subcoriaceous, by the ligules 

 Lacking oil-cells and being 11 — 12-fibrous in the front-ficld. The styles are a little 

 beak-formed above and the fruits more rounded. The turios consist of transformed 

 branches in bud-state in the lower axils; they are about 10 mm Long with short ± 

 ouspidate appressed outei Leaves and obtuser enclosed inner Leaves. They resemble 

 in a higfa degree the turios of /'. j><tin>rmitanns and ezigWM ni. At first I theiv- 

 fore believed thal V. badius oould be olassed with the former of those. Låter the 

 differenees have appeared too oonsiderable and 1 now think it bet ter bo establish 





