CHARA CANESCENS. 17 



of Galway, R. A. Phillips. Galway, S.B., small lake 

 near Kinvarra, R. A. Phillips. 



First record : Babington, 1850. 



Outside the British Isles C. canescens is recorded 

 from Sweden, Denmark, Eussia, Belgium, Holland, 

 Germany, Austria, Hungary, Roumania, Bulgaria, Spain, 

 France, Italy and Greece, also from Asia, N. Africa and 

 N. America. It occurs in the Baltic Sea. 



A small to medium-sized plant, usually with rather rigid stem 

 and branchlets, often growing in dense tufts. The long numerous 

 persistent spine-cells and the sharp stipulodes and whorled bract- 

 cells combine to render it the most bristly-looking of our Charas. 

 If often happens that adjacent internodal cells of the cortex 

 nearly correspond in length, so that the spine-cells appear to 

 be partially whorled. It is readily distinguished from any other 

 European species by the absence of secondary cortical-cells, so 

 that the number of cortical series is equal to that of the branchlets. 

 It is also the only European species with one-ranked cortex to 

 the branchlets, the number of sheathing tubes corresponding 

 with that of the bract-cells. 



Another remarkable characteristic, shared, so far as we know, 

 by no other species, is its parthenogenetic reproduction. The 

 male plant has been found in very few localities throughout the 

 world ; ripe oospores which germinate freely are nevertheless 

 produced in gxeat quantity. In the specimens of the male plant 

 which we have examined, collected in Hungary, the spine-cells 

 are frequently solitary. Dr. Migula records it from France, 

 •Greece, and the Caspian Sea, and Dr. Petkoff from Bulgaria. 

 As regards the Greek plant in the specimen in Heldreich's ' Herb. 

 ■Graec. Norm.,' No. 996, which we have examined, the female 

 plant is correctly identified, but the male belongs to a triplo- 

 stichous species, C. galioides, with which it is frequently found, 

 and which it superficially resembles. There is therefore an 

 element of doubt as to the record for Greece. 



C. canescens, though so widely distributed, is a compact species, 

 the principal variation being in the length of the internodes, the 

 length and number of the spine-cells, the size of the stipulodes 

 and bract-cells, and the size and shape of the oogonia and 

 oospores. In the plant from the Orkney I. the latter are excep- 

 tionally stout and broad. An extreme form described by Dr. 

 Migula, under the name of var. thermalis, from mineral springs at 



VOL. II. 2 



