32 BRITISH CHAROPHYTA. 



Austria, Hungary, Spain, France, Switzerland, Bulgaria, 

 Italy, Greece and Turkey, also from Asia (Siberia) and 

 North Africa. 



The largest and most robust European species, often attaining a 

 height of 70 cm., with branchlets sometimes 8 cm. long. A very- 

 stout form (G. equisetina, Kiitz.) has the stem nearly 3 mm. 

 thick. The plant is nearly always much incrusted, but entirely 

 unincrusted states occasionally occur. The spine-cells are mostly 

 clustered, and fairly long, but are usually deciduous, so that 

 while the upper internodes are densely covered with spines," the 

 lower parts of the stem are often quite destitute of these appen- 

 dages. The cortex sometimes out-grows the internodes, splitting 

 and bulging out. The torsion _ of the cortex is very marked. 

 The lower stem-nodes are occasionally thickened, and Giesen- 

 hagen records the occurrence of small root-bulbils. 



C. hispida assumes a great variety of forms, varying from 

 elongated to condensed, attentuate to robust, the branchlets 

 very long to very short, and nearly straight to incurved, the spine- 

 cells very long to very short (in the form macracantha they are 

 twice as long as the diameter of the stem), and persistent to 

 deciduous, the cortical-cells conspicuous to obscure. In young 

 states of the plant several of the uppermost branchlet-segments 

 are often elongated and ecorticate (f. gymnoteles). 



A plant collected many years ago at Goldens Common near 

 Freshwater, Isle of Wight, was referred by H. & J. G. in ' Journ. 

 Bot.' xviii, pp. 133 (1880), to var. horrida {C. hotrida Wahlst., 

 C hispida subsp. horrida Braun & Nordstedt), which occurs in 

 the Baltic and some of the countries adjoining, and is charac- 

 terized by having numerous clustered persistent spine-cells, by 

 the posterior bract-cells being almost as long as the anterior, 

 and by being usually without incrustation. The Isle of Wight 

 plant has remarkably long posterior bract-cells, but is not other- 

 wise so extreme as that from the Baltic, and we think it better 

 referred to C. hispida proper. 



C. hispida differs from C. vulgaris in the larger size and thicker 

 stem, in having the spine-cells mostly clustered, the stipulodes, 

 spine-cells and bract-cells more or less acute, by the greater 

 development of the posterior bract-cells and by the much larger 

 fruit and antheridia ; from C. rvdis by the generally stouter 

 stem and branchlets, the less unequal primary and secondary 

 cortical-cells, the production of geminate spine-cells almost 



