424: T. Holm — Studies in the Cyperaeece. 



outer epidermis is quite thick-walled and covers a few, one or 

 two, layers of chlorenchyma. There are only two mestome- 

 strands, both with a support of stereome on the leptome- and 

 hadrome-side, while no isolated strands of stereome were ob- 

 served between the veins. 



Characteristic of Carex eapitata is, thus, the very conspicu- 

 ous epidermal protuberances which protect the stomata* ; more- 

 over the relative strong development of stereome in stem and 

 leaf, but accompanied by a hollow pith and a chlorenchyma 

 traversed by broad lacunes. The specimen, described above, 

 was collected by the writer on dry rocks at Egedesminde in 

 Greenland, and we noticed exactly the same structure in other 

 specimens from wet soil at Sukkertoppen (Greenland), from 

 swamps in the mountains of Sweden and Tyrol, besides from 

 Yukon. 



If we compare now the structure of our Carex with that of 

 other u formce hebetatm" we notice that a cylindric and hollow 

 stem is not so seldom met with among these. This stem-struc- 

 ture is characteristic of the following species from dry rocks : 

 0. elynoides, G. Oreocharis, C. nardina and pyrena/ica. On 

 the other hand, the stem is cylindric and solid in C. circinita, 

 but triangular and hollow in C. rupestris. 



A cylindric and hollow stem is, furthermore, to be observed 

 in the following species from bogs : C. dioica, C. gynocrates 

 and C. paralela, while a triangular, hollow stem occurs in C. 

 lejocarpa, C. exilis and C. nigricans ; in the last of these, 

 however, the stem varies from triangular to cylindric A tri- 

 angular and solid stem was found in C. polytrichoides, and a 

 pentagonal, solid in C. pulicaris. The chlorenchyma of the 

 leaves is very open from wide lacunes in all these species, and 

 the cortex of the stem shows, also, lacunes in these with the 

 only exception of C. elynoides and 0. exilis. But in regard to 

 the position of the stomata, C. eapitata is the only one in 

 which these are sunk and protected by papillae ; in all the other 

 species the stomata are superficial. 



In considering the " formce hebetatce " of Yigneai and Carices 

 genuine/a it appears as if the anatomical structure is not influ- 

 enced by the nature of the surroundings, since we have observed 

 an oyen chlorenchyma and cortex in species from dry rocks 

 as well as from bogs ; moreover the position of the stomata 

 is the same in these except C. eapitata. From this comparison 

 it would, appear as if our Carex represents a peculiar typeof 

 Vignea, and at the same time a remarkable " -forma hebetata " 

 on account of the protected stomata. 



* Similar epidermal projections have been observed in some of the more 

 evohite types of Vignece and C. genuince, for instance : C. particulate/,, tereti- 

 uscula } vesicaria, ampullacea (Schwendener), riparia and provincialis 

 (Mazel). 



