350 T. Holm — Studies upon the Gyperacece. 



species do not show, however, any persistent central vegetative 

 shoot, but the flower-bearing stems appear, nevertheless, as if 

 they were lateral. We might suppose in these cases that the 

 age of the vegetative shoot does not exceed one year. G. 

 graoillima and G. arctata are perhaps to be compared with 

 the above described G pilosa. 



A marked characteristic of these monopodial species is that 

 the floral shoots are surrounded at their base by scale-like 

 leaves. In the sympodial the flower-bearing stems are com- 

 monly, if not always, surrounded by proper leaves with closed 

 sheaths and long, green blades. The monopodial ramification 

 is, therefore, represented in this country by a number of 

 species, most of which are common and abundantly occurring. 

 These species are not exclusively southern forms, since several 

 of them extend as far north as Canada, according to Macoun.* 

 The character of being monopodial does, therefore, not seem 

 to be favored by any special climate ; we can only state that it 

 seems to be especially well represented on this side the Atlan- 

 tic, and we might perhaps feel justified to add, that it is preva- 

 lent among our sylvan forms. Purely vegetative shoots are, 

 however, not exclusively connected with the monopodial rami- 

 fication. There are among the sympodial species some, which 

 yearly develop assimilatory shoots, which die off in the first 

 year of their growth. Such species show, then, besides the 

 flowering stems, a number of very densely leaved shoots, for 

 instance G. tribuloides Wahl. with its varieties, G Muskin- 

 gumensis Schw.^ G straminea Willd. and G. Sartwelli Dewey. 

 These sterile shoots develop sometimes, as figured on our Plate 

 IX (fig. 2, by b) small lateral buds in the axils of their leaves, 

 which, however, die off at the same time as the entire shoot 

 itself. It is, at the same time, interesting to observe the base 

 of the shoots, both the floral and vegetative, of G tribuloides 

 and G Muskingumensis (Plate IX, figs. 2 and 3). We find 

 here distinct internodes which are not hidden within the 

 sheaths of leaves, but which are free to quite a considerable 

 extent. These basal internodes are even sometimes geniculate 

 and show the nodes almost as distinct as in the Graminew. 

 But otherwise, as it is stated in the Manuals, etc., the basal 

 internodes in Garex are very short and perfectly invisible on 

 account of the densely crowded leaves. 



Washington, D. C, February, 1896. 



Explanation op Plate IX. 

 Figure 1. — Specimen of Carex platyphylla at its vernal stage, showing a central 



vegetative shoot and a number of lateral floral ones. Natural size, 

 Figuee 2. — Specimen of Carex tribuloides, showing one floral and one vegetative 



shoot. The base shows distinct internodes. About one-third of 



the natural size. 

 Figure 3. — Base of a floral shoot of Carex Muskingumensis with long internodes 



and distinct nodi. Natural size. 



* Catalogue of Canadian plants, Part IV, Endogens, Montreal, 1888. 



