T. Holm — Studies in the Cype'racece. 417 



Aet. XXXIX. — Studies in the CyperacecB ; bj Theo. Holm. 

 XYII. Segregates of Car ex Tolmiei Boott. (With figures 

 in the text.) 



SiMiLAE to the prevalent distribution in the north the genus 

 Carex^ as represented in tlie Rocky Mountains of Colorado, 

 does not attain its greatest development nntil the timber-line 

 is reached, where conditions exist which are favorable to the 

 development of Carices. From the timber-line with the low, 

 open thickets of willows {S.glaucops) accompanying the water- 

 courses, to tlie alpine slopes with the snow-banks, we meet with 

 no small number of species over a relatively limited area. 

 Those localities correspond, in many respects, with those of 

 the north, and it is quite natural that we often find ourselves 

 confronted with species that are, also, known to occur even in 

 the polar-regions. Several of these alpine and subalpine 

 Carices have been well recognized as being identical with 

 certain northern, arctic and circumpolar, species, and we need 

 only refer to such as: C. nardina^ incurvcu f estiva^ rupestriSy 

 atrata^ niisandra^ etc., while others appear as indigenous only 

 to the Kocky Mountains, e. g. Carex jilifolia, Engelmannii^ 

 elynoides^ variahUis^ etc. 



The mode of variation in alpine Carices corresponds well 

 with that of northern species, indeed we have exactly the same 

 variations exhibited by several of these, e. g. C. alpina^ atrata, 

 rigida, misandra^ etc. Aud Carex variahilis, at least the 

 plant from the Sphagnum-swamps at higher elevations in the 

 Spruce-zone, varies so much, that we have observed forms that 

 are absolutely analogous with the subarctic C. angiiillatay 

 hijperhorea^ stans and the various forms of C. rigida^ even if 

 they may not be looked upon as specifically distinct. We have 

 collected a number of such forms of C. variabilis growing 

 almost side by side, and possessing the same structure and 

 shape of utri cuius, besides the same color of squamee, but vary- 

 ing in the length of bracts, peduncles and spikes, characters 

 that are very prominent in C. anguillata^ stans and hyper- 

 horea ; in these species, however, the utricle offers such charac- 

 ters as seem to afford good evidence of their specific validity, 

 as they were formerly established by Salomon Drejer, the most 

 critical of Caricographers. 



However, the ability to distinguish and recognize several of 

 these species from the alpine regions depends to a large extent 

 upon observations in the field as well as a thorough acquaintance 

 with their homologues in other countries. And one of the 

 species, which we intend to describe in the present paper, 

 Carex scopulorum^ offers an excellent exaQ:iple of analogous 



