318 T. Holm — North American Species of SteUaria. 



ground ; then the leaves begin to wither, and nothing will be 

 seen of the plant until next spring. We have, thus, in SteUaria 

 piibera two kinds of shoots : floral and vegetative, of which 

 the latter remain active for a much longer period than the 

 floral, and of which the function is to give rise to new individ- 

 uals. This may be readily observed during the spring, by 

 lifting the plant carefully. 



As shown in our figure 1, the specimen shows a long, hori- 

 zontal, leafless branch, which consists of several stretched 

 internodes, and with a pair of flowering stems (F) developed 

 at each node, in the axils of the leaves, which have now faded 

 away. This long, horizontal branch represents a vegetative 

 shoot (V*) in its second year, and when the axillary shoots (F) 

 have reached maturity and developed roots, the old internodes 

 die off, and a series of independent individuals is produced. 

 These vegetative shoots being above ground, and no subterra- 

 nean stolons being developed, our plant may be well character- 

 ized as being perennial, but without a rhizome. However, the 

 base of the floral shoot does not die off with the aerial por- 

 tions, but stays alive and produces axillary buds, which, later 

 on, develop into aerial stems ; such perennial stem-bases are 

 called pseudo-rhizomes. It is thus characteristic of this spe- 

 cies of SteUaria, that some of the aerial shoots remain vege- 

 tative : that they become horizontal, and develop new, axillary 

 shoots, which soon become separated from the mother-plant as 

 independent individuals. These vegetative shoots thus become 

 developed as stolons above ground. We find this same method 

 of reproduction in Phlox divaricata L. with the only excep- 

 tion that the stolons persist here for several years and continue 

 their growth, developing axillary shoots without becoming 

 separated from the mother-plant. In Phlox reptans Michx., 

 on the other hand, the stolons become terminated by an inflo- 

 rescence preceded by a rosette of leaves in the same manner 

 as in Antennaria. But in regard to the CaryophyUacew we 

 have only observed this type of reproduction in SteUaria 

 2)ubera. 



In the second type we have plants which persist by means 

 of hibernating buds above ground and by subterranean sto- 

 lons ; as an example of this method of reproduction may be 

 mentioned : 



SteUaria longipes Goldie. 

 Common on the arctic shores, and not infrequent in the 

 alpine region of the Rocky Mountains,* this little herb shows 

 a remarkable power to withstand the severity of the winter ; 

 it has been described by Ivjellman in his interesting paper on 



* Collected by the writer on several peaks in Colorado at an elevation of 

 12,000 to 12,500 feet. 



