40 VEGETATION IN COLORADO-HOLM. Wtaw " [ |8!$gg£ 



this species has a small rhizome in the shape of stolons with the intemodes very short and mostly 

 shorter than the small, fleshy, scalelike leaves. Beside these stolons the vegetative reproduc- 

 tion is secured by means of small buds located in the axils of the withered leaves. These buds 

 develop into aerial shoots during the next season. In specimens from lower elevations the 

 stolons are much longer with the intemodes stretched. A corresponding structure recurs in 

 Stellaria longipes, which is not infrequent (the var. laeta) in the Alpine region and which is 

 very common on the Arctic shores as far north as 82° 27' north latitude. This little herb shows a 

 remarkable power to withstand the severity of the winter. The rhizome consists of long, sub- 

 terranean stolons with small, scalelike leaves and stretched intemodes. The aerial shoots are 

 ascending, and the foliage is more or less crowded on account of the shortness of the intemodes. 

 When the winter commences, the leaves are still attached to the shoots, but in a withered 

 condition. The stems, on the other hand, remain alive and persist throughout the winter. 

 At the beginning of the spring small buds become visible in the axils of the withered leaves, 

 soon developing into small leafy shoots. These shoots frequently remain purely vegetative 

 for one or two years until they become terminated by an inflorescence. This type of vege- 

 tative reproduction is also characteristic of Stellaria longifolia Muehl., S. Jiumifusa Rottb., 

 S. Holostea L., and S. crassifolia Ehrh. 



Swertia perennis has a creeping but relatively short rhizome, with slender, secondary 

 roots; the development of horizontally creeping stolons, was observed only in the plant at 

 much lower elevations. The leaves form an open cluster, surrounding the inflorescence, which 

 appears to be terminal. 



Stolons above ground, consisting of a single, stretched intemode, and terminated by a 

 rosette of leaves are characteristic of Androsace Cliamaejasme and Saiifraga fiagellaris, both of 

 which have been described by the writer in Novaia Zemlia's Vegetation (1. c); in Antennaria 

 runners above ground are also a characteristic feature; they are exceedingly short, but numer- 

 ous. In the subalpine species of Antennaria, A. nardina Greene, A. Eolmii Greene, etc., the 

 stolons are far better developed, not including the lowland species, A. arnoglossa Greene, etc. 

 The Alpine species of this genus thus show a tendency to form cushions; with regard to A. 

 alpiiux I found only the pistillate plant, while both sexes were equally common in A. rosea, 

 especially at lower altitudes. Finally Chionophila' is also stoloniferous, and the ascending 

 stolons are almost aerial; they are terminated by a rosette of opposite leaves, and do not sepa- 

 rate from the mother plant until the next spring. The shoot above ground of Chionophila 

 (pi. 5, figs. 32-35) represents a typical monopodium. In the specimen figured, the foliage con- 

 sists of three pairs of opposite leaves, forming a rosette; in the axil of one of the leaves of the 

 outermost pair (L 1 ) the inflorescence is developed, borne upon a short stem of three intemodes. 

 In the center of the rosette a small bud (B) is visible; this bud, the apical of the shoot, is vege- 

 tative, and will during the succeeding season develop a new set of leaves and an axillary inflo- 

 rescence. Chionophila has no persisting primary root, and the short vertical rhizome bears only 

 some secondary roots, which are quite long and fleshy. The foliage is very thick, and almost 

 glabrous, only some few pluricellular hairs (in one row) being developed; in living specimens 

 the calyx is distinctly folded (fig. 33), a structure that becomes lost when the specimen is pressed 

 and dried. Similar to several of the other Scrophulariaceae, and especially the parastic, Chiono- 

 phila turns black when dried; when fresh the foliage is glaucous. 



These stoloniferous species are thus able to wander, and in Saxifraga cemua we have a 

 type, the only one, however, in which the vegetative reproduction is secured by means of bulb- 

 lets. These bulblets (pi. 2, figs. 13-16) are situated in pahs in the axils of the upper stem 

 leaves, and they consist of thick leaves, or, to be more correct, of thickened leaf sheaths, the 

 blade being merely represented by a minute lobe; some bulblets develop also at the base of the 

 stem, close to the roots; when the bulblets fall off, they develop new individuals, and, as a 

 matter of fact, they are necessary to the multiplication of the species, since they actually have 

 taken the place of flowers. In the Arctic regions S. cernua is very frequent, often accompanied 



' Holm, Theo: Chionophila Benth. (Am. Journ. Sci., Vol. 1. 1921, p. 31) 



