252 PSYCHROPHYTES SECT, ix 



perennials because seed-production is arrested, and through correlation the 

 vegetative organs consequently become more vigorous and longer-lived. 



2. Development commences late, but proceeds with great rapidity 

 during the vegetative season. The spring season in Polar countries is 

 hurried through. Plants that in the plains belong to the late-flowering 

 species blossom earlier in the Alps, though they commence to develop 

 much later. The growing season of many species, thanks to the action 

 of winter-cold, is on the whole much shorter than elsewhere (in high 

 latitudes precociously ripening varieties are brought into existence 

 for instance, barley in northern Norway). 



3. Early flowering. Subglacial species in general are spring-plants, 

 that is to say, they blossom very early, before the foliage is fully developed ; 

 Soldanella, Primula acaulis, Crocus vernus, and others, even blossom 

 under the snow ; this depends on the circumstances that the flowers have 

 been initiated in the year preceding that of flowering, and that the flower- 

 buds are provided with rich supplies of food stored in the surrounding 

 bud-scales. 1 The consequences are that flowers may possibly find insects 

 to pollinate them, and that the short vegetative season can be fully 

 utilized for the maturing of seeds, as could otherwise scarcely be the 

 case owing to lack of heat. Exceptions are provided by Compositae 

 that can ripen their fruits within a few weeks, and by such species as the 

 northern forms of Cochlearia, which can pursue the processes of blossoming 

 and ripening of fruit, uninjured even after the most severe and prolonged 

 periods of frost. 2 



4. Vegetative propagation, particularly by the aid of detached buds, 

 plays a great part in the life of certain species, perhaps to atone for 

 failure to set seed or produce flowers, as in Saxifraga cernua, S. stellaris 

 var. comosa, S. flagellaris, Polygonum viviparum, and viviparous grasses. 

 In many stations the conditions are so unfavourable to existence that the 

 soil is not covered by plants, which are scattered about at considerable 

 distances from one another. 



B. Structural Features. 



1. Most shoots are epigeous : in this way neither time nor food is 

 lost in shooting out of the soil. The shoots usually live longer than one 

 year, and produce a series of vegetative year's-shoots before they blossom 

 and thereafter perish ; a prolonged period of manufacturing nutriment 

 necessarily precedes the production of flowers, to which the final year of 

 the shoot's existence is dedicated. 



2. Evergreen shoots characterize a number of species of herbs and 

 dwarf-shrubs : this is of advantage, in that favourable temperatures and 

 illumination can be utilized throughout the year. 3 The hibernating 

 foliage-leaves of some species, at least, contain abundant food, which is 

 consumed in spring, after which the leaves wither. Kerner 4 very appro- 

 priately compares the short rosulate-leaved shoots of species of Saxifraga 

 and the like with epigeal bulbs. The withered leaves persist for a long time. 5 



3. True bulbous and tuberous plants are rare, perhaps a more direct mode 

 of development of shoots involves no loss of time : yet in the Alps such 



1 Kjellman, 1884; H. Jonsson, 1895; Middendorff, 1867 ; Warming, 19080. 

 * See p. 23. 3 See p. 25. 4 Kerner, 1869. 5 See p. 75. 



