E. V. Wulfif —76— Historical Plant Geography 



isolated, relic part of an extensive area, which itself may not be relic in 

 character. In the latter case a species occupying the said area will be 

 relic only in that part of its area which bears a relic character. 



The main, non-rehc part of an area may: (i) occupy its original 

 territory, in which case the parts separated from it must at one time 

 have constituted the periphery of the ancient area and have become 

 isolated from the main part of the area due to changes in habitat con- 

 ditions occurring within the Hmits of this peripheral region; or (2) be 

 the result of a secondary dispersal of the species. In the first case the 

 relic portions of the area constitute the remnants of a once-continuous 

 but now greatly disrupted area. As an example of the second case we 

 may take the common pine, Pinus silvestris, which in mountains has 

 relic, detached portions of its area, while its extensive area on sandy 

 soils is the result of a secondary dispersal. 



It is usually considered that a relic area must be in a state of 

 constant contraction, since a relic species is in disharmony with its 

 present habitat conditions. Such a view of a reUc area holds true only 

 for certain rehcs and cannot be taken as a general rule for all. It 

 holds good, for instance, in the case of Cyclamen count, preserved only 

 in one locaHty in the northern part of mountainous Crimea, where it 

 finds itself in disharmony with existing climatic conditions, since it 

 begins to flower only in November, when the Crimean winter is al- 

 ready well under way. Each year its flowers are destroyed by frost, 

 and, consequently, its preservation in the Crimean flora to the present 

 day is explicable only on the basis of vegetative propagation. 



But there are many relic species which, as regards their biological 

 peculiarities, have attained such a degree of adaptation to their present 

 habitat conditions that their area is not now in the process of con- 

 traction and they are not becoming extinct. It is true that in most 

 cases, if we regard the area of such a species not only in relation to 

 that flora to which it now belongs but also in relation to its entire 

 former area of distribution estabHshed on the basis of paleobotanic 

 data, there can be no doubt that curtailment has occurred and also 

 that the species has died out over all its former area with the excep- 

 tion of that part where it has been preserved and where, consequently, 

 there did not take place changes in climatic or other habitat conditions 

 in disharmony with the biological nature of the given species. For 

 instance, the box tree, Buxus sempervirens, undoubtedly a Tertiary 

 relic, has a much disrupted area, the various parts of which are char- 

 acterized by dissimilar cHmatic and edaphic conditions. Nevertheless, 

 this species grows in all parts of its area, which is not now in process 

 of contraction ; moreover, it does not occur isolated but as a co-member 

 of a characteristic phytocoenosis, having become adapted to the specific 

 habitat conditions in each separate part of its area (Christ, 1913). 



However, the fact that the area of a relic species is not contracting 

 is not always occasioned by its adaptation to new habitat conditions 

 but may be due to the climatic conditions in the given area not having 

 changed. Similarly, the isolation of an area may be the result of 

 purely geomorphological causes or of changed climatic conditions in 

 regions surrounding the given territory, while within the latter con- 

 ditions have preserved their main features, if not completely, in con- 



