A Note on the Distribution of Primula Scotia Hook

Abstract

In the past the distributional pattern of Primula scotica has stimulated a certain amount of speculative discussion of the phytogeographical problem which it presents. The focus of previous examinations of this and other related problems-such as the Teesdale 'refugium'-has been whether the present-day area is the result of per-glacial survival or of post-glacial colonization. Godwin (1949) has initiated a recent reorientation of emphasis by indicating that the increasing mass of evidence that many of our native species have occupied, in Full-glacial and Late-glacial times, areas which were greater than those within which they are extant, implies that the basic problem is 'essentially one of post-glacial movements and adjustments rather than of per-glacial survival'. P. scotica is a member of the Artic-Subarctic element (Matthews, 1937), and the macroscopic remains from the Cam Valley deposit are ascribed by Godwin (1953) to the Fullglacial period. Discussing the factors which might have effected a restriction of the areas of plants of which there is evidence for greater areas in the past, Godwin (1949) suggests as the most important the spread of dense forests and peat mires with a complementary disappearance of open habitats with base-rich mineral soils. Further, he indicates that the first phase in this sequence of substrata was one of 'sheets of dead ice decaying in situ, often covered with gravel and sandy debris and even vegetation clad before their final disappearance'. In the light of this new approach, an examination of the present-day distribution of this plant in relation to its ecological amplitude is of value in a study of the environmental changes in the past which might have effected a reduction in the size of the area occupied by the plant, while it is recognized that a complete basis for accounting for the history of the plant can be established only from fossil records. The significance of seed dispersal and the availability of suitable habitats in determining the distribution is recognized, and will be considered along with the ecological amplitude of the plant.