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The marked closeness of the iso-lines for severalclimatic functions has often been commented on;this feature is most evident in the western andcentral parts " of the borderland, where the coincidencewith topography and phytogeography is alsobest.The Borderland 171Floristic aspectsGROUPING OR SCATTERING OF DISTRIBUTIONLINES?-An analysis of the floristic limits of southernand northern species (cf. ALMQUIST 1949a,pp. 454-455) within and near the borderland showsa more blurred picture than one would expect. Evenif outpost localities are disregarded and the emphasislaid on limits of more or less continuousdistribution (cf. MYRIN 1832, p. 176, SJORS 1958),these lines are diffusely and also criss-cross dispersed.Moreover, the maximum density of such linesis not found at the topographic borderline but somedistance below or ·south of it, at least in the V armlandand Vastmanland sections (HARD AV SEGER­STAD 1952, p. 83, SJORS, op. cit.). The reason for thisseems to be the eda phic richness of the areas nearLakes Vanern and Malaren and along the eastcoast as contrasting with the relative poverty ofthe above-mentioned forested lowland that lies betweenthese areas and the elevated upland, particularlyin eastern Varmland, central and north-eastVastmanland, north-west Uppland, and centralGastrikland. HARD AV SEGERSTAD (op. cit., mapp. 83) found the floristic gradient to be sharpestbetween the ancient shoreline VG 2 of Lake Vaner;n(op. cit., map p. 33; at about 60-95 m) and the uplandboundary (map p. 55; taken as the 200 mcontour). This zone of sharpest transition is at ahigher level in western than in eastern Varmland,according to HlRD AV SEGERSTAD (op. cit.) due to a"climatic depression" in the eastern part, but perhapsalso to a more broken topography in the west.Numerous southern species penetrate furthernorth, partly into the valleys, partly into the uplanditself, often in ravines, on hillsides and in similarsites that are edaphically favourable or with respectto local climate. Their upper limits of distributionare irregularly scattered (almost dispersedat random), e.g. in the Dalalven valley up to theSiljan Cambro-Silurian area and even further north-12- 652151 .APhS 50Fig. 3. Distribution within the province of Vastmanlandof (a) Trifolium montanum, f south-eastern species,(b-e) the southern species Spirodela polyrrhiza, Prunusspinosa, Spergula vernalis, Luzu,la campestris, (f-h) thenorthern species Selaginella selaginoides, Luzula sudeticaand Phleum commutatum. Maps by A. Hamrin, from Sjors1958.west (ALMQUIST 1949a, pp. 42-43, 53-58, 455,1949b, pp. 58-64). Many of these species are moreor less favoured by cultivation, and some of theareas have been widened by accidental dispersal duechiefly to man. There is, consequently, a high percentageof hemerophilous species (apophytes andsynanthropes) among these plants.HARD AV 8EGERSTAD (1936, p. 389, 1952, p. 82)maintained that even if the climatic functionsvaried quite gradually, phytogeographical variationwould not be equally contilnuous, owing to theexistence of groups of plants with similar requirementswith regard to a special climatic factor. Thisview is in need of confirmation,. however, and inActa Phytogeogr. Suec. 50