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238 GUNNAR WASSENFig. 5. The meanderingU me river upstream ofthe Hemavan delta. Theconspicuous series of olderlevees on the inner side ofthe curve carry birchwood;willow scrub prevails at asomewhat lower level. Signsof former hay-making (rightedge). Aug. 15, 1961. Airphoto Lars Bergstrom (bypermission).thicket being especially broad because the footof the terrestrial spruce forest zone is displacedupwards due to the waves increasing the reach ofthe high water.These two lakes are still in the coniferous forestbelt, but near the western end of Lake Gautajaure,for example on the slopes of Mt. Laxfjallet not farto the west of Tarnaby, the spruce has its westernmostoccurrence, except for very few outposts.We now enter the subalpine birchwood belt inwhich the remaining lakes are situated. This sourcepart of the catchment area of the Ume river includessome valleys of extreme scenic beauty andscientific interest, the latter largely referable totheir great dissimilarity in other respects than zonalsituation.LAKE T.ARNASJON.-Drained through an easterntributary, this remote lake, the future of whichhas not yet been decided, lies in an uninhabitedarea due east of some high-alpine summits adornedwith small glaciers. To the north and north-eastare other high mountains, but to the south andeast only low foothills. The lake is long and narrow,running straight north-south at an elevation of603 m. The climate is obviously more cold-continentalhere, as evident from the many signs of heavyfrost action, including palsas (to the north-east ofthe lake, cf. "Northern mires"), much solifluction,frost-heaved knolls, stone-pits and littoral polygonsin small but well-developed fields.The amplitude is only 1.6 m and the littoralzones narrow and not well-defined. In the completeabsence of Calluna, the part of the geolittoral correspondingto the Calluna belt is dominated byN ardus stricta, Cassiope hypnoides, V acciniumuliginosum, etc. Although a great variety of speciesgrow here, some elements characteristic of thebroad lake shores in the conifer belt are absent, e.g.Viola montana and (as far as shores are considered)Galium boreale. The southern part is barely reachedby Prunella vulgaris, Veronica scutellata and theconspicuous, now rare endemic dandelion of freshwatershores in north-central Fennoscandia, Ta-Acta Phytogeogr. Suec. 50