Lowland single malts are single malt whiskies distilled in Scotland's lowlands. The region now only has four currently producing distilleries: Ailsa Bay, in Girvan owned by William Grant & Sons, Glenkinchie distillery, near Edinburgh; Auchentoshan, near Clydebank; and Bladnoch in Galloway.
Two new distilleries (Daftmill in Fife and Annandale in the Borders) have started distilling but have not yet brought a single malt to market. Daftmill could legally start bottling a single malt (or supplying blenders) at any time, because its first batches have now been in cask for over three years. Three years is the legal minimum pre-bottling aging period for a product labelled Scotch whisky, but single malts this young are usually only marketed in countries like Italy. It is not known whether Daftmill are supplying malt to producers of blended whisky or vatted malts, but this is likely (the majority of most distilleries' production is sold this way).
At least six other lowland single malts are still available, but are no longer distilled: Rosebank, Kinclaith, St. Magdalene, Ladyburn, Inverleven, and Littlemill. Traditionally Lowland single malts are triple distilled (though this has not been true of all of them), often giving them a lighter taste (From Wikipedia).