Great big flowering Dahlias need some good support early in the season. A walled garden helps but these 4 by 4 canes with string every 12″-18″ add that bit extra. When the plants leaf-up and start to flower they will be heavy and liable to damage without support.
Young trees sometimes called ‘whips’ need support and the ability to flex in the wind. These angled posts are ideal with a support about one third the way up the young stem. After 3 years they should become self supporting. The angle keeps the support away from the roots.
I have just tied some raspberry canes to wires between strong supports. The photo is of gooseberries treated in the same way. Plants produce better crops if they do not waste effort fighting the elements and get a bit of help from gardeners.
Trellis, walls and fences can provide good support particularly for your climbing plants.
These canes or stakes are to support the tree guards or animal protectors but they also provide some support for the plant themselves.