mulberry
桒 centers on the mulberry tree, a plant valued for its leaves (used in sericulture) and fruit.
桒 is a variant form of 桑 (mulberry). The top component 卉 likely represents the branches and leaves of the mulberry tree, while 木 (tree) at the bottom reinforces the plant meaning. The exact historical development of this variant is uncertain.
The top 卉 looks like a cluster of leaves and branches, and the bottom 木 is a tree. Together they form the mulberry tree, whose leaves feed silkworms.
For ソウ, imagine sewing (ソウ) a silk garment made from mulberry-fed silkworms: sew -> ソウ, and the mulberry tree provides the leaves.