They are uniformly low, skirted with marsh and forested on the higher ground with strands of cottonwood, willow and tough little crab apple trees.
(They; are; uniformly low, skirted with marsh and forested on the higher ground with strands of cottonwood, willow and tough little crab apple trees)
They
are
uniformly low, skirted with marsh and forested on the higher ground with strands of cottonwood, willow and tough little crab apple trees