Woody vine on fence id
This reminds me of sweet autumn clematis which has small white flowers. It is a nice wildflower but can be aggressive. I would keep it for its ornamental value but if you need a fence cleared, you may have a reason to remove it.
The Missouri Botanical Garden describes it as:
Easily grown in average, medium, well-drained soil in full sun to part shade. Unlike almost all other species of clematis, this plant will thrive and bloom well in considerable shade. Blooms on new growth. Prune hard in fall after flowering or in early spring.
Sweet autumn clematis, as the common name suggests, is a fragrant fall-bloomer. It is a vigorous, deciduous, twining vine with an extremely rampant growth habit. If given support, it will climb rapidly with the aid of tendrilous leaf petioles to 20-25' in length. Without support, it will sprawl along the ground as a dense, tangled ground cover (to 6-12" tall and 10' wide) which typically chokes out most weeds. Features aromatic, 1" diameter, cruciform, pure white flowers (each with 4 narrow petal-like sepals) in terminal panicles from late August to October in a profuse bloom which typically covers the foliage. Flowers give way to attractive, plume-like seed heads. Compound, leathery-textured, shiny green leaves (3-5 oval to elliptic leaflets with cordate bases). Sweet autumn clematis can aggressively self-seed in the landscape, and has escaped cultivation and naturalized in many parts of the U.S., particularly in the East and Midwest.
No serious insect or disease problems. Spreading, sometimes hard-to-control vine.http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=a300