look in the white pages under US GOVT ... and find the soil conservation district.. and talk to them about what you would like to do ...

they even sell bargain plants in spring and fall for what you want to do ...

by definition .... retaining the sidewalls of a ditch is SOIL CONSERVATION .... so i suspect them will be more than willing to help ..

do NOT plant any type of invasive near water ... ken

Most trees out in the landscape can be planted on a slope.

Day lilies, although the seeds may move down the slope into the ditch over the years - the common orange ones are called ditch lilies around here as they are in many of the country road ditches. The ones in front of my house are full of them - unfortunately the county comes and mows the sides of the road at about the same time as they should bloom, so there isn't much of a show some years. I can hope the late freeze slowed things down so I will see lots of blooms.

You might want to check with the county authorities to see how widely from the edge of the road they normally mow, AND how wide of a right of way they are entitled to mow, even if they don't do it every year. No point in planting anything but flowers in the right of way, as it will be gone sooner or later. A shrub that could take summer cutting back might do.

Otherwise, almost any of the trees and shrubs native to your area should be fine - I would advise against the re-sowers like persimmon - they are in all the fencerows and roadsides here and are a major pain to weed out of my veggie and flower beds. And if the tree will overhang the road, maybe the fruiting trees wouldn't be a good idea, esp. for the purple fruited ones - plus, if it's near your drive, the birds will leave purple droppings all over.

Berry bushes - blueberries, high bush cranberry, choke cherry, etc. - have attractive spring flowers and nice berries - for the birds if you don't want to pick from next to the road. Some have good fall color.

Any of the more aggressive rooted trees like Sycamore, Bur oak, Red maple, Sweetgum, Hackberry, Hickory, and Green Ash should work just fine.

Sorry - I forgot to add that the ditch is not along a road. It's along the edge of my property that borders a farm field. I'm the last house on the end of the development, so I have a 15' drainage easement on my property that I have to maintain.

I was thinking I could do the daylily thing to "naturalize" or plant crown vetch, but I would still like to get a couple trees there. I like the idea of hickory or burr oak.