The bark of willow can be very decorative with yellow or orange colour in winter, and they have pussy willow catkins in spring. They is also the grey sally. Alder can be the main choice as it makes a fine woodland if there is space. It has greenish yellow catkins in spring.
What kind of trees would grow in marl soil?
Marly soil is heavy and retains water, often preventing drainage, or slowing it down in the wetter months and even in summer sometimes. The two best kinds of trees for wet ground are willow and alder. Both of these are native trees and have adapted to cope with wet soil.