Take a walk through the Beehive conservation area on the east-side of Welwyn Garden City. There are many unusual trees on the streets and in the open spaces.
A few to look out for in the autumn are:
Black Walnut
(Juglans nigra)

Common, or English, oak
(Quercus robur)
This example, showing splendid colour, is on Beehive Lane. Turning a reddish-brown in autumn, oak trees hold on to their leaves later than most trees.

Norway Maple
(Acer platanoides)
This can be found in Thumbswood. The picture shows it just starting to change colour, but this large and shapely tree will look wonderful as the weeks go on. Trees in the acer family have some of the best autumn colour.

Rowan
Also known as the mountain ash, is a familiar sight in town and country. It has an abundance of autumn berries, hanging in large clusters, to attract the birds.

Or pick up from bookshops in town.