Juglans nigra - Black Walnut

The black walnut is a huge deciduous tree growing in the wild to over 100'. Several in town are at least 60-70' and 40+ wide. They develop an oval to rounded canopy that's pretty dense. Quite often with a long straight unbranched trunk.

This is "our" black walnut on Cedar St. Not close to 100 feet but was almost dead at one time and was cut back severely. It seems to be pretty happy and growing strong. 

Odd pinnately compound leaves, 12-14" long (up to 24") with 12-23 or so lanceolate 3" long leaflets with fine serrations. The lower surface is lighter green.  Terminal leaflet is often missing or poorly developed.

Stems and branches are stout. Younger stems covered with a copper pubescence. Large leaf scars, terminal bud pointed, lateral buds smaller.

You can see they have multiple buds, the smaller one close to the leaf scar is a vegetative bud while the larger rounder ones are flower buds.

Flowers are on separate inflorescences, males in long drooping catkins.

Fruit is a nut, or a dry drupe. Covered with a green husk most of the summer you can tell when they are ripening as the squirrels start eating them. They have a very think "shell" with almost no meat inside. Lot of work compared to an English walnut.

Comparison with an English walnut on the right.

Bark is  beautiful. Gray on the top, and dark gray almost black between the deep plates.

Massive trunks and primary laterals. This one is downtown.

Not really know for great fall color, they do color up pretty well if it gets cold enough, but not too cold.

Misidentification:
Most likely the CA walnut which has fewer leaflets that tend to be smaller.

Location:
Aptos
Aptos Beach Road and Bayview Ct.

Captiola
110 Central Ave (Depot Hill)

Santa Cruz
Cedar St just by Center St.