Hardy Citrus (Poncirus trifoliata)

The hard lemon-like fruits that this small tree (8′) produces may be brought in the house in the winter where they will soften and suffuse the air with a lemony fragrance (I’ve heard). The fruit when left in the house for a while can also be used in cooking. The flowers of the tree are very fragrant, but as you can see, the really important aspect of this tree is the thorns. When planted as a hedge, the result is impenetrability. zone 5

Golden Catalpa (Catalpa bignoides 'Aurea')

With the large leaves that you would expect from a catapa except that they are golden! What a sight! zone 5

Gold Cone (Juniperus communis 'Gold Cone')

Here are the good things about Junipers: they are hardy and easy to grow. Here are the bad things: they continue to get larger long after you are sick of them. But no, Gold Cone stays small (6-8′), upright and compact and all the good things still apply.

Franklinia (Franklinia altamaha)

The Franklin Tree was found on a river bank in Georgia and has since disappeared from the wild. The tree will grow to about 20′, has rich scarlet fall color and flowers at the same time; they are a challenge to grow and I don’t guarantee them. zone 7

Dove Tree (Davidia involucrata 'Sonoma')

Dove Tree or Handkerchief tree is at its most spectacular in the late spring when the white bracts attending the seeds hang on the tree–like handkerchiefs. The tree will easily reach 35′. The problem with the Dove Tree is that until a few years ago, there were no cultivars available and the seedling took 20 years to flower. Now with Sonoma, we have a Dove Tree that will flower in the second year. zone 6

Disanthus (Disanthus cercidifolius)

This tall shrub grows up thinly in your understory, and unnoticed most of the year, in autumn transforms your woody garden into a cathedral with its stained glass window effect. Zone 6

Columnar Japanese Holly (Ilex crenata 'Sky Pencil')

Sky Pencil stays very narrow and grows slowly to 6-8′. Best in zones 5-7. Great in a pot or formal garden.

Chilean Firetree (Embothrium coccineum)

Chilean Fire Bush is demanding about its location, but if you qualify, this is a must. The soil should be lime-free, deep and well-drained. The orange scarlet flowers in May and June among blue green (almost-evergreen) leaves are a sight to see. In normal life will get 15′ but some giants do exist. zone 7

Blue Ice (Cupressus arizonica 'Blue Ice')

Blue Ice is blue. It is not a small conifer; it will grow to 25′ before you know it and 15′ wide, but if you have the space, it is a beauty. Can stand wind but needs decent drainage. Zone 5.