Fremont cottonwood

Colorado blue spruce (Picea pungens) is a narrow, stiffly pyramidal conifer from the central and southern Rocky Mountains, and the source of nearly every silver-blue evergreen in cultivation. The colour is real and is the reason it is planted: the needles carry a waxy bloom that reads anywhere from grey-green to an almost metallic pale blue, sharpest on selected cultivars. In its native range, between roughly 6,000 and 11,000 feet from Wyoming and Idaho south to Arizona and New Mexico, it is a cool-climate mountain tree of moist stream sides and canyon bottoms. Planted far outside that range - which is where most people meet it - it is one of the most reliably disappointing conifers in the eastern United States, where humid summers bring on needle cast and cytospora canker and a fifteen-year-old specimen often loses its lower branches and never recovers them. It is also planted far too small: the nursery pyramid becomes a 30-to-60-foot tree. Given cool air, full sun, room, and honest expectations, it is superb and long-lived.

A tough, widely adaptable native shade tree of central and northeastern North America, growing 40 to 60 feet tall and wide with a rounded, spreading crown. Mature gray bark develops the warty corky ridges that make it instantly recognizable, and the round purple drupes are edible and feed dozens of bird species. One of the most pollution- and stress-tolerant street and shade trees available - it shrugs off wind, urban conditions, and wet, dry, or poor soils alike.

A very large Pacific Northwest conifer - 40 to 80 feet in cultivation but topping 300 feet in the wild - and one of the most important timber trees in North America. Unique forked, trident-shaped cone bracts that protrude between the scales distinguish it from every other conifer. Flat, spirally-arranged dark green needles are fragrant when bruised and leave raised circular scars on the twigs.

One of the largest and fastest-growing native hardwoods of eastern and central North America - a streambank and bottomland tree reaching 50 to 80 feet (occasionally far more) with a broad, open-rounded crown. Its glossy triangular (deltoid) leaves with coarse marginal teeth and flattened petioles flutter and clatter in the wind, and female trees release the cottony seed fluff that gives the tree its name. Fast, tough, and tolerant of drought and urban conditions, but messy and weak-wooded - Missouri Botanical Garden calls it generally inappropriate for ornamental or urban use, better suited to rural lowspots and stream corridors.

A large, fast-growing native legume tree of central and eastern North America, reaching 60 to 80 feet with a rounded, spreading crown and airy, bipinnately compound leaves that cast filtered shade and turn bright yellow in fall. Wild trees arm their trunks and branches with stout branched thorns up to 3 inches long and drop long, twisted, dark purplish-brown seedpods to 18 inches; the sweet pod pulp was dried and ground as a sweetener by southeastern Indigenous peoples. Tolerant of wind, high summer heat, drought, saline, clay, and urban conditions.

The dominant pine of the western United States - a large, long-lived conifer that grows in a conical form to 60 to 125 feet in cultivation and far taller in the wild. Mature trunks wear distinctive bright yellowish-brown to reddish-orange bark furrowed into broad scaly plates, often smelling of vanilla or butterscotch on warm days. Dark yellow-green needles up to 10 inches long crowd the branch ends in bundles of three, and the species is highly drought- and deer-tolerant once established.