| American elm |
Ulmus americana |
2 |
| Amur maple |
Acer ginnala |
1 |
| Arizona walnut |
Juglans major |
2 |
| aspen/poplar |
Populus spp. |
4 |
| Austrian pine |
Pinus nigra |
1 |
| black locust |
Robinia pseudoacacia |
2 |
| boxelder |
Acer negundo |
2 |
| bristlecone pine |
Pinus aristata |
1 |
| Callery pear (Bradford pear) |
Pyrus calleryana |
1 |
| cherry plum |
Prunus cerasifera |
1 |
| corkscrew willow |
Salix matsudana |
1 |
| crabapple and apple |
Malus spp. |
1 |
| Douglas-fir |
Pseudotsuga menziesii |
1 |
| Engelmann spruce |
Picea engelmannii |
1 |
| English hawthorn |
Crataegus monogyna |
1 |
| European bird cherry |
Prunus padus |
1 |
| European mountain-ash |
Sorbus aucuparia |
2 |
| European white birch |
Betula pendula |
1 |
| Gambel oak |
Quercus gambelii |
1 |
| giant sequoia |
Sequoiadendron giganteum |
1 |
| green ash |
Fraxinus pennsylvanica |
1 |
| honeylocust |
Gleditsia triacanthos |
1 |
| limber pine |
Pinus flexilis |
2 |
| linden |
Tilia spp. |
2 |
| London planetree |
Platanus hybrida |
2 |
| northern red oak |
Quercus rubra |
1 |
| Norway spruce |
Picea abies |
1 |
| ponderosa pine |
Pinus ponderosa var. scopulorum |
1 |
| quaking aspen |
Populus tremuloides |
1 |
| Rocky Mountain juniper |
Juniperus scopulorum |
1 |
| Siberian elm |
Ulmus pumila |
2 |
| silver maple |
Acer saccharinum |
1 |
| subalpine fir |
Abies lasiocarpa |
1 |
| two needle pinyon |
Pinus edulis |
1 |
| water birch |
Betula occidentalis |
1 |
| white fir |
Abies concolor |
1 |
| white poplar |
Populus alba |
1 |
