Trees

NPS Photo

Common Trees at Lake Roosevelt

 

NPS/E. Gelfat

Ponderosa Pine

Pinus ponderosa

• Grows to heights of 60–125 feet with a straight trunk, 32–48 inches in diameter; Broadly conic to rounded crown

• Relatively long needles grow in bundles of 3, 5–10 inches in length, sharp-tipped and flexible

• Distinctive bark is orange-brown to cinnamon in color, deeply irregularly furrowed, with large puzzle-shaped plates that flake easily

• Cones are egg-shaped 3-5 inched long with sharp-tipped scales

• Bark has a faint scent, often descried as vanilla or butterscotch

• Forms open forests in dry valleys and southers exposures; drought and heat tolerant

• Most widely distributed pine species in North America, and the most common tree in northern part of the park

 

NPS/J. Woerner

Douglas Fir

Pseudotsuga menziesii

• Interior Douglas fir variety found in the park; Shorter than the coastal variety

• Large conifer, 70–148 ft tall, trunk typically 3 ft in diameter, pyramidal crown with irregular branching

• Bark is grey-brown, smooth with resin blisters when young, becoming rough, thick, and corky with age, with tawny-brown ridges separated by dark, vertical fissures

• Needles are spirally arranged, yellow-green or blue-green, flattish, 1 in long

• Distinct cones are narrow, oval shaped, between 2-4 in long, with prominent 3-pronged bracts that extend beyond scales

• Widespread at mid to high elevations in northern areas of the park

 

NPS/E. Gelfat

Black Cottonwoods

Populus balsamifera ssp. trichocarpa

• Also known as the Balsam Poplar

• Deciduous broadleaf tree, grows 90 to 160 ft, straight trunk between 3-6 ft in diameter; crown of mature tree is open and irregular

• Bark is grey, smooth when young, becoming deeply furrowed with age

• Leaves are triangular to heart-shaped with pointed tips and finely toothed edges; glossy dark green above, silvery green on underside, turning yellow in autumn

• Produces seeds with long, cotton-like hairs which allow the lightweight seed to be carried by the wind

• Widespread and common on moist to wet lowlands, riverbanks, gravel bars, streambanks and lakeshores at low to mid elevations

 

NPS/J. Kuehnert

Aspen

Populus tremuloides

• Small- to medium-sized deciduous tree

• Grows 50–60 ft at maturity, crown is short and rounded

• Smooth bark with a waxy appearance, greenish grey to white in color with black scars where branches previously grew

• Leaves are nearly circular with pointed tips and irregularly round-toothed edges; deep green above, paler green below, turning bright yellow in autumn

• Occurs in moist, open forests to the edges of dry grasslands

• Reproduces from root suckers, forming clones that can cover several hectares

 

NPS/J. Woerner

Black Locust

Robinia pseudo-acacia

• Native to the eastern united states, considered an invasive species due to its impacts on open landscape ecosystems in the west

• Medium-sized deciduous tree, growing between 50-100 ft

• Compound leaves grow up to 14 inches long, with 7-21 oval-shaped 1-2 inch bluish-green leaflets on the upper side, lighter green on the underside, turning yellow in fall

• Thorns form in pairs on twigs at the base of leaves, 0.5 inches long

• Fragrant white flowers with five irregular petals bloom May-June in long clusters

• Bark deeply furrowed into grooves and ridges; reddish gray and tinged with red or orange in the grooves

• Grows in dry soil with bright light; Capable of forming dense colonies that crowd out native trees

• Cultivated historically around Fort Spokane

 

NPS Photo

Box Elder

Acer negundo

• Grows up to 35–80 ft tall, with a trunk diameter of 12–20 inches

• Often has several trunks and can form dense thickets

• Bark on trunks is pale gray or light brown, deeply cleft into broad ridges, and scaly

• Pinnately compound leaves with typically three leaflets 2–4 in long

• Small yellow-green flowers appear in early spring, growing in clusters

• Is considered a weedy species in some parts of North America and Europe

• Prefers bright sunlight; Grows on flood plains and other disturbed areas with ample water supply

• Cultivated historically around Fort Spokane