• View from the Canyon Rim Trail. Photo by Jeff Kochevar


    National Monument Colorado

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Single-Leaf Ash

Single leaf ash

Single-Leaf Ash (Fraxinus anomala)

Other Names: dwarf ash

Family: Oleaceae (Olive Family)

Description: may grow up to 6 m tall, though most individuals are shorter and more shrub-like in this area. Bark is dark brown and furrowed. Single leaves are broad, 1½-2 inches long and 1-2 inches wide, with a pointed or somewhat rounded tip. Leaf edges may be slightly serrated. Whitish-greenish flower are ⅛ inches long and produce flattened winged fruit up to ¾ inches long.

Range: occurs throughout the Rocky Mountain Region from Nevada to Colorado and south to New Mexico and Arizona. It grows most commonly at Colorado National Monument in canyon bottoms.

Did you know: as the single-leaf ash's species name anomala suggests, this shrub-like tree is an anomaly among ash trees. While the leaves of most ash trees are characteristically compound (split into multiple leaves), the leaves of the single-leaf ash are unsplit. This may be an adaptation for survival in the hot, arid environments in which the single-leaf ash lives: unsplit leaves reduce the surface area through which water is lost by a process called transpiration.

Did You Know?

climbers on Independence Monument

Each Independence Day, local climbers scale the iconic Independence Monument in Colorado National Monument and raise an American flag on top. This tradition dates back to early park promoter John Otto, whose route up Independence Monument climbers still follow.