[The Genus Physocarpus East of the Cascade Mts.]
Mallow Ninebark

Physocarpus malvaceus

The photo above shows a close-up of the inflorescence of mallow ninebark as seen several hundred meters below the summit of Chewelah Peak in the Colville N.F....................June 23, 2006. Mallow ninebark differs from the similar Pacific ninebark in generally having 2 pistils while the latter has 3-5 pistils. The flowers seen above have 2 pistils.
Photo at right of the upper surface of a leaf of mallow ninebark from Squaw Creek Viewpoint off of Interstate 84, east of Pendleton, OR.......July 6, 1999.
Characteristics:

Mallow ninebark is an attractive shrub with several to many spreading to erect branches from 0.5-2 meters high. The leaves alternate along the branches and are simple with ternate venation (3 main veins) with the blades ovate to heart-shaped and with 3-5 lobes which are incised less than half the length. The lobes are rounded to acute and doubly toothed. The leaves are 4-8 cm long and almost as wide. The upper surface is dark green and smooth while the lower surface is lighter and abundantly haired.

The flowers are in corymbs or small hemispheric clusters of many white flowers. Each of the 5 petals is suborbicular and up to 4 mm long. The flowers have about 30 stamens which equal or slightly exceed the length of the petals, and usually 1-2 pistils, although 4-5 pistils are possible.

In general, this species is similar in appearance to Physocarpus capitatus, but mallow ninebark generally has smaller leaves and a slightly smaller inflorescence, and it is shorter in stature.

Importance:

Mallow ninebark is browsed occasionally by wildlife. It grows aggressively following a fire. It would also make an attractive shrub for the woodland or shrub-steppe garden on the east side of the Cascades.

Habitat:

Mallow ninebark may be found beneath ponderosa pin and Douglas-fir on canyon slopes or valley bottoms. It may also be found on nonforested scrubland sites.

Range:

Mallow ninebark may be found from southern British Columbia south along the eastern edge of the Cascades to central and eastern Oregon. It is found eastward to the Rocky Mts. of Southwestern Alberta, Montana, Wyoming, and Utah.

Physocarpus malvaceus

This photo shows a good view down onto the flower, showing the numerous stamens and the two-carpe pistil with 2 styles of mallow ninebark. Photographed off Interstate 84 east of Pendleton, OR at the Squaw Creek Viewpoint in the Umatilla National Forest........................June 25, 2008.
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The photos above show 3 close-ups of the flowers of mallow ninebark as seen about 10 miles up Hat Pt. Road in Hells Canyon National Recreation Area............................May 28, 2007. Note that one hair covered pistil is present at the center of the flower. Click each photo to view enlarged versions (2x).
The photo above shows several rounded inflorescences and leaves of mallow ninebark as seen several hundred meters below the summit of Chewelah Peak in the Colville N.F....................June 23, 2006.
Paul Slichter