Streambank Globemallow / Mountain Hollyhock

Iliamna rivularis

Malvaceae

• Eastern Washington Native
• Sun
• 3'–6' tall x 3'–5' wide
• Drought Tolerant: Moderate — most vigorous with some summer moisture but tolerates periodic drought once established;
• Evergreen: no
• Flower Color: Soft lavender-pink to rose-purple (June–August)
• Wildlife value: Excellent native bee forage; attracts bumblebees; flowers used by hummingbirds; foliage is preferred browse for deer in post-disturbance areas.
  

Iliamna rivularis is a striking native perennial occurring naturally east of the Cascade Range in Washington state on sunny streambanks, mountain meadows, open coniferous forest slopes, and disturbed ground. It is associated with natural disturbance, particularly wildfire: seeds possess an extremely hard, impermeable coat that can remain viable in the soil for over a century, germinating explosively after the heat of a fire scarifies the seedcoat. In post-fire landscapes, mountain hollyhock provides early-successional forage and floral resources before taller vegetation closes in to shade it out. In the garden, it is a reliable perennial, reaching full height by early summer. It performs best in full sun in moist to average, well-drained soil and declines quickly in shade or in wet, poorly drained soils. 

Mountain hollyhock has one of the most striking upright structures for a native perennial in Spokane gardens. Its large, heart-shaped, palmate leaves resembles maple or hollyhock foliage with soft and slightly hairy is handsome from emergence through the entire growing season, forming a dense, full mound creating a small shrub even before bloom. From June through August, tall, upright racemes rise above the foliage, densely set with cup-shaped, five-petaled flowers two to three inches across in soft shades of lavender-pink to rose-purple — the unmistakable family shape of Malvaceae, recognizable to any gardener familiar with hollyhock or mallow. The flower display is extended and generous, lasting six to eight weeks, and individual racemes carry dozens of blooms. The overall effect is a lush, cottage-garden exuberance with a distinctly western native character. After frost, the plant retreats quickly.

Iliamna rivularis is a high-value native plant for pollinators and large herbivores alike. Its abundant, open-faced flowers produce accessible nectar and pollen for a wide range of native bees — particularly bumblebees, and butterflies. Hummingbirds also visit the tubular floral bases.  Ethnobotanical records for Iliamna are limited, but plants of the mallow family broadly were used by various Interior Salish peoples of the Pacific Northwest for fiber, food, and poultice applications.

Mountain hollyhock is an outstanding choice for the back of a sunny, moist-to-average perennial border, a naturalistic meadow or rain garden planting, or a streamside landscape where its native habitat conditions can be replicated. Its shrub-like stature and long bloom season make it a structural anchor for large-scale native plantings, and its deep pink flowers pair beautifully with the yellow, blue, and silver tones of many co-occurring native species. Suggested plant partners in a Spokane-region native garden include Penstemon speciosus (royal penstemon) and Penstemon richardsonii (Richardson's penstemon) for complementary verticality in adjacent bloom seasons; Geum triflorum (prairie smoke) as a low-growing early-season contrast; Linum lewisii (wild blue flax) for soft blue color harmony; Achillea millefolium (yarrow) for contrasting white and foliage texture; Artemisia ludoviciana (silver sage) for silver-against-pink foliage drama; and ornamental grasses such as Helictotrichon sempervirens (blue oat grass) or Festuca idahoensis (Idaho fescue) for textural contrast and year-round structure. Allow at least four feet from neighbors and note that deer pressure may require initial protection in browsing-heavy areas.