Iliamna rivularis (Streambank Globemallow)

Iliamna spp.

Malvaceae Western and central North America

Attracts Pollinators Attracts Butterflies Drought Tolerant

Native to North America

SunFull Sun – Part Shade

HardinessZones 4–8

Overview

Iliamna spp. is a small genus of about seven perennials in the mallow family, Malvaceae, native to North America and known as wild hollyhocks or mountain hollyhocks. Plants form upright, somewhat coarse clumps of branching stems 3 to 7 feet (0.9 to 2.1 m) tall, clothed in broad, palmately lobed leaves that resemble those of maples. From summer the stems carry stalkless or short-stalked flowers in the upper leaf axils, each with five notched petals in shades of pink to pale lavender-pink surrounding the central column of fused stamens typical of the family. Flowering is followed by disc-shaped clusters of hairy seed segments. The genus is spread across the western and central United States, from the Rocky Mountains to scattered eastern sites, where the plants grow in moist meadows, streamsides, canyon slopes, and recently burned ground. Several species, including I. remota and I. corei, are rare and restricted to a few populations, and their seed often germinates only after fire or physical scarification of the hard coat. The coarse foliage and tall stems need room, and plants can be short-lived without periodic disturbance.

Native Range

Iliamna spp. is native to North America, mainly the western and central United States. The genus ranges from the Rocky Mountains and Great Basin to isolated populations in the eastern states, with several narrowly distributed rare species.

Suggested Uses

Iliamna spp. is used in native plant gardens, wild meadows, and naturalistic borders, and in restoration of burned or disturbed western sites. The tall stems suit the back of a border or a meadow planting. The flowers add summer nectar for bees and other pollinators.

How to Identify

Plants are tall, upright perennials 3 to 7 feet (0.9 to 2.1 m) high with broad, maple-like palmately lobed leaves and star-shaped hairs on the stems and foliage. Pink to lavender-pink mallow flowers, about 1 to 2 inches (2.5 to 5 cm) across with five notched petals and a central staminal column, are clustered in the upper leaf axils. The hollyhock-like flowers on a wild perennial with maple-shaped leaves separate Iliamna spp. from true hollyhocks (Alcea spp.) and from globe-mallows (Sphaeralcea spp.).

Appearance

Size & Dimensions

Height3' - 7'

Width/Spread2' - 4'

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~6 weeks

Summer

Flowering occurs in summer, roughly June to August depending on elevation and latitude. The flowers are pink to pale lavender-pink with five notched petals, opening in succession up the stems over several weeks. Bees and other pollinating insects visit the flowers for pollen and nectar.

Detailed Descriptions

Flower Description

pink to lavender-pink

Foliage Description

green

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 6-10 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 7.5(Neutral)

357912

Soil Types

loam rocky sand

Drainagewell drained

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

2-3 years

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Iliamna spp. grows in full sun to light shade in moist, well-drained soils, and tolerates a range of garden conditions from loam to rocky ground. The genus is hardy across roughly USDA zones 4 to 8 and dies back to the root each winter, reappearing in spring. Plants are adapted to disturbance and may be short-lived, persisting in gardens through self-sown seedlings rather than long-lived crowns. Seed germinates poorly without treatment, and soaking, scarifying, or brief heat that mimics fire raises germination rates. Established plants are drought-tolerant once their deep roots develop, while they grow more strongly with summer moisture.

Pruning

Spent flowering stems can be cut back after bloom, which can reduce self-seeding where that is not wanted. Stems are cut to the ground in late autumn or left standing through winter for the seed heads. No detailed pruning is needed beyond this seasonal cleanup.