Mountain Spiraea — Plant Guide

🌿 California native

Quick facts

Habitat: Wet Subalpine meadows, streambanks, and lakeshores

Form / size: Low deciduous meadow shrub, 1–3 ft

Sun: Part shade · Water: Moderate (wet ground)

Blooms: Rosy-pink flat-topped clusters in late summer · Pollinator value: High

Description

A knee-high pink-topped shrub of wet mountain meadows. The tiny flowers are packed into dense, dome-shaped to flat-topped clusters, rosy pink and softened by long protruding stamens into a look often described as a fuzzy pom-pom, and they carry a sweet, clove-like scent. The leaves are light green, oval, and coarsely toothed toward the tip, turning yellow in fall. It forms leafy thickets on the reddish-brown twiggy stems, and the dry brown seed clusters persist into winter. It is still widely known by its older name, Spiraea densiflora.

Ecological role

Mountain spiraea is tied to seasonally wet, cold ground: wet meadows, streambanks, and lakeshores in lodgepole, red fir, and subalpine forest. Calscape lists it as a larval host for roughly 30 butterfly and moth species, and its nectar-rich summer clusters draw bumblebees and other native bees to habitat that blooms late. It spreads clonally by rhizome, forming colonies that bind wet-meadow and streambank soils.

Habitat & range

Wet montane and subalpine meadows, streambanks, and lakeshores the length of the Sierra Nevada, roughly 5,000 to 10,500 ft. It grows in the Lake Tahoe basin and continues south through the high country into Mono and Inyo counties around the Mammoth Lakes and Eastern Sierra.

In the garden

A good bank, streamside, or rain-garden shrub for cold-winter gardens with reliably moist but fast-draining soil; it will not take drought or hot, dry lowland summers. It tolerates part shade to fairly open sun and needs moderate summer water. Being deciduous, it drops to bare pink-brown twigs in winter and rewards with summer bloom and yellow fall color.

Propagation

Readily from softwood or semi-hardwood cuttings taken during the growing season, or by division of the rhizomatous clumps. The very fine seed can be surface-sown on moist mix, cold-moist stratified, and kept continuously damp.