Pyramidal Spiraea - Spiraea x pyramidata
Pyramidal spiraea is a rhizomatous shrub with erect or spreading branches, 5-10 dm (20-40 in) tall. The alternate leaves are elliptic and 2-7 cm (1-3 in) long with margins that are entire below but sharply toothed above. Leaves and stems are generally short-hairy. Numerous tiny flowers occur in finely branched globose clusters that are grouped in a pyramid-shaped inflorescence, 5-10 cm (2-4 in) wide at the base, at the top of the stems. Each flower has a sparsely hairy, cup-shaped calyx, ca. 2 mm long, with 5 reflexed lobes, and the 5 pink-tinged petals are 2-3 mm long. Stamens 25-50; the ca. 5-lobed ovary matures into a capsule 2-3 mm long.
Flowering in July.
This plant is thought to be a hybrid between S. betuflifolia and S. douglasii. The inflorescence of the former is flat-topped, while the latter has a branched but spike-like inflorescence.
BC, MT south to OR and ID (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
Observations in Montana Natural Heritage Program Database
Number of Observations:
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Moist forests and streambanks in the valleys and montane zone.
- Additional ReferencesLegend: View Online Publication
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- Hess, W.J. 1969. A taxonomic study of Spiraea pyramidata Greene (Rosaceae). SIDA 3(5):298-308.
- Lackschewitz, K., P. Lesica, and J. S. Shelly. 1988. Noteworthy collections: Montana. Madrono 35:355-358.
- Lesica, P., M. T. Lavin, and P. F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
- Schassberger, L.A. 1991. Rare plant inventory of the East Pioneer Mountains. Prepared for the USDA Forest Service, Region 1, Beaverhead National Forest. Montana Natural Heritage Program, Helena, MT. 55 pp.
- Schassberger, L.A. and J.S. Shelly. 1990. Sensitive plant surveys in the Bull River and adjacent drainages, USDA Forest Service, Region 1, Kootenai National Forest. Unpublished report. Montana Natural Heritage Program, Helena, MT. 60 pp.