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Holodiscus dumosus

Holodiscus dumosus

Holodiscus dumosus
Holodiscus dumosus. Synonym: Holodiscus discolor. (Mountain Spray, Rock Spirea)
Rosaceae (Rose Family)

Montane, subalpine. Rocky sites, cliff faces, woodlands, openings. Summer.
Above and left: Lands End, Grand Mesa, July 13, 2017.

Holodiscus dumosus grows to six feet wide and tall with a super abundance of tiny white-to-pink flowers. The plant's preferred habitat is scenic cliff faces with fantastic views. The plants in the photographs on this page hang off ledges 5,000 feet above the Grand Valley.

The genus was named by Carl Johann Maximowicz in 1879. Thomas Nuttall named this species Spirea dumosa in 1847 from a collection he made near the Platte River in 1834. Amos Heller placed the species in the Holodiscus genus in 1898.

John Kartesz separates this genus into H. dumosus and H. discolor, but all floras I have examined choose one or the other specific epithet and recognize only one species.
Colorado Flora: H. discolor.
Flora of Colorado: H. dumosus.
Manual of the Plants of Colorado: H. dumosus.
Trees and Shrubs of Colorado: H. dumosus.
A Utah Flora: H. dumosus.
Intermountain Flora: H. dumosus.
Flora of the Four Corners Region: H. dumosus.
The Jepson Manual: H. discolor.
The Flora of North America: H. discolor var. discolor and H. discolor var. dumosus.

According to the FNA:

Some overlap in morphology occurs between the two varieties recognized here, particularly when populations occupy sites that are outside the normal habitat range. The basic morphology and habitats occupied by average populations of var. discolor and var. dumosus are sufficiently distinct that recognition at the varietal level is warranted. The physiological and ecological tolerances appear to be quite different between the two varieties, allowing their survival in different habitats.

"Holodiscus" is Greek for "entire disk", describing the flower. "Dumosus" is Latin for "a bramble" + "abundant", i.e., "very bushy".

Holodiscus dumosus

Holodiscus dumosus. Synonym: Holodiscus discolor. (Mountain Spray, Rock Spirea)
Rosaceae (Rose Family)

Montane, subalpine. Rocky sites, cliff faces, woodlands, openings. Summer.
Lands End, Grand Mesa, July 13, 2017.

Flower petals are only about 2 mm long; sepals are about 1.5 mm long. Petals and sepals are white, cream, or somewhat pink. Hairs abound.

Holodiscus dumosus

Holodiscus dumosus

Holodiscus dumosus. Synonym: Holodiscus discolor. (Mountain Spray, Rock Spirea)
Rosaceae (Rose Family)

Montane, subalpine. Rocky sites, cliff faces, woodlands, openings. Summer.
Lands End, Grand Mesa, July 13, 2017 and Navajo Reservation near Teec Nos Pos, Arizona, June 24, 2006.

New growth is flexible and tan/pink becoming woody and gray and sometimes weakly spinescent.

Leaf blades vary from about a half inch wide and long to well over an inch wide and long and in some areas of the plants range leaves are up to two or three inches wide and long. Teeth and lobes are prominent and may be along the upper edges (top photograph at left) or along almost the entire leaf margin (bottom photograph at left). Leaf hairiness varies from nearly glabrous to pilose and glandular. Smaller leaves are quite reminiscent of those of Cercocarpus montanus.

Range map © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Eradicated
Questionable presence

Holodiscus discolor

Range map for Holodiscus discolor

Holodiscus dumosus

Range map for Holodiscus dumosus