National Collection of Imperiled Plants

CPC National Collection Plant Profile

Photographer:

Tom Ward

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CPC National Collection Plant Profile

Rhododendron prunifolium

Family:	Ericaceae
Common Name:	plumleaf azalea
Author:	(Small) Millais
Growth Habit:	Shrub
CPC Number:	3738

Distribution
Protection
Conservation
References

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Photographer: Tom Ward
tomward[at]arnarb.harvard.edu

Rhododendron prunifolium is Fully Sponsored

Primary custodian for this plant in the CPC National Collection of Endangered Plants is:

The Arnold Arboretum of Harvard University

Irina Kadis contributed to this Plant Profile.

Rhododendron prunifolium

Rhododendron prunifolium is one of the showiest native azaleas and can grow up to 18 ft in height (Wilson and Rheder 1921, Cox 1990, Dirr 1998). The clustered, brightly crimson-colored flowers bloom from mid-July to mid-August, and occasionally in September (Foote and Jones 1994) . The flowers' stamens are very long and project beyond the flower. It is the most glabrous species of all American rhododendrons. Its leaves are alternately arranged on the stem in tight clusters, dark green above, light beneath, smooth (except for the small hairs on the margins). It was first collected by R. M. Harper in the early 1900's and first grown at the Arnold Arboretum in 1918.

Distribution & Occurrence

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State Range

Alabama
Georgia

Habitat

R. prunifolium can be found growing in low, moist sites in forested (beech-maple-magnolia) ravines along streams. In Canyon Park, Georgia, it is common at forest edges near streams at the bottoms of 150-foot canyons that emerged as a result of farming practices during the mid-19th century (Cox 1990, Dirr 1998, Foote and Jones 1994).

Distribution

R. prunifolium was historically found in western and southwestern Georgia, eastern and southeastern Alabama (Georgia-Alabama border) (Godfrey 1988).

Number Left

The Georgia Natural Heritage program discovered 41 populations known from southeastern Alabama and southwestern Georgia recorded from seven counties in Georgia (USFWS 1989)

Protection

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Global Rank:	G3	5/12/1995	Guide to Global Ranks
Federal Status:	RT	1/19/1996	Guide to Federal Status
Recovery Plan:	No

State/Area Protection

State/Area	Rank	Status	Date
Alabama	S2S3		8/1/1996
Georgia		T	7/27/2002

Conservation, Ecology & Research

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Ecological Relationships

Ecological relationships are unknown.

Threats

R. prunifolium is in danger of extinction, as few new seedlings are found in the natural habitats.
Natural habitats vanish due to plant succession.
Due to erosion after logging, many of the sites suitable for R. prunifolium have vanished.
Disturbance by thinning of trees in its immediate proximity.
In places where the habitats are still available, it is vandalized and robbed by irresponsible amateur gardeners.

Current Research Summary

This species has been successfully propagated from seed:
Sow into milled Sphagnum, maintain humidity under cover, water carefully. Seedlings are tiny and growing slowly. Put them a few per pot first, to reduce the risk of overwatering; repot once they achieve sufficient size.

And from softwood cuttings:
Take cuttings in May-June, keep them under fog or mist in 50/50 sand-perlite. With 2,500-5,000 ppm K-IBA or H # 3 treatment, the rooting rate is 70-80%. Cuttings become more secure once they survive through the first winter.

R. prunifolium was successfully cultivated near Philadelphia, PA (on a southern slope at Gladwyne) and at Callaway Gardens, Pine Mountain, GA.

Current Management Summary

There is no formal management plan.

Research Management Needs

Management needs include habitat protection, population monitoring and establishment of new populations. Research of this species general biology and reproductive ecology would aid in conservation efforts.

Ex Situ Needs

References

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Books (Single Authors)

Cox, P.A. 1990. The Larger Rhododendron species. Oregon: Revised Ed. Timber Press.

Dirr, M.A. 1998. Manual of Woody Landscape Plants. Champaign, Illinois: Stipes Publishing L. L. C.

Foote, L.E.; Jones, S.B., Jr. 1994. Native Shrubs and Woody Vines of the Southeast. Oregon: Timber Press.

Godfrey, R.K. 1988. Trees, shrubs, and woody vines of northern Florida and adjacent Georgia and Alabama. Athens, GA: University of Georgia Press. 734p.

Wilson, E.H.; Rehder, A. 1921. A monograph of azaleas. Rhododendron subgenus Anthodendron. Publications of the Arnold Arboretum, No. 9. Cambridge, Massachusetts: The University Press.

Books (Sections)

Kartesz, J.T. 1999. A synonymized checklist of the vascular flora of the U.S., Canada, and Greenland. In: Kartesz, J.T.; Meacham, C.A., editors. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden. Chapel Hill, NC.

Electronic Sources

(2000). Showy Native Trees, Shrubs and Woody Vines. [Web site] NC State University. http://www.ces.ncsu.edu/depts/hort/consumer/factsheets/native/scientific_namea-e.html. Accessed: 2002.

Hyatt, D.W. (2001). East Coast Native Azaleas. [Web site] Middle Atlantic Chapter ARS Species Study Group. http://www.tjhsst.edu/~dhyatt/azaleas/index.html. Accessed: 2002.

Silverman, G. (2002). Species In Our Midst: Rhododendron prunifolium. [Web site] The American Rhododendron Society, Massachusetts Chapter. http://www.rosebay.org/chapterweb/specprun.htm. Accessed: 2002.

Journal Articles

1995. Plumleaf azalea wins GCA medal. American Horticulturist. 74: 24.

Braman, S.K.; Beshear, R.J. 1994. Seasonality of predaceous plant bugs (Heteroptera: Miridae) and phytophagous thrips (Thysanoptera: Thripidae) as influenced by host plant phenology of native azaleas (Ericales: Ericaceae). Environmental Entomology. 23, 3: 712-718.

Braman, S.K.; Pendley, A.F. 1992. Evidence for resistance of deciduous azaleas to azalea lace bug. Journal of Environmental Horticulture. 10, 1: 40-43.

Kron, K.A. 1993. A revision of Rhododendron section Pentanthera. Edinburgh Journal of Botany. 50, 3: 249-364.

USFWS. 1989. Regional News--Region 4. Endangered Species Technical Bulletin. 14, 1-2: 14.

Waldman, P. 1994. R. prunifolium and Its Children. Journal of the American Rhododendron Society. 48, 1: 73.

Reports

Nicholson, R.G. 1987. Propagation of some woody endemics of eastern North America. Jamaica Plain, MA: Arnold Arboretum. p.12. Notes from a talk given by author in 1987.

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This profile was updated on 3/4/2010