Aniśko, Tomasz.  2008.  When Perennials Bloom:  An Almanac for Planning and Planting.  Portland, Oregon:  Timber Press.

Anonymous.  1982.  Soil Survey of Clackamas County Area, Oregon, United States Department of Agriculture, Soil Conservation

Service, in cooperation with United States Department of Interior, Bureau of Land Management, and Oregon

Agricultural Experiment Station.

Anonymous.  1972.  Soil Survey of Marion County Area, Oregon, United States Department of Agriculture, Soil Conservation

Service, in cooperation with Oregon Agricultural Experiment Station.

Armitage, Allan M.  1997.  Herbaceous Perennial Plants:  A Treatise on Their Identification, Culture, and Garden Attributes,

Second Edition.  Champaign, Illinois:  Stipes Publishing, L.L.C.

                              .  2001.  Armitage’s Manual of Annuals, Biennials, and Half-Hardy Perennials.  Portland, Oregon:

Timber Press.

Bailey, L. H.  1963.  How Plants Get Their Names.  New York:  Dover Publications, Inc.

Ibid.  1951.  Manual of Cultivated Plants, Revised Edition.  New York:  Macmillan Publishing Co., Inc.

Baldwin, Bruce G., Convening Editor.  2012.  The Jepson Manual:  Vascular Plants of California, Second Edition.  Berkeley:

University of California Press.

Bishop, Ellen Morris.  2003.  In Search of Ancient Oregon:  A Geological and Natural History.  Portland, Oregon:  Timber Press.

Brenzel, Kathleen Norris, Editor.  2007.  Sunset Western Garden Book, Eighth Edition.  Menlo Park, California:  Sunset

Publishing Corporation.

Brickell, C. D., and B. Mathew.  1981.  Daphne:  The Genus in the Wild and in Cultivation.  Woking, Surrey, England:  The

Alpine Garden Society.

Brickell, Christopher, and Judith D. Zuk.  1996.  The American Horticultural Society A-Z Encyclopedia of Garden Plants. 

New York:  DK Publishing, Inc.

Brookes, Martha H., Robert W. Campbell, J. J. Colbert, Russel G. Mitchell, and R. W. Stark, Technical Coordinators.  1987.

Western Spruce Budworm, Forest Service Cooperative State Research Service Technical Bulletin No. 1694.   Portland:

Pacific Northwest Research Station, Forest Service, U. S. Department of Agriculture.

Brotak, Ed.  A Matter of Degrees, Horticulture 108:3, 24, 26-27, April 2011.

Bryan, John E.  2002.  Bulbs, Revised Edition.  Portland:  Timber Press.

Burns, Russell M., and Barbara H. Honkala, Technical Editors.  1990.  Silvics of North America, Volume I, Conifers, Agricultural

Handbook 654.  Washington, D.C.:  U.S. Department of Agriculture, Forest Service.

Burrell, C. Colston, and Judith Knott Tyler.  2006.  Hellebores:  A Comprehensive Guide.  Portland, Oregon:  Timber Press.

Cappiello, Paul, and Don Shadow.  2005.  The Genus Cornus:  Dogwoods.  Portland, Oregon:  Timber Press.

Chatfield, Jim, Joe Boggs, Pam Bennett, and Maria Zampini.  “Why Names Matter.”  American Nurseryman, September 2013,

pages 14-17.

Cubey, Janet, Editor-in-Chief.  2016.  RHS Plant Finder, 2016.  London:  The Royal Horticultural Society.

den Boer, Arie F.  1959.  Ornamental Crab Apples.  Washington, D. C.:  The American Association of Nurserymen.

Dirr, Michael A.  2009.  Manual of Woody Landscape PlantsTheir Identification, Ornamental Characteristics, Culture,

            Propagation and Uses, Sixth Edition.  Champaign, Illinois:  Stipes Publishing L.L.C.

Eckenwalder, James E.  2009.  Conifers of the World:  The Complete Reference.  Portland, Oregon:  Timber Press.

Farrar, Jon.  1990.  Field Guide to Wildflowers of Nebraska and the Great Plains.  Lincoln, Nebraska:  NEBRASKAland

Magazine.

Fiala, Fr. John L.  1994.  Flowering Crabapples:  The Genus Malus.  Portland, Oregon:  Timber Press.

Evison, Raymond J.  1998.  The Gardener’s Guide to Growing Clematis.  Portland, Oregon:  Timber Press.

Flora of North America Editorial Committee, Editor.  1993-2014.  Flora of North America, Vols. 2, 3, 4, 5, 6, 8, 9, 19, 20, 21, 22,

23, 24, 25, 26, 28.  New York:  Oxford University Press.

Google Search.

Graham, Linda E., James M. Graham, and Lee W. Wilcox.  2003.  Plant Biology, Second Edition.  Saddle River, New Jersey:

Pearson Prentice Hall.

Greer, Harold E.  1996.  Greer’s Guidebook to Available Rhododendrons, Species & Hybrids.  Eugene, Oregon:  Offshoot

Publications.

Hardison, Linda, Director.  2016.  Oregon Plant Atlas, Oregon Flora Project, Herbarium, Oregon State University, Corvallis,

Oregon.

Harris, James G., and Melinda Woolf Harris.  1994.  Plant Identification Terminology:  An Illustrated Glossary.  Spring Lake,

Utah:  Spring Lake Publishing.

Haynes, C. L.; O. M. Lindstrom, and M. A. Dirr.  1992.  “Cooling and Warming Effects on the Cold Hardiness Estimations of

Three Woody Taxa,” HortScience 27:1308-1309.

Heims, Dan, and Grahame Ware.  2005.  Heucheras and Heucherellas:  Coral Bells and Foamy Bells.  Portland:  Timber Press.

Hill, Susan, and Susan Narizny.  2004.  The Plant Locator, Western Region.  Portland, Oregon:  Timber Press.

Hitchcock, C. Leo, and Arthur Cronquist.  1976.  Flora of the Pacific Northwest.  Seattle:  University of Washington Press.

Hogan, Sean, Chief Consultant.  Flora, 2 volumes.  Portland, Oregon:  Timber Press, Inc.

                    .  2008.  Trees for All Seasons:  Broadleaved Evergreens for Temperate Climates.  Portland, Oregon:  Timber Press.

Horn, Suzanne M., Consulting Rosarian.  Rose de Rescht.  Online:  Santa Clarita Valley Rose Society.

Huxley, Anthony, Editor-in-Chief.  1992.  The New Royal Horticultural Society Dictionary of Gardening, 4 vols.  New York:

The Stockton Press.

Irish, Mary, and Gary Irish.  2000.  Agaves, Yuccas, and Related Plants:  A Gardener’s Guide.  Portland, Oregon:  Timber Press.

Jacobson, Arthur Lee.  1996.  North American Landscape Trees.  Berkeley, California:  Ten Speed Press.

                                   .  1992.  Purpleleaf Plums.  Portland, Oregon:  Timber Press.

Jaynes, Richard A.  1997.  Kalmia:  Mountain Laurel and Related species.  Portland, Oregon:  Timber Press.

Kruckeberg, Arthur R.  1996.  Gardening with Native Plants of the Pacific Northwest, Second Edition.  Seattle:  University of

Washington Press.

Krüssmann, Gerd.  1976.  Manual of Cultivated Broad-Leaved Trees and Shrubs, 3 volumes.  Beaverton, Oregon:  Timber Press.

Kuitert, Wybe.  1999.  Japanese Flowering Cherries.  Portland, Oregon:  Timber Press.

McRae, Edward Austin.  1998.  Lilies:  A Guide for Growers and Collectors.  Portland, Oregon:  Timber Press.

Metcalf, Lawrie.  2006.  Hebes: A Guide to Species, Hybrids, and Allied Genera.  Portland, Oregon:  Timber Press.

Meyers, Stephen C., Thea Jaster, Katie E. Mitchell, and Linda K. Hardison, Editors.  2015.  Flora of Oregon;  Volume 1,

            Pteridophytes, Gymnosperms, and Monocots.  Fort Worth, Texas:  Brit Press.

Miller, Howard A., and Samuel H. Lamb.  1985.  Oaks of North America.  Happy Camp, California:  Naturegraph Publishers Inc.

Mills, Linn, Horticulturist, Southern Nevada Water Authority, in Southwest Trees & Turf, November 2002, page 8.

Nold, Robert.  1999.  Penstemons.  Portland, Oregon:  Timber Press.

Northup, Ann.  “Laboratory Report,” Pacific Horticulture, 74:02, 31, Spring 2013.

Parker, Janet, and Margaret Malone, Managing Editors.  2003.  Flora:  A Gardener’s Encyclopedia, 2 vol.  Portland, Oregon:

Timber Press.

Peck, Morton Eaton.  1961.  A Manual of the Higher Plants of Oregon.  Portland:  Binfords & Mort.

Pickens, Jeremy M., and Jeff L. Sibley.  Picking the Right Palm, American Nurseryman 205:9, 25-29, May 2007.

Randolph, L. F., Editor.  1959.  Garden Irises.  St. Louis:  The American Iris Society.

Rehder, Alfred.  1940.  Manual of Cultivated Trees and Shrubs, Second Edition.  New York:  Macmillan Publishing Co., Inc.

Rice, Graham.  2002.  RHS Wisley Handbooks:  Hellebores.  London:  Cassell Illustrated, The Royal Horticultural Society.

Rogers, Allan.  1995.  Peonies.  Portland, Oregon:  Timber Press.

Salley, Homer E., and Harold E. Greer.  1992.  Rhododendron Hybrids, Second Edition.  Portland, Oregon:  Timber Press.

Schauer, Thomas, and Claus Caspari.  1978.  A Field Guide to the Wild Flowers of Britain and Europe.  London, England:

William Collins Sons and Company, Ltd.

Simpson, Benny.  Texas Native Trees, http://dallas.tamu.edu/native

Small, David, and Ella May T. Wulff.  2008.  Gardening with Hardy Heathers.  Portland:  Timber Press.

Stergios, B.G., and G. S. Howell Jr.  Evaluation of Viability Tests for Cold Stressed Plants, Journal of American Society

of Horticultural Science 98:  325-330, 1973.

Still, Steven M.  1994.  Manual of Herbaceous Ornamental Plants.  Champaign, Illinois:  Stipes Publishing L.L.C.

Taylor, George.  The Climate of Oregon, Zone 2, Willamette Valley:  Special Report 914, May 1993, Agricultural Experiment

Station, Oregon State University

Trehane, Jennifer.  2007.  Camellias:  The Gardener’s Encyclopedia.  Portland, Oregon:  Timber Press.

van Gelderen, D. M., P. C. de Jong, and H. J. Oterdoom.  1994.  Maples of the World.  Portland, Oregon:  Timber Press.

Wade, L. Keith.  1979.  Phenology of Cultivated Rhododendrons in the Lower Mainland of British Columbia.  Vancouver, B.C.:

The Botanical Garden, University of British Columbia.

Way, David, and Peter James.  1998.  The Gardener’s Guide to Growing Penstemons.  Portland, Oregon:  Timber Press.

Wyman, Donald.  1969.  Shrubs and Vines for American Gardens.  London:  The Macmillan Company.