Polygonaceae (Polygonum)
Polygonum (davisiae)
Polygonaceae
Knotweed
Polygonum
davisiae
Brewer ex Gray
Polygonum
newberryi
Small
Davis's knotweed; Klamath knotweed; Fleeceflower
PODA
Crater Lake National Park at 5,000 to 7,500 ft elevation
Pacific Northwest to Idaho and California; on open slopes and ridges; well drained soil. Found in abundance on pumice flats at Crater Lake.
plants
vegetative
Container (plug)
1-yr crowns in 6
1 Years
Healthy crowns with feeder roots throughout pots; 1 or more crowns with healthy top growth
Large root pieces dug down to 8" deep from pumice flats and stored in moist peat at 3 t0 5 C. Seed collection was also attempted; but in some years seed is very scarce; and when seeds were collected, many shriveled during storage / stratification attempts.
Seed (when available) is large and was easily cleaned with an air screen. Root pieces needed no processing.
Not known for seed (see comments above) Root pieces propagated successfully after nearly a year in cold moist storage (3 to 5 C in moist peat / sand) Some of the crown pieces with visible buds were beginning to show signs of sprouting by mid April. Crowns were divided into pieces containing at least one of these visible buds or "eyes".
Crown pieces were planted into a soil-less mix containing one part horticultural sand with one part peat / perlite mix , with added 3-month Slow-release Osmocote N-P-K fertilizer and Micromax trace elements. Pieces were planted with the "eyes" just at soil level, and pots were kept in a poly greenhouse that was fairly warm (up to 80 +F on sunny days) and 55 to 65 F night temps.
Within 3 weeks, larger root crowns had sprouted; some of the smaller root pieces took longer. No shoots emerged from root pieces plantedwithout visible buds or "eyes". Soil was kept lightly moist during initial growth but was not allowed to become soggy.
3 to 6 weeks.
Crown development continued slowly throughout the summer; and were kept in the poly greenhouse which was coated with "white-out" shade compound over the summer. Temperatures occasionally reached around 100 F in the poly house which was left open to cool to ambient night temperatures until early October. Pots were allowed to become fairly dry between waterings once plant growth was established.
4 months
No special steps were taken to harden plants off; most were completely senescent by early November. Crown die back to soil level at dormancy.
? 4 to 6 weeks
Plants shipped at the end of summer in refrigerated truck up to Crater Lake National Park fared well; although top growth soon died off, healthy crowns remained.
As noted before, dormant crowns survived nearly a year in cold moist storage.
This would be a good candidate species for salvaging prior to construction work - although we did not test the ability of non-propagated crowns to grow in situ
Hitchcock , C.L. and A. Cronquist 1973 Flora of the Pacific Northwest. University of Washington Press, Seattle Wa.
Link, Ellen, ed. 1993 Native Plant Propagation Techniques for National Parks Interim Guide; Compiled by Rose Lake Plant Materials Center 7472 Stoll Road East Lansing, MI 48823
USDA, NRCS. 2001. The PLANTS Database, Version 3.1 (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
Flessner, Theresa R; Trindle, Joan D.C.. 2003. Propagation protocol for production of Container (plug) Polygonum davisiae Brewer ex Gray plants 1-yr crowns in 6; USDA NRCS - Corvallis Plant Materials Center Corvallis, Oregon. In: Native Plant Network. URL: https://NativePlantNetwork.org (accessed 2025/02/24). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.
