All plants for the 1984 and 1985 distributions, except the Ulmus, resulted from a 1982 plant exploration to Hokkaido and northern Honshu, Japan. The exploration was conducted under the auspices of: the USDA-ARS , the U.S. National Arboretum , the Chicago Botanic Garden , and the Martin Foundation. It was through the generous cooperation of the Chicago Botanic Garden that these plants were propagated and made available for testing.
More information on these accessions and their performance can be found in the article, "Performance of Landscape Plants from Northern Japan in the North Central United States" by M. Widrlechner et al in the Journal of Environmental Horticulture 16(1):27-32, March 1998. In part, the models used in this article "predict that plants from northern Japan are best adapted to sites in the northeastern United States where moisture surpluses exceed those typically found in the north central United States."
Betula ermanii PI 479321 Cham. Erman birch. This medium-sized, densely branched tree is noted for its erect strobiles and peeling, light bark. Two accessions were offered for testing:
PI 479321 was collected from the Akkeshi Prefectural Forest at Bekambegyu, Hokkaido, 43 06' N. 145 00' E., minimum temperature -20 C. Probable hardiness USDA Zone 6a.
PI 479322 was collected on Mt. Tamoyachidake, Aomori-shi, Honshu at an elevation of 1324 m, 40 37' N. 140 56' E., minimum temperature unknown. Probable hardiness USDA Zone 6a.
Callicarpa japonica Thunb. Japanese beautyberry. This is a medium-sized shrub noted for its violet-colored fruits, displayed in autumn and early winter.
PI 479331 was collected from cultivated plants growing in the Arboretum of the Hokkaido Forest Experiment Station, Southern Branch, Kikyomachi, Hokkaido, 41 49' N. 140 48' E., minimum temperature -18C. Probable hardiness USDA Zone 6a.
Cephalotaxus harringtonia (Knight) K. Koch. var. nana (Nakai) Rehd. Dwarf Japanese plumyew. This is a low-growing, suckering evergreen, resembling Taxus except for its subglobose, drupaceous seeds.
PI 479344 was collected from the Arboretum of the Tokyo University Furano Forest, Yamabe, Hokkaido, 43 14' N. 142 24' E., minimum temperature -30F. Probable USDA Zone hardiness 5b.
Hydrangea macrophylla (Thunb.) D.C. var. macrophylla. Bigleaf hydrangea . This is a large, coarse, deciduous shrub having both sterile and fertile florets, either white or pink in color.
PI 479425 was collected at Yunatai, Honshu, 40 37' N. 140 58' E., minimum temperature -18C. Probable hardiness USDA Zone 5b.
Hydrangea petiolaris Sieb. & Zucc. Climbing hydrangea. This is a hardy clinging vine and that develops in more than one plane; branches protrude out from the support structure giving the plant an interesting habit and texture. Older stems are exfoliating. Bark color is a rich cinnamon-brown. Leaves are handsome, glossy dark green in summer and abscise green. Flowers are white and appear in late June to early July for 2 weeks or more. Flowers are borne in 18 to 35cm diameter flat-topped corymbs with the outer flowers sterile and showy, inner flowers fertile and dull white; overall flower effect is very showy.
PI 479431 was collected from a woodland along a river at Oirose, Yakeyama, Honshu, approximately 40 37' N. 140 58' E., minimum temperature -20C. Probable hardiness USDA Zone 5a.
Lonicera chrysantha var. crassipes. Honeysuckle. A deciduous shrub 1.8-2.1 m tall. Branches are light gray and many. Leaves are bright green above with impressed veins, light green beneath. Fruit fleshy, somewhat translucent, red. This accession was found growing in a woodland.
PI 479476 was collected in the Akkeshi Prefectural Forest a Hichirippu, Hokkaido, 43 04' N. 145 05' E., minimum temperature -19C. Probable hardiness unknown.
Rosa rugosa Thunb. Rugosa rose. Rhizomatous, deciduous rose growing to 2 m in height, with deep rose-purple, fragrant flowers and large, dep orange-red, lustrous fruits.
PI 479562 was collected on a high beach near the sea at Wakkanaishi, Hokkaido, 45 21' N. 141 40' E., minimum temperature -19C. Probable hardiness USDA Zone 3.
Ulmus hybrid 'Regal'. The 'Regal' elm was developed at the University of Wisconsin at Madison by Dr. E. B. Smalley and Dr. D.T. Lester. It is a DED resistant variety selected from a cross between PI 341755 and PI 341763. These PI's are two Dutch hybrids, N274, the 'Commelin' elm and N215. 'Regal' has upright growth, suitable for boulevard plantings. Trees for trial were donated by Dr. Smalley. For more information, see HortSci. 18:960, 1983.
Ames 3503 has a probable hardiness at least USDA Zone 5a.
Weigela hortensis (Sieb. & Zucc.) C.A. Mey. Japanese Weigela. This is a medium-sized, deciduous shrub with arching branches and carmine flowers.
PI 479649 was collected in the Mori National Forest at Akaigawa, Hokkaido, 42 00' N. 140 39' E., minimum temperature -18C. Probable hardiness USDA Zone 6a.