Acer saccharum Marsh. Caddo Sugar maple. In the box canyons of western Oklahoma, isolated populations similar to the eastern Sugar maple persist (see Rhodora 85:439-56, 1983). These populations may be useful in regions where summer stresses and alkaline soils mare the attractiveness of populations from the east. A major limitation of the Caddo type may prove to be late or poorly developed fall color and reduced winter hardiness.
Ames 3495 was collected in Red Rocks Canyon, Caddo County, Oklahoma by J. Pair in 1984. Soil pH at this site was 6.8.
Asimina triloba (L.) Dunal. Pawpaw. This small tree is widely distributed throughout the southeastern United States. It reaches the northwest edge of its native range in moist, protected sites from Kansas and Nebraska east to southern Ontario. When open grown, the trees often make attractive specimens with large, "tropical" leaves; but they are rarely seen in the trade. Cultivars have been selected for fruit characteristics, but not for adaptation to midwestern landscape conditions. It is hoped that this collection, which was thriving after the 1983-84 test winter, may be well adapted to more northerly sites.
PI 495599 was collected at Monkey Mountain Wildlife Area, Holt County, Missouri by M. Widrlechner in 1984.
Campsis radicans (L.) Seem. ex Bureau. Trumpet-creeper. As with Asimina, this is a southeastern species which enters the milder parts of our region. Although Campsis is in the trade, the material sold is of unknown provenance and often suffers winterkill in Zone 4. The large population sampled in 1984 fruited heavily after the 1983-84 test winter and showed no signs of injury.
PI 495600 was collected at Brickyard Hill State Wildlife Area, Atchison County, Missouri by M. Widrlechner in 1984.
Cercocarpus montanus Raf. True mountain-mahogany. This rose-family shrub is a common element of western shrublands, but is rarely grown in our region. Its small, dark green leaves are held late in the fall and it is especially attractive when covered with fuzzy, plume-like fruits. This species should be best adapted to the western parts of our region. Farther east, it may prove most useful on very well drained, sunny sites.
PI 495886 was collected near Central City, Clear Creek County, Colorado, elev. 2462 meters, by J. Klett and J. Feucht in 1984. Soil pH at this site was 7.0.
Cornus amomum Mill. 'Indigo' Silky Dogwood. This selection was made by the NRCS Rose Lake Plant Materials Center, East Lansing, Michigan. This is a dense, multistemmed shrub that can grow to 10' tall. The stems are red when young but turn brown and gray as they mature. Yellowish-white flowers bloom in mid-June. Abundant fruit is often produced, and ripen in September. The fruit is pale to dark blue and about 1/4 inch in diameter. 'Indigo' is adapted to a wide range of soils and grows from somewhat poorly drained to well drained sites. It is moderately shade tolerant, but not drought tolerant.
PI 468117 is a selection made from a population originally collected in the Rose Lake Wildlife Experiment Station, Clinton County, Michigan in 1961.
Cornus drummondii C. Meyer. Roughleaf dogwood. This is the common, thicket-forming dogwood of the southern Great Plains. In protected sites and points further east, attractive tree forms can also be found. It should perform well on poor sites and is attractive to wildlife for food and cover. This particular collection came from a population with wine red fall color and very heavy production of white fruits.
PI 495604 was collected at Lake of Three Fires State Park, Taylor County, Iowa by M. Widrlechner in 1984.
Cornus sericea L. Red-osier dogwood. Red-osier dogwood is widely distributed in North America and many populations have already entered the trade. High-elevation types have not been widely tested and may show useful variation for growth habit. This particular collection may also be better adapted to very alkaline soils. Twig color is darker than the 'Cardinal' selection distributed in 1987.
PI 495887 was collected along Colorado Rt. 145 in Dolores County, elev. 2643, by J. Klett and J. Feucht in 1984. Soil pH at this site was 8.4.
Euonymus hamiltonianus Wallich. Chinese spindle-tree. This deciduous shrub is noted for its colorful pink fruits with red-orange arils, similar to our native wahoo. This particular collection was made on a sand dune at the coast and may suggest that it has a significant level of salt tolerance. Dirr notes that this species is particularly susceptible to Euonymus scale.
NA 55282 was collected at Chungchong Namdo, Sowon Myon, S. Korea by the 1984 Korean Expedition sponsored by the U.S. National Arboretum and the Holden Arboretum. Plants were donated by the Holden Arboretum.
Physocarpus monogynus (Torrey) J. Coulter. Dwarf ninebark. When not in flower this shrub resembles Ribes alpinum, but tends to be more arching. It is not widely used, but could make a worthwhile addition to the range of dwarf flowering shrubs. It might also be worthy for one to attempt the hybridization of this species with the more rank ninebarks.
PI 495901 was collected in Georgetown, Clear Creek County, Colorado, elev. 2553 meters by J. Klett and J. Feucht. Soil pH at this site was 7.0.
Platycladus orientalis L. Oriental arborvitae. A multitude of cultivars has been selected from this heat and drought-tolerant conifer. The wild type grows to be a very large rounded shrub made up of distinctive planar branches. This population was collected in a region with a climate similar to parts of Kansas.
PI 491521 was collected in the vicinity of Beijing, Peoples' Republic of China and was donated by Wan Shou Shan of the Chinese Academy of Forestry.
Quercus gambelii Nutt. Gambel's White oak. White oaks generally perform poorly in the drier areas of our region. Q. gambelii is a small tree that deserves to be tested as a more diminutive alternative to burr and white oak. It is well adapted to long periods of drought and alkaline soils.
PI 495905 was collected along Colorado Rte. 141 in Mesa County, elev. 1862 meters by J. Klett and J. Feucht in 1984. Soil pH at this site was 7.3.
Quercus muehlenbergii Engelm. Chinquapin oak. This attractive specimen tree is hard to find in the nursery trade. This is likely due to the facts that it is not often a common tree anywhere in its native range and that besting the squirrels in collecting the low-tannin acorns can be quite a challenge. In Iowa this tree is usually found on the ridge tops overlooking our major rivers and is associated with calcareous soils. When open grown, its form is similar to burr oak but is a bit less coarse. The range of fall color resembles that for white oak.
Ames 7814 was collected in eastern Iowa and liners were supplied by the Smith Nursery Co., Charles City, Iowa in 1987.
Rhododendron mucronulatum Turcz. Korean rhododendron. This early-flowering, deciduous rhododendron is probably best known in the trade by the cultivar 'Cornell Pink'. Although the floral display of this species can be damaged by late winter frosts, there are other merits to consider. The foliage is reminiscent of Myrica until autumn, when it can ignite into a blaze of oranges and reds. The colored leaves tend to persist late in the fall. Recommended for acidic soils only.
Ames 6078 was collected near Shenyang, Liaoning Province, Peoples' Republic of China by Guo Xichang. Plant were donated by J. Weigle in 1986.
NA 55181 was collected on Paekryong Island, S. Korea by the 1984 Korean Expedition sponsored by the U.S. National Arboretum and Holden Arboretum. Plants were donated by the Holden Arboretum.
Viburnum dentatum L. Arrow-wood. This viburnum is well known for its clean, dark to bright green foliage and attractive clusters of dark blue fruits. The accession being distributed was found in southwest Iowa at the northwest edge of its native range. Farther north it is replaced by V. rafinesquianum. The population collected had plants that were more upright than typical forms with shrubs up to 4 meters tall.
PI 495621 was collected in Lake of Three Fires State Park, Taylor County, Iowa by M. Widrlechner in 1984. Soil pH at this site was 5.8.
Weigela praecox (Lemoine) Bailey. Early-flowering weigela. Here is another source of the early flowering type that was distributed in 1986. The plants of this accession (Ames 4583) grew in containers much more vigorously than did Ames 4582, but Ames 4583 was not distributed in 1986 due to taxonomic problems.
Ames 4583 (NA 55111) was collected on Taechong Island, South Korea by the Korean Expedition sponsored by the U.S. National Arboretum and the Holden Arboretum. Seedlings donated by the U.S. National Arboretum.
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Please send questions or comments to Mark Widrlechner at nc7mw@ars-grin.gov