Eight garden club members made a trip to the Arnold Arboretum in Boston on Thursday, October 18. We were lucky to enjoy a day that was chilly, but sunny – the best of fall weather in New England. We parked near the Hunnewell Visitor’s Center and made our way towards Bussey Hill, noting many interesting trees along the way.
One of the interesting trees we found was the Lavalle Cork Tree (Phellodendron amurense var lavallei.) This tree is native to East Asia and to North and Central Japan. Although not native to the United States, there are no reported instances of invasiveness in this country. It is hardy in zones 5 to 9. This species includes the oldest example at the Arboretum, planted September 14, 1874, as a seed from a tree in the Imperial Garden of St. Petersburg, Russia. This was only two years after the founding of the Arboretum. Another example standing next to it is a tree that was grafted on Nov 18, 1882 from a cutting taken from the original tree.
Some of the cork trees we saw had dropped their leaves, others had leaves that were turning from green to deep yellow. Some of the latter were very striking as they were also heavily laden with dark blue berries.
Not all of the cork trees had these berries. This is not surprising, as these trees are dioecious, meaning that some of the trees bear male flowers and others bear female flowers. Only the female flowers become berries. Unfortunately, the heavy shade from the leaves didn’t allow enough light to produce a good photograph of the berries. The flowers of this cork tree are small and inconspicuous.
At the entrance to the Arboretum we had been disappointed by the Clerodendrum trichotomum (Harlequin Glory Bower) which was only barely in bloom. As we made our way up Bussey Hill, we were rewarded with a magnificently blooming hedge of this exotic looking deciduous shrub. Hardy to zone 7, it may even grow in zone 6, though it will probably die back to the ground in the winter. New growth will emerge in the spring. Harlequin Glory Bower is tolerant of sun to part shade and requires a moderate amount of water. It will grow 10 to 20 feet tall with a similar spread.
Many people know Bussey Hill as the path lined with lilacs in the spring. Fewer are familiar with the beauty along this path throughout the year. As we continued around the hill, we saw a large cloud of dusky red above the leaves of a tall tree, with smaller clouds of red occuring on lower branches. Of course, we had to walk across the field for a closer look. This turned out to be one of the woody plants included in my plan for this visit, Heptacodium miconoides, or Seven Son Flower. The lovely red color was not the flowers, but the red calyces that remain long after September’s fragrant white flowers have dropped. Seven Son Flower, provides year-round interest, as it also has lovely tan bark that exfoliates in strips that are almost paper-thin.
Although native to China, there are no reports of this tall shrub being invasive, and I’ve seen it suggested as an alternative to the ever-popular, but invasive, butterfly bush (Buddleia davidii.) It is also suggested as an alternative to invasive Amur honeysuckle (Lonicera mackii.) The plant is attractive to butterflies and hummingbirds, and tolerates occasional drought. One of our members has this tree growing at her ocean-front summer home, and reports that it is salt-tolerant and grows quickly.
Seven Son Flower will grow 10 to 30 feet tall and 6 to 15 feet wide. It thrives in full sun to part shade in zones 5 to 9. It’s natural habit is to produce suckers until it reaches maturity, when most of it’s new growth will occur at the top of the tree. It can also be pruned, when young, to encourage growth as a single-stemmed small tree.
We also paid attention to some of the native woody plants that we encountered. One of these was a specimen of Hamamelis virginiana, or American witch-hazel, in the early stages of fall-blooming. This native plant will grow 15 to 20 feet tall with a similar spread. It will grow in open shade, under trees, but will also grow in full sun. It requires little pruning other than the removal of suckers. The flowers are not showy, but any flower is welcome in the September to December timeframe of this plant’s blooming.
We had an itinerary planned, to include the Arboretum’s Conifer Path, but had to cut our visit short before we reached that, as we stopped to explore so many other trees along the way. We will simply need another visit to see the wonderful conifers in this public garden.