Friday, December 5, 2008

OAS Volunteers remove some of the weedy curtain on the forest below the Beech Woods

There was much cutting and pulling of invasive plants Friday above the bridge over Hickey Run below the Lilac Field. On a fairly cold but sunny day volunteers from the Organization of American States showed up to help the Fern Valley Staff (there were two of us this morning, one tonight) clean up yet another small but visible spot that had been overwhelmed by non-native invasive plants. We, mostly they, removed Ampelopsis, Lonicera, and other assorted plants to open up a view into a wonderful flood-plain forest.

This is just one more place that we are stretching a thin staff to try to recover. I know that few visitors will notice this area but we have done others and we will do more. Month by month, walking and driving through the Arboretum reveal fewer unsightly spaces. The experience just gets better and better. Not to mention the fact that with the shrubs and vines out of the the way it will be possible to walk through next spring and chemically attend to the Lesser Celandine that carpets this area and is choking out the Spring Beauties. Baby steps.

Quercus acutissimia...A good sunrise can even make a non-native tree look great!:

Here's another non-natie that is somewhat out of synch with the seasons. Everybody else, even most of the oaks, have lpst their leaves for the winter and here's the Sawtooth Oak trailing along happily.

This is an oak that seems to be relatively unaffected by the complex of issues that result in Oak decline, and have distressed and killed so many of our native oaks It has abundant large acorns (not this year!) that resulted in its being widely planted in a number of eastern states for wildlife. It turns out that the high tannin acorns are so bitter that they are only eaten by birds, but I guess that's good for turkeys. It is maybe not so good for the natural areas that now have another Asian competitor with a competitive advantage?

Thursday, December 4, 2008

New Trails in Fern Valley

The new trails will allow access to plants that had previously been inaccessible; In the picture this new section runs between the beautiful Blueberry (with some residual red leaves) on the left and a Mountain Laurel on the right. Visible on the right-hand side of the picture are leaves of a native Azalea, Rhododendron viscosum serrulatum that has fragrant flowers in late summer.

What you see in these photographs is the base layer that will eventually be overlaid with red gravel and finally red stone dust.

Wednesday, December 3, 2008

A South African Mesemb and a hybrid Asian Viburnum hanging in after multiple hard frosts

The problem with cheating Mother Nature is that you almost always have to use non-native plants to do it. Seasonal trickery doesn't work on plants that are evolutionarily adapted to our climate. Witch hazels are the only native plants that come to mind that flower in the winter...and Skunk Cabbages and a few Carex spp.. Fortunately we can use plants from around the world (non-invasive only) to help us out in the off season. Our project today was blowing leaves in the Intro Garden (the areas around the Administration Building) today; there are still a few plants flowering including these two.

I don't know the identity of the Mesemb but the Vibutnum is 'Cayuga', introduced by the USNA more than 40 years ago. It normally flowers in March but the vagaries of the season have allowed some of the flowers on each flower head to open. They have a wonderful fragrance but I had to lean in close to small it. Still....beggars can't be choosers and I'll take what I can get this time of year!

Monday, December 1, 2008

Idesia polycarpa...that's a lot of red berries!

Driving through the Arboretum in the winter some of the most striking sights are deciduous plants with red berries. The vast majority are selections of Ilex verticillata and hybrids between that holly and its Asian counterpart Ilex serrata. These shrubs rarely exceed 12 feet in height, The tree pictured, Idesia polycarpa is easily 75 feet tall and could qualify as the world's largest holiday decoration.

When I first came to work at the Arboretum in the early 90's I met Idesia in the Japanese Woodland section of the Asian collections. I was quite taken by it but was put off both by its size and the fact that it is dioecious so you need a male and a female. That takes a good deal of space. And they're not common in commerce. I did find unsexed plants at Forestfarm, but that meant I would have had to buy three and hope I didn't get unlucky and get three males or three females. Even so, I would have had to plant them blind without knowing who was going to have berries and who was just going to supply pollen. By the time they were mature enough to fruit, their size would make them difficult or impossible to move. Plus I didn't hae the sort of space. And anyway I can go visit this plant below the Crape Myrtle field across Valley Road from Beech Spring Pond. It'll look good for at least another few weeks.

Sunday, November 30, 2008

Magnolia stellata 'Centennial'....named for the hundreth anniversary of the founding of the Arnold Arboretum

Not unlike people, some plants look better undressed than others. I have always liked the look of Magnolia stellata, or The Star Magnolia, in the winter. It is compact with wonderfully meandering branches and smooth grey bark. An abundance of large flower buds, greenish and hairy in a good way hint at the profusion of fragrant white flowers that will festoon the naked branches early next spring.

One attribute of a good Bonsai is "taper" meaning that the trunk and branches start out thickest, then narrow gracefully and gradually through their lengths. What's aesthetically pleasing in a bonsai looks good on full sized trees. Look at the picture; that's perfect taper, not only in the branches, but also in its forked trunk...and it works! That tree looks good.

Garden Centers in the Washington area carry a variety of magnolias including the natives M. grandiflora, a large evergreen and M. virginiana, a smaller tree, semi-deciduous to evergreen with wonderfully fragrant white flowers in summer. A variety of Asian species, varieties, and hybrids are available. They're good plants for us, not minding our hot humid summers, clay soils, and unpredictable rainfall. The one issue that does come up is that the early flowering varieties are sometimes tricked into bloom by unseasonable warmth in late winter or early spring, only to be toasted by a subsequent frost. Well, sometimes you have to take chances for the big payoff. Or if you are of a more conservative bent, use M. x 'Galaxy', a USNA release that flowers late enough to miss almost all late frosts.

The trail work in Fern Valley moves into its final phase!

In addition to resurfacing the existing trails, a few spurs and one fairly major section have been added down the middle of the shady cultivar area. The existing trails have been rerouted a bit here and there in an attempt to avoid disturbing the roots of existing trees.

The new trail will consist of a base of what is the "Green" equivalent of CR-6 overlain with two inches of red gravel and topped with an inch of red stone dust. The final tamped surface will pack down (notice the power tamper in the picture) and become a smooth hard surface that will make many parts of FV handicapped accessible. The light brown material on the left-hand trail is the base material. The trail reflected on the right-hand side of the picture is the new section. Joan tells me that this is actually a reincarnation of an older trail that was fell into disuse and was allowed to return to its natural state. It is a pleasant trail with, I think, a nicer "feel" than the existing trails around it. Anyway one result of this work is that the plantings in the area will be far more accessible both visually and physically.