Visiting the Arnold Arboretum

Last week I visited Harvard University’s Arnold Arboretum while I was in Boston. When I first arrived I talked with Kevin, a researcher at the arboretum who is studying hemlock woolly adelgid (HWA). My M.S. research involved HWA, so we spent some time talking about methods and analyses. He showed me some of the hemlocks he is working with and gave me a quick driving tour of the arboretum. We also looked at a hemlock specimen on the grounds that is thought to be a new species, which is currently being called Ulleung hemlock (as far as I know it does not have a scientific name yet). It was fun to talk about research and hemlocks again.

After our conversation I started walking through the arboretum. It contains 265 acres, with winding trails and large open plantings, so I spent many hours traipsing around. Very few plants were in bloom, so I had to imagine what many of the plants would look like in their peak flowering season and in the fall when their leaves changed color.

Hamamelis mollis (Chinese witch-hazel) at the Arnold Arboretum.

I saw some great Hamamelis and Clethra specimens–including Clethra acuminata, a plant I’ve been wanting to see.

In one garden there was a unique azalea. It was flowering when few other shrubs were in bloom, so there were many flying things around it. It looked like a deli counter at noon. I managed to isolate one patron in this picture:

A butterfly visits an azalea.

Clematis hexapetala (six petal clematis) surprised me, I did not realize there were any Clematis species that were not vines. It turns out there are several.

Clematis hexapetala at the Arnold Arboretum.

A weeping European larch caught my eye. It’s the plant equivalent of a Shih Tzu.

A weeping European larch.

When goldenrain trees are in bloom they are striking. Two goldenrain trees were in bloom at the Arnold Arboretum.

Goldenrain trees.

In the middle of the arboretum there stands a little hut; the hut is locked and alarmed. It contains the Lars Anderson bonsai collection, with specimens dating back into the 1700s. I took this picture up against the bars on one side, giving the illusion that I was inside the cage.

Part of the Larz Anderson bonsai collection.

I walked up Hemlock Hill, which was fun. I’ve read about Hemlock Hill, so being there and seeing the plants was great. Chinese hemlocks are being planted in some of the areas where eastern hemlocks have been devastated by HWA.

The path that leads to the top of Hemlock Hill.

The morning was hot and sunny. As the afternoon progressed I noted that clouds were rolling in. In the late afternoon the wind began to pick up, and I decided to head for my car. Soon after I arrived at my car the rain began to fall. I’m glad it only began in the late afternoon–once it started it continued for many hours.

I’d love to visit the Arnold Arboretum again in the future. I’m sure the lilac display must be nothing short of amazing in the spring.

The Fruit of Maples: Samara or Schizocarp?

What is the fruit of maples (Acer spp.) called? I’ve always thought of maple fruit as a samara. In fact, I think of maple fruit as the classic example of a samara. A samara is a winged achene. So the fruit is an achene (a small, indehiscent, single-seeded fruit, with the seed and pericarp attached only by a funiculus) which is paired with a wing.

The achene at the bottom of the wing.

But there is a problem with this. Maple fruit consists of two samaras that are joined together. So are the samaras just held in pairs, or is there a better word to describe what they are?

A typical maple fruiting structure contains two joined samaras.

Enter schizocarp. A schizocarp is a dry or fleshy fruit derived from a two-to many-carpellate gynoecium that breaks into one (or few) seeded segments at maturity. Wings are not part of the definition. But do not lose hope! A winged schizocarp is described as a samara-like schizocarp or (in my favorite phrasing) a samaroid schizocarp.

References will conflict on the classification of maple fruit. My experience is that most formal botany sources will side with a version of schizocarp, most informal tree guides and horticultural books will side with some use of samara.

This is an example of plants choosing not to fit perfectly into the categories we have created for them.

You might think this is worthless information, but I bet you’ll find a way to drop this in conversation if you try. Samaroid schizocarps are worthy of some attention.

References:

Judd, W.S., C.S. Campbell, E.A. Kellogg, P.F. Stevens, and M.J. Donoghue. 2002. Plant systematics: A phylogenetic approach. 2nd ed. Sinauer Associates. Sunderland, MA.

Murrel, Z.E. 2010. Vascular plant taxonomy. 6th ed. Kendall Hunt. Dubuque, IA.

Raven, P.H., R.F. Evert, and S.E Eichhorn. 1999. Biology of plants. 6th ed. Freeman Co. New York, NY.

The Bellevue Botanical Gardens

On Labor Day I visited the Bellevue Botanical Gardens in Bellevue, WA. For hours I walked around looking at plants, taking pictures, and soaking in the beautiful day and beautiful gardens

In my Kubota Gardens post I mentioned seeing impressive Hydrangea flowers, the Bellevue Botanical Gardens had even more.

A pretty purple lace cap hydrangea inflorescence.

A large perennial border garden provided much entertainment for me. It was great to see so many plants I worked with years ago. I was surprised that almost all the names came back to me, though some took a bit of thinking. Highlights in the perennial gardens include the huge white and pink Gaura plants, the metallic looking Echinops, the massive groups of Agastache, the different species and cultivars or Salvia, the blue Caryopteris specimens that looked so perfect they seemed artificial, the clusters of Verbena bonariensis that reminded me why I once loved that plant, and I’ll stop there because the list could get too long.

I’m not sure if I like playing poker or poker plants more. Kniphofia species are very cool. One look at the flowers and the common name–red hot poker or poker plant–is fully explained.

A poker plant.

Beside the border gardens there was an area containing a collection of maple trees, many of them I had never seen before. There is something very exciting about seeing a plant in real life that you have only read about. Seeing an Acer circinatum made my day.

Acer circinatum foliage.

I saw a maple that reminded me of Acer pennsylvanicum, but I suspected it wasn’t. Sure enough, it was an Asian species similar to the plant I know from Pennsylvania. Both trees have a common name of snake bark maple.

Acer capillipes bark.

I saw a small shrub that totally stumped me. Thankfully it had a name tag. Lindera obtusiloba, Japanese spicebush. As I stood there looking at this plant I addressed it, “Frankly, I had no idea you existed. I know Lindera benzoin well, which is called spicebush in the eastern US, I did not realize there was a Japanese version.

Lindera obtusiloba foliage.

In the woodlands there were plantings of ferns and herbaceous plants. Solomon’s seal and false Solomon’s seal are two similar looking plants. In the east the true Solomon’s seal is common, while in the west the false one is more common. I found an impressive planting of Maianthemum racemosum, false Solomon’s seal.

False solomon's seal fruit.

Beside that plant I found one of my favorites, Tricyrtis.This one was a hybrid called ‘Tojen’ that I had heard of, but not seen as a mature planting before. Toad lilies are so cool. The detail on the flower parts is exquisite.

A toad lily in full bloom.

The ferns were very impressive. All the moisture in the North Pacific makes for happy ferns.

A collection of ferns.

Behind the ferns a trail beckoned. The Lost Meadow Trail, to be exact. Of course I followed it. It was about a third of a mile long, winding through a forest of hardwoods and conifers. The canopy trees were spectacular. I was filled with admiration. My journey on the trail turned into a prayer walk, for I cannot imagine any other response.

On the Lost Meadow Trail.

I really enjoyed the mix of carefully managed gardens and natural landscapes at the Bellevue Botanical Gardens. It was definitely worth visiting. I appreciated that many plants were labeled.

By mid-afternoon I departed for Seattle to see the Museum of Flight. From plants to planes.

A Tale of Two Trees

A happy Bradford pear

Once upon a time there lived two Bradford pear trees in State College. These trees grew on neighboring commercial properties. For the sake of entertainment we’ll call one property Nimh and the other one Oz.

The trees grew quickly after being planted. Both of them were proud of their rounded canopies, dark green leaves, showy spring flowers, and scarlet fall foliage.

One day a person brought a pruning saw to Nimh. Much carnage followed. Instead of a beautiful rounded canopy, the tree in Nimh had a sparse canopy. And scars.

Scars in Nimh

Reduced canopy in Nimh

This made the tree in Nimh very sad. The tree in Oz began to feel a bit superior to the tree in Nimh.

Then one day something happened that changed everything.

That spring day started very innocently. A slight breeze was blowing. But the wind progressed from a gentle caress to a devastating right hook. From Fabio to Kimbo (Slice, that is).

The tree in Nimh swayed in the wind. The tree in Oz swayed in the wind. Suddenly, with a sickening crack, the tree in Oz split; it’s beautiful rounded canopy destroyed.

Canopy failure in Oz

When a veterinarian visits a horse with a broken leg he brings a shotgun (well, actually it’s most likely a needle, but shotgun is more dramatic). When an arborist visits a tree with a split trunk he brings a chainsaw. This bodes poorly for the horse and the tree. 

Today the tree in Nimh still stands. The tree from Oz is compost.

So lets talk about this.

One landscape manager was wise. The manager of the Nimh landscape realized that Bradford pear trees have a serious genetic flaw. They produce many branches at one point on the trunk, and as the canopy grows it becomes too heavy and splits the tree. To combat this, the canopy must be thinned. The longevity of the tree is extended by making an aesthetic sacrifice.

Now if the landscape manager from Nimh actually planted the Bradford pear in the first place all this goes out the window (wise –> idiot). No credit is due to someone who creates an unecessary problem and then solves it. That’s just stupid. 

Any person with horticultural training who plants a Bradford pear should be rebuked soundly. Better alternatives exist. There are cultivars of pears that are less likely to break (i.e. ‘Chanticleer,’ ‘Aristocrat,’ or ‘Cleveland Select’). There are flowering trees that are better options (dogwoods, cherries, etc).

I once heard a horticulturist recommend a Bradford pear. That’s like your doctor saying “You really should try freebasing cocaine this weekend.” Or your financial advisor saying “You should invest your life savings in Alf action figures.” Or your travel agent saying “I’d recommend Antartica for a nice honeymoon getaway.” 

If you overextend yourself beware of storms. You might break.

Moral of the story = Do not plant Bradford pears.

Misconceptions of Roots

Today we talked about roots in my soil ecology class. During the lab we saw a digital 3D model of a root system (viewing it involved wearing 3 glasses). It was pretty cool.

All this talk about roots made me think of the misconception of root systems that exists. When most people look at a tree they fail to imagine the scope of the root system. You might hear someone say that the root system is approximately the same size as the tree’s canopy. This is not true.

I made a simple sketch to illustrate this:

Tree A is rocking the root system the average person imagines. You’re not going to find many any trees with roots like that. Tree B is much more realistic. Now for a few points.

• Many false statements have a bit of truth to them. The root system size being approximately equal to canopy size is no exception. You see, there are two major classifications of roots. Coarse roots and fine roots. If you looked exclusively at the coarse roots you would might see something like Tree A in the sketch above. The coarse roots provide anchorage, manipulate pore space, and move water. But the story doesn’t end there. Fine roots are extremely important. They are the primary source of nutrient and water uptake and are also involved in carbon and nutrient cycling. They typically extend well past the canopy of the tree and are quite thick in the top twelve inches of soil. When you add fine roots to the picture, the canopy and root system no longer look alike.
• You’ll notice little clusters of roots deep in the soil on Tree B. These represent roots that develop near pockets of available water or nutrients.
• Different plants produce very different root systems. Broad all-inclusive statements about plant roots are difficult to make because so many differences exist.
• It is very easy to cause severe damage to trees by compacting the soil, raising the soil level, or excavating soil around their root systems. It might take weeks, months, or even years for symptoms to show up.

OK, I’m finished thinking about roots for the day.