Dutch Elm Disease

The fourth blog post I ever wrote featured the American elm (Ulmus americana). And that seems totally appropriate, as the American elm is probably one of the most exquisitely beautiful trees that we can claim as our own.  Most prevalent along the riverbeds in the midwest, the tree has lovely golden-orange fall color, large ovate, toothed leaves (with asymmetrical leaf bases) and beautifully fissured bark on branches which elegantly spread into a v-shaped canopy. 

Sadly, too often any remaining specimens left -- especially those in the wild -- look like this, or worse.  That's because since the 1960's the population of American elms has been decimated by Dutch elm disease, or various species of the fungus Ophiostoma. The vector (or carrier) for this pathogen is the elm beetle, which first emigrated to the United States via a delivery of Dutch logs shipped to Ohio to use as veneer for furniture.  The beetle burrows into the bark of the elm to lay eggs.  While borers like this can damage trees simply by this process, more dramatic is the resulting infection of the fungal pathogen.  Even in areas where no beetles are present, one infected tree can pass on the fungus to a neighbor if the roots graft underground. 

The tree's defense against this infection is to essentially close up shop; the canals of xylem and phloem close, blocking further spread of the disease.  Unfortunately, at this point damage has been done and the tree slowly dies back.  These photos well demonstrate the appearance of an untreated American elm. Ironically enough, European elms such as the English elm (Ulmus procera) are equally devastated by the disease and first contracted it in a shipment of American timber. (See Wiki for more.)

Land management strategies in some wild populations of elms and the famous allees in Central Park and along the National Mall keep the disease at bay. Frankly, I'm surprised these two trees (near the Yards Park in DC) have remained standing.

Courtyard Garden at the Art Institute of Chicago

With all the attention tourists and locals pay to the new (ish) Millennium Park, this small courtyard at the Art Institute of Chicago is now mostly ignored, or at least underappreciated.   Which is a shame, because it's a lovely space.

A large pool with bubbling fountains arranges the space, grouping planters of low, wide-spreading hawthornes (Crataegus) on each side. 

 

English ivy (Hedera helix) are trained up the trunks, which has to be a bit of a maintenance issue - I would think they need to clip them back a few times a year!

 Buffering the traffic of Michigan Avenue are large planters of honey locusts (Gleditsia triacanthos var. inermis).  Much like at Paley Park, honey locusts are used to terrific effect as plants that can get quite tall in maturity but yet grow very well in the space to which it is confined.  In the open, the tree could have a broad, spreading shape.  But in narrow confines, it has a loose, columnar habit. 

Euphorbia amygdaloides var. robbiae

Last night was my first day of class back at the program in DC -- this semester I'm teaching a perennials for fall course, which I suspect will include no shortage of wonderful grasses and ferns.  

In the meantime, we did take a look at this handy groundcover -- Euphorbia amygdaloides var. robbiae.  The common name, besides Robb's Euphorbia, can also be wood spurge, which led to some confusion last night, since that is also a name for the native Pachysandra, P. procumbens.. Add to that, this plant is similar(ish) to Pachysandra, in that it's an evergreen groundcover that spreads easily and quickly.

Of course, the radial leaf arrangement (the almond shape of the leaf accounts for the species name amygdaloides which means almond-like) is quite different and this plant has tall spikes of yellow flowers in the spring.  The flowers (which are most noticeable due to their showy bracts and involucres) persist for several weeks in the spring.

Millennium Park Water Feature/Canal/'Stream'

A wooden promenade and shallow canal bisect Lurie Gardens just south of the Gehry amphitheater (seen to the left). It runs at a diagonal, which presumably accommodates pedestrians passing through the park while walking through the city, as well as creating a quite open space to simply people watch or read a book. 

The ipe (FSC certified, of course) boardwalk runs at a pitch downhill, meeting the cross street to the south just a few steps above grade.  The canal achieves the drop in grade with the placement of weirs, allowing the water to step down in grade and be consistently shallow enough to rest your feet on the bottom.  The boardwalk steps down as well, creating a long bench which, as you can see, is well used by visitors.

 

Metal bridges traverse the canal and are composed of naval brass, bronze and powdercoated steel. 

Millennium Park Site Details

Here are a few shots of some of my favorite site details at Millennium Park. 

I love the bench composed of separate 2x6s (or 2x8's-- I didn't measure it).  It makes for a great ad-hoc work space or picnic area in a park that is skimpy on lawn.

This fence separates a lawn area from the Frank Gehry designed stage to the right.

 

Check out how the profile diminishes as the fence gains height. 

 

The plant beds in Lurie Garden have stone retaining walls that are cut at an angle, so the appearance of a curb is minimized. 

A slip guard as one approaches a bridge over the water that runs through the park, bisecting Lurie Gardens from the rest of the site. 

The paths through the gardens are made out of small, long pieces of granite that vary in color between pink, peach, sand and white.

Millennium Park Lurie Garden

I've posted about Millennium Park twice before, though both times I used photos my mother had taken when she was in Chicago with my father.  These, I am happy to say, are photos I took myself.  I was recently in Chicago for the first time and of course, this park was my first destination.  

I was particularly excited to walk through the park's Lurie Gardens.  The park itself is designed by Gustafson Guthrie Nichol Ltd., though the plant selection was a collaboration with Piet Oudolf who is quite the "it" planting designer these days (he also worked with Jim Corner and Diller Scofidio on the High Line Park).

It's a beautiful garden, with painterly drifts of native perennials and grasses.  And obviously, it's a wonderfully appropriate context, as it evokes the prairie landscapes that are typical to the midwest.

 

I'll be posting a few more shots of the park in the days to come, with some focus on design details and plant species. 

Yikes

Wow, my last post was 11 days ago!  Shameful!

If you're reading this, well, thanks for coming over, even though I have been posting infrequently.  My own back-to-school resolution is to maintain 3-5 posts/week.  Wish me luck, things have been piling up lately!

Speaking of being of "piling up" (cheesy segueway alert!), here are some shots I took on a run yesterday near the Air Force Memorial in Arlington.

Locals probably recognize the memorial immediately, as it's visible from DC and the Potomac.  It's also within the first and last mile of most of my runs.  It's also - as you can see, at the crest of a very large hill.  A great spot for firework viewing, it's also a little brutal to climb after a long run, and there's a good chance I end up walking some of it.  In any case, I know this stretch of land quite well.

 
Which was why I was so fascinated with the recent storm damage that occurred there.  You see the way the ground sheared off in the top photo?  I'd say the ground dropped about 24-30" -- a very small landslide.  From there, the soil, beneath the turf, slowly migrated downhill, rippling the turf like a buckled carpet.

In the shot above, you can see how the guardrail bows out a little from the pressure of the soil.  It also reaches the top of the guardrail, piling up to a height of around 30".  We've all seen evidence of the power of water lately (I was on a site in Vermont last week doing damage assessment -- I wish I could share those pics), but I thought I'd share this small example.

Stewartia ovata

This was an exciting new find for me at Kenilworth --  Stewartia ovata or mountain camellia.  As you may know, I looooove Stewartia pseudocamellia .  In fact, one of the only downfalls of that plant (to me) is that it is not native.

This species however is native to the southeast US mountains.  And while it's not as elegant as S. pseudocamellia -- the bark is not as lustrous -- I am desperate to plant this on an upcoming project.

You can see the flowers on the ground above and below -- it appears we were just a week away from seeing this at its peak.

The flowers are very similar to S. pseudocamellia, and both species are in the Theaceae family, which does indeed include Camellia itself.

Sadly, the plant seems to be somewhat rare -- a brief google search came up with a few native specialists that provide 1 gallon specimens, so I'll need to keep my eyes peeled for large specimens.

Cunninghamia lanceolata

I think anyone who has been teaching plants (horticulture or botany) for any length of time gets comfortable with telling students 'I don't know.'  It's bedeviling how many different species are out there and after a few years, you aren't too concerned with appearing as if you don't know *everything*.

 

That said, it is a thrill when you encounter some horticultural oddity in the landscape and you know right away what it is.  In this case, I instantly recognized it because on some cold winter in New York, I saw it at the Japanese Garden in the Brooklyn Botanic Garden (in fact, I met this plant the same day I encountered Wollemia, parachute plant and Asclepias physocarpa

Above you can see the iridescent suckers at the base of the trunk. Evidently these suckers can be harvested with ease.  The foliage is a bright light blue (this is probably a 'Glauca' cultivar) and is distinctive in that the leaves fall from the stem in two ranks, much like some species of Taxus.  In fact, this plant was classified in the Taxodiaceae family for some time, though is now considered a Cupressaceae plant.

 The spiney leaves are very sharp -- frankly I'm surprised this isn't in the Pinaceae family, related to Picea -- and when the leaves fall to the ground and dry they can become a fire hazard.

As the name implies, the plant is native to China and islands off the coast of China. There, the wood is frequently harvested for timber.