Elaeagnus pungens

Last week, I gave my students a tour of Dumbarton Oaks, so we could catch the last of autumn color and see what was otherwise notable in the gardens. We were passing the shrub below with little interest until we were almost knocked over by the fragrance.

The fragrance was a touch more pungent than a gardenia, and incredibly strong.  I recognized the smell right away as an Elaeagnus.  This particular species is appropriately named Elaeagnus pungens. It's a large spreading evergreen shrub with rough scratchy green leaves and brown stems (the stems are worth noting since - as you can see in the above pic - it does muddy up the overall color of the plant).  The undersides of the leaves are silver with the occasional brown scale.

This time of year the plant is teeming with small tubular white flowers - the source of the fragrance.  The flowers are very easy to miss, were it not for their scent (and on an evolutionary angle, that makes sense - the fragrance is key in drawing in pollinators when the flowers are relatively unremarkable).

In April, cherry like drupes occur on the plant in modest quantities - they are easy to miss, though the birds usually find them.  Native to Japan, this plant is not as invasive as its cousins, E. umellata and E. angustifolia.

Yellow Flags

I'm sort of teasing readers this week -- I made a mention of visiting Meridian Hill Park and have yet to share photos yet.  I haven't had a chance to really read up on the history of the park, but hope to have a post for that by Friday.

 

In the meantime, here's a glimpse of the water feature that is the key part of the park's design and, flanking the goblin's face, Iris pseudacorus or yellow flag iris.  Below, note how short the standards (upright petals) are, compared to the falls (the lower petals).

Yellow flags are European plants and are quite invasive in the United States -- they are very tough plants and are even used for treatment of sewage and for removing heavy metals from contaminated sites.  That said, in a site like this, it's a shame a native aquatic iris, such as Iris versicolor (purple flag iris) couldn't have been used.

Vinca minor

These pics were also taken during the run I mentioned in yesterday's post.  I had passed by this modest little stand of Vinca minor several times already and kept putting off getting a few pictures of it.  Honestly, I thought I'd encounter a better use of this common groundcover...but why put off til tomorrow what you can do today?

As I mentioned, this plant is often used as a groundcover, actually, I think it's only used as a groundcover.  And as far as groundcovers go, I rank this high above Pachysandra or Hedera helix.  The flowers are pretty in the spring, much more attractive than Pachysandra and it's not likely to take over your landscape (and buildings) the way English ivy would. 

 

That said, it is noted by some as invasive, though I've personally discovered its relative, Vinca major 'Variegata' to be far worse.  My folks put some in planters in their backyard once and in the fall, dumped the soil, which contained a few of the variegated vines.  They overwintered and began to colonize the backyard.  We're steadily removing them now.  

Vinca is in the Apocyanaceae or dogbane family.  The flowers are fairly distinctive among this family which includes Plumbago auriculata and Alyxia ruscifolia.

Ruellia angustifolia

The plant below is Ruellia angustifolia, or Mexican petunia.  It's also known as R. brittoniana.  As you may guess, it's not related to the bedding plant Petunia at all, it just has similar tubular flowers.  

Ruellia is an upright, stalk-forming perennial that grows in almost any condition, in areas of the tropics, as far north as Texas and Florida.   Its hardiness accounts for why this is considered a top-ranking invasive in Florida. 

Bauhinia purpurea

Yesterday, we had temperatures in DC reaching 59° yesterday, which was downright heavenly.  I took some time away from work to go for a run along the mall, eying all the trees' buds, which are slowly fattening up to burst this spring.  Today, we're back to colder temperatures, so I've decided to commit this week to more tropicals and live in denial. 

This was a specimen I shot in March 2009 in San Juan, Puerto Rico.  I don't know how I failed to post about it at NYPAOS, but I didn't so I'm happily introducing it now: Bauhinia purpurea, AKA Hong Kong orchid tree, Hawaiian orchid tree or purple camel's foot. 

That last common name should be evident when considering the assymmetrical bilobed leaves which look similar enough to the footprints of a camel.

The flower, as the other common names suggest, is orchid-like, with long slender petals and showy, spurred stamens. Of course, the other huge clue to identify this plant appears in the photos above and below and that's the long, flattened fruits which clue us in that we're looking at a member of the Leguminosae family.

Bauhinia is a popular ornamental tree int he tropics and it native to Southeast Asia.  In the states, it's prevalent in Texas, Florida, Hawaii and Puerto Rico.  There's some debate about its invasive quality --the plant sets very successful seedlings which can be a management problem. 

Phragmites australis

I have been spending a lot of time traveling between DC and Philly lately and finally decided to take some very quick snapshots of the Phragmites australis stands I pass when driving through Delaware.  If you have even a passing knowledge of landscape design or horticulture, chances are you know this noxious weed.  

 

The story goes that Phragmites was brought to this continent in the early 20th Century in the form of packing material.  But, what may have been an innocent, reed-like plant in Europe has been destructive to many wetlands here in the United States.  Phragmites is tenacious, growing in wetlands with as much as 3' of water, to areas where the soil is merely damp.  Runners can travel as much as 15' in one growing season.  It's an incredibly common plant along highways -- the drainage ditches along the sides of 95, from Maryland straight up to the Meadowlands in New Jersey, are densely populated with this species. 

 

The plant is also halophytic, which means it tolerates some alkalinity in the soil (which means it can handle growing amongst crushed concrete and other demolition debris) and it also grows well in brackish water, so it's often seen in tidal estuaries, competing with our native salt marsh plant, Spartina. 

For a long time, it was assumed that Phragmites was only an invasive, exotic species, however recent research has indicated that there is also a native species of Phragmites (P. australis subspecies americanus).  This plant is evidently less virulent but physically only distinguishable as separate due to its shorter ligules.

Invasive Insects in the News

I feel like I decided to leave New York City just in time to avoid the near-panic about bedbugs that's taken place in the past six months or so.  There's no doubt that bed bugs (or more locally, stink bugs) have dominated the press lately, as far as articles about insects go.

That's why I was pleased to see an article in the Post today about the invasive insects that don't threaten our bedrooms, but instead, our local forests and greenswards.  The article briefly reviews the recent attention paid to combating the Asian longhorn beetle (or ALB in industry shorthand), the emerald ash borer and the Asian gypsy moth. 

New York has been vigilant in keeping the ALB at bay.  They have developed "wanted" posters that are frequently seen at the subway stations and provided more information elsewhere. (Check out infographic's breakdown of one such poster -- the information is a very comprehensive but condensed description of the ALB threat.) My favorite anti-ALB propaganda is a card that mimics a metrocard and has an ALB identification checklist on it, with a scaled shothole you can use to inspect the trunks of your local trees for boring damage.  Chicago has also been a leader in educating the public about these insects and protecting their trees and even has it's own (anti) EAB blog. 

At NYPAOS, I blogged about the intricacies in forming an only-native plants stance or not.  One reason people advocate using only native plants is that foreign plant materials can bring foreign pests or diseases.   But with the pests mentioned above, they have stowed away on pallets and other ornamental stock and are not a by-product of the ornamental use of exotic species.  Unfortunately, our global economy dictates that materials are shipped from one end of the planet to the other, and there are (ahem, sorry for this) inherent bugs in the system.  What's most important to me is not selecting native plants but instead, advocating for municipalities and state and federal government to strengthen its surveillance of shipments and be prepared to respond as quickly and comprehensively as possible when an threatening pest is detected.  

Sycamore Maple and Incestuous Nomenclature

First of all, apologies.  It's already after 5 on a Tuesday and I've yet to update this site.  I'm in New York until tomorrow and have been a bit overrun with meetings and catching up with some good friends.  But I still managed to get in a run in Central Park yesterday and today.  

 

I stopped to take these shots of sycamore maple, or Acer pseudoplatanus, since we've been covering trees with fall color quite a bit lately and this tree is probably at its peak. As you can see, while the leaves are not as fiery as its cousin, Acer saccharum, they are a fairly clear, bright yellow.  The leaves are also serrated, unlike sugar maple, Norway maple, or even hedge maple.  Acer rubrum, or red maple, also has serrated leaves, as do other species in the genus, but I've yet to post on them.  But, if you're familiar with red maple leaves, you may notice that the leaf below is a broader shape, with five distinct lobes, whereas A. rubrum often has trident-like leaves.  The lobes on sycamore maple also are a touch fatter or wider at the mid-point; red maple lobes consistently taper in size and are widest near the middle of the leaf, narrowing to the points.  Finally, and perhaps obviously, red maple leaves this time of year are usually, well, red.

Sycamore maple is called thus because the bark has a thick, scaly bark similar to sycamore (Platanus occidentalis).  And here's a good example where nomenclature can get a touch confusing:

London plane tree is Platanus x. acerifolia and the species name is indicating the leaves look like Acer, or maple.

Norway maple is called Acer platanoides because the leaves look like london plane tree, or Platanus x. acerifolia.

Sycamore maple is called Acer pseudoplatanus because the bark (below) looks like sycamore (and probably because platanoides was already taken!).

The whole thing gets a bit cyclical, like a flawed math formula, doesn't it?

The tree is not native and while it is not as outrageously invasive as Norway maple, it can conquer over natives due to its high tolerance to salt, drought and wind.  It's just that resilience which lead to the plant being brought here from Europe and Southwest Asia, sometime in the late 19th century.

Mahonia, again

Last week, I blogged about Berberis haematocarpa and it's resemblance to Mahonia.    I illustrated this by posting some photos of Oregon grapeholly, or M. aquifolium, but another common Mahonia species is M. bealei or the leatherleaf mahonia.  Here's a shot of one growing in northern Virginia.

 

Leatherleaf mahonia has, as the common name implies, thicker, larger leaves with sharp spines.  It's stiffer plant than M. aquifolium though is also far hardier. You're more likely to encounter this performing well in zone 6, which makes sense when one considers this species is native to China. 

 You can see the small yellow flower buds have already taken shape on this plant.  Mahonia bealei does bloom much sooner than M. aquifolium, and will display yellow, slightly fragrant flowers as soon as January.  After they bloom, the plant sets large blue berries which tend to languish on the plant, since its non-native status means local wildlife generally avoid the fruit.  (Read: deer-resistant.)

Though it's tempting to use a broadleaved evergreen - especially one that deer avoid and has showy flowers and fruit - I'd pass on Mahonia bealei.  The plant is invasive and threatens to become a management problem in forests where it's begun to appear. 

Berberis and Mahonia

Here's a shot of the desert scrub outside of Sedona, taken during the jeep tour I mentioned in previous posts.  Exploring the desert plants growing here was a delight -- some were familiar, like the prickly pear and mesquite, some were new, like pinyon pine.  Other plants straddled between the two categories - they were vaguely familiar and in some cases I was able to make a guess at their genus or family.

This scrubby plant below was one such specimen.  The pinnately compound, waxy leaves reminded me immediately of Mahonia and when I returned to the East Coast, my bag a bit heavier due to a load of plant books I had bought, I started researching.

Indeed, the plant is in the same family as Mahonia but is actually Berberis haematocarpa, or red barberry.  Both genera exist in the Berberidaceae family, though the leaf reminded me far more of Mahonia.  One supposes that the structure of the small yellow flowers, which bloom from February until April, are genetically more similar to Berberis and that is why they are grouped as such.

 

After the plant flowers, small purple berries form and are evidently quite tasty.  They are quickly eaten by birds and small mammals but if leftovers exist they are often used to make jellies.  The plant has never been 'domesticated' however, because it is a secondary host for black stem rust, a disease that affects grains. 

Back on the East Coast, in Central Park Zoo, we have the more refined looking Mahonia, possibly M. x media or M. aquifolium.  Commonly called Oregon grapeholly, the plant (the straight species, that is, not the hybrid) was discovered by Louis Lewis* and Clark during their expedition of the Pacific Northwest.  The plant is similar to the red barberry, not only in leaf type but in flower color and fruit as well.  However, the fruit on Oregon grapeholly, as the common name would suggest, are larger and look like concord grapes.
 

It is puzzling why the Arizonan plant is classified as Berberis considering how much more it looks like Mahonia.  Chances are you are familiar with other species of Berberis: B. thunbergii and B. julianae, though I would be hard-pressed to endorse the use of either; the former being invasive and the latter being prohibitively thorny.  

*Oof.  How embarrassing.  

Clematis paniculata

I have a fond spot in my heart for Clematis paniculata, or sweet autumn clematis, since it was one of the very first plants I learned in my ornamental plants class at Virginia Tech, way back in 1993.  

It's a lovely fall-blooming perennial vine, which is somewhat unnoticeable until this time of year. 

Below, it is growing near the boardwalk in Southern New Jersey. 

 

I have blogged about Clematis before, though those species were crosses of Clematis x jackmanii.   As you can see the flowers below are far different.  They are smaller, with strappier petals and only occur in shades of white. 

 

There's some debate as to whether this plant is invasive or not (some simply call it "vigorous").  I haven't seen this invade woodlands or pop up along highways but inevitably I will start to see that now that I've posted this.  What about you?  Any chance you've seen this plant where it shouldn't be?