A Touch of the Exotic: Persian Ironwood

Mid-November peak autumn color

I read about Persian Ironwood (Parrotia persica) in one of my gardening magazines about 12 years ago. I’m a sucker for trees and shrubs with exfoliating bark, and the description of the bark of this tree sounded like a worthy addition to my growing collection of special plants.

Native to Iran, this tree is a member of the Witch Hazel family (Hamamelidaceae), which means it blooms early and relatively inconspicuously, but it’s not the flowers that sell this plant.  In fact, I’ve never actually caught my tree in bloom; I’m not even sure it does bloom, although I think I’ve found dried-up remnants of flowers when the leaves begin emerging.

My tree is only now getting big enough for the bark to begin exfoliating. In his Manual of Woody Landscape Plants, Michael Dirr notes that branches must attain diameters between 4-8 inches before exfoliation commences. Luckily for me, this tree has another attribute that was immediately obvious during its first autumn in my landscape. See the photo at the top? That was taken this past November. This tree looks that fabulous every single autumn, and the leaves persist on the tree for almost a month. Like a glowing golden magnet, this tree in its autumn splendor draws praise from all who see it. Here’s a close-up of the leaves from last November:

Leafy sunshine

Dirr says this tree will mature to a height between 20-40 feet, so it’s a good fit for suburban Piedmont landscapes. And it seems to be pest and disease free. I always worry about a non-native plant’s potential to become invasive, but all reports seem to agree that this tree politely stays where it is planted. To see a photo of this species in bloom, try here.

As you can see in the top photo, the leaves create quite a dense cover during the growing season, so I must wait for every winter to admire the bark. I did so this morning. Here’s most of the tree:

Parrotia persica showing off its bark in winter

You’ll note that some leaves are still clinging to the tree. Botanists call this being tardily deciduous. Still, enough of the leaves fall so that branches can be admired. Here’s a closer shot:

Gray and silver mottled branches of Persian Ironwood

My apologies for the less-than-ideal photo. The morning light and my camera were not entirely cooperative. If you could see these branches a bit more closely, you’d notice that they are just beginning to show signs of exfoliation. I am hopeful that this will increase quickly now that the branch diameters seem to have attained the required size.

Many of the exfoliators in my landscape have reddish-brown bark — the Bald Cypresses, for example. Another non-native — Seven-Son Flower Tree — has almost pure white bark. The bark of Persian Ironwood reminds me a bit of the color of my American Beeches or my Ironwoods, but they don’t exfoliate. In my yard, this tree is near a Stewartia and a cluster of blueberries, both of which have reddish-brown exfoliating bark. The Persian Ironwood thus provides pleasing visual contrast in my winter landscape.

I have a feeling that if my tree does bloom, it’s likely to happen soon. This year, I’m going to make a special effort to watch for the flowers of this Persian beauty. If I succeed, I’ll be sure to let you know.

, ,

  1. #1 by Matthew Nenninger on February 17, 2012 - 1:00 am

    Great post on a really nice tree. I just ran across your blog in the Nature Blog Network’s newest blogs newsletter. Good stuff! We have at least two things in common – North Carolina and nature/garden blogging. I grew up in NC, and I just recently posted pics of my Persian Ironwood’s blooms on my blog – the Nature of Portland (Oregon). I didn’t know the bark was so interesting on these trees. Something to look forward to as mine matures!

    • #2 by piedmontgardener on February 17, 2012 - 6:45 am

      Welcome, Matthew! Yes, this is a special tree, isn’t it? I’m not surprised that a North Carolina gardener found his way to Oregon. I hear the gardening climate there is fantastic — as long as one can stand the many cloudy days.

  2. #3 by Jim Edwards on May 23, 2020 - 2:38 pm

    Our ironwood has been in our yard 3 years. It was 5 ft tall when we brought it home from nursery. Last year a late freeze here in Wheaton , IL, nipped the tender new ends. It came on out but seemed to be in neutral growth mode. It came out late this year and has never bloomed. What problem might it have?

    • #4 by piedmontgardener on May 23, 2020 - 5:24 pm

      Welcome, Jim! From your description, I would say your ironwood is doing alright. Have you ever heard the old gardeners’ expression “First year sleep, second year creep, third year leap”? It refers to the way transplants behave when we plant them. Growth the first year focuses on roots, so you don’t see much change above ground. In the second year, some above-ground growth is evident, but not much. Finally, in its third year, a healthy transplant will start to grow more significantly. Your reference to “neutral growth mode” makes me think this is what you’re dealing with. Plus, you planted quite a large tree, which means it likely needed a bit more time to establish a healthy root system.

      Next, this non-native species is hardy to zone 5, which means it likes colder climates. When I planted my tree (much smaller than yours at the beginning), I was in Zone 7b. Thanks to climate change, we are now Zone 8. I deliberately planted my Persian Ironwood on the coldest part of my yard, because I was trying to discourage early spring leaf growth before danger of frost/freeze is past in my area. If your tree is not planted on a north-facing part of your yard, the microclimate around it may be encouraging it to leaf out sooner than is ideal for it. Any tree is vulnerable to nipped tender new ends if that leaf growth stage correlates with a cold snap. I’ve experienced killed tender new growth on entire 70-foot tall native canopy trees when a late killing freeze hit one year. The trees recovered, but it took them 6 weeks to summon the energy to produce new leaves.

      My tree did not begin to bloom until I’d had it at least 15 years. It may have taken longer than that. And the flowers are so inconspicuous that they are easy to miss. This is not a tree planted for its flowers. Its beautiful autumn leaf color and magnificent bark are its top landscape assets.

      Thus, my advice to you is to cultivate a bit of patience. We plant trees, even smaller one, for the future. Time is your ally here.

      Good luck with your Persian Ironwood!

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: