So there I was earlier this week, on the way to see a client in Wellesley, MA, and I passed this huge colorful streetside show:

Trees with colorful flowers? Think about it: How many of them bloom early in the Spring? All those pink cherries. Those pink or yellow magnolias. Rosy-pink "redbuds"? Those lavender paulownias?


And then, the dogwoods come out, and so all the trees thereafter have white flowers only? Stewartia, catalpa, fringe tree, franklinia. Think about it: A tree that blooms later than May and doesn't have white flowers?


Only two, I think: Mimosa (pink blossoms, ugh) and the other one here on that Wellesley streetscape: Goldenrain tree.  Ugh, what a sticky-sweet name, and way too similar to yet another early-Spring yellow-flowered tree (Golden-chain tree, laburnum) plus a climbing rose (Golden Showers).


Let's flip over into the Latin:Kohlreuteria paniculata. Thank you, Mr. Kohlreuter whoever you were. "Paniculata" means that it has big panicles of flowers. Does it ever:

I had never gotten this close to the flowers before—get a load of my grimy man-of-the-earth fingernail!—so I was surprised to see the orange-red flare at the base of the petals.  The pollen is orange-red too—nice coordination!—and the petals are folded back to expose it completely.


Kohlreuterias in my experience are fool-proof as long as they're planted up a slope, even a tiny one.  They lose their confidence if surface water doesn't drain right away.
Sun and heat are welcome, and the trees are drought-proof too.   So tough they can be used as street trees.


We'll take another look at kohreuterias later in the season: As if these unique flowers weren't enough, they mature to colorful inflated pods by August.


In the Fall we'll confirm if the tree gets good Fall foliage.  The branching and bark are very satisfying in the Winter too.  A four-season tree then?  Very possible, and very essential anywhere (Zone 5 - 9) it's hardy.

The chrome-leaved Scotch elm is Number Ten of my favorite twenty plants: see the full line-up here.
I love this plant first and foremost because the hot-yellow leaves stay hot and yellow the entire Summer. No scorching, and (almost) no fading.
And also because the tree is so responsive to pollarding. Late in April, I cut all the branches that had grown up the Summer before...

... down to stubs.

Truly, an inch or less of I get the heavy stubs in the jaws of my loppers.

But did the elm falter, let alone fail? Not a chance: Six weeks later, the new branches are already over a foot long.

And there are several dozen of them too.
This is a tree of singular enthusiasm—or is it stubbornness? I massacre it annually, and it roars back, annually, with I'll-show-you intensity. These new growths will be eight or ten feet long by September, growing a yellow flame of foliage that's as dense as it is compact. (Unpruned, the elm could top eighty feet.) We're a good pair, my elm and me.

Foliage foliage foliage. Flowers are fun, but foliage is where the garden's sustained interest lives. Plus foliage can be fabulous in itself.
Wrede's elm has small bright-yellow leaves on vertical new stems. Perfect for a gray day as well as a sunny one. You can let the elm revel in its inner-elmness, to become a big soft-yellow shade tree. Here's the lovely one at Wave Hill.
Pull up a chair, indeed.
What a warm beauty the tree is.
If you have acres to fill, not just a garden, why not plant a grove of Wrede's? Plant each one thirty feet from any of the others in a loose grid. And then, a hundred feet away, plant a purple-leaved beech. Or (hey, this is why you have all that acreage, right?) plant three purple beeches in a triangle a hundred feet on a side. Make sure the trunk of any beech is no closer than seventy feet to the trunk of any elm: You don't want anyone's elbow into anyone's armpit fifty years down the road.
For the next century and more, your gold & burgundy arboreal show will be famous.
But if you're like me, gardening on "only" ad acre and a half, you can keep the Wrede's shrub-sized indefinitely, pruning back each Spring. The new growth is particularly yellow, as well as vertical.
Here's my youngster, only this Spring old enough and big enough for some training-wheel pruning.

Wow, what foliage!
Not a chestnut, not a sassafras. It's a .... well, what IS it?
Firmiana simplex, a Chinese species very popular as a street-tree in Japan, and naturalized here the South. So it must be plenty calm even when there's heat, pollution, heavy soil, and the occasional lifted dog-leg. I've kept one in a pot for years for Summer display in Rhode Island. Here it was, a star of the shot in a Summer feature in Design New England. Click twice to see the photo full-size.

But here's a firmiana enjoying the cool life, right in the ground, in the East Village: Tompkins Square Park.
The green bark on young branches and even trunks is unique in sort-of-hardy trees.
The good news is that the tree is definitely and firmly Zone 7, which means NYC out to Long Island, plus the Cape and Islands and Southeastern Rhode Island. (Googling, I see it's also happy in the Missouri Botanic Garden. St. Louis is Zone 7? St. Louis is Zone 7! Who knew?)
I'll trial it in future Zone 7 projects. Hooray! But the downside of being Zone 7 is that Southwest Rhode Island isn't in it: The eastern tip of the North and South forks of Long Island keep the Gulf Stream at bay, alas. So my firmiana will stay in a pot, and hunker down, dormant and happy, in the basement all Winter. But a big potted firmiana—in Rhode Island, no less—is it's own statement. (And no, not because I let the tree grow bigger and bigger, with a huger and huger pot.) Why? Let's mozey back to those Japanese street scenes. (Oh I hope I have a picture from our Kyoto trip. I know this weekend!)
The trees are pruned back severely—you'd think that the entire city horticulture department had been taken over by the French.
And the trees were clearly handling the pruning well, too, in addition to all the other hard work of being alive in a hole in a sidewalk.
And so: being alive in a pot of Rhode Island dirt not that much smaller than the soil pocket for an entire street tree? Possible, very possible. And it's the pruning that makes it possible: As it limits the above-ground size of the tree, the below-ground part, the roots, are limited naturally.
It would be a thrill if the pruning also resulted in luxuriantly extra-large foliage, like it does when paulownia trees are pruned. To have these leaves twice and thrice as big as they are already?
That would be a performance indeed.

An enormous paulownia tree in full bloom is an astounding thing. Click on the photo twice to see it in all its huge full-size glory.
And to see the show in action, click the One-Minute Max here. The foot-high flower clusters point skyward, each with a score and more of two-inch lavender trumpets.
When the flowers fall to the ground, they keep their interest. This cardinal was scoping out the scene as long as I was, hopping back and forth, from the fallen flowers to nearby shrubs and then right back to the blossoms.
This bird is a florist of a sort. Who knew?

 First, the trees get a disease that screws up their famously dense and columnar habit. In the Northeast, those poplars are scraggly and patchy, with dense twiggy areas as well as bare ones. A mess.

And then there are the famously water-hungry roots. Like (some) willows, poplars are one of the few trees that actually do "invade pipes" and clog up septic systems, wells, irrigation systems. If you need to see happy poplars, go up to Quebec, where, I'm guessing, the patchy-scraggly disease isn't hardy. (Or maybe because so few other trees are hardy up there, they grow it out of desperation.) 

For gardens South of the (Canadian) Border, poplars should be cut down, never planted. Except for this one:

Gold foliage. Gold! And that stays gold all season. The backs of the leaves are pure white too, so in a breeze the tree shimmers. 

For some reason, this poplar doesn't get the patchy-scraggly thing either.   It might still have the water-hungry roots, but mine is a good sixty feet from any well or septic system, so I say to its roots, "Truffle away!" 

Plus—so atypical for a poplar, which are normally so fast-growing they are trumpeted in those "Gets Thirty Feet Tall In Three Years" ads we all used to see in the Sunday Supplement—the gold-leaved poplars are amazingly slow-growing. Mine is eight years old, by which time a Sunday Supplement popular would be sixty feet tall.

Like many trees and shrubs with interesting foliage, gold-leaved poplars welcome severe Spring pruning (that is, after they get big enough to have anything to prune). I'm not quite ready to pollarding mine. All I've done is to clipping off the branches from the trunk below, so the tree gets the idea that it is in fact a tree, with a "clear" trunk. Even so, the poplar is already like a still photo of a gold explosion.

Gold explosion: I like that in a garden.

PS: The patchy-scraggly poplar is native to the Mediterranean.  So maybe it doesn't like the rain and humidity of the Northeast. The gold-leaved poplar is native to Canada:  it's the fancy cousin of all those happy poplars up in Quebec.  So maybe it grows so slowly here in New England because it doesn't like our sweltering Summers and (comparatively, mind you) namby-pamby Winters.

Whatever: it's a blessing to have a poplar whose roots doesn't have designs on the entire neighborhood, and whose foliage is such a shimmer from May through October.

Being flushed with color is, at least in my garden, the real intrigue of Spring. Flowers? We know about flowers. Children know about flowers; I too was stunned at a red tulip when I was three.

But foliage? That's for adults. And foliage that is flushed?  For sophisticated adults, like all of us dabbling in Dirt.
Here's my very-young Chinese chestnut. It's still a yard-high stick, gawky and scrawny. But even with just (let me count) twenty-four leaflets to its entire "canopy", the promise of major excitement is confirmed. Yes, it's clearly chestnut foliage, but in Spring these chestnut leaves are a beefy red instead of the usual native-American green.  And they shoot up from exploded-back deep-pink leaf scales.

Whooee this is a display of my-way-or-the-highway confidence.  No lambs and chicks here; this is Spring as a slap, not as some fluff.