A Gardening Journal

Flowering of Free-Range Scots Elms

Since my recent post on my own glorious but oh-so-sparsely-flowering Scots elm, I chanced upon two other Scots elms. Both are growing free-range, and both were at heights of floral display so high and so heavy that to call them voluptuous was understatement: These trees' shows were rampant. 

 

First, the same cultivar as mine—Ulmus glabra 'Aurea'—growing free-range in the display gardens of this astonishing nursery on Long Island.

 

Ulmus glabra Aurea Landcraft overall 050617 640

 

Sited at the end of an allee of pollarded lindens and bounded by a chest-high hedge of yew, this natural-growth specimen of Ulmus glabra 'Aurea' is a triumph. That's a friend in the yellow slicker; the photograph doesn't show the chilly pelting rain. The lindens were weeks' more eager to leaf out than the elm, conveniently providing a dense green contrast to the frothy pale yellow of the elm's countless pale-green samaras. When the elm's bright gold leaves emerge, the contrast with the lindens will still be strong, but just of color, not texture: the elm leaves are also large, rounded, and pointed.

 

Were these lindens in leaf so early that their foliage also counterpointed the clusters of feathery red flowers that preceded the elm's samaras? Alas, it's unlikely I'll ever be able to travel down to Long Island early enough to check out the combination directly. Instead, I'll compare the timing of these two tree's spring performances via those of my garden's own lindens and that of this magnificent weeping elm a mile or two down the street.

 

Ulmus glabra Camperdownii overall 050917 640

 

Could this specimen of Ulmus glabra 'Camperdownii' be any more dramatic? Its domed canopy is perhaps twelve feet high and twenty-five feet wide. The tree's full skirt of samara clusters permits only glimpses of the muscular architecture of its stiffly cascading branches. Happily, a gap shows off the mighty trunk as seductively as a thigh-high slit in a dress would accentuate a woman's leg.

 

Ulmus glabra Camperdownii trunk 050917 640

 

But the difference with an old elm such as this one is that the "leg"—the trunk—is more massive than that of any elephant.

 

Ulmus glabra 'Camperdownii' is propagated by grafting the young cascading scion onto the trunk of our native elm species, Ulmus americana. The bark of Ulmus glabra is more scaly and cross-hatched, whereas that of Ulmus americana is vertically ridged and furrowed. In the picture below, you can see that Ulmus americana bark extends up the tree just a few feet before the bark (and the lowest of the contorted and ultimately weeping growth) of Ulmus glabra 'Camperdownii' begins.

 

Ulmus glabra Camperdownii overall cropped 050917 640

 

Often, a noticeable ring of protruding bark develops decade by decade where the trunk and the cascading canopy atop it were joined. This specimen is all the more impressive in that no such awkward point of transition is evident: The contorted, angled top growth of the Camperdown cultivar seems to have arisen smoothly from the upright trunk of the straight species below.

 

Decades ago, one nurseryman told me of the ultimate strategy to ensure that a Camperdown elm always maintained a "rimless" trunk: the Camperdown scion would be grafted almost directly onto rootstock of the understock. A single Camperdown stem is then retained, to be trained upward for years until it is high enough to allow it to branch into a natural cascade. If a graft scar ever did develop, it would be at ground level or even below.

 

The trunk of this Camperdown elm is unusually short: just four feet or so. (Camperdowns are more often grafted atop understock that is six to seven feet high.) Given that the Camperdown canopy is so strikingly dome-like, with all its branches eventually cascading nearly vertically downward, why not graft even higher? This would give opportunity for a longer cascade and, hence, an even more dramatic effect.

 

But even if a young Camperdown cascade were grafted atop that somewhat-higher trunk, its weeping branches would still be starting out just a single-digit number of feet above ground. How much does the height of the graft related to the overall height of the mature tree anyway? This old specimen Camperdown was grafted lower and, as in the picture below, the slender young tips of its branches are growing almost vertically downward.

 

Ulmus glabra Camperdownii branch tip 050917 640

 

And yet, even with these advantages of a severe cascade starting from a lower height—let alone several decades for growth—it's striking how rarely this specimen's branch tips have extended all the way down to the ground.

 

Ulmus glabra Camperdownii overall full height 050917 640

 

Only the branch at the left of the canopy as seen above (and in detail, below) has touched down.

 

Ulmus glabra Camperdownii branch tips at the ground 050917 640

 

These branch tips seem to be nosing along in search of yet more declivity to descend.

 

Ulmus glabra Camperdownii branch tip across the ground 050917 640

 

If allowed to remain for years, it's possible that they would root in, slowly transforming this weeping soloist into a weeping grove.

 

Here's one likely reason that so few stems of this tree manage to reach the ground despite the vigor of the growth, the verticality of the cascade, and a starting "jump off" point just a few feet high. Take another look at the shot of the entire tree, this time peering through the heavy display of pale-green samaras to the architecture of the tree's woody growth.

 

Ulmus glabra Camperdownii overall full height 050917 640

 

Some of that growth is among the tree's oldest: the trunk itself plus the various mighty limbs arising directly from it. Newer growth is much more slender; it's younger, remember. The habits of the older and younger growth are quite different. Those heavy limbs are contorted, and wander outward or even upward. It's their branches and young stems that form the tree's actual cascade.

 

Decades ago, when this tree was much younger, was the new growth exclusively upward or outwardly contorted and, only in maturity, did the newest growth emerging from those by-then old limbs form the cascade? No. Here's a youngster at a nursery in Holland. All of its growth is young, and nearly all of it is already cascading.

 

Ulmus glabra Camperdownii in holland 640

 

That "nearly" makes all the difference. Notice that a single twig to the right of the tree's training stake is not cascading. Its tip is even angling upward.

 

Here's a somewhat more mature Camperdown.

 

Ulmus glabra Camperdownii older in Van der Berk 640

 

While most of its branches are cascading, one has arched upward first.

 

Camperdown elms can live for generations, and one or two of its youngest stems are always likely to be exploring upward, even if just a bit. Each year, then, the top of the canopy rises another few inches; eventually, that height becomes significant. Although almost never grafted higher than six or seven feet—and, as with the specimen in the village down the road, sometimes much lower—mature Camperdown elms can range from fifteen to twenty-five feet high. With the understock's height seven feet at the max, that means that nearly twenty feet of potential additional height could be gained, inch by inch, as the occasional top twig grows upward for a season or so before putting out growth that cascades.

 

Look yet again at the mature specimen. The initial height provided by that understock is almost insignificant compared to the height that has accreted almost by stealth, decade by decade, as the occasional Camperdown twig had arched upward for a bit.

 

Ulmus glabra Camperdownii overall full height 050917 640

 

Now to this tree's unstinting mid-spring display. Earlier in the spring of 2018, I'll check on the tree regularly so that I can catch it in full flower. This apple-green show is those flowers' samaras, which are as showy as the display of any spring-flowering trees out now: crab apples, dogwoods, cherries, magnolias, and cornelian cherries.

 

It's normal that the farther from vertical that woody stems are, the more profusely they flower and fruit. (This is the original reason for espaliering fruit trees: to enable them to bear more heavily.) Stems that are weeping are even farther from vertical than the espaliered stems, which are horizontal at the lowest. Are the weeping stems the most floriferous and fruitful of all?

 

Lets compare the two forms of Ulmus glabra I just saw. The density of the display of samaras of the weeper, Ulmus glabra 'Camperdownii', is impressive, indeed. Is it more profuse than, say, the display of an Ulmus glabra whose habit is broad and upright? Here again is that free-range upright Scots elm, Ulmus glabra 'Aurea', which is the same gold-leaved cultivar as my pollard.

 

Ulmus glabra Aurea Landcraft overall 050617 640

 

Its display of samaras is also impressive, and I can't discern that it is any less dense or extensive than that of the Camperdown. At least with Ulmus glabra, then, flowering and "samaraing" seem profuse regardless of the orientation of the branches. This is very good to know, in that this year's floral and samara display of my pollarded Scots elm—whose stems are overwhelmingly upright—was barely a splatter compared to the tsunami produced by these free-range upright and weeping forms.

 

If I give some of the stems of my pollard more time, then, they are likely to perform as spectacularly.  Hooray!

 

 

Here's how to grow golden Scots elm.

 

Here's how lengthy and vigorous the first-year growth of a pollarded Scots elm is.

 

Here's how the canopy of this pollarded Scots elm looked in late February, giving no clue as to whether or not any stems were bearing flower buds. This post concludes with my strategy for becoming a "pollarding gradualist:" each season I prune some of the branches back to force a steady supply of young growth, even as I let selected other branches continue to grow and mature in hopes that, in a year or two, they will at last mature to flowering—and fruiting.

 

Here's a look at one of few branches of my pollarded Scots elm that produced flowers and samaras this spring.

 

 
 
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