Transatlantic Gardener

Shamrocks and four-leaf clovers

Just a quickie for St Patrick’s Day on the four-leaf version of the Shamrock. Got to be extra lucky, right?

The Irish Shamrock is usually what the rest of us call white clover, Trifolium repens, or sometimes lesser clover, T. dubium. But there’s at least one variety that always produces four leaves, and sometimes five.

Trifolium repens 'Purpurascens Quadrifolium' – a bit of a mouthful, I know -not only has almost all its leaves with four divisions, there are sometimes five. What’s more, they’re purple with a slender green rim (left, click to enlarge).  It’s very pretty.

But what about that clover in the top of the picture? That’s ‘Green Ice’, one of a number of attractive varieties that turned up by chance in a project designed to develop better varieties for forage.

These are both great foliage plants, but susceptible to attack from weevils which nip the edges of the leaves – and also attack garden peas.

But hey, seems like cheating, doesn’t it, to actually plant a four-leaf clover? Don’t you have to find them by chance for them to be lucky?

How to kill a Leyland hedge

Leyland cypress is a really useful hedging evergreen. It grows quickly, it’s a good color for a background to flowers, and it makes an effective screen and windbreak. The problem is that it keeps growing and growing and growing. Even on poor soil it can grow 3ft/90cm a year. The tallest is over 130ft/40m tall and still growing. And so, of course, it has to be trimmed regularly to keep it to a modest size.

With regular trimming you can keep it to very reasonable 6-8ft/1.8-2.4m high. But if you let it go for a few years, and then try to cut it back hard – this is what happens (above, click to enlarge). Not a pretty sight.

Why not plant an Arborvitae, Thuja occidentalis ‘Smaragd’ (sometimes known as ‘Emerald Green’), instead? It’s a good colour, less vigorous but not slow, and needs much less trimming to keep it to a manageable height.


Plant name note (deep breath, please): Leyland cypress was for many decades known botanically as xCupressocyparis leylandii – a hybrid between the Californian Cupressus macrocarpa and the Alaskan Chamaecyparis nootkatensis. The hybrid generic name combines of the generic names of the two parent plants, which helps grasp what’s going on. Ah, but then…

Ten years ago botanists decided that Chamaecyparis nootkatensis was so distinct from other species of Chamaecyparis that it needed a genus of its own, so it became Xanthocyparis nootkanensis. Then a few years later, after further botanical brain boiling, another generic name, Callitropsis, was proposed.

If that wasn’t confusing enough, whenever Chamaecyparis nootkatensis is put in a different genus the botanical name of the hybrid, Leyland cypress, must also change. So, if you think Chamaecyparis nootkatensis should really be Xanthocyparis nootkanensis then Leyland cypress becomes ×Cuprocyparis leylandii. But if you think Chamaecyparis nootkatensis should really be Callitropsis nootkatensis, then you probably also think Cupressus macrocarpa should be Callitropsis macrocarpa – which makes the Leyland cypress become Callitropsis x leylandii! Got that? Have I got that right (steam comes out of his ears)?

No no, hold the rotten tomatoes... it’s not my fault... It’s the rules!

Help with crab apples, please

I'm having some trouble with crab apples. Not that they've got some terrible disease or the voles are eating them as well as everything else, no.

I have some great pictures of their flowers that I'd like to use - but I don't know what varieties they are. I know some expert plantspeople check in here, so can anyone help?

The first one (left, click to enlarge) has distinctive bi-colored flowers which I thought I'd be able to find, but not so far - not even in Father John Fiala's monumental book Flowering Crabapples.

The second one (right, click to enlarge) we thought might be 'Golden Hornet' but the  flowers seem a little large, a little too blushed, and the foliage a little pale.

Finally, a very prolific one with darkish leaves (left below, click to enlarge) – not with purple foliage like 'Royalty' but with a purplish tint. It makes a neat rounded tree, with small purple-red fruits. 'Lemoinei' perhaps? It's not an old tree, so perhaps one of the more recent ones.

Crab apples are just not something I know a huge amount about. So any help will be gratefully appreciated.

Name changes - don't you just love 'em?!

OK, it's the subject you love to hate… Your familiar plants have their names changed. Well, here's more - as reported in the latest issue of the The Plantsman magazine.

First thing – don’t shoot the messenger. And it's not the fault of the botanists, either, they're just doing research and applying the rules to what they find. It's all the fault of Carl Linnaeus. It was the great man who came up with the system that connects the name of every plant with its classification, with its relationship with other plants. And the result is that when science advances and we reach a new understanding of how plants relate to each other, sometimes the names have to change. That's all there is to it.

Now, I'm not going to go into all the background of the latest modest changes – I'm just going to tell you what they are.

First, that lovely honey scented shrub Cytisus battandierii. We can all see that it doesn't look much like other species of Cytisus. Well, now it's been decided that it's so very different that it deserves a genus all of its own. It's now Argyrocytisus battandierii (left, click to enlarge).

The black "iris", Hermodactylus tuberosus – finally it's been decided that it's really so similar to irises that it's been placed irrevocably in Iris as Iris tuberosa. Belamcanda has moved into Iris as well.

And finally Schizostylis, invaluable late summer and fall flowering perennials for Britain and warmer zones in  the US. They've been moved into Hesperantha, so Schizostylis coccinea is now Hesperantha coccinea (right, click to enlarge).

Well, that wasn't so very bad was it? Or was it?

Brits don't grow New York's top roses

Once I've looked through each issue of The American Gardener, the excellent member magazine from the American Horticultural Society, it goes - let's be honest - into the bathroom. Where it's perused again, now and then, before finally going on the shelf.

The other day I was looking through the March/April edition when I came again on the list of the top-rated roses at the Peggy Rockefeller Rose Garden at the New York Botanical Garden (NYBG). Frankly, many of them I didn't know. Then I wondered: how many of these are well rated in Britain?

So I started to look them up. Top of the NYBG list is Brother's Grimm Fairy Tale (right, click to enlarge). It's not listed at all by the Royal Horticultural Society in Britain, a Google search turns up almost nothing. First thing – that rogue apostrophe. Its correct name does not have that apostrophe.

Turns out it has five, yes, five other names. All but one are selling names used in various countries – Brothers Grimm Fairy Tale is also sold as Eternal Flame (in Britain), Joli Tambour, Gremlin, and it was first sold in the USA as Gebrüder Grimm. And the one thing that ties them all together is the correct cultivar name, which is 'Korassenet'.

In roses, the cultivar name, in this case 'Korassenet', is often more like an originator's code name and in those cases the rose is never sold solely under that name. You may have noticed them all in my recent review of David Austin's new rose book.

But the international naming rules that govern these things state that the cultivar name must always be given with whatever selling name is being used, so no one ends up buying the same rose under two different names. Bad for the home gardener, but a disaster for a nursery which might buy 500 of each. Unfortunately, The American Gardener list did not include the cultivar name, neither does the NYBG's own list.

So… Once I'd discovered its true cultivar name, via the invaluable Help Me Find Roses website, I was able to look it up in Britain and found that there's only one British supplier and it has no awards. Not very encouraging.

I did the same with the rest of the top five. Next on the NYBG list was Caramel Fairy Tale ('Korkinteral') (left, click to enlarge), also known as Caramella and Reminiscence - no British suppliers. Third on the list was Cinderella Fairy Tale ('Korfolbalt') (right, click to enlarge), also known as Cinderella and La Giralda - no British suppliers. Fourth came 'Ducher', from way back in 1869 when muddling about with names was never even considered – no British suppliers. And fifth came Easter Basket ('Meiopoten') – no British suppliers.

So, not only did the five top roses at the Peggy Rockefeller Rose Garden at the NYBG not have any awards or recommendations but only one was actually on sale in Britain – and from just one nursery.

And the research would have been far simpler if the names had been given as the international rules say they should be.

How "unique" is this new perennial?

Unique, or not?

Yesterday I was looking over the new introductions from the international perennials grower Darwin Perennials (Darwin Plants in Europe) and I noticed the new actaea that I’d written up over on my RHS New Plants blog back in February - Actaea pachypoda ‘Misty Blue’ (above, click to enlarge).

They descibe it as thus:
“Cimicifuga pachypoda 'Misty Blue' Unique blue foliage, with white flowers in spring. In fall will make white berries on a little red stem. VERY Unique” (their CAPS)

It’s a lovely thing, but three points:

1.    Why do they call it Cimicifuga pachypoda ‘Misty Blue’? It’s true that a few years ago the two genera, Actaea and Cimicifuga were amalgamated – but under the name Actaea not under the name Cimicifuga. And this species was not placed in Cimicifuga even before the change, it’s always been an Actaea. So why confuse everyone by suddenly, out of the blue, calling it Cimicifuga - a name no longer valid? Aren't gardeners muddled enough by plant names?

2.    They describe it as "VERY unique" (their capitals) - which means it must be more unique than just, well, unique. So there must be other plants which are, perhaps, moderately unique or mainly unique or not very unique at all. No: it’s either unique, or it’s not unique. There’s either just the one, or there are more.

3.    In this case, as it happens, "not very unique at all" is more like it. There’s at least one other form of this species with that distinctive silvery/bluish foliage and it looks pretty much the same. Actaea pachypoda ‘Pewter and Pearls’ (above, click to enlarge) was selected by the British nurseryman Kevin Hughes and I spotted it at the 2009 Chelsea Flower Show. So ‘Misty Blue’ is, you might say, not "VERY unique" but only "slightly unique"! [The leaves are actually more similar in colour than my pictures suggest.]

I know, this might seem like pedantic and esoteric stuff. But we already have nurseries trumpeting as "new" plants which have been around for years. I'm just trying to keep them on their toes…

Either way, this/they is/are (a) lovely plants(s).

The Communist Lilacs

 
 Browsing through an old copy of The Gardener magazine – Tom Cooper’s superb but short-lived venture put out by White Flower Farm a few years ago – I came across a piece entitled The Communist Lilacs!

It was by Peter Schneider (author of Taylor's Guide to Roses ) and discussed the range of large-flowered, super fragrant lilacs raised in Russia in the middle of the last century. I’d forgotten all about them. They sound fantastic - especially the names.

Obviously they were all originally named in Russian – but in English they have names like ‘Beauty of Moscow’, ‘Banner of Lenin’, ‘Soviet Arctic Region’ and, from 1958, originally ‘Korok let Komsomola’ - splendidly translated as ‘40th Anniversary of the Communist Youth League’!

Now I often think that some of the names of modern hostas and daylilies are pretty extraordinary – Hosta ‘Outhouse Door’ and Hemerocallis ‘How Beautiful Heaven Must Be’, for example. But surely nothing beats Syringa vulgaris ‘40th Anniversary of the Communist Youth League’!

Image © Lottah Nursery, with thanks.

Parthenocissus ‘Fenway Park’ – the original plant

A couple of weeks ago I was telling you about ‘Fenway Park’, the lovely yellow leaved form of the Boston Ivy, Parthenocissus tricuspidata, and how it was found as a sport on a plant growing on a building near the Fenway Park stadium in Boston.

Well, regular Transatlantic Plantsman follower Ron Rabideau of Rare Find Nursery in Jackson, NJ has done us all a great favor by sending me a picture of the original plant, as first discovered on that old apartment block near the stadium. And here it is.

The picture was taken by Peter del Tredici, who first spotted the plant on the way to the ball game and made sure it was propagated. Unfortunately the plant is now gone.

Isn’t it great to see a fine new variety at the moment of discovery? Thank you Peter and thank you Rob (and Anne at Rare Find for telling me the picture even existed).

And you can check out the original post about Parthenocissus tricuspidata ‘Fenway Park’ here. In that post I mentioned Plant Delights nursery as a source - they’re now sold out.

But Parthenocissus tricuspidata ‘Fenway Park’ is available by mail order from Rare Find Nursery.

A colourful climber gets its name…

Plants are discovered, and come by their names, in some intriguing ways…

One day in 1988 Peter Del Tredici of the Arnold Arboretum in Boston Massachusetts was walking to a sports game. He was on his way to Fenway Park to watch the Boston Red Sox (For Brits: They’re a big baseball team. Baseball? You know about baseball? OK.).

The dramatic self-clinging climber Parthenocissus tricuspidata grows on so many buildings in Boston that it’s long been known as Boston Ivy. As he walked to the stadium he noticed that there was a yellow-leaved shoot on a plant climbing up an apartment building. He begged some material to propagate and so when the plant was introduced it was called Parthenocissus tricuspidata ‘Fenway Park’.

It’s an impressive plant. The leaves open bright yellow and in a sunny situation they retain their color. In shade, the leaves tend become a limey green color. In the autumn the leaves develop fiery red, orange and yellow tones.

It just takes a moment and a good eye to spot a great new plant - and to give it an appropriate name. Now if only we had a picture of the yellow shoot on the plant on the building...

Parthenocissus tricuspidata ‘Fenway Park’ is available from Plant Delights Nursery (though their story is slightly different.) In Britain it’s also available from these RHS Plant Finder nurseries.

Getting plant names right – and up to date

 We all want to use the correct botanical names for our plants, right? And we know that, as plant science evolves, names sometimes have to change. Well, the annual online update of correct plant names is now available – free to everyone – courtesy of the Royal Horticultural Society.

For British gardeners the RHS Plant Finder reveals which of over 600 nurseries stock each of 70,154 plants. But for gardeners around the world the RHS Plant Finder has wider value as the fount of all wisdom on correct plant names. Overseen and regularly updated by a team of horticultural botanists based in Britain but with connections around the world, the team and its associates look at the naming of plants at all levels.

So the Plant Finder will confirm that the correct name, accepted around the world, for the dreaded Japanese knotweed is not Polygonum cuspidatum nor Polygonum reynoutria nor Reynoutria japonica but is Fallopia japonica – which reflects its close botanical connection with the rampaging mile-a-minute vine, Fallopia baldschuanica. (Fallopia baldschuanica, by the way, is the correct name for what has been called Bilderdykia aubertii and half a dozen other names.)

This year, after much deliberation, the team has accepted the splitting from Dicentra of a number of species and elevating them into genera of their own. So the yellow-flowered climbing types are moved into Ichthyoselmis and Dactylicapnos and a favorite spring perennial, Dicentra spectabilis (left, click to enlarge) – in full flower now, frost permitting – has been elevated into the genus Lamprocapnos. They have not yet decided to accept the splitting of the American members of the genus Aster into many smaller genera.

But perhaps the most startling of this year’s changes is the transfer of Antirrhinum, Digitalis, Hebe and Penstemon to the plantain family (Plantaginaceae) – which most of us know as wind-pollinated weeds. They may look so clearly very different but the reason for this, and a number of other changes, is explained in a new essay written by RHS Chief Scientist Dr John David. Basically, it’s all down to the analysis of the plants’ genetic material (the genome). Verbascum and Phygelius, by the way, remain in their original family (Scrophulariaceae) where they are now joined by Buddleja.

The essay, although rather long and a little technical for the casual reader, is well worth reading for its overview of the changes at family level.

Name changes will continue. The one downside of the Linnaean system is that when we discover more about the way in which plants are related to each other, the names have to change. At least with the free online RHS Plant Finder we can easily find out what the correct names are.

And you can find out more about the changes in Dicentra in the excellent book from Timber Press called Bleeding Hearts, Corydalis, and Their Relatives. It's very welcome to finally have an opportunity to recommend this invaluable book.