Natives (American)

New ways with phlox

PhloxEarlibeautyZenithDaughterofPearl
The tall and colorful American native summer phlox, Phlox paniculata, has been popular for more than a hundred years. In 1917 five hundred and eighty four (yes, 584) different varieties were grown in the USA and in 1907 one Scottish nursery alone listed well over three hundred varieties. In Britain, the Royal Horticultural Society currently has a grand total of 577 in its database.

Most of these have now vanished, but there are a number of impressive breeding programmes, many using other species in addition to P. paniculata, going on in both North America and in Europe. Hans Hansen at Walters Gardens in Michigan, with his Opening Act and Fashionably Early series, and Charles Oliver at The Primrose Path in Pennsylvania, with his Earlibeauty Series (above), are leading the way along with Gosen Bartels in The Netherlands with his Flame Series.

But some of the best known varieties of the summer phlox have arisen in another way – they’ve been spotted in the wild or in abandoned gardens by plants people with a good eye, and an appreciation of something special.

I’ve mentioned these in my article about phlox in the current issue of The American Gardener but space was tight so I thought you’d be interested in a little more detail. These were all chosen for their freedom from mildew, but it’s important to remember that mildew resistance is not constant. I’ve seen ‘David’, and ‘David’s Lavender’, completely ruined by mildew.

‘Common Purple’ Found in 1982 by Marc Richardson and Richard Berry, founders of Goodness Grows Nursery, at an old abandoned homesite in Greene County, Georgia. The plant was in full bloom, with no sign of disease or problems. It was introduced by Goodness Grows in 1984.

PhloxSpeedLimit45‘David’ Selected at the Brandywine Conservancy, Chadds Ford, PAennsylvania by nurseryman Richard Simon and the Conservancy’s Horticulture Coordinator Mrs. F. M. Mooberry for its unusually large white flower heads and freedom from mildew. ‘David’s Lavender’ is a sport discovered in 2002 by Kathryn Litton at ItSaul Plants, Georgia.

‘Jeana’ Found in the 1990s by Jeana Prewitt of Nashville, Tennessee, growing mildew-free among "many thousands" of mildew-covered wild plants. Introduced in 2001 by the much missed Seneca Hill Perennials.

‘Speed Limit 45’ Spotted by Pierre Brunnerup, in the company of Allen Bush, by the sign on the roadside near Bush’s nursery in North Carolina and seen to be mildew free. Propagated by Bush and introduced in 2003.

These are exciting time for phlox enthusiasts, with so many new introductions. Those such as the Earlibeauty Series, with no P. paniculata in their background, seem best placed to remain mildew-resistant in the long term.

* Thank you to Charles Oliver and Allen Bush for the pictures.


Roadside orchids

Pyramidal orchids (Anacamptis pyramidalis) growing on an English roadside ©Plantlife
A few days ago, friends here In Northamptonshire reported on some orchids they'd found. They were growing in the grass on a roadside along a very quiet country lane. They thought there were about forty early purple orchids (Orchis mascula), so I went up to take a look.

Sure enough, there they were (below) – about sixty five of them as it turned out - scattered through the long grass, their vivid colours standing out from quite a distance. They were all together, none for miles on either side. Lovely.

Early purple orchids (Orchis mascula) growing on a Northamptoinshire roadside.And it so happened that this find coincided with the a new burst of publicity for the campaign by Plantlife, the British plant conservation charity, aimed at protecting the plants growing on Britain’s roadsides. [Their website helps Brits ask your local council to protect roadside plants.]

Just a mile or two away plants of the bold tawny spikes of the uncommon parasitic plant, the knapweed broomrape (Orobanche elatior) grow on their only host, the greater knapweed (Centaurea scabiosa), along another quiet lane along with literally miles of meadow cranesbill (Geranium pratense)

Close to home over in Pennsylvania, I’ve noticed that roadsides are often the only local location for a number of interesting plants. The only clumps of false Solomon's seal (Maianthemum racemosum) (below) that I’ve seen nearby are on roadsides and I’ve also noticed more may apple (Podophyllum peltatum) and Dutchman's breeches (Dicentra cucullaria) along roadsides than anywhere else.

Partly, I presume, this is because the deer tempted to eat roadside plants are more likely to be killed by traffic and so the plants are more likely to flourish.

The key factor, of course, is mowing. Just a few hundred yards from those early purple orchids the roadside grass has been shaved like a suburban lawn. Why?! Once a year is ideal, unless the mower turns up at flowering time; mowing too early can prevent flowering and seeding and debilitate the plants. In many areas of Britain, local councils are saving money by mowing less and in some areas special marker posts are used to warn the mowers off.

And then, today, the Journal of the Hardy Orchid Society arrives and there’s an article about a stretch of roadside in Essex, east of London, which is packed with orchids. Along a busy, relatively recently constructed road, there are 350 bee orchids (Ophrys apifera) and 250 pyramidal orchids (Anacamptis pyramidalis) - a dramatic increase from 50 bee orchids and 60 pyramidal orchids six years ago. Much of this increase is down to reduced mowing brought on by budget cuts.

So, when you’re stopped in traffic, look out of the window and see what you can see. When you’re a passenger, keep your eyes peeled. But please, when you’re driving, keep your eyes on the road!

  False Solomon's seal (Maianthemum racemosum) growing on a Pennsylvania roadside=


Graham’s Transatlantic Guide to Weeding

CalystegiaSepium700I’ve been doing some weeding. This is in our British garden where the weeds are always jumping at this time of year, especially when it’s been so wet and it’s been unwise to get on the soil.

I’ve also been having a clear out, bringing files and folders out from the back of the file cabinets and what did I find? My weed collection, three fat folders of pressed plants, that I made when I was a student at the Royal Botanic Gardens at Kew in London almost forty years ago (below right, click to enlarge).

And the first pressed plant I found in the first folder I opened was the same plant I’d just been pulling out of the garden: hairy bitter cress (Cardamine hirsuta). We have a close relative, Pennsylvania bitter cress (Cardamine pennsylvanica) in our American garden.

And this brings me to my first rule of weeding: our top weeding priority should always be to pull out are the weeds that are in flower or developing seeds. Hairy bitter cress rarely grows more then 10in/25cm high but can still can produce 700 seeds and fling them 31in/80cm, but it can also produce seeds when just two inches (5cm) high. So pull it out. Now.

Many of the traditional rules of gardening have little value but “One year’s seeding makes ten years weeding” really is true. Dandelions (below), which as annoying in Pennsylvania as they are in Northamptonshire, can produce over two hundred seeds in one seed head. So - obviously - don’t let them seed.

My second rule of weeding is always to shake the soil off the roots after you pull out the weeds and before they go on the CardaminePressedcompost heap or (in those cities with green waste recycling) in the green waste bin. You can ship out a huge amount of good soil if you’re not careful.

And my third rule of weeding is this: get them when they’re young. When nasty perennial weeds like bindweed come through at this time of year, a one inch shoot is often an indicator of yards of root underneath. Later, when their twirling stems become entwined with our garden plants, it’s all but impossible to remove them. It’s so much easier when they’re just an inch high and, at this time of year, if you disturb the plants you’re trying to protect when extracting bindweed roots they’ll soon settle down again. By the time the bindweed is strangling your cistus (top) it’s far far FAR too late.

My final rule is this: Don't spend half a day weeding and then the rest of the week nursing your aching back. I did half an hour this morning and half an hour this afternoon and I’ll try to keep that up. But if I’d spent two hours forking out weeds at a single stretch this morning (as I was tempted to do) I’d not be able to get out there again tomorrow or the next day or the rest of the week. Little and often…

OK, it's time to get back to the bindweed and dandelions and the dreaded hairy bitter cress.

TaraxacumOfficinale700


Sycamore? Or sycamore?

American sycamore, Platanus occidentalis, growing on the New York side of the Delaware River. ©GardenPhotos.com

Gardeners and botanists both use common names as well as scientific names when referring to plants. Using common names for plants is more widespread in North America than it is in Britain, even among botanists, and even though common names are often simply made up if there doesn’t seem to be one already in use. But common names are confusing. After all, there are more than twenty different plants, from around the world, that are called “bluebells”.

Native Americans must have had local names for many native plants when settlers first arrived in North America but the settlers didn’t bother to learn them and simply made up new ones - or, as with birds like the robin, transferred a familiar common name to a plant that looked vaguely similar to one from back home.

So when I saw a large mature sycamore (above) way across the Delaware River the other day, its white branches ghosting against the oaks and maples behind, I was reminded of this: in Europe, sycamore is used for Acer pseudoplatanus; here in North America sycamore is Platanus occidentalis. The leaves are very similar, so I presume settlers simply transferred the name. But surely, native Americans must have had a common name for P. occidentalis. After all, I’m told they used to tap it for sap in the same way as sugar maples.

In Europe, P. occidentalis is the plane tree and its hybrid with P. orientalis is a familiar city street tree. In Paris, large plane trees in the streets are pruned – literally – into a plane with all the branches parallel to the street and none overhanging.

The sycamore of Europe, Acer pseudoplatanus (below) - whose botanical name, by the way, literally translates as “the maple that looks like a plane tree”! - is a menace. There’s a huge one in our neighbor’s garden in England and its seedlings spring up all over the place. What’s worse is that they get their new roots down deep quickly so that even when they’re less than a foot high they can be tough to extract, especially between the cracks in paving.

I’d much rather have the American version.

European sysamore, Acer pseudoplatanus, growing at Parc de Mariemont in Belgium © Jean-Pol Grandmont. Licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.
Acer speudoplatanus image (above)  © Jean-Pol Grandmont. Licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.


The day our echinaceas died

Echinacea 'Flame Thrower' © Terra Nova Nurseries
The day the echinaceas died... It was yesterday. And this is how it happened.

Echinaceas, coneflowers, and especially all the fancy hybrids that have come on the market recently, like ‘Flame Thrower’ (above) and all the doubles (below), hate bad drainage in winter. That’s what kills them. But yesterday that’s exactly what they got.

On Sunday night the temperature in our garden here in Pennsylvania went down to -10F (-23C). So, after a temperature almost as low the night before, and low temperatures for a few days before that, the ground was frozen solid to a depth it was hard to assess.

And then it snowed. Not a lot, just a couple of inches and the whole garden looked lovely. But then, yesterday, Monday, it got warmer. A whole lot warmer, and quickly. By early afternoon the temperature had risen to 48F (9C), and the snow had melted and the top inch or two of soil had thawed out as well.

But because the soil was frozen down deep, all the melted snow just sat there on the surface, in puddles – it could not drain away because the soil underneath it was frozen. Our borders were covered in pools of water, yesterday, and they’re still there this morning.

And in those puddles of thawed snow are the crowns of our last remaining echinaceas (this has happened before...) – and echinaceas hate bad drainage. So those last few may well die.

Of course, this is not a phenomenon that comes into play in Britain all that much, or in parts of the USA where the winters bring less ferocious frosts. Because if the soil is not so solidly frozen, melted snow drains away and impacts much less on our, rather sensitive, echinaceas.

But here's what's important: it reminds us that, wherever we garden, it’s bad drainage in winter that prevents us enjoying the vast range of exciting new echinaceas for years and years after we first planted them. Which is a shame, because they really are gorgeous. As you can see.

Double echinaceas from Marco van Noort. ©Luc Klinkhamer


Transatlantic touch-me-not

ImpatienscapensisCloseIt’s always intriguing to find a plant that’s native near our American home in Pennsylvania growing near our English base in Northamptonshire (and vice versa) and the other day a stroll by the River Nene not far from our Northamptonshire house provided an enjoyable surprise. Spotted touch-me-not or jewelweed, Impatiens capensis, was growing on the bank (below, click to enlarge).

There were only a few patches, all grouped near each other, and I wondered for a moment if I myself had inadvertently introduced it on my shoes as perhaps I did in Pennsylvania when it suddenly it turned up in our garden. I walk this same stretch of river every time I’m back in England.

Mike Grant, editor of the Royal Horticultural Society magazine The Plantsman, pointed out in a comment on my piece about this plant turning up in the garden that “it has the distinction of first being recorded in the wild by the philosopher, John Stuart Mill Impatienscapensis(in Surrey in 1822)” and it is now well established in Britain, though mostly a little farther south and west from where I came across it.

In fact, we’d been thinking that perhaps we have the wrong native Impatiens in our Pennsylvania garden. Touch-me-not, Impatiens pallida, is bright yellow instead of red-speckled orange and would show up more effectively from a distance. Tomorrow I’m going to collect some seed from the plants that I’ve seen a few miles from our PA home. In which case look out for it in Northamptonshire a few years from now!

Thoughts on another non-native Impatiens species next time.


Sundews on the shore

Droserarotundifolia_G024808
We’ve been here at the house on the lake for thirteen and a half years, and it took my five year old grandson to find an insectivorous plant that we didn’t know we had.

Monty is mad about insects – and so, by association, insectivorous plants. He has pitcher plants growing in their kitchen in the London suburbs. So when he was exploring along the banks of our lake with his dad Carl (below, click to enlarge), he knew a sundew when he saw it because he has some in a pot at home. And he knows what they do to insects. He’s not at all squeamish and watched with interest while I hit the bass his dad caught on the head so we could have it for supper.

So it turns out that we have a flourishing colony of Drosera rotundifolia (above, click to enlarge), the round leaved sundew, growing on the bank of our lake. But they’re growing in an unlikely spot. They’re only a few feet from the water, even now when the water levels are very low, but they’re on an east facing sandy bank where the soil is actually quite dry. Not the soggy sphagnum which we associate with these plants. While there is some moss, some plants are growing in bare sand.

Most of the bank is overhung by low shrubs, so only a five year old is short enough to make his way easily along there and look closely at the plants. But for two or three feet at the point where this colony is happy enough to have produced quite a few seedheads, it’s much more open.

This is a plant that grows all around the world – in a band through the Northern Hemisphere that takes in much of North America, north and eastern Europe and much of northern Russia. In Britain, it occurs mainly in Scotland, Ireland and Wales as well as southern and south west England. It's found scattered across Pennsylvania, in our county (Pike County) it’s recorded from seven sites but surely occurs more widely than that. But it took a five year old to find it on our own property.
MontyDadShoreline


Purple loosestrife - is it really that bad?

Purple loosestrife (lythrum salicaria) in northern New Jersey. Image ©GardenPhotos.com
It’s purple loosestrife season here in Pennsylvania. Swamps and other wet habitats are vivid in its purple coloring (above, click to enlarge), in some places it looks as if it’s smothered everything. This colourful European native is generally viewed as a destructive menace and many millions of dollars are spent every year in a futile attempt to eradicate it.

In Britain, by the way, where purple loosestrife (Lythrum salicaria) originated, it’s far less common and is a popular plant for bog gardens with over a dozen named varieties, two of which have been awarded the prestigious Award of Garden Merit by the Royal Horticultural Society.

In North America, purple loosestrife is generally regarded as evil but part of its reputation derives from the simple fact that it’s so colorful, it’s so obvious that it’s there. If it had dull brown flowers no one would notice. Ken Thompson, in his important book that I reviewed here recently, put it this way: “Very tall people with red hair, big tattoos and conspicuous facial scars rarely have successful careers as bank robbers, and purple loosestrife has a similar problem: it’s just too conspicuous for its own good.” He goes on to emphasize: “Recognition of loosestrife as a problem was largely based on anecdotal observations, which are likely to be particularly unreliable in the case of a tall species with such bright, obvious flowers. This is a well known problem that standard textbooks warn against: it’s easy to conclude that an otherwise rather dull wetland has been completely taken over if you look at it when loosestrife is in flower…, even if a more careful examination would reveal no such thing.”

My local experience indicates that it does not necessarily spread once the first plant arrives, and that it can also decrease over time. On the lake where we live, I spotted two plants growing together about ten years ago. I checked the whole lake last week and those two plants are still the only ones present in spite of there being many suitable habitats all along the margins. Native swamp loosestrife, Decodon verticillatus, is far far more aggressive.

And in the swamp where I first saw it flowering colorfully it has declined, as it has elsewhere, and a striking feature is that native shrubs including dogwood (Cornus) and arrowwood (Viburnum) are establishing themselves on individual clumps of purple loosestrife.

Monarch butterfly on Purple Loosestrife (Lythrim salicaria). Image © Liz West (EWestPhotos.com)And it’s not as if purple loosestrife is entirely useless for wildlife. It’s been shown that a number of native species are more likely to grow in habitats containing purple loosestrife and in a study of over 250 plots it was found that there were more birds in those with purple loosestrife than in those without. I’ve seen around thirty individual butterflies on one plant and over sixty insect genera use it, including adult monarchs (left, click to enlarge). Birds even nest in it. Another significant study that looked carefully at this issue found that there was no difference in species richness between plots with and those without purple loosestrife.

Ken Thompson says, as he concludes his discussion of the issue: “Persecuting loosestrife is, and always has been, a waste of time.”

I was tempted to pull out those first two plants that appeared at the far end of our lake but I just left them and kept an eye on the situation. Ten years later they’re doing no harm.

Don’t get me wrong. I’m not saying that anything and everything that could be, and is, invasive should just be left alone. What I am saying is that it’s not as simple as “native good, non-native bad”. Especially when you look at how fast US native swamp loosestrife (Decodon verticillatus) can spread and the monocultures that result.


Monarch butterfly on Purple Loosestrife (Lythrim salicaria). Image © Liz West (http://www.EWestPhotos.com). Used here under Creative Commons Attribution 2.0 Generic License.


Intriguing recent plant discoveries

Asclepias tuberosus (butterfly weed) with golden leaves. Image ©GardenPhotos.comMaking the hour’s drive back and forth to my cardiac rehab three times a week, and often walking woodland trails on the other days, I’ve spotted some interesting plants along the way.

A couple of years ago I wrote about a yellow-leaved form of common milkweed, Asclepias syriaca, which I spotted growing by the side of the road and last week in a quiet area at the back of the radiology unit (yes, I was just poking around…)  I found a yellow-leaved plant of a different Asclepias species – A. tuberosa, butterfly weed. As you can see (left, click to enlarge) it looks very dramatic and doing very nicely amongst the crown vetch (Coronilla varia).

There were also normal green-leaved plants scattered about the area, which had clearly been disturbed during construction work so we’ll see if that coloring was the freak result of something nasty in the soil or a genuine mutation. I’ll stop back later in the summer for another look.

A white-flowered form of wild bergamot, Monarda fistulosa. Image ©GardenPhotos.comWhite flowered monarda

Just at the moment our local wild bergamot, Monarda fistulosa, is in full flower. This seems to be a “first respondent” if you like, one of those plants that quickly arrives in freshly disturbed soil on open sunny sites. It occurs as a few plants or in huge drifts which, when you look closely, include an occasional plant with darker, or paler flowers.

But this week I screeched to a halt as I spotted a plant - just one - with white flowers (abiove right, click to enlarge). It turned out not to be the white flowered species M. clinopodia (which has a few purple spots on the flowers), but a genuine white-flowered form of M. fistulosa (wild bergamot). There were only a few plants in that location, but I’ve marked it and will collect some seed later.

UPDATE That was a few days ago - and yesterday I found another one, twenty miles farther south. I've been all these years and never seen one white one, and now I come across two.

An Asian bush honeysuckle with attractive amber berries. Image ©GardenPhotos.comAsian bush honeysuckles

I’d never stopped to look closely at all the shrubby honeysuckles along the roadside (please forgive my severe dereliction of botanical duty), they’re growing along a stretch of road where it’s not safe to stop the car. But they’re quite a sight in May when covered in white or cream or pink or red flowers, and again now when they’re in fruit.

Then in a parking area the other day I spotted a plant with lovely amber orange berries (left, click to enlarge). Frankly, I’m not sure if it’s Lonicera maackii, L. morrowii, L. tatarica, or L. x bella (the hybrid between L. morrowii and L. tatarica)  – all of which are collectively known as Asian Bush Honeysuckle; I’ll have to make more of an effort to check them when they flower next year. But, although I know they’re all rated as invasive, they’re very attractive especially those with brilliant scarlet berries (rather than a dull and dirty red) and this pretty amber berried form.

Variegated oak

And finally, on the way up the hill to the ledge from which I shot this wonderful picture of a field of Black-eyed Susans (Rudbeckia hirta) – a variegated oak seedling (below, click to enlarge). I think this may be the only one I’ve ever seen outside a botanic garden, and here it is growing by a woodland trail in Pike County, Pennsylvania.

Variegated seedling of red oak, Quercus rubra. Image ©GardenPhotos.comIt’s a seedling of red oak, Quercus rubra, and a quick online search for variegated red oaks reveals only ‘Greg’s Variegated’ and one named as 'Foliis Variegatis' in the Journal of Arboriculture in October 1987. It’s growing very near the trail; I may have to move it to the garden in the fall.

The only other one I’ll mention here is the vanishing trumpet vine (Campsis radicans). There are occasional plants all the way along my drive, all with the usual orange flowers. But, last week, I spotted one cluster of purplish red flowers.

There was too much traffic to stop examine it but it turns out this is a known variation - ‘Atropurpurea’ – but very rarely seen. So rarely seen, in fact, that when I did stop a few days later – I couldn’t find it!


A field full of Black-eyed Susans

Black-eyed Susan (Rudbeckia hirta) growing in the Delaware Water Gap National Recreation Area. Image © GardenPhotos.com
There I was, driving along counting all the European plants growing - and often looking very attractive - along the Pennsylvania roadside when in the distance I noticed a whole field of orange. In this part of the world it could only be one thing: Black-Eyed Susan (Rudbeckia hirta). And so it proved, a large field covered from edge to edge in R. hirta, with a scattering of fleabane (Erigeron annuus).

This is in the Delaware Water Gap National Recreation Area, a park ripe with alien plants as well as natives and also very rich in bird life. But acres and acres of rudbeckia? It didn’t look natural. The park people had a hand in that, I’m sure, they must have sown seed. But it looks spectacular.

There were also three interesting features about the uniquely colorful field. Firstly, I spent two half hours, on two different sunny days, walking through the field and looking at the plants and I did not see a single insect of any kind feeding on the flowers. Not one.

And secondly, the flowers varied in shape noticeably: some flowers were very starry with narrow ray florets (the petals) and some much more full with broader rays; and many were in between.

RudbeckiaHirtaCloseUp-GPAlso, I noticed that on all the plants the flowers were bicolored: dark yellow-orange at the base and a paler tone at the tips (left, click to enlarge). That two-tone coloring is a feature of many garden varieties but the Flora of North America – the most authoritative work on North American native plants - is very specific: it says that the rays are “usually uniformly yellow to yellow-orange”. I’ve since checked other plants in the area and they’re all two-tone.

The Flora of North America also says: “or with a basal maroon splotch, sometimes mostly maroon”; I’ve never seen a wild plant with maroon flowers in the wild. But it shows that the rusty coloring of many garden varieties and the development of the first red flowered form 'Cherry Brandy' (below, click to enlarge) are based on an inherent genetic capacity for darker shades.

So, naturally, many people want to grow this colorful plant in their gardens. But, as a friend said to me the other day: “We keep planting them, but they never come back the next year.” The reason is that they’re biennial, and they die after flowering and you either have to sow more seed or hope they self sow. If you want a perennial form, grow Rudbeckia fulgida.

Rudbeckia hirta 'Cherry Brandy'. Image © Johnsons Seeds
UPDATE: And here's a view of the field a few days later from the top of the nearby escaprpment, hundreds of feet above.

Field of Rudbeckia hirta (Black-eyed Susan) seen from the overlook above Cliff Park, Milford, PA. Image ©GardenPhotos.com