When you’re trying to identify local wild flowers, or see if a plant is invasive in your area, plant distribution maps for individual species are invaluable. Plant distribution maps simply show you where in the country individual species grow. Britain and Ireland’s online plant map website, the Online Atlas of the British and Irish Flora, is superb.

This is the online version of the truly stupendous – but enormously heavy and expensive – book The New Atlas of the British and Irish Flora. On the site, you simply input the common or botanical name of the plant, and the next page brings you a fairly basic map together with a text summary.

However, click on the Maps button and then on Link to Interactive Map and you come to a topographical map with the distribution of the plant clearly marked. You can zoom in and out, and there are other interactive features. The country is divided into 10Km squares and the map shows the squares in which the chosen plant grows. This  is the distribution of Pinesap, Monotropa hypopitys, that I wrote about here recently, in Britain and Ireland (above, click to enlarge).

The site allows you to zoom, overlay county boundaries, get information on the records in individual squares. I’ve zoomed in to illustrate mostly just England - which is about the same area as our state here in Pennsylvania. Produced by the Botanical Society of the British Isles and the Biological Records Centre I have to say, this is absolutely brilliant.

In the United States, the Department of Agriculture’s Plant Database is the place to start. Again, search on the common or botanical name and a distribution map for the whole country comes up on the next page with a note on whether the plant is native or introduced. Click on your state and you get a county-by-county distribution map. Below (click to enlarge) you’ll see the county-by-county distribution for Pinesap in Pennsylvania.

In North America, individual states have their own flora mapping projects. Here in Pennsylvania, the Pennsylvania Flora Project eventually brings you the same map as the USDA site. The Calflora site is a much more impressive resource for California, again with sites shown on topographical maps.

Knowing whether a plant has ever actually ever been found in your area can be a big help when trying to identify wild flowers, especially when trying to distinguish between similar species.

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!

Pottering about in the woods, looking at the downed trees from the hurricane, I came across this little clump of Pinsesap, Monotropa hypopitys. It’s not a rare plant, but I’d never spotted it near the house before. The name, Pinsesap, is said to be derived from the fact that it grows under pine trees and saps its juices. It grows in Britain, too, where its common name is, rather mysteriously, Yellow Bird’s-nest.

Like the entirely white Indian pipe, Monotropa uniflora, which we have in the garden as well as the woods, Pinesap has no chlorophyll and was always thought to be a saprophyte – getting its nutrients from rotting leaf litter. It was also usually placed in its own family, Monotropaceae.

But the world of the pinesap has been turned upside down! Well, no, the pinesap carries on as it has for thousands of years. It's our understanding of pinesap that has changed dramatically.

First of all, it turns out that rather than using rotting woodland leaf litter for its nutrients, it’s actually parasitic on a group of woodland fungi. Also, the latest thinking is that it belongs, rather surprisingly, in the Erica family with rhododendrons and heathers. Finally, there are some who believe that it needs separating from the Indian Pipe, Monotropa uniflora, into a genus of its own. The genus Hypopitys has been created for it – and in that case what would its new name be? Instead of Monotropa hypopitys it would then be called - Hypopitys monotropa! Oh, those botanists like a joke...

Oh, and there’s another odd thing about the North American form of this plant. It comes in a yellow version that flowers in summer, and also the reddish version seen in the picture (above, click to enlarge) that flowers in the fall.

Anyway, it’s good to have such an intriguing plant turn up in our local woods.

The phlox are blooming and I have questions about them…. lots of questions, mainly about the tall American native Phlox paniculata, a classic British border perennial. So I turn with a relief to a new book on the subject Phlox: A Natural History and Gardener's Guide by James H. Locklear (Timber Press).

I'm looking for an expert's opinion:
* Why is P. paniculata 'David' no longer mildew resistant, was 'David's Lavender' ever resistant?
* I'm wondering if the many recent much shorter varieties from Holland are forms of P. paniculata or hybrids – and if they're hybrids, do they spread more, as we might expect (one parent does, the other not) and do they still get eelworm (again - one parent usually does, the other not)?
* What's the best way to take root cuttings and so avoid eelworm? Many home gardeners have problems with this eelworm-avoiding technique?
* Lots of ID confusions… Is 'Blue Paradise' the same as 'Blue Evening', for example, or is one being sold as the other?
* Do some varieties respond better to cutting back in May than others – so they flower on shorter plants and don’t need staking?

But it turns out that it's not that sort of book. This is an impressive and authoritative botanical work, with detailed descriptions of all the wild Phlox species. The wild distribution of each species is discussed, there are many details on the habitats of the plants at different sites, and invaluable accounts of the plants with which each species is associated – something rarely found in this detail in plant monographs and testament to the author's ten years of diligent research.

But, although enjoyably written and comprehensive when dealing with plants in the wild, the book answers none of my questions. Few cultivars of any species are mentioned, eelworm gets less than three lines, there is little on propagatrion, and cultivation advice is generally basic.

That would be fine, if there was also a book on Phlox for gardeners. But there's not. And I know from experience that once one book on a specialist plant subject has appeared – good or bad, comprehensive or not – it's very tough to persuade a publisher that another is needed.

Phlox: A Natural History and Gardener's Guide is a superb Natural History - but, sadly, not so hot as a Gardener's Guide.

With more variegated ceanothus appearing, we now seem have about eight, this seems a good moment to take a look. Any evergreen shrub that features variegated foliage to spark interest in all those months when there are no flowers is well worth having. With ceanothus the flowers and the foliage look good together too.

The first variegated ceanothus I grew, back in the 1990s, and the first to appear was 'Zanzibar' (above, click to enlarge), less often but more correctly known as 'Pershore Zanzibar'. It's still the most often seen in Britain, its broad leaves each with a central dark green stripe and wide lemon-lime edge. It's a sport of the old favorite 'A. T. Johnson'.

This is an upright and bushy plant and from a distance the effect is of a pale yellow cloud, so it makes a good back-of-the-border feature. Then in spring the clusters of pale blue flowers are shown off beautifully. The foliage can be little sparse in early spring, as it tends to lose its oldest leaves in the winter, but new growth soon makes up the deficiency. El Dorado ('Perado'), found as a sport on 'Pershore Zanzibar', is similar, but less bright and with a broader green stripe, and some say its softer coloring helps it integrate with other plants more effectively.

The next I grew - I have a feeling it was sent to me in England by the Seattle plant nut Bob Lilly also in the 1990s - was 'Diamond Heights', one of two variegated forms of the spreading C. griseus. Lurking in the back of my memory is the notion that this was found amongst an extensive planting along a road in the district of San Francisco of that name. With a much lower, more spreading and mounding habit of growth, its deep green center and broad limey yellow edge, and its pale blue flowers in late spring and early summer  - 'Diamond Heights' is ideal trailing over a sunny stone retaining wall.

More recently we’ve had a rather different variegated form of C. griseus, 'Silver Surprise', a sport of 'Yankee Point', which is more upright and bushy than 'Diamond Heights', but less big and bold than 'Pershore Zanzibar', and with the edges of the dark green leaves marked in silvery white. The blue flowers appear in late spring.

Now, recently introduced, from England, and with longer, more slender foliage ' Lemon and Lime' (left, click to enlarge) is a variegated version of the old favorite 'Cynthia Postan' and has a more airy and refined look than 'Pershore Zanzibar'.

There are more… 'Golden Elan', with pink flowers; 'Bright Eyes', said to be similar to 'Diamond Heights'; 'Blue and Gold', which is said to revert to green. But these I've never seen.

The problem, of course, is that with their progenitors originating in California they're not as hardy as we'd like. Can't grow them here in north east Pennsylvania. Planting against a west or south wall is a big help for the more upright ones, as is good drainage and knocking off any winter snow accumulation.

All we need now is a variegated form of the black-leaved Ceanothus 'Tuxedo'. Wow!

While I've been woozing over my jet lag, judy has been inspecting the increasingly prolific orchids in our Pennsylavina garden.

It’s that time of year at the lake when the hardy Epipactis helleborine orchid is in bloom again. It’s not a native orchid – only one Epipactis, E. gigantea, is a native American. The Broad-leaved Helleborine Orchid is from Europe originally, and, in fact, in some places in the United States (especially Wisconsin) this beautiful plant is invasive, so much so that it’s called the Weed Orchid. It’s been naturalized in the States since at least 1879. (I read that originally it was introduced by American colonists as a medicinal plant, theoretically good for gout. There are scientific studies showing its in vitro activity as an antiviral against HIV-1 and HIV-2 as well as influenza A.)

Here in our 1400ft (425m) high Pennsylvania mountain garden, though, the helleborine orchids just kind of pop up, usually one at a time in scattered spots, often gone the next year, and we are rather fond of the gently random nature. Although they spread by rhizomes, ours seem to spread more by seed, so clearly we have conditions conducive for the necessary mycorrhizal fungi that help the seeds germinate. Generally these orchids grow in semi-shade, but sometimes in lots of sun, and though supposedly Epipactis prefer moist – or even wet – environments, ours are exceedingly adaptable and drought-tolerant, a good plant for dry shade.

Helleborines make tall spikes of little half-inch to three-quarter inch (1.2-2cm) flowers; some of our plants have nearly 50 blooms, with the inflorescence reaching over 2ft (60cm) high. This year there seems to be a vast number of pollinators on the ones in the most shade (I’ve noticed bees on them), and the flowers, which open successively from the bottom up, are turning into seedpods almost immediately upon opening.

Last year I took some seedpods and scattered them around the various garden beds, so there are some unexpectedly nice woodland plant combinations this month. With green sepals and lavender-tinted petals, the helleborine flowers are looking lovely with a lavender-toned Japanese painted fern cultivar (Athyrium nipponicum var. pictum) that we’ve lost the tag of, amid the lacy sweet woodruff (Galium odoratum). A few are blooming under the Hydrangea arborescens ‘White Dome’, which is also in full flower, and one helleborine has struck up the tallest presence our main garden border in a fair amount of sun; it’s opening much later than the others.

The name “helleborine” supposedly is because they resemble hellebores. I don’t get it. No part of them, not the flowers, and definitely not the plant habit, look like hellebores in the least to me. I’ve even got the two growing side-by-side. Linnaeus must have been a little drunk on Swedish schnapps when he named the species.

All over the woods here in north east Pennsylvania the flowering of the Mountain Laurel (Kalmia latifolia) is at its peak. And it's intriguing to see how much the flower color varies in these lovely evergreen rhododendron relatives.

The three in the picture (click to enlarge) are all from wild in the woods no more than about 100ft/30m from our front door. Farther away there are darker pinks, almost red, and I noticed 15 miles away last night that great drifts of them were all noticeably dark.

This variation in wild plants has been enhanced by plant breeders, as can be seen in the pictures of the kalmias stocked by Rare Find Nursery and in the only book on this invaluable acid-loving shrubs – Kalmia: Mountain Laurel and Related Species by Richard A. Jaynes (Timber Press). Sadly, that book is now out of print but you can find it used at you-know-where for about $30 and new at up to almost $300! (£20 used or £25 from their British site.)

The only problem is deer - all those in the woods here are stripped bare to about 5ft/1.5m and those now inside our deer fence are slow to recover. We need deer candy Kalmia latifolia crossed with the short and suckering, 100% deer resistant Kalmia angustifolia. I discussed this idea a couple of years ago. We live in hope.

Back in March, I wrote about Amsonia hubrichtii, the 2011 Perennial plant Association Plant of the Year. I also wrote about its fantastic fall color in October last year. Now I know how it was discovered, thanks to the Yardflower.com blog from Mississippi horticulturalist Gail Barton.

Amsonia hubrichtii was discovered in Arkansas in 1942 by the renowned malacologist (snail expert) Leslie Hubricht - he named 81 new kinds of land snails! His day job for much of his life was working for Remington on early computers but in 1942 he worked at the Missouri Botanical Gardens and after he brought back his amsonia from a snail hunting trip to Arkansas, it was his supervisor who confirmed that it was indeed a new species.

There's an interesting slant to the story which Gail Barton tells on her Yardflower.com blog – but rather than cut-and-paste it here I'll simply suggest you hop over and take a look.

It's great to find how these plants were discovered and in this case it's also surprising that a colorful plant that grows across two states (it also grows in Oklahoma) was discovered so recently.

About ten days ago, here on the Transatlantic Gardener, I was talking about Dicentra spectabilis (as was). Then, after I’d posted that piece, I suddenly remembered one of its wonderful relations, a biennial American native climber called Adlumia fungosa, also known as the Allegheny Vine.

I grew this years ago in one of my earlier British gardens, in my picture (above, click to enlarge) it’s scrambling over an especially good form of Euphorbia characias called ‘Blue Hills’, raised by the great British plant breeder Eric Smith. The euphorbia is noted for its very long, very blue leaves.

The adlumia makes an overwintering rosette of very attractive, lacily divided foliage and then long, long, rather succulent shoots develop carrying strings of flowers in a slightly impure pinkish purple. It clings in the same way as clematis, by curling its leaf stalks round its support.

I was always impressed by the fact that it was shedding its tiny, shiny black seeds towards the base of the stems while there were buds still waiting to open towards the tips. It’s a really valuable climber to grow through shrubs in a sunny place.

It turns out that Adlumia fungosa is native here in Pennsylvania, though not in our county, but it looks like popular deer food to me so it’s surely on the decline. I’ve not seen it in the surrounding counties where it’s said to grow.

Looking it up in the book I mentioned in my last post, Bleeding Hearts, Corydalis, and Their Relatives by Mark Tebbitt, Magnus Lidén, and Henrik Zetterland (Timber Press), I’m reminded that it has an uncommon white-flowered form. I notice that Summerhill Seeds in the USA have a pale pink form, which looks very pretty. And seed of the normal form is available for shipping all over the world from Britain's Chiltern Seeds – which is where I got it many years ago.

But can anyone tell me where I can get seed, or plants, of the white-flowered form?

 

Yesterday we went to the annual Native Plant Sale at the Pocono Environmental Education Center here in north east Pennsylvania. Back in 2008 I wrote about one of our earlier visits, noting the remarkable number of plants from around the world being sold as natives. These included Aquilegia ‘Biedermeier Mixed’ and Agastache ‘Blue Fortune’.

Well, this year we went again to support their educational work by buying a few plants. And, frankly, I was keen to see if they now had a clearer idea of what constitutes a native plant. But three years later it's the same old story. They may have a huge sparkling new building in which to hold the sale but, again, there were some remarkable "natives" on sale.

The top prize goes to the plants labeled "native orange daylily". Step forward, all the way from China - Hemerocallis fulva (above, click to enlarge). This is often seen on roadsides as well as in wilder areas in these parts, sometimes in its double form. The Pennsylvania Department of Conservation and Natural Resources has a Fact Sheet on the plant headed Invasive Exotic Plant Tutorial for Natural Lands Managers. It reports that these daylilies "… infest natural areas where they pose the greatest threat to meadows, floodplains, moist woods and forest edges." Not exactly the sort of “native” that an environmental education center should have on sale.

The second “native” that stood out at this “native plant sale”, apart from the ‘Victoria’ rhubarb, was Corydalis flexuosa ‘Blue Panda’ (above, click to enlarge). This was collected in China in 1985 by American horticulturalist Reuben Hatch. A lovely plant, well worth growing, but not many of those scattered through Pennsylvania’s forests.

Now, just in case you think I’m being unnecessarily harsh, there were quite a few genuine native plants on sale as well. We bought a few natives, as well as a 'Blue Panda'. Also, I wrote to them about this issue years ago, after our first visit. When I blogged about them in 2008 I didn’t mention their name, but I sent them a link to my post and invited comment. But they didn't comment.

They specialize in environmental education for kids – I wonder what they’re teaching them about native plants?

Thank you for images to:
Hemerocallis: GardenPhotos.com
Corydalis: Terra Nova Nurseries