Sunday, 31 July 2011

White poppies

Pure white Papaver somniferum flowering in the new gravel garden, from seed kindly provided by Sibylle Kreutzberger, sown in May. They look spectacular floating above the other plants and surrounded by grasses. I don't know of any purer white flower.

Saturday, 30 July 2011

Mostly Compositae

Ligularia 'Britt Marie Crawford' and Helenium 'Sahin's Early Flowerer'

Iberis gibraltarica 'Betty Swainson' (white) and Sedum 'Angelina' (yellow in foreground): Argyranthemum 'Jamaica Primrose' and Dahlia 'Tally Ho' behind.

Helenium Sahin's Early Flowerer, Monarda 'Ruby Glow'. Lythrum salicaria 'Blush'. The Helenium and Monarda make a lovely combination.

Achillea 'Pomegranate' - another Sahin selection

Salanova lettuce from Rijk Zwaan: delicious and highly ornamental

Wednesday, 27 July 2011


Hanburyana is the scientific journal produced by the Royal Horticultural Society, principally as a vehicle for taxonomic notes and records. My copy of this year's issue (no. 5) arrived today and I've read it through this afternoon. There are all sorts of interesting nuggets, as always, but among them are two important longer articles. For bulbous people, John David from Wisley discusses 'Nomenclature of intergeneric hybrids of Zephyranthes', unravelling a distinctly tangled tale in this group of New World amaryllids.

Secondly, James Cullen from Cambridge, a well-known Rhododendron expert, writes on 'Naturalised rhododendrons widespread in Great Britain and Ireland'. In this very interesting article he makes the case that the aggressively invasive plant ubiquitously known as "ponticum", is in fact a hybrid swarm involving R. ponticum (from scattered sites in Europe and western Asia), the eastern North American natives R. maximum and R. catawbiense, and the Western American R. macrophyllum, dating from hybridisation events in nurseries in the early nineteenth century. All the evidence suggests that true R. ponticum is not an easy plant to grow in Britain, being rather tender, so added hardiness from the very tough North American species was desirable. Other work has demonstrated, on DNA evidence, that the R. ponticum ancestors were all from Iberia, where the species grows in small areas of suitable habitat, unlike the much more expansive populations in north-eastern Turkey. The admixture of genetics has left its mark in the morphology of the plants, with features of the different species showing up to a variable extent in individual plants. As a consequence, Cullen has published the name Rhododendron × superponticum to cover all the plants belonging to this swarm. It will take a while to catch-on, no doubt, as everyone is so familiar with "ponticum'" as the name for this thug that is not only Britain's worst invasive plant but also a major host for Phytophthora ramorum.
Rhododendron × superponticum is undeniably attractive in flower, but a terrible ecological menace.
Hanburyana is published in hard copy in only limited numbers, but its full content is usually available online, though this issue has not yet been posted.  

Tuesday, 26 July 2011

Allium ovalifolium var. leuconeurum

Allium ovalifolium var. leuconeurum
The Summer 2011 issue of The Rock Garden Quarterly (Bulletin of the North American Rock Garden Society) contains a fascinating article by 'Mr Allium', Mark McDonough, describing a selection of attractive alliums that are poorly known in cultivation, if at all. Some of them are eminently desirable, especially the high alpine A. chrysanthum with soft yellow flowers from Yunnan. The article prompted me to look more closely at a plant in the garden here, obtained from Cotswold Garden Flowers a few years ago under the name Allium ovalifolium var. leuconeurum. It has taken a while to get going in what is probably a rather drier site than it would really like, but this year it has produced sufficient flower heads to make a gentle impact.

The plant grows from a narrow bulb and consists of a pair of leaves and a scape bearing a round head of small flowers. The leaves are broad and pointed, borne on distinct petioles, suggesting those of Ramsons (A. ursinum) but without the rank garlic stink. When broken they are, of course, smelly, but the odour reminds me more of a stock cube than an onion outright. Their most interesting feature is the presence of longitudinal white veins, which make them rather handsome; the lamina is light green now, but it emerges with a red flush on which the stripes are particularly conspicuous. The plant's name refers to both the leaf shape (ovalifolium) and the stripes (leuconeurum). According to Flora of China, the variety is found in forests in western Sichuan between 2800-3800 m. There are several broad-leaved Allium species in China, but only this taxon has white-veined leaves.

Foliage of Allium ovalifolium var. leuconeurum

The flowers are individually small, but together make up a rounded head about 4 cm in diameter, carried on a long red scape well above the leaves. Although nothing about the flowers is individually showy the combination of red scape, pink pedicels, white petals, yellow anthers and green ovaries is very pretty.

Here it is growing on a sloping bed among other plants: in fact the foliage is under the overhang of an adjacent hellebore but seems none the worse for this shading, suggesting it is well adapted to life on the forest floor. I suspect it would prefer a little more moisture than it gets so I'll split a bulb off as it goes dormant and try it in the humus-rich bed.

Flower heads of Allium ovalifolium rising above the foliage of Helleborus x hybridus.

Monday, 25 July 2011

A third season of beauty

Paeonia 'Aurelia'
 I've featured Paeonia 'Aurelia' three times in this diary this year: on 13 March for its emerging red shoots: on 18 April for its flowers and on 19 May I included a picture of a developing fruit. Now, after a dull patch for a couple of month,  it has metamorphosed into its final phase of beauty through the opening of the fruits to reveal a glowing mass of colour, set above foliage that is developing distinctly autumnal tints. The fruits are made up of three follicles, which split longituinally to reveal the fertile, shiny blue-black seeds surrounded by a mass of red 'bits.' These 'bits' are derived from ovules that were never fertilised and are often called, oxymoronically, 'sterile seeds', but they have a valuable function in attracting birds to the fruits to act as dispersers. Red and black is a classic attractant pattern, but they are usually combined in the same seed of fruiting unit (think Abrus precatorius or Taxus baccata). In peonies the two colours are separate but the effect is the same. People find the combination very attractive too!

Sunday, 24 July 2011

By the tap

Lilium 'Red Velvet': in the old bath planter by the door, twice as tall this year as last and quite magnificent.
While filing up the watering cans earlier this evening I thought 'I need a picture of those lilies,' so scuttled inside for the camera. Filling two cans takes a surprising length of time, so I photographed a few other things in the vicinity, and again at the next filling, all within a short distance of the tap. Here are a few of them.

Unfurling frond of Polypodium cambricum Cambricum Group. This is one of the latest plants to produce new growth in the year, but the beautiful fronds remain green throughout the winter.
Larix kaempferi 'Wolterdingen' - a dwarf larch, acquired in Prague some years ago, and now mounding up into an almost velvety heap of silvered soft-green foliage. It turns yellow in autumn.

A white Gentiana septemfida. This is in a pot bought from the greengrocer in Cirencester a few days ago, consisting of at least six different seedlings ranging from blue to white through bicolor. I'll separate them and pot them separately later in the year.

A hybrid between Digitalis (Isoplexis) canariensis and a purple foxglove, raised by Maarten van der Sar at Sahin in Holland. Esentially a shrubby foxglove, it produces a succession of flowering stems through the summer.

Friday, 22 July 2011

Morning ‘Mönch’

Aster × frikartii ‘Mönch’
According to Graham Stuart Thomas (Perennial Garden Plants): 'one of the six best plants, and should be in every garden. (Please do not ask for the names of the other five!).'

Thursday, 21 July 2011

A visit to the Harcourt Arboretum

Ken Burras and Ben Jones discuss leaf anatomy in Sciadopitys umbellata, one of the first trees to be planted at the arboretum in 1964 and used to supply material for generations of demonstrations in taxonomy classes.
This afternoon was one of those happy occasions when friends and plants combine and time flies by. I met up with my horticultural mentor and friend of almost 25 years, Ken Burras, formerly Superintendent of the Oxford Botanic Garden, and Ben Jones, Curator of the Harcourt Arboretum of Oxford University, for a walk around the arboretum that Ken was responsible for establishing and Ben is now responsible for.

The Harcourt Arboretum was started in 1964 as an adjunct to the University of Oxford Botanic Garden, which, in its small site in central Oxford, lacked space to grow a range of large trees, especially conifers, from which material was required for classes in the Botany School. It was established on 30 acres around a core of nineteenth century plantings on the Nuneham Estate, originally owned by the Harcourt family, and included a bluebell wood as well as the arboretum. It has now expanded to cover 130 acres, including an area of coppice woodland and some large former arable fields (Palmers Leys) that are now being restored to meadowland. To go round it with two enthusiasts and hear both about its past and plans for its future was a huge pleasure.

Torreya nucifera, appropriately bearing its nut-like fruits, a single large seed covered in a fleshy aril.

Pseudolarix amabilis, the Golden Larch.

Picea smithiana: a tree planted by Ken Burras in the early days of the Harcourt Arboretum, now a beautiful specimen.

Cones of Picea smithiana.

Lomatia myricoides, a truly hardy Australian member of the Proteaceae, flowering freely and attracting masses of honeybees to its fragrant flowers.

A leaf of Ulmus laciniata, a Far Eastern Asian species that is extremely rare in cultivation. The two small specimens at the Harvcourt Arboretum were the only ones traced in Britain for New Trees, and they are not really thriving.
Peacocks have been a feature since the arboretum's foundation, nominal descendants of the Harcourts' birds.

Monday, 18 July 2011

It pays to enrich your word power

Heavy rain this afternoon
In his entry in Trad's Diary for 9 July, Hugh Johnson has coined a new word. He is, he says, a pluviophile, a lover of rain, and he extols the pleasures of watching rain. I'm also glad to think of myself as a pluviophile, enjoying both the spectacle of it falling and the effect it has.

Hugh also mentioned a related pleasure, the scent released by soil after rain. There is a word for this: petrichor, first brought to my attention by the American horticultural scholar Bobby Ward. It's a neologism invented by two evidently classically-minded Australians in 1964, from the Greek petra, rock, and ichor, the fluid flowing in the veins of the gods. They state that it's caused by aromatic compounds from plants being stored in soil and rock being released on wetting, which is presumably why it's so ephemeral. I think of it mostly in conjunction with the rain on parched African soil, a first  fine, careless rapture.

Sunday, 17 July 2011


Linaria vulgaris f. peloria
 In 1742 a Swedish student, M. Liöberg, found a strange plant growing near Stockholm. In its vegetative characters it looked just like the common Yellow Toadflax, which his professor named, in his new binomial system, Linaria vulgaris. But this plant was very different. Instead of the familiar bilaterally symmetric toadflax flowers, those of this plant were really bizarre-looking, with five spurs instead of one, a long tube and a rounded, five-lobed object at the top, quite unlike the usual bunny-shaped flowers of a toadflax. He took material to Linnaeus for the great man's opinion and it caused him quite a stir of consternation. Linnaeus was a creationist and assumed that species were immutable, but this plant was a problem.

Normal Linaria vulgaris
In his own 'sexual system' for classifying plants by their reproductive parts Linnaeus had placed Linaria vulgaris in the section Didynamia, as it had two unequal pairs of stamens. This odd plant, however, had radially symmetrical flowers, with five anthers matching the five spurs. This placed it into the class Pentandria, along with other plants from many families having five stamens. But its evident connection with Linaria gave Linnaeus pause. How could such a difference have come about? There was no genetic framework to think in and mutations that were known could be easily understood - differently coloured flowers and so on - but such a change in a flower's shape was unheard of. In the end Linnaeus decided it must be a hybrid between Linaria and some other (unknown) plant, and named it Peloria, from the Greek for a monster, but in so doing he had to confront the philosphical problem that this meant that not all plants had been placed on Earth by the Creator.

A peloric Phalaenopsis
(img: M. Bishop)
Now understood as a mutant under the name Linaria vulgaris forma peloria, this odd plant has been used by evolutionary biologists from Darwin onwards as an example of how mutation can lead to change in morphology; peloric flowers occur in many genera and can cause them also to look quite bizarre. A radially symmetrical terminal flower is common in Digitalis, for example, and it occurs in orchids too, often with dramatic effect. The phenomenon is of great interest to those studying developmental pathways, and it's clearly not only, or not always, a simple mutation that causes it.

Peloric Linaria purpurea
In October 2010, on the last occasion that I was able to visit the garden of the late Elizabeth Parker-Jervis, I spotted a peloric flower or two on a plant of white-flowered Linaria purpurea, so dug it up and brought it home. Cuttings rooted well over winter, so I now have several plants, all flowering. What has surprised me is that while all inflorescences show some pelorism, not all flowers show it, with many being entirely normal and some being intermediate, with two or three spurs on an otherwise more normally shaped flower. There is certainly no simple mutation here, but a change in genetic expression as the inflorescence develops. This needs laboratory investigation, but on a manageable, horticultural scale I am keen to see what happens in the next generation, or generations. The normal flowers mean that normal pollination can occur, so seed will be set, whereas in peloric flowers in Linaria the curious floral shape precludes the normal pollination process and no seed develops, if artificial pollination is not performed. Now I'm thinking I should get busy with my paintbrush...

A peloric form of Linaria purpurea has been recorded before, but it is an unusual phenomenon. I wonder how often it has occurred in L. vulgaris: I notice some differences between online images, so there may be different clones, but I suspect that this too is a rare occurrence. L. vulgaris is a vigorously spreading perennial maintaining itself by vegetative growth, meaning that it is easily propagated and maintained, whereas L. purpurea is a short-lived perennial at best. Not many people would welcome normal L. vulgaris into the garden because of this rampancy, but forma peloria is desirable for its curiosity and, it has to be said, it contributes a very useful patch of colour. Only one nursery currently offer it it in the UK: this is a plant that should be more widely grown.

Linaria vulgaris f. peloria at Colesbourne Park

Thursday, 14 July 2011

An odd combination

An old stone wall enveloped in Campanula poscharskyana is a common sight in the Cotswolds, and usually doesn't warrant a second glance, but I was struck by the sheer incongruity of seeing it in combination with a King Penguin. This apparently unlikely pairing is at Birdland in Bourton-on-the-Water, which I visited yesterday evening with the Cotswold Pheasant and Poultry Club. The presence of vegetation is not actually anomalous: the King Penguin, unlike its relative the Emperor, lives on vegetated islands in the Southern Ocean, so bleak snowiness is inappropriate. However, according to our guide for the evening, Assistant Head Keeper Chris, the penguins find the Cotswolds summer too warm for comfort and must be supplied with cooling devices, including shade umbrellas and ice blocks. The biggest problem is that the females are apt to lose their eggs when they feel the urge to cool off with a swim, so the eggs are usually removed for incubation and hand-rearing while a floating substitute is provided.

Birdland is not a horticultural destination, but it has a lot of beautiful, lovingly cared-for birds that in many cases are part of an organized captive breeding programme.

Palawan Peacock Pheasant

Tuesday, 12 July 2011

By the lake

By the lake at Colesbourne Park today: Lysimachia punctata (reverted from 'Alexander'), Astilbe 'Straussenfeder', Zantedeschia 'Friesdorf Bastard' and Primula florindae.

Sunday, 10 July 2011

A different scale of flower show

After leaving Caterham yesterday I went a little further west in Surrey to Pyrford, the next village to Wisley, where my brother Tom and his wife Caroline were exhibiting at the Pyrford and Wisley Flower Show.  It's a classic village flower show, with stalls and entertainments on the cricket field, tea, cakes and a threat of rain.  The horticultural show is held in a large marquee, but exhibits were sadly sparse, as is so often the case. I know it's early in the season for produce, but many more people could enter a vase of flowers or a cut rose or two and fill up the benches.

The horticultural marquee
Tom and Caroline had done what they could to remedy this, entering both produce and floral sections from their immaculate garden, and gained a selection of  awards. Their triumph came from the award of the George Chick Memorial Cup for an exhibit of six Fuchsia flowers - 'Rufus' in this case, displayed embedded in sand. It's a strange way of showing a pendulous flower, but that's how it's done and the judges approved.

Tom receives the cup

Saturday, 9 July 2011

The Bicentenary of Caterham School

Caterham School
Today I've been in Surrey to attend Speech Day at Caterham School, where I was a pupil 1978-1985, and to take part in the launch of its Bicentenary Celebrations. The school was founded in 1811  by the Revd John Townsend for the education of sons of Congregational Church ministers. As one such I benefited from this founding purpose, but the school soon accepted a much broader intake (it is now fully coeducational). Originally located at Lewisham in south London, it moved to its present site in Caterham, Surrey, in 1884, and is now regarded as being in the top flight of independent schools in England - see its website for more information. Its Bicentenary is a major achievement, as the establishment had long rocky patches before achieving its present fame and fortune, and it was a huge pleasure to be there at the start of the celebrations today. I have to congratulate the school and its Head, Julian Thomas, on the occasion and for the thriving state of the place today.

An ephemeral souvenir

John Jones and Jim Seymour:
my understanding housemasters.
Caterham has no gardens worth mentioning, but it lies in a leafy valley on the North Downs in Surrey: it is really at the last tip of the tentacle of the London conurbation, and the setting, with the Home Field in front, is beautiful. It is an easy walk from there through woodland to the ridge of the downs and their fascinating flora of chalkand plants, which I was able to fully explore during my schooldays. It was also while there that my interest in gardening really got going, unusual in a schoolboy perhaps, but fully supported by the staff, an understanding for which I am eternally grateful. Not surprisingly, there wasn't much of horticultural interest in the school library, but there were two books that have been very influential. First, Frank Kingdon-Ward's Plant-hunting on the Edge of the World, which gave me a lifelong fascination for plant-hunting and exploration in remote places, and secondly, the magnificently produced The Gardens in the Royal Park at Windsor by Lanning Roper, from which I learnt about garden-making and the joy of plantsmanship. The public library in Caterham greatly extended the options and it was from there that I first borrowed the My Garden trilogy of E.A. Bowles, so often mentioned in this blog. I have much to be grateful to Caterham for, in an association lasting, so far, one-sixth of its existence.

Thursday, 7 July 2011

Early evening in the garden

Looking across the garden at about 6.30 this evening. Anthemis 'Tinpenny Sparkler' in the foreground.

Geranium 'Nimbus' and Buphthalmum salicifolium 'Dora'

Clematis 'Prince Charles'

Hemerocallis 'Joan Senior' and Lathyrus 'Tillyperone'

Morina longifolia

Geranium pratense