Cornus controversa

Cornus controversa 'Variegata'
Cornus controversa ‘Variegata’

Best known in gardens in the form of Cornus controversa ‘Variegata’ this plant has had a convoluted history. The species C. controversa Heml. was first “discovered” in cultivation. In January of 1909 an article was published in Curtis’s Botanical Magazine which discussed the naming of Cornus macrophylla and the authors noted that there appeared to be confusion regarding the name. Though introduced back in 1827 it was not widely grown but it was known to be a tall and bushy plant when observed in the wild and this varied little over it wide natural range.  William Botting Hemley who had retired as Keeper of the Herbarium and Library at Kew the year before had studied this and noted that the examples in cultivation were a mixture of two species: one with opposite leaves and the other alternate.

Cornus controversa 'Variegata' foliage
Cornus controversa ‘Variegata’ foliage

The simple fact was that the naming had got into a mess but when the original specimen that Wallich had named C. macrophylla was checked it had opposite leaves and the original description in Flora indica of 1820 described the leaves as “sub-opposite”. Next Meyer in 1845 had also described the plant in a Saint Petersburg publication but naming it C. brachypoda. All this resulted in America and continental Europe using Meyer’s name of C. brachypoda for the form of the plant with opposite leaves and C. macrophylla for the alternate leafed form while in Britain both forms were known as C. macrophylla. In an attempt to clear things up the German botanist Bernhard Koehne tried to split the species in the belief that the Himalayan form was a distinct species which he called C. corynostylis but got confused between the opposite and alternate leaf arrangements. To clear up this confusion William Hemley proposed that if the plant had its leaves arranged opposite one another on the branches it should be called C. macrophylla Wall. as has been Nathaniel Wallich’s intention and the alternate leafed form should be a separate species Cornus controversa Hemsl. meaning cornus controversial, a most appropriate name. And that is as it has remained; apart from an attempt to place several of the cornus species, this one included, in the genus Swida in the 1960’s.

Cornus controversa 'Variegata' foliage close up
Cornus controversa ‘Variegata’ foliage close up

That would be the end of it with C. controversa Hemsl. providing us with a very garden worthy small tree with tiered branches and masses of cream flowers in May, but towards the end of the 19th century a variegated from was found and shortly before 1890 Veitch Nurseries introduced it as Cornus brachypoda ‘Variegata’. Now known as Cornus controversa ‘Variegata’ this is a plant which stands out to gardeners and non-gardeners alike. Smaller growing than the original but retaining the tier arrangement of branches, the leaves are longer and narrower and tend to be asymmetrical in shape with an irregular creamy-white margin. Known by the common name The Wedding Cake Tree its hardy in the UK and was awarded an AMG by the RHS in 1993.

Its size and shape means it is best suited to a larger garden where it has room to grow and show off its tiered habit and would look particularly effective in a large border with an under planting of spring bulbs. The flowers are followed by berries and on some soils attractive autumn foliage. The plant is often produced by grafting and so care should be taken to watch out for suckers from the more vigorous rootstock which need to be removed as soon as seen.

Aesculus hippocastanum

Aesculus hippocastanum flower
Aesculus hippocastanum flower

The Horse Chestnut tree immediately brings to mind the quintessential English village green with its broad spreading canopy, masses of white summer flowers and autumn games of conkers. In reality this is a plant which contradicts itself at every turn. Originally coming from the Balkans Peninsula (the bit that hangs down to the right of Italy with Greece hanging on the bottom) it was unknown outside of the region until the 16th century. The first written reference to it was in a 1557 letter from Istanbul by the wonderfully named Willem Quackelbeen. A description of the plants discovery and rediscovery by Professor H. Walter Lack can be found here . Even when first introduced it was believed to be from Asia and the first botanist to claim to have found the plant growing wild in the Balkans was disbelieved. In France its common name is still Marronier d’Inde which literally translates as Chestnut of India. The English Horse Chestnut comes from the belief that it could be used to treat horses, though it is actually poisonous to them, and that it was a close relative of the edible Sweet Chestnut, though all parts of the plant are poison to humans. In fact A. hippocastanum L. is only distantly related to the Sweet chestnut (Castanea sativa Mill.) with taxonomists placing them in separate orders.

Aesculus hippocastanum
Aesculus hippocastanum

So as well as not been a chestnut A. hippocastanum L. does not produce nuts, the conkers loved by generations of school-children are seeds and the spiky case they are found in, the actual fruit, is a “valvate capsule”! The scientific name is little better Linnaeus chose Aesculus as the genus name but it is the Latin name for a kind of Oak which bears edible fruits and the specific name hippocastanum comes from the Greek name for the plant hippocastanon with Greek for horse ίππος is pronounced “hippos.

The rapid A. hippocastanum L. spread across western Europe following its introduction and its continued popularity are testament to its value as an ornamental tree as it is of very little commercial value; it is poisonous and the wood is little used. This is soft, not very durable and difficult to give a good finish to. In the wild it is a short lived component of mixed hardwood woodland and only in cultivation is it allowed to grow to an impressive sizes of over 30m forming a wide dense canopy of leaves.

Aesculus hippocastanum young flowers and foliage
Aesculus hippocastanum young flowers and foliage

The tree is easily grown in normal garden soils but it does need a lot of space. Since 2000 the disease bleeding canker has become a wide spread problem but it appears to progress slowly and given time trees do appear to recover from it. The main problem with the disease is that it can weaken all or part of the tree and so cause a danger in that way.

Aesculus hippocastanum fruit
Aesculus hippocastanum fruit

A number of cultivars are available including Aesculus hippocastanum ‘Baumannii’ which is sterile so preventing the problem of conkers. There is also a red hybrid Aesculus x carnea which you see planted but it rarely lives up to expectation and the improved cultivar  Aesculus x carnea ‘Briotii’ should be chosen if a red chestnut is wanted.

Garden Myths: Number 5

Slugs and snails can be kept off Hostas by raising them high up or setting them in gravel.

Hostas are a versatile and attractive genus of garden plants; used and loved by gardeners. Unfortunately the large succulent leaves that make them so attractive are also irresistible to slugs and snails. This has led to an all-out war between gardeners and gastropod, with peace loving elderly spinsters turned into pathological nocturnal hunters. In an attempt to keep the Hostas safe many ploys have been tried, including raising them off the ground. It doesn’t work, I’ve seen snails more than 2 metres up vertical brick walls. Sadly gravel is no more effective and so far the only reliable way I have found is regular use of chemicals.

Dicksonia antarctica

OLYMPUS DIGITAL CAMERAAs one of the most popular examples of this fascinating and fashionable group of plants, it is seen more and more available for sale. Appearing like a fern on top of a short trunk its slow rate of growth is reflected in its relatively high price. There is a lot of confusion over its hardiness with some saying it is only hardy in the mildest areas of the UK while others, including Kew, say its foliage is hardy down to -2°C but the plant itself is hardy down to -10°C. Part of this may be expectation as it is only found in the tropical regions of the southern hemisphere, but may also reflect the location a particular plant has been collected from as it is found at up to 1000m above sea level where plants would be expected to be more cold tolerant. With that in mind, and considering the cost of the plants it may be as well to adopt a cautious approach as frost below -10°C are not unknown in most parts of the UK and provide some frost protection. This is commonly achieved by wrapping the plants in horticultural fleece or straw secured with chicken wire.

Dicksonia antarctica
Dicksonia antarctica

Dicksonia Antarctica Labill. Thrives in cool damp situations: given time and the right conditions it can achieve a 3 metre trunk and 2.5 metre long fronds. To do well it needs plenty of water and given enough water it is quite tolerant of exposure to sun. As you might expect from its natural habitat it does best in a humus rich acid loam but it is quite capable of growing in most soils, even poorly drained ones. There slow rate of grow makes them very suitable a pot plants, which allows them to be moved indoors in cold weather, but they do resent being pot bound. The strange structure of the trunks means the top of a tree fern can be cut off and will regrow if being planted; but the lower potion will not as it is composed of dead material.

The extant species of tree ferns are a remnant of a far greater group which helped lay

Dicksonia antarctica trunk cross section
Dicksonia antarctica trunk cross section

down the coal seams mined today. They do not form a taxonomic group as such and the term only refers to any tree with a wood like trunk raising the fronds off the ground. In UK gardens Dicksonia Antarctica Labill.is the species most commonly found and as originally described by Jacques J.H. de Labillardière. M. Labillardière published his description in the second volume of his to volume Novae Hollandiae Plantarum Specimen, which was the first flora published of Australia (or New Holland as it was then known). The journey from Australia to the floras publication in 1806 was anything but straight forward. Labillardière was a naturalist attached to the expedition the French sent out to find what had happened to the expedition lead by Jean-François de Galaup, comte de Lapérouse. They failed to find the lost expedition but did explore parts of Australia, New Zealand and surrounding islands. While they were away The French Revolutionary wars were causing upheaval in Europe and on reaching Java the expeditions scientific collections were seized by the British. It was only by appealing through influential British contacts that he was able to secure their return and so publish their descriptions.

References:

Dicksonia trunk showing aboriginal carving
Dicksonia trunk showing aboriginal carving

http://www.kew.org/plants-fungi/Dicksonia-antarctica.htm

Encyclopaedia of Ferns by David L. Jones

Hardy Garden Plants (3rd Edition) by Graham Stuart Thomas

http://www.forestferns.co.uk/

‘The International Plant Names Index (2012). Published on the Internet http://www.ipni.org [accessed 24 June 2013]

Novae Hollandiae Plantarum Specimen by Jacques J.H. de Labillardière

Taxus baccata

Yew hedge at Warwick
Yew hedge at Warwick

The Yew tree is an easily recognisable plant of gardens and the countryside, being one of the few native British plants to be widely grown as an ornamental plant. It is a very adaptable plant growing in most situations with the exception of water logged ground and it responds very well to cutting. This, with its dense evergreen foliage has made a very popular material for hedging and topiary. It is also said it is slow growth is an advantage as it reduces the amount of cutting needed but it is not nearly as slow as is sometimes made out. Young plants can make 20 to 30 cm of growth a year; only slowing with age, as we all do!

Taxus baccata foliage
Taxus baccata foliage

Many selections have been made of Yew including fastigiated and variegated ones but it is still at its most impressive as a green hedge where it does an excellent job of defining spaces and providing a foil to the more colourful occupants of the garden. If planting it as a hedge make sure to prepare the site well, necessary with any hedge, and make sure the soil drains freely; even if this means installing drainage. Its dense evergreen foliage forms a very long lived hedge even in the shade and it has been said a yew hedge has a longer working life than a brick wall. The other advantage over a brick wall is its adaptability; creating a new opening in a wall is difficult and will always show up while with a yew hedge a saw and hedge clippers is all that is needed. Once the new opening is made the plants will soon break away as it happily forms new shoots from the old wood and so heal the wound made.

Taxus baccata 'Fastigiata'
Taxus baccata ‘Fastigiata’

It is remarkably good at growing away from old wood, I’ve seen yew trees cut down to ground level and shoot away from the stump. Hawthorn is the only other plant I know with such a strong regenerative ability. This is a very un-conifer like characteristic, but yews are not very conifer like though there appears know doubt that it should be classed as one.

Though now the yews are seen mainly as garden plants; it has been an important plant to humans for a long time. The Yew combines great long levity with a valuable wood which was prized was making bows, the most valuable weapon for most of human history. The ancient Greeks called the yew τόξο (or toxo) and the Romans called the yew taxus. As with any plant with such an important and long history with humanity a lot of superstitions have grown up around it, and this can be seen in its importance to druids and its presence in church yards. The Fortingall Yew at over 2000 years old is believed to be the oldest tree in Britian and grows in the churchyard of the village Fortingall in Perthshire.

Taxus baccata 'Elegantissima'
Taxus baccata ‘Elegantissima’

In 1753 Linnaeus named the Yew Taxus baccata L. in the second volume of “Species plantarum” the Taxus from the Latin for yew and the baccata from the Latin for berry after the distinctive red fleshy arils which enclose the black seed and look like berries.  It is only this red fleshy fruit-like part of the yew which is not poisonous as all other parts of the plants can kill humans if sufficient is eaten. Yew exists as separate male and female plants and so these colourful arils are only found on the female plants. The species Taxus baccata can be found as both male and female plants its cultivars will be only one sex and this should be considered when choosing one.

Fatsia japonica

Fatsia japonica
Fatsia japonica

One of the classic garden plants for shade Fatsia japonica is much admired for its large, glossy, evergreen leaves and easy temperament. It grows happily in any reasonable garden soil and does particularly well in shade, though not so well in dry shade. It is also tolerant of a maritime garden though its large leaves will need some shelter from strong winds. The large fleshy leaves evoke the image of lush tropical rain forests but the plant is reliably hardy, though the result of crossing it with ivy produces the less hardy x Fatshedera lizei. Quickly forming a medium sized shrub with flowers borne on the end of the shoots. The flower buds and white flowers look a lot like a scaled up version of Ivy flowers, appearing in autumn. This late flowering means though the buds are reliably formed in the UK the flowers are often damaged by frost.

Fatsia japonica leaf
Fatsia japonica leaf

Known by a variety of common names including Japanese aralia, castor oil plant, fatsi, fig-leaf palm and glossy-leaved paper plant; F. japonica was originally described by Carl Peter Thunberg in 1780. This followed his trip to Japan where it grows wild and he named it Aralia japonica. It was re-named in 1854 by Joseph Decaisne and Jules Émile Planchon, two botanists working in France. They took it out of they genus Aralia and created the new genus Fatsia for it; so the name is now Fatsia japonica (Thunb.) Decne. & Planch.

In the wild Fatsia japonica is found from central Japan south along the Japanese islands almost to Taiwan and in South Korea. It is sometimes described as a monotypic genus, meaning that there is only one species init, but in fact there is at least two other species of Fatsia, Fatsia oligocarpella Koidz. and Fatsia polycarpa Hayata.

Fatsia japonica 'Variegata'
Fatsia japonica ‘Variegata’

It was introduced to western horticulture in 1838 and though the plain green Fatsia japonicais the one most often seen in gardens others are available and the variegated form Fatsia japonica ‘Variegata’ which has splashes of white on the leaves is worth looking out for.