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.

Viscum album

Viscum album
Viscum album subsp. platyspermum on limes trees at Hampton Court Palace, London

Mistletoe has fascinated humans for millennium, many plants have superstitions attached to them but mistletoe seems to have attracted more than most. It’s not hard to understand that a clump of evergreen leaves growing out of dormant tree in midwinter would grab the imagination. The druids are said to particularly venerate mistletoe growing on an oak tree, something it rarely does, harvesting it with a golden scythe on the 6th day after a new moon. Consisting that the plant is woody and gold is an extremely soft metal I not sure how true that is and as they left no written records of themselves this could just be dramatic invention. It still plays an important part in culture with the tradition of kissing under the mistletoe at Christmas but the plant is poisonous with a few berries bring on stomach ache though serious poisoning is rare.

Viscum album is wide spread across Europe and it has over the centuries been seen as a cure of a vast range of ailments right up to the present time. Diokorides (the 1st century AD Greek physician) reported that Hippocrates (in the 4th to 5th century BC) believed mistletoe could be used in the treatment of complaints the spleen and menstruation. Over the following centuries it has been recommended as a treatment for swellings, tumours, epilepsy, infertility and ulcers. In more recent times people have tried to use is to treat hypertension and cancer.

Viscum album
Viscum album (Mistletoe)

The genus Viscum L. contains about 100 spices but only V. album L. is native the UK and then mainly in the south and midlands. In naming Viscum album L.. Linnaeus took the Latin for mistletoe as the genus and album, no doubt referring to the distinct white berries, for the species name and listed it in volume 2 of his Species Plantarum. The genus Viscum L. is presently in the family Santalaceae along with 6 other genera. The common name Mistletoe comes from the old English mistel and many semi-parasitic plants around the world have the same common name. It is also known as including All-heal and Masslin in England and has many other names across Europe, Germany having a particularly large collection of names for it.

Mistletoe is notoriously difficult to establish and the species is now divided into 3 sub-species depending on the host plant it lives on.

Viscum album subsp. abietis (Wiesb.) Abrom. which grows on Abies species.

Viscum album subsp. austriacum (Wiesb.) Vollm. which grows on pine trees and very rarely on spruce.

Viscum album subsp. platyspermum Kell. (subsp. album) which grows on hard wood trees.

This goes in part towards explaining why it is so difficult to establish mistletoe as the sub-species are very specific to their chosen host but there also appears to be genetic factors as not all potential host can be infected with equal ease. For example, oak is rarely infected but even then there is a wide range of how readily a plant will be infected with a particular oak species. Therefore, where a plant has only a few mistletoe plants on it not become host to a lot and only specimens with a lot of mistletoes will host a lot.

Mistletoe is evergreen with tiny flowers that are insect pollinated and would never be noticed; the insects are attracted by the sweet smell . The male and female flowers are on separate plants with about 4 times as many female plants as male ones. The plants flower between the end of February and April  and the fruits (or berries) appear from October to May with Mid-March to mid-May being the best time to sow the seed, making sure to brake the outer coating and allowing the sticky contents to help the seed adhere to the bark of the host tree.

Mistletoe is a parasite, all be it a partial one, taking water and minerals from the host tree and this weakens the tree. Infected apples trees will yield between 7% and 56% less depending on how vigorous the rootstock is, with the plants growing on the more vigorous rootstocks affected the least. Once established the Mistletoe shoot doesn’t divide for the first 3 or 4 years then each year the shoot divides in two, ultimately reaching about 1 metre across, so giving a very rough and ready guide to its age.

 

Prunus laurocerasus

Prunus laurocerasus foliage
Prunus laurocerasus foliage

The cherry laurel is one of the most widely planted screening plants in gardens having reached western Europe by the end of the 16th century and is recorded in cultivation in Britain in the 17th century. It has been cultivated that extensively its geographical origins seem to be a little hazy but would appear to stretch from the east coast of the Adriatic sea eastwards along the south coast of the Black seas as far as the Caspian sea.

It is hard now to appreciate the effect that this plants arrival would have had in western gardens at the time of its arrival. Gardens at the time would have had very few evergreen bushes and along comes this large vigorous bush with its mass of large smooth shiny evergreen leaves. Added to this is the masses of white flower spikes in late spring and the small black fruits in autumn. Few plants offer such a range of attractive features. Sadly now it has been relegated to being a plant of little garden value.

Prunus laurocerasus flowers
Prunus laurocerasus flowers

This is in part because we have so many more plants to choose from now but also it has been a victim of its own success. It has been over planted in the past because of its appeal as a fast growing evergreen leading it to being used where a fast evergreen hedge is wanted’ a role it isn’t really suited to. Its large leaves look tatty and unattractive when it is cut with shears or a hedge cutter and it should really be cut back with secateurs. If you must have an inappropriately fast growing hedge you are better with × Cupressocyparis leylandii. On the rare occasions it is allowed to grow unmolested it makes a fine large flowering shrub in a large garden. Unfortunately it most often ends up crammed into far too small a space with its hacked leaves blacked at the cut edges. I have seen examples of people trying to grow it as a 600 mm high by 300mm wide hedge, something such a large and large leaved plant will never do successfully and which there are far more appropriate plants for.

Prunus laurocerasus 'Castlewellan'
Prunus laurocerasus ‘Castlewellan’

In most cases the form Prunus laurocerasus ‘Rotundifolia’ is grown in place of Prunus laurocerasus having leaves half as broad as long and a yellower green than the species. Other cultivars of note are Prunus laurocerasus ‘Castlewellan’ (syn. P. ‘Marble White’) a less vigorous plant with white marbled leaves, Prunus laurocerasus ‘Otto Luyken’ )a low shrub with upward pointing leaves and stems and Prunus laurocerasus ‘Zabeliana’ a low horizontally branching shrub which makes excellent ground cover even under the dripping shade of trees.

Prunus laurocerasus fruit
Prunus laurocerasus fruit

Along the way it acquired a variety of names until Linneaus set it as Prunus laurocerasus L. in the 1753 in the first volume of Species Plantarum. Prunus is the Latin for a plum tree which is in the genus and laurocerasus comes from laurel, the Latin for laurel, and cerasus, the Latin for cherry. This and the common name reflect the small round black fruits which resemble cherries. These cherry like fruits or their common name of cherry laurel should not lead you to believe the plant is in any way edible. All of the plant is poisonous and the reason you do not hear of people being poisoned by it is because you will be very ill before you have chance to eat sufficient to poison yourself. These poisonous chemicals are also the ones which produce the almond smell from the crushed leaves. That said this has not stopped people from trying to use it as a quack medicine. Laurel water was used for various treatments but is basically a solution of hydrogen cyanide of varying concentration and so extremely dangerous.

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.

Actinidia kolomikta

Actinidia kolomikta foliage
Actinidia kolomikta foliage

This beautiful wall shrub deserves to be far more widely grown yet currently only about 53 suppliers are listed in the RHS plant finder. This is surprising as few other wall grown plants provide such an attractive display for so long. The foliage opens green but quickly develops a white and pink variegation as if they had been dipped in pots of white and pink paint. This variegation only develops in the presence of plenty of sunlight and along with the shrubs scrambling habit means it is always seen grown against a south facing wall, although I can imagine it would also be very attractive scrambling over a south facing bank.

Actinidia kolomikta growing against a wall
Actinidia kolomikta growing against a wall

It’s white, slightly fragrant, summer flowers are over shadowed by the foliage and as it is both dioecious and it is only the male plant which appears to be in cultivation you are unlikely to see the fruits which are said to be edible. The closely related A. deliciosa (A.Chev.) C.F.Liang & A.R.Ferguson which is better known as the kiwi Fruit and several of the 100+ species of Actinidia Lindl. are cultivated commercially for their fruit.

Actinidia kolomikta (Rupr. & Maxim.) Maxim. is easy to grow not being particularly fussy as to soil type and vigorous, reaching up to 4.5 to 6 metres up a wall. They are reasonable easy to propagate by cuttings or layering and are perfectly hardy.

Actinidia kolomikta grown as a shrub
Actinidia kolomikta grown as a shrub

First described by Carl Johann Maximowicz and Franz Josef Ruprecht two botanist working in Saint Petersburg in the 19th century; they initially placed the plant in the genus Prunus but subsequently both revised their decision and Maximowicz placed it in the genus Actinidia created by the British botanist John Lindley which he named after the Greek for ray because of the styles in the flowers. The plant is native to the region of Amur in Russia where it is known as kolomikta and Maximowicz described the plant growing wild in his 1859 book Primitiae Florae Amurensis (Beginnings of an Amor Flora). Amur Oblast is still a largely remote region with temperatures that can range from above 30°C in summer to below -40°C in winter.

How to choose a tree

The first stage is deciding where the tree is going and why you want it there. This may seem obvious but unless you are clear about this from the start you are almost sure to end up disappointed. A tree will provide height and structure to your garden and with careful placement can provide privacy by blocking the view of overlooking windows or screen an unsightly building.

When choosing your tree bear in mind it will take up a significant part of the garden and is going to cast shade. Therefore think about how the sun moves around the garden and when the tree is going to block the sun and cast shade in the garden.

Once you’ve imagined how you and the tree are going to get along together in the garden it’s time to start considering the actual tree. A mature cedar is a magnificent specimen but in normal sized garden it’s never going to work; that said no tree will just grow to a particular size and just stop. Yes some will end up a lot smaller than others because of their genetics; but climate, soil and may other factors will influence how quickly they grow and how large they are after say 10 or 20 years. You also need to bear in mind that some trees have a lot longer period of interest than others (flowering cherries look lovely in flower but that may be only for a couple weeks and the rest of the year they can look rather drab). A lot of people are tempted by an evergreen tree but this will restrict your choices a lot, the shade is all year round when in winter you want all the natural light you can get, and you will still have the problem of clearing up the dead leaves as all trees lose their leaves, just evergreens do not lose them in one go at autumn.

There are many thousands of trees available and so I’ve made a list below of some suitable plants with their main attractions. That said this is a personal list and I’m sure other people would come up with other names, but I would hope there would be considerable overlap.

Lastly you cannot hope to walk into any nursery or garden centre and expect to find all of these, it would be impractical for many good reasons, but you should be able to find an example of a cultivar  which is very close to it if you are prepared to look around. It is all well and good setting your heart on a particular plant put there is no guarantee any nursery will actually have any for sale. Be prepared to be a little bit flexible.

 

Trees for the garden
Tree Flowers Foliage Berries Bark Ever-green Autumn Colour
Acer campestre
Acer griseum
Acer pseudoplatanus ‘Brilliantissimum’
Betula pendula
Betula pendula ‘Laciniata’
Betula utilis subsp. jacquemontii
Crataegus laevigata ‘Paul’s Scarlet’
Eucalyptus gunnii
Eucryphia x nymansensis ‘Nymansay’
Ilex aquifolium
Laburnum x watereri ‘Vossii’
Prunus ‘Amanogawa’
Prunus cerasifera ‘Nigra’
Prunus ‘Cheal’s Weeping’
Prunus ‘Kanzan’
Prunus pendula ‘Pendula Rubra’
Prunus serrula
Prunus x blireana
Prunus x subhirtella ‘Autumnalis’
Pyrus salicifolia ‘Pendula’
Rhus typhina
Salix babylonica f. pekinensis ‘Tortuosa’
Sorbus aria ‘Lutescens’
Sorbus aucuparia
Taxus baccata

 

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

Succulents Simplified by Debra Lee Baldwin

First off I was kindly lent a review copy of this book by the publishers Timber Press.

Its is clear from the book that Debra is a very knowledge and experienced grower of a group of plants which is often overlooked by UK gardeners, but non the less a very useful one. She does fall into the trap of all specialist plant books of seeing the subject of her interest as the solution to a gardens wants; but still finds many interesting and original uses of succulents.

The book is very richly illustrated with some mouthwatering plants and interested uses making it a useful reference book. The only real drawback is that the author is living and gardening in southern California where she enjoys a far milder climate that the UK, or for that matter most of America. This means a large majority of the plants are only going to be suitable as house-plants for most of us.

 

Taxonomic rank

This relates to the level within the hierarchy of plant names. The series of taxa for botany are set out in the International Code of Nomenclature for algae, fungi, and plants. Not all plants have an entry for every taxa and above the level of genus there is often a great degree of disagreement as to what belongs where. The important thing is that any plant can be identified by its genus and below.

 

Taxonomic rank

Kingdom

Subkingdom

Division

Subdivision

Class

Subclass

Superorder

Order

Suborder

Family

Subfamily

Tribe

Subtribe

Genus

Subgenus

Section

Subsection

Series

Subseries

Species

Subspecies

Variety

Subvariety

Form

Subform

(The principal taxa or in bold)