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Posts Tagged ‘E.H. Wilson’

At this time of the year the seasons are changing from winter to spring and with it comes unstable weather. One minute it is bright and sunny and the next it is almost dark and poring with rain, it is a challenge to get out into the garden to work. At this time I go for a quick walk in the park between rain showers and in a spot of light near the evergreen trees is a bright Rhododendron lutescens shining in the distance. Its pale buttery yellow flowers are almost unreal and beckon me to come closer.

Rhododendron lutescens is a delicate plant with the bright sunny flowers.

Rhododendron lutescens is a delicate plant with the bright sunny flowers.


Like many of our favorite plants Rhododendron lutescens comes from the treasure trove of China. The plant is found in north-east Yunnan, Sichuan, Hubei and Guizhou where is grows on the hillsides, thickets, mixed forest and limestone slopes.  It grows at elevations of 1700 to 2000 m (5600- 6600 ft.) . In China it is called Huang hua du juan.
 The brilliantly colored flowers of Rhododendron lutescens are a beacon of light in the garden at this time of the year.

The brilliantly colored flowers of Rhododendron lutescens are a beacon of light in the garden at this time of the year.


Rhododendron lutescens was discovered by Pere Jean Marie Delavay(1834-1895) in 1886 who was stationed in Kunming, Yunnan at that time. He was one of the important French Jesuit missionary collectors who explored China and other parts of the world and sent botanical samples(herbarium collections in this case) back to be identified and named by scholars at the National Museum of Natural History in Paris. When these collections were received in Paris Botanist Adrien Franchet would study them and classify the new plant material.  E.H. Wilson recollected the plant when he was working James Veitch  & Sons Nursery and  it was re-introduced in 1904.
There are 2 Rhododendron lutescens found at Finnerty Gardens as well as 2 at Playfair Park.

There are 2 Rhododendron lutescens found at Finnerty Gardens as well as 2 at Playfair Park.


There are 2 leaf forms(one being narrower than the other) known of  Rhododendron lutescens although they do not seem to be recognized by specific names. Rhododendron lutescens ‘Bagshot Sands’ is a form of the species which is said to have stronger primrose yellow colored flowers. A notable feature of the species is the exquisite coloring of new foliage which can take on an amazingly deep wine red coloring, this appears to happen after the flowering has occurred.  With the yellow flower color, fine delicate leaves and early bloom time, Rhododendron lutescens has been used for crossing with other species to create new hybrids. Several are quite well-known such as ‘Bo Peep’ with its creamy flowers and “Goosander’ which has larger buttery yellow flowers slightly flushed with coral on their backsides. Both of these named hybrids are small in stature and are worth having in any garden.
Rhododendron 'Goosander' shows a similar yellow coloring of parent Rhododendron lutescens.

Rhododendron 'Goosander' shows a similar yellow coloring of parent Rhododendron lutescens.


Rhododendron lutescens is a graceful plant which deserves to be better known than it is. It grows best in a location with dappled light or spots of sun as the flowering will be better and leaf color more deep.It likes loamy to slightly sandy soil which is slightly acidic but is tolerant to more neutral qualities as long as it is not too clay rich.  These plants like good drainage and are somewhat drought tolerant. Like all Rhododendrons it has shallow root fine fibrous roots which do not like to compete with other plants, therefore mulch or a groundcover may be the best thing for under the plant. It should be sheltered from drying winter winds.
The flowers of Rhododendron lutescens vary in the yellow coloring from very pale to deeper shades and sometimes appear almost greenish.

The flowers of Rhododendron lutescens vary in the yellow coloring from very pale to deeper shades and sometimes appear almost greenish.


Rhododendron lutescens might be hard to find, check at a specialist nursery or society sales. It is fairly hardy and tolerates temperatures down to at least -10 c. (4 f.). It can grow to a reported 5.5 m. (18 ft.) tall and a narrower width often  a multi-stemmed tree form with age. Best placement is in shrub borders, winter gardens, for early spring interest or specimen plantings. it can be mass planted and even is used as an informal hedge in some places.

Some beacons of information about this plant:

The most informative page about this plant: http://www.aussiegardening.com.au/findplants/plant/Rhododendron_lutescens

UBC has an interesting picture and info about the plant: http://www.ubcbotanicalgarden.org/potd/2008/04/rhododendron_lutescens_1.php

My page which tells the story of Pere Jean Marie Delavay and another of his wonderful dicoveries: https://namethatplant.wordpress.com/2010/05/17/delavays-maroon/

……..Until we meet here along the garden path, soon I hope………

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When I was in Horticulture school we learned many plants ranging from small ground covers, larger shrubs and finally to the majestic trees. Some of these plants are very overused while others are not seen enough, it all depends on how well known and in fashion they are.  One tree I learned is much more common in Vancouver than it is in Victoria and that truly is a pity. What I am referring to is the ‘Katsura’ tree (Cercidiphyllum japonicum) which has many features that it should be on most peoples lists of ‘must have’ trees.

Cercidiphyllum japonicum or 'Katsura Trees' on a rainy spring day in Vancouver.

Cercidiphyllum japonicum or 'Katsura Trees' on a rainy spring day in Vancouver.

At one time, long ago, Cercidiphyllum japonicum grew wild in a much larger area. Fossil records show Katsura trees lived in Europe and western North America during the Miocene Epoch 5 to 23 million years ago. Now They are found only in Japan and China. They are found in south central China,  particularly in north west Szechwan province where E.H. Wilson found forests of them in 1907. The trees found in China were considered to be a variety Cercidiphyllum japonicum var. sinense at one time and were said to be more tree-like.  In Japan they are found at valley bottoms where the soil is richer and there is more rainfall which these trees need.

The attractively shaped leaves is one of the most appealing aspects of 'Katsura' trees

The attractively shaped leaves is one of the most appealing aspects of 'Katsura' trees

Cercidiphyllum japonicum was introduced into cultivation in a most unusual way. Thomas Hogg  Jr(1819-1892) who owned a plant nursery with his brother James. He was appointed a U.S. Marshal by President Abraham Lincoln in 1862 and was then assigned to a diplomatic mission to Japan. While he was there, Thomas sent seeds of Cercidiphyllum japonicum to his brother  in 1865. His brther germinated them. Thomas was in Japan 10 years and also introduced several other well known plants;  Hosta ‘Thomas Hogg’  now called H. undulata var. albomarginata is probably the most famous.

Typical fall color of Cericidiphyllum japonicum found in the perennial border at Playfair park in Saanich.

Typical fall color of Cericidiphyllum japonicum found in the perennial border at Playfair park in Saanich.

Katsura trees tend to be multi trunked specimens which have strongly ascending branches. The leaves are relatively small and delicate compared to what the trunk and branches can become when these trees become more massive with age. It is intersting to note that these trees are also somewhat unusual in that they are dioecious meaning they are male or female plants.

A massive trunk of a Cercidiphyllum japonicum found in Beaconhill Park in Victoria.

A massive trunk of a Cercidiphyllum japonicum found in Beaconhill Park in Victoria.

In an ideal world Katsura trees grow to be enormous, Wilson found forests of trees with trunks of 2(6cm) and 3ft(90cm) widths and had regrown from their original stumps after the original trees had been harvest.  The largest one he noted was a remnant of a 17.5ft(5.33m) wide stump base. In the wild these trees can attain a height of 100ft(30m), but about half this in garden settings.  These trees are the most important source of wood  in Japan, and is used extensively for cabinetry and paneling there.

The color range of Cercidiphyllum japonicum ranges from crystal clear yellows through oranges and crimsons into plums as seen here.

The color range of Cercidiphyllum japonicum ranges from crystal clear yellows through oranges and crimsons into plums as seen here.

As autumn approaches Katsura trees put on a display for the senses, visually they are stunning with a color range few trees can achieve. On any day you will feast your eyes on shades of clear yellow, butter, many shades of peach and apricot, and into more striking crimsons and plums. You will notice they give of a pleasant odor as the leaves turn color, some describe it as ‘honey like’ and others say it has more of a’caramel’ or ‘brown sugar’ quality. How ever you explain it, it is a pleasant surprise which many people look forward to every year.

The striking golden tones of a happy Katsura tree changing color in the fall.

The striking golden tones of a happy Katsura tree changing color in the fall.

Cercidiphyllum japonicum is almost a perfect tree. It is very pest free and adaptive to most locations. In a garden setting it will grow to about 50ft(15m) tall which will fit in nicely to many landscapes. It makes an excellent multi stemmed residential, commercial, golf course or park tree. One thing you must keep in mind when placing it is having an adequate supply of water during the dry months.  Plant them in deep, rich, well drained soil. They need full sun to look their best.  This tree tolerates temperature down to 20f(29c). Newly emerging leaves can be damaged by late frosts.  there are several forms now on the market worth looking into if you are interested. the weeping forms are very attractive in the right location.

The same Cercidiphyllum japonicum in summer and fall. The corner planting along Quadra and Fairfield in Victoria.

The same Cercidiphyllum japonicum tree in summer and fall. The corner planting along Quadra and Fairfield in Victoria.

More on Cercidiphyllum japonicum:

Excellent summation of  Katsura trees: http://www.arhomeandgarden.org/plantoftheweek/articles/katsura_tree_11-2-07.htm

A very complete listing of important plant people, scroll down to Hogg: http://www.plantsgalore.com/people/plant-people-H.htm

Wiki’s listing of the famous Katsura tree and relatives: http://en.wikipedia.org/wiki/Cercidiphyllum

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