International Oaks The Origin, History and Development of Arboretum Trompenburg

by J. R. P. van Hoey Smith Arboretum Trompenburg Rotterdam, Holland

he history of the arboretum started in 1820 when a small county seat was built in the vi llage of Kralingen, now part of T Rotterdam, 4 km from the center of the city. The owners had their permanent house and work in Rotterdam, but the weekends were spent at Kralingen. The house was not built on poles, as is the custom now, but on casks with long willow branches in them. These were put vertically on the earth and loaded, whereby the willow twigs bend outwards and so give a considerable canying capacity. This old­ fashioned way of making foundations is a consequence of the weak structure of the underlying soil. Forty percent of Holland, including Rotterdam, lies below sea level-our arboretum by four meters! During the floods of 1953, the dykes were half eaten away by the water before the tide turned and saved us. Originally, the Rhine Maas Delta consisted of peat swamps. In the Middle Ages, and also later, these were used commercially, and the peat was removed for burning. Of 20 to 30 meters of soft peat, 4 meters were removed and the rest flooded again at each tide. So, a small layer of heavy river clay covered the thick peat layer and mud was deposited on top. The peat sti ll contains many stems of oaks, birches, and alders. When digging our swimming pool, the stem of a heavy oak had to be removed. The wood was still in perfect condition and used for repairing a Viking ship, uncovered by reclaiming land from the Zuiderzee. A reclaimed area enclosed with dykes is called a polder, and when the water was pumped out of the polder Kralingen, long straight ditches were dug, about 45 meters apart. Trompenburg consisted of

contd. on pg. 20

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Arboretum Trompenburg garden from his father's death in 1919 until on top of a hole filled with old bricks and • • • 1950, when he retired to his country home. roofing tiles in a small quantity of soil. This His son took over, extended the oak specimen has grown slowly this way. contd. from pg. 19 collection already started by him, changed Quercus coccifera, definitely not hardy here more meadows into gardens, and started under normal conditions, was planted on top three plots 45 meters wide but 350 meters it with bales of peat moss, then covering by several new collections, such as the of a low brick wall, and also in this way long. In 1820, when the house was built, asphalt; or, the second method, digging by Rhododendron collection, which now con­ grows slowly but is hardier. Instead of only the middle plot was laid out as a garden huge dredges a canal, removing all the peat tains 800 taxa. He expanded the succulent improving the soil, which most gardeners do, and the other plots remained meadows. down to the original sand 20 meters below collection, started by James van Hoey Smith we have to reduce fertility sometimes. Our soil consists of a layer of good and after that, filling the canal with sand just after World War I, as a result of a visit to The first plantings of dendrological disintegrated mud of about 50 em over a again. Both methods are very expensive, and the Canary Islands. Every spring the big interest were made about 1870. Before that layer of heavy impenetrable clay of about 30 one may be astonished that we nevertheless specimens are moved from the greenhouse date, from the original plantings of 1820, em, all resting on the 20m of loose light peat. have good roads. into the open and so contribute to the general only some oaks remain. From the 1900 The clay must be kept carefully, because Trompenburg was bought by James interest and attraction of the Arboretum. As when it is removed oxygen enters the peat, Smith, a Rotterdam shipowner and agent in a specialty, we grow 350 succulent taxa of contd. on pg. 22 which disintegrates, and the soil collapses. 1850. His grandfather had come from Euphorbia. This circumstance means that only a small England more than a century earlier, and he Our yearly rainfall is 760 Map of Aboretum Trompenburg but very fertile layer of garden soil is still had both English and Dutch citizenship. mm. The climate is more available. In dry periods we have to water He immediately extended the house and in continental than in England, often because the layer of clay is level with 1870 ordered the well-known Dutch garden and we have 10° C more the water table of the polder and no moisture architect, Zacher, to lay out the western part. frost. This just prevents us enters through the heavy clay from the side, His son, William, planted a long alley on the from growing the beautiful and roots cannot penetrate the clay. This, in edge of the eastern part in 1900. James van rhododendrons of hardi­ a country of plentiful water, but where the Hoey Smith got the opportunity to lay the ness 3, and even some of water is controlled so carefully. We know basis of the present arboretum, and his son hardiness 4, as rated in the this from experience, as a former head now completes this work. William added the Royal Horticultural Society gardener once thought it would be a very name "van Hoey" for his son in order to Rhododendron Handbook. good thing to remove the clay from an area prevent confusion in the shipping business From 1963 on, many big­ often by ten meters. Still now, 40 years later, to England, where the names James and leaved rhododendrons have we have to bring in new soil each year, the Smith are so common. been tried, but that year was old having sunk away. The opportunity to develop the arboretum the last with a severe winter. The Romans built through the swamps arose from a circumstance at the time Rhododendronflctolacteum corduroy roads, which were discovered in considered a disaster-the Dutch Elm flowered last year for the Holland in several places. These were built disease. Looking back, we may now first time. The soil is very from wooden sticks 2 m long and with a consider this to be a blessing to the fertile, with a pH about 1. Entrance 9. Heather Garden & diameter of I 0 em, connected to each other arboretum, although elsewhere it remains a 4.5, ideal for rhododen- 2. Visitor Center Succulent Border and in this way forming a reliable road. We disaster, as there has not yet been found an drons. 3. Hosta Walk 10. Goldfish Pond brought sand on to our roads and when the equivalent elm substitute for planting along Araucaria araucana, 4. Perenhof 11. Rosarium road sagged, new sand was put on top. The roads and dykes. Imagine that if the 400 large although growing in sev­ 5. Woudesteyn 12. Evergreen Oaks more sand, the quicker the sagging elms were still growing, then only a forester eral other places in Hol­ 6. Hintzen 13. Cedar Group -, 7. Nursery 14. Quercus robur 'Pendola' progressed. Now the modern method of could enjoy the long straight stems under land, always froze at 8. Succulent Greenhouse 15. Pinetum building roads in Holland is by one of two which not even grass would grow. Trompenburg. Now a 16. Sheep Meadow systems: removing all the sand and replacing James van Hoey Smith managed the specimen has been planted

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War, a herbaceous border, rose garden, ered 50 years ago; Arboretum Trompenburg • • • goldfish pond, heather garden and succulent • Pinus pumila 'Dwa1f Blue', the original house were laid out on this plot, and the plant from which Mr. den Ouden contd. from pg . 21 original vegetable garden was made a described this form; nursery for woody plants only. • Quercus pontica, 50 years old; Plot 4. "Perenhof," situated east of Plot 3, plantings, we still have a Gymnocladus from the plantings of 1820, the elms having was transfeiTed to the management of the • Q. dentata, also 50 years old; dioicus and a Fraxinus xanthoxyloides var. been cut down. The former orchards have arboretum in 1965 in order to synchronize its dumosa. The latter one had to be moved 80 • Q. pontica X Q. dentata, 35 years old (Q. maintenance with that of the arboretum. It meters, which was done with complete ' Pondaim'); was also laid out around 1820 in the English success with a frozen soi l ball of 4 meters in • Q. macranthera x Q. frainetto , 35 years landscape style, but bad been terribly diameter. During three years everything was neglected. It has been reorganized com­ old (Q. 'Macon'); prepared for the relocation, and photographs pletely, maintaining the English style. • Fagus sylvatica 'Aureopendula', 40 of the event appeared in the Rotterdam Plot 5. "Woudesteyn," situated east of years old; newspapers. Plot 4, was leased some years ago from the James van Hoey Smith was the first to • Q. robur 'Pendula' , 40 years old; municipality of Rotterdam in order to extend plant interesting trees on a large scale with • Liriodendron tulipifera 'Fastigiatum', the Arboretum. During wartime it was used the intention of starting an arboretum. Only for allotment gardens, but these were given 50 years old; after all the elms had been removed could we Photo by JRP van Hoey Smith up after nothing had been done, and the • L. tulipifera 'Mediopictum', 40 years carry out these plans. From 1928 onwards, Quercus (macranthera X frainello) 'Ma con.' clearing was tremendous work. At the old; every year he ordered plants from Hesse, been transformed into a beautiful group of present time it has shrub borders, and the Germany and Yilmorin, France, along with blue Atlas cedars, and another part was • L. tulipifera 'Crispum', 40 years old; dahlia collection is planted there. local nurseries. Every Sunday, together with replanted with different rhododendrons. • L. tulipifera 'Integrifolium', 40 years old. Of special interest to visitors are: his sons, he visited some nurseries and Plot 2. The western part of the original 1. The collection of oaks: 94 species and I 00 ordered plants. His son, the writer of this plots was laid out, also in the English cultivars; of these taxa, 20 are evergreen. Many visitors ask how we have succeeded article, went on ordering, but also from Mr. landscape style, in 1870 by Zocher, who also 2. The collection of beeches: 50 taxa. in collecting such an assortment. Indeed, Hillier in England. Moreover, he continues planned the Rotterdam municipal park and 3. The collection of rhododendrons: 325 many have been received in unusual ways. A collecting and ordering seeds and scions and many other famous gardens. Apart from a species and 475 hybrids. witch's broom that we found in a Picea obtaining plant material from around the Thuja plicata and a Taxodium distichum, gave a new dwarf Sitka spruce 4. Ginkgo biloba: 13 cultivars. sitchensis world. only some old Taxus, a Ginkgo, and a I 00- 5. Liriodendron: 2 species and 8 cultivars. Picea sitchensis 'Strypemonde' . When The Arboretum consists of five parts laid year-old grove of the orange-red azalea, 6. Cedrus: 4 species and 24 cultivars. driving from the airport to the city of out at different times. Originally, there were Rhododendron. japonicum remain of the 7. Chamaecyparis: 7 species and 135 Hamburg, l saw a nice umbrella-shaped only three plots. The 1870 plantings. A cultivars. shrub. It proved to be a weeping oak, and a fourth and fifth plots meadow with sheep at­ 8. Pinus: 40 species and 145 cultivars. much better form than the existing one. This were added in 1965. tracts visitors. In 1928 shrub is the mother of our Quercus robur The five plots are de­ part of the meadow was The above are only a part of the total 'Pendula' growing over the pergola. scribed as follows. made into a pinetum. coll ection of over 3,000 woody plants, From Fagus sylvatica 'Zlatia', the golden Plot 1. In 1820 the Plot 3. The eastern part among which some outstanding specimens beech, I bred several plants with leaves center of the three origi­ of the original plots was are: ranging from yellow to green and deep nal parts was laid out as edged in 1900 by an purple to yellow-brown. From Fagus • Fraxinus xanthoxyloides var. dumosa, 90 a garden in the English avenue pl anting, mainly sylvatica 'Rohanii' I grew many incised landscape style. We find Photo by JRP van Hoey Smith of elms with some inter­ years old, transplanted 20 years ago; here a couple of com­ esting trees in between. • Picea omorika 'Expansa' which I discov- Quercus x/ibanerris 'Rolterdam.' contd. on pg. 24 mon European oaks left After the First World

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Arboretum Trompenburg • • • disease, many large specimens of common unscientific. However, all differences are trees were planted in order to give shelter. easily visible, and in that way I can show Now these have done their duty and can be everybody the specific features of the oaks contd. from pg. 23 removed. We do this very slowly, in order we grow. not to disturb the public, who also, in The full list of 177 oaks is available to forms with colors also ranging among green, much as possible, evergreens and decidu­ Holland, protest against every tree cut down. anyone asking for it. Below, in alphabetical purple-green and yellow (F. sylvatica ous trees, for winter interest; Sometimes, we have to make a choice sequence, are some of those which grow 'Rohan Gold'). Fagus sylvatica 'Dawyck', 2. I give much attention to colors; two between two trees when they touch each well here and have proven to be of interest thought to be sterile, fruited and 40 percent contrasting pinks, for example, will not be other. Doing nothing is also a decision, for parks and gardens. were fastigiate. These 40 percent consist of adjacent; which often results in two ugly trees instead Quercus acuta from Japan, an evergreen mainly the original green form, but also some 3. I keep the vistas open; of one nice one. species with big leathery leaves, needs in dark purple and yellow. Now, 20 years 4. The axe (now chainsaw) is my paint­ In 1956 a foundation was formed with the protection here when young. Now we need later, these seedlings are 10m high and are a brush. purpose of securing the Arboretum for only cover the lower parts of the trunk, and welcome extension to the nursery assort­ future generations. The foundation, partly the 25-year old, 6 m tall bush fruits yearly. ment, as they keep their dense fastigiate habit Also, visitors often ask how we manage to financed by the van Hoey Smjth famjJy and Q. acutissima from Japan, Korea and very well. Some of them are now available produce only beautiful specimens in nice partly by the Foundation Volkskracht, in China is of medium size. It is deciduous, and under the names of F. sylvatica 'Dawyck surroundings. The answer is very simple: we 1970 received additional support from the the serrate leaf resembles that of Castanea, Purple' , 'Dawyck Gold', and 'Red Obelisk'. cut vigorously every plant that is growing Rotterdam Municipality, and so its future but is narrow and - contrary to Q. Our Arboretum of only 5 hectares (13 badly. This especially refers to some was confirmed. This was important because variabilis - is bright green underneath. acres) has limited possibilities. Therefore, conifers, which grow well when young. As our Arboretum is visited not only by Q. alba, the common American white we have to make use of every inch. soon as they are around 50 years old, some botanists and dendrologists, but also by oak, native from eastern Canada to Florida. Specializing is essential under such circum­ of them get thin and leggy. We cut them out many Rotterdam residents looking for a The name alba refers to the white bark. In stances, not only in species, but also from a and replace them with younger ones. Abies nice, quiet place to relax from the turmoil of Europe this species does not grow to the size selected species-only the interesting and and Picea in our climate and in our the city, with its harbors, industry, oil it reaches in America, where 40 m tall is not nice trees are kept. Moreover, our principle is Arboretum generally have to be replaced refineries, etc. They all enjoy the blessing of unusual. In autumn the deeply lobed leaves that the trees must grow in aesthetically after such a term, and specialists have this oasis of green. color from red to purple-red. Acorns justified circumstances. This means that we advised that the reason is that our climate In 1991 we had 45 ,000 visitors, and for impmted from America are often infested do not plant too does not give them enough rest in winter 1992 four gardening groups from the USA with worms, and all acorns with round holes closely, and that (they need lower already are booked for guided tours. should be destroyed immediately. It seems we do not plant temperatures likely that some selection done with seed similar trees then) and in The Genus Quercus in Arboretum from the wild or with seed from one of the next to each summer, in dry Trompenburg few European trees will result in a good other. Asked by periods, our air In the Arboretum Trompenburg and in cultivar. The wood is of the same good visitors what is lacks the mois­ the nursery we grow 93 species and 84 quality as our common oak. our system of ture they always cultivars of Quercus, and we hold the Dutch Q. aliena var. acuteserrata from China, management, I have in the reference collection. We also grow oaks of Korea and Japan has toothed leaves of 15-20 always answer mountains. minor interest. However, having at our em. It is a deciduous but smaller tree. that my system Pinus and disposal only 5 hectares, we are obliged to Q. bicolor from eastern North America. It is having no Junip e rus , specialize. We do not grow many of the is a large tree with leaves grey beneath, and system, but I however, do not common forms of Quercus robur and can be recognized by the many dead young suffer at all. 1' Quercus petraea. I simply have to select (for have four Photo by JRP van Hoey Smith shoots which form in the crown and by its Moreover, lack of space) in a very personal way and guidelines: A general view of Arboretum Trompenburg, near the go/fish pond. 1. I mix, as just after the elm with a personal taste, which is of course very contd. on pg. 26

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Arboretum Trompenburg However, the clone we usually grow is very against the dark brown of other leaves. The • • • nice, and makes such a good tree that further acorns are bl ack with yellow stripes. selections seem a waste of energy. Q. imbricaria, also from the eastern USA, contd. from pg . 25 Q. garryana from northwestern North is another favorite of mine. I planted a America, especially Oregon, is of medium specimen when I was 17, in 1939, and now it bark peeling off like that of a birch. imported scions and grafted them on Q. size with a short, stout trunk and a wide­ is already a large tree of 18 m tall and the Q. castaneifolia from Caucasus and Persia robur, again with no success. The following spreading crown. The leaves are shiny dark trunk has a diameter of 60 em at 1.7 m. The has buds like those of Q. cerris, with long year we tried Q. dentata seedlings for green above and deeply cut into oblong leaves are entire, narrow, oval and dark narrow scales. The leaves are larger, with understock - still no success!. The next lobes. This beautiful oak, which with Q. alba green. Although Hillier says that it has rich sharp pointed teeth. Like Q. cerris, it grows year, we tried Q. pontica seedlings, again belongs to the white oak group, should be autumn colors, this has not been our very well in chalky soil. It is difficult to find a with no success. We nearly did not dare to planted much more frequently and grown experience. It produces many good acorns, true specimen for sale at nurseries. ask our American friends for more scions. from seed. Will nurserymen please see to it which come fairly true. I can recommend Q. cerris from southern Europe and Finally, grafts on seedling Q. macranthera that it becomes more readily available? this tree for every purpose. Q. glandulifera (syn. Q. serrata Thunb., Q. libani, in its native habitat in Syria and Turkey is a large tree and grows quickly in all and Q. 'Macon' F2 seedlings were success­ soils. It is very wind resistant. The leaves are ful, and we now await to see which will prove not to be confused with Q. serrata Blume, Turkey, is a medium-size tree. With us it quite variable, and the large acorns have cups to be the best stock. After five years of syn. Q. acutissima Carruth.) from Japan, makes only a very large shrub. Its small, with long scales. The reason why this tree is experimenting, we now have only three one­ Korea and China is one of the oaks from serrate, narrow leaves are as conspicuous as never used in forestry is that the trunk easily year-old grafts. which in 1951 acorns were collected in Kew, the large acorns. At Trompenburg it splits in winter, which limits its timber value. Q. falcata, from seeds received from the and one grew at Trompenburg into a hybridized with Q. cerris, and all those Its cultivar 'Variegata' is a small tree with eastern USA. In 1959, we selected a beautiful large tree. The leaves are small with hybrids are named Q. xlibanerris. One of creamy white leaf margins. specimen with the typical leaf with two long gland-tipped teeth. them I will discuss later in the hybrid section Q. coccifera from the Mediterranean is a pointed lobes. It moreover has a good Q. ilex from the Mediterranean region of this article. slow-growing, dense evergreen shrub. The conical habit, but has not the red autumn grows in England into a large tree. In central Q. macranthera from the Caucasus and small leaves are very prickly, but in Turkey color of many other red oaks. It is Europe it is generally only a large shrub. This northern Persia is a fast growing medium to and Morocco they are an important food for astonishing that in their native habitat red evergreen tree with leaves like flex is not large tree. It can be recognized easily by its goats. In those countries whole areas are oaks do not hybridize more, although they generally hardy here, but when grown from stout one-year shoots clothed with a yellow­ covered by this oak and after having been grow together in the wild. Occasionally, acorns collected from certain trees in a brown velvety tomentum. The young bark eaten down every year, they show a great however, they do, and in the Monographie London park, those will be hardy. Either can be grey with long wide plates and only a variety of topiary shapes. Plants grown from des Chenes of the French professor Camus those trees, already introduced in the l6'h few furrows. This robust tree has an seed collected in cool areas are more hardy. one finds many hybrids. We have Q. Century, are from a hardier ecotype, or they interesting, dense, compact appearance. Q. dentata from Japan, Korea and China xsubfalcata (Q. phellos X Q. falcata) or Q. have adapted themselves to colder weather. Q. marilandica from the eastern USA is a makes a small tree here, with remarkable ludoviciana (Q. pagoda X Q. phellos), but In England this tree is called Holm Oak. It is small, slow growing tree of spreading habit. large leaves, sometimes 30 em long and 18 why is the hardiness insufficient here? found in nearly every park and large garden, The dark green glossy leaves are triangular em wide. They often remain on the tree until Q. frainetto as seen in the wild has leaves and it should be planted widely both on the and tawny yellow beneath. The clone from next spring. Our specimen has very small, which are quite variable, from something European Continent and in the milder parts local nurseries is a selection with really round acorns of 1 em diameter and it fruits resembling those of Q. petraea to those of of America. magnificent leaves, which justify its planting abundantly. The young shoots are yellow­ our Q. frainetto obtained from nurseries. Q. ilicifolia from the eastern USA is a in the garden. brown and downy. It is one of my favorites. Our specimen is a beautiful, double-lobed spreading shrub. In the Arboretum Tervueren Q. mongolica var. grosseserrata from From America came a cultivar with deeply selected clone which should have a cultivar near Brussels, it borders groups of large Japan, together with Q. aliena var. cut leaves. They arrived grafted on Q. name and is always propagated vegetatively. J trees. The leaves of this red oak, although not acuteserrata, suffers with us from die-back macrocarpa stock. In the next year, the Some years it produces acorns abundantly, coloring well in autumn, are white-felted of young branches (as do several other East stock threw off the scion. Two other and perhaps one could make selections with ' beneath. They persist in the winter, and many importations did exactly the same. Then we still more deeply cut double-lobed leaves. leaves then turn and show their white side contd. on pg. 28

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deeply cut, lobed leaves are pubescent on Kew acorns and our present crop comes true Arboretum Trompenburg • • • both sides. In nurseries generally the cultivar from seed for 50 per cent. 'Pendula' is sold, and the normal-growing 'Fastigiata' is well known although not contd. from pg. 27 species is very rare. llike it so much because always grafted from a good specimen. of the leaves. Therefore, more selection work is needed, so Q. robur is too common here to give that only first class material becomes Asiatic species). They are very similar and petraea is elegant. Several cultivars are much attention. However, it has many available. have large and wide serrate leaves. Although available, including the following: cultivars, of which I would recommend the 'Pectinata' only reaches large shrub size. both are said to be medium size trees, at 'Mespilifolia' can reach a large size and following: The leaves are very deeply cut with long, Trompenburg it looks as if at maturity they has narrow, 15-20 em, nearly entire, dark, 'Atropurpurea' is a very slow-growing narrow, pointed lobes. We tried 1000 acorns will reach a considerable size. glossy green leaves. It is a solitary beauty in purple-leaved oak, mostly not larger than a and not one came true. Q. myrsinifolia from China and Japan is a a park. shrub and suitable for small gardens. 'Pendula' has drooping branches but beautiful, small, compact, densely branched 'Laciniata Crispa' is most interesting. The 'Concordia' generally also remains a grows to a large size. It is very suitable to evergreen tree. The shining leaves are leaves of the first flush are long and very yellow shrub, but I have seen larger fruiting train over a pergola . lanceolate, green above and grey beneath. narrow, like threads. The second flush has specimens in eastern Europe. From seed of 'Salicifolia' is a very interesting oak. Although said to be tender, it has survived more or less normal leaves. Consequently, one of these, the Arboretum Trompenburg Hillier assigns it to Q. petraea because of the the last three severe winters undamaged. changing with the season, it is more peculiar has a promising normal-growing specimen. petioles of the leaves. The very small acorns, Q. palustris from eastern North America than beautiful. 'Cristata' has deeply lobed, folded and grows there in wet conditions. My experi­ Q. phellos, the willow oak from the curled leaves. Our specimens are from 1951 contd. on pg. 30 ence is that it grows best in dry places here southeastern USA, is a large tree with small, and even in a street it is a success. The deeply entire, willow-like leaves. It is a striking tree cut, pointed leaves are very similar to those with a good shape. of Q. coccinea but they are smaller, and Q. phillyreoides is the eastern Asiatic sometimes the autumn color is as good. counterpart of Q. ilex, and is hardier. It Unlike Q. rubra and Q. coccinea, this tree grows into a very large shrub. The leaves of does not make large limbs but grows into a this evergreen are oval, leathery bronze­ columnar trunk with many smaller side green with minute teeth. It should always be branches. Also, the many dead small planted in groups to get acorns, since cross branches in the crown, which an very pollination is required. This oak is ideal persistent, are a help in its recognition. where an evergreen shrub is required. Q. petraea has its habitat in all of Europe Q. pon.tica from Armenia, Caucasus and and Turkey. It grows more upright than Q. northeastern Turkey generally grows as a robur and the bark is less furrowed. Unlike large shrub and can in 20 years reach 6 m tall Q. robur, the leaves have I em petioles, the and 6 m wide. The large leaves are very vein is yellow, the fruits are sessile and the similar to those of Castanea sativa, but buds are pointed. Owing to the typically wider. The large, sessile acorns fall early in taller trunk, the timber is more valuable than September, and the shrubs start fruiting that of Q. robur and is often used for when I m tall. This plant grown by itself in a plywood. In forestry, especially in Ger­ lawn, as in Trompenburg, is quite a sight. many, Q. petraea is grown mostly in Grafting is difficult, and from seed it grows mountainous areas, and the famous Spessard very slowly. It is one of my most beloved Oaks are all Q. petraea. Even standing alone, treasures. ©Guy & Edith Sternberg this species never has the wide-spreading Q. pyrenaica grows wild in southwestern The famous old specimen of the shrubby oak species Quercus pontica at Arboretum Trompenburg. habit of Q. robur-Q. robur is robust, Q. Europe and Italy to a medium-size tree. The

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Arboretum Trompenburg ... hundreds of hybrids are described, but these Q. 'Macon' (Q. macranthera x Q. are mostly of little horticultural interest and frainetto) also originates from Trompenburg. not available anywhere. It's name is derived from the parent Q. contd. from pg. 29 Q. xhispanica comprises a group of macranthera and an old name (Q. conferta) seedling hybrids of Q. ce1-ris and Q. suber. for the other parent, Q. frainetto. The leaves however, have very long peduncles. The and Japan has serrate leaves similar to those These species hybridize very easily, and the are similar to those of Q. frainetto, but the leaves on some young trees still have some of Q. acutissima, but they are white beneath. seedlings are variable. The leaves vary from indumentum of the young shoots and the lobes, but mature trees have only entire The bark is corky and is very beautiful when resembling either parent to every thinkable buds is identical to that of Q. macranthera. leaves. From seed it comes true nearly 100 mature, as seen at Kew. The hardiness is a intermediate form, and the bark does the The acorns are 3-4 em long and only 0.5-0.8 per cent. Its origin is not known. It was problem here, and consequently the origin of same. The second generation seedlings (F) em wide. It makes a beautiful tree. known in Germany in 1873 and I doubt the seed is very important. Acorns from are even more variable. Out of an enormous Q. xrosacea 'Columna' is the hybrid of Q. whether it grows Eastwood Hill in New Zealand produced number of hybrids, some have been given petraea 'Muscaviensis' and Q. robur anywhere else in seedlings, which freeze down to the ground cultivar names, and these should be 'Fastigiata'. It commonly is referred to as a the wild. I would every year. A plant from acorns collected at propagated vegetatively. From Q. suber all cultivar of Q. petraea. When young, the not object if it is high altitude on Mount Omei, China, is doing inherit the evergreen leaves and sometimes habit is good, but it starts broadening after 15 given species very well. the corky bark. From Q. cerris originates the years. At Trompenburg it has fruited rank. Q. warburgii (syn. Q. 'Warburgii' of the large size. Best known, since 1763, is abundantly, and progeny Mendel back to the Q. rubra is 1998 World Checklist and Bibliography of 'Lucombeana', a large tree. 'Diversifolia' parents. But among them we found two with too common to Fagales by Govaerts & Frodin) is of has very peculiar leaves, and 'Ambroziana' a better, compact fastigiate shape. The first, · warrant com­ uncertain origin. The only original tree is originates from Mlylany, the estate of Count 'Westcolumn', has leaves like those of the F, ment, but it has growing in the Botanical Garden at Ambrozy in Czechoslovakia. hybrid parent, is 8 m tall and 60 em wide. The one outstanding Cambridge, England, and I doubt very much Q. xleana is the cross of Q. imbricaria X Q. other, 'Eastcolumn', is the same size, but has cultivar, Q. whether it is a species or hybrid. Seedlings velutina. The leaves are long and lanceolate only a single leader on top and much smaller rubra 'Aurea'. could solve that problem, but at Cambridge like those of Q. imbricaria, but with a few leaves, thus the first impression is better. It was found in the acorns are always collected by birds and pointed lobes. They are leathery like those of Q. 'Pondaim' (Q. pontica x Q. dentata) at Photo by JRP van Hoey Smith 1878 in Holland squiiTels before ripening. My young graft Q. velutina. The latter property helps Trompenburg appeared as a chance seedling among seedlings, had some good acorns two years ago, but Quercus robur 'Pectinata.' di stinguish it from Q. Xruncinata (Q. where the parents grow near each other. It is and comes true most of the seedlings at one year old look imbricaria x Q. rubra) and Q. xheterophylla intermediate between the parents. The leaves from seed for a good percentage. Planted very uniform and very similar to Q. robur. I (Q. phellos x Q. rubra), which have similar, are very large, like those of Q. dentata, but against a dark background oflarge conifers, it did find two seedlings which lead me to but thin, leaves. serrate like those of Q. pontica, and the can make a marvelous sight. suspect the parentage to be Q. robur (or Q. Q. xlibanerris, mentioned previously, is growth and size are that of Q. dentata. It Q. sadleriana from Oregon and California petraea) xQ. rugosa (syn. Q. reticulata), an the cross of Q. libani X Q. cerris. It originates keeps its leaves in winter. It is a very is sometimes creeping, but can in the wild evergreen oak from Mexico. They will have from the Arboretum Trompenburg. The remarkable tree indeed. reach a height of2 m. It has leaves like those of to be examined for several more years before leaves are intermediate between those of the Q. Xturneri 'Pseudoturneri' (Q. ilex x Q. Q. pontica but smaller, on stout branches. It is any conclusion can be drawn. It is a semi­ parents, but it has the vigor and size of Q. robur) was the only evergreen oak available fully hardy here and one of the smallest oaks. evergreen tree, and when just out, the leaves cerris. The first seedling was named in Dutch nurseries at the time we obtained it, Q. trojana (syn. Q. macedonica) is very are a beautiful pink and have petioles like 'Trompenburg'. Later, a seedling appeared listed under the old name Q. austriaca var. similar to Q. libani. It grows in the Balkans those of Q. petraea. with the same good growth but serrate leaves sempervirens. It can grow to a medium size, and in Turkey. The small leaves, however, This article would not be complete exactly the size of those of Q. libani and but is very wide. The green leaves fall in are glossy dark green and they remain in without mentioning some other hybrids as acorns even larger than those of Q. libani. spring when the buds open. It originated in brown color on the tree all winter. That well. I shall restrict myself to those which I This outstanding cultivar I named the nursery of Mr. Turner of Essex, England, accounts for its very compact impression. have found interesting to grow. In the 'Rotterdam'. The vigorous narrow habit Q. variabilis from China, Korea, Formosa Monographie des Chenes of Camus many makes it very suitable for street planting. contd. on pg. 32

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Arboretum Trompenburg • • • contd. from pg . 31

in the late 18th Century. It is troubles and have more time the hardiest of all evergreen to travel and collect for the oaks we have tried, even arboretum. I also am prepar­ when in a severe winter it ing a history of the arbore­ drops its leaves only at very tum, which wi ll be published low temperatures. in Engli sh as well as Dutch. You are most welcome to EPILOGUE, 1999: This visit this very active, living article, written 8 years ago, is garden, and see for yourself! for the most part sti ll valid. JRPVHS, 9 February 1999 The number of species in our collections has increased Editor's note: James Rich- considerably; the seeds ob­ ard Pennington van Hoey Smith tained via the Second Inter­ (Dick Smith to his many national Oak Conference in friends), one of our original California added 20 more members, is the only surviving species! A more laciniate ©Guy & Edith Sternberg founding member of the /mer­ national Dendrology Society. form of Q.frainetto now has J.R.P. van Hoey Sm ith with his se­ He follows a family tradition lections of Quercus xrosacea, been selected from seedlings of five generations as the ' Westcolumn ' (left) and and awaits a good cultivar 'Eastcolunm' (right). current Director of the fa­ name. A sprinkler system mous Arboretum has been built; the greenhouse will be Trompenburg, built over the ruins of the estate doubled to house a large and old collection of of Honigen Castle in Rotterdam. In July of cacti; and some adjoining parcels have been 1999 he will be honored at the 75'" anniversary symposium of the Dutch Dendrol­ added. ogy Society for his 40 years on the board of I also turned over ownership of Arboretum the Arboretum Foundation (see announce­ Trompenburg to another foundation to avoid ment on on inside back tearout page). Dick death taxes and safeguard its continuation. has assembled a world-famous collection of Now the arboretum depends no more upon tree photographs, contributing the illustra­ my being alive, and the foundation guaran­ tions for several fine tree books, and he tees its financial survival. We have a new presented a beautiful slide program at our curator, Mr. Gert Fortgens, who is very Second Triennial Conference in California in 1997. He also has been actively involved with knowledgeable and whom some Interna­ the Oak Open Days events organized by our tional Oak Society members might know European members. from many lectures in the United States. Our fami ly remains very interested and involved, and holds two seats on the board, but I have relief from daily management

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