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Oak Open Days at Trompenburg

You can view full-size versions of the photos in this entry and other photos of the the event in a Photo Gallery here.

The Oak Open Days at Trompenburg were a great success, with interesting lectures and garden walks among the Netherlands Plant Collection for Quercus in Rotterdam.

A week before the event, Gert asked me if I could pick up Taiwanese Professor Fuh-Jiunn Pan and Dr. Li-Ping Ju at Schiphol airport.

On a rainy Tuesday 26th I went to Amsterdam and picked them up at the airport, where I had already very interesting discussions on Taiwanese flora while driving to Rotterdam. On the way I asked if they would want a tour in Trompenburg, or if they wanted to rest, after the long journey from Taipei. They both said immediately they wanted to see the garden (as everyone of us would do when arrriving in Taiwan, with the opportunity to see plants, which are exotic to us, or unknown), so I gave them a private tour of the oaks of Trompenburg, as a warm up for the Oak Open Days. The funny thing was that plants which are so ‘normal’ for us where of great interest for them!

Prof. Pan: ‘’Oh, WOW! Quercus robur L.!!!’’, and Dr. Li-Ping-Ju (Julie) immediately started to collect some acorns (like we do when we are in a foreign arboretum, and get an opportunity to collect interesting acorns). So it was great fun guiding them through the gardens, and also to explain the names given to some of the Trompenburg oaks, like Q. ‘Macon’ and Q.’Pondaim’.

At the end of my private tour I received some seeds of Fagus hayatae Palib. ex Hayata, the rare endemic beech from Taiwan, and a couple of acorns (probably a little immature) of Lithocarpus konishii (Hayata) Hayata, or Pasania konishii Hayata, as it is named by the Taiwanese. They treat it as a distinct genus. So this was already a day not to forget, for a young person interested in exotic plants, especially Fagaceae.

Day 1 - August 28

Oak name badges

I arrived early to register and greeted some of the IOS members I met during the 7th IOS Conference in Bordeaux, held in 2012. It was really great to meet once again some of the good friends I met there. Gert and I waited until the group was complete, and we walked to the ‘tea house’ where the event would take place. Of course the walk was a bit longer, because there were so many interesting things to see (and ask)!

  • After a good cup of coffee, and a brief delay, Gert gave his welcome speech and introduced some of the oaks of the Trompenburg collection, in his lecture ‘’Oaks of Trompenburg”. An interesting lecture, where he explained the unique way of naming cultivars in Trompenburg, like Q. ‘Pondaim’ (Q. pontica K. Koch (Armenian oak) × Q. dentata Thunb.(Daimyo oak), or Q. ‘Tromp Deerpon’ (Q. pontica K. Koch × Q. sadleriana R. Br. ter (deer oak)), a tradition started by Dick van Hoey-Smith.
  • After his lecture he took us in the garden for a first walk among some of the oaks. A highlight was of course the nursery, where several wild-collected oaks from Gert’s collecting trips are tried in full soil, to test hardiness (the real test still has to be done, as we had no frost last winter, so Q.candicans Née grew almost 2 meters in one season), another oak which can’t be missed in Trompenburg is the huge Q. pontica K.Koch, near the entrance of the garden.
  • After having a great lunch in the tea house, it was time for a discussion forum on the propagation of oaks, an interesting subject. Still a lot of research has to be done to find the answer to Delayed Grafting Incompatibility, which means a grafted oak can be rejected by its rootstock, even after several decades. Very good feedback on this subject was given by several nurserymen who were present at the event. There was great discussion about the different species of oak which can be used as a rootstock, and their success rate can vary greatly when various rootstocks are tested.
    Admiring a specimen of Quercus kelloggii 


  • Back into the gardens again to see more of the Trompenburg collection and learn more about oak hybrids, cultivars, and some great evergreen oaks in the collection, like Q. acuta Thunb., and Q. hypargyrea (Seemen ex Diels) C.C. Huang & Y.T. Chang (now considered a synonym of Q.multinervis (W.C.Cheng & T.Hong) Govaerts). Both these oaks are of the subgenus Cyclobalanopsis, proven completely hardy in our climate. Unfortunately it was too early in the season for acorn collecting on these interesting oaks. As we walked back towards the entrance building, where our dinner awaited us, we gathered in the totally renovated succulent greenhouse, where we had a drink and a nice chat inside, because it started to rain. The group was also amazed by the great work done in the greenhouse, by planting out the cacti and succulent collection in geographical order. I showed Shaun Haddock the seedling raised from his Q. baloot Griffith, and he was amazed that it has come true from the acorns collected while visiting his arboretum during the Post-Conference Tour in 2012. Back in the entrance building we had a great Indonesian buffet, and some discussion while enjoying our meals.

Day 2:  August 29

After a good night’s sleep, I woke up early, feeling somewhat nervous, because Gert asked me to do my own lecture, my first ever for the IOS, about my online activity on oaks, where I share my knowledge on oaks,and gather more knowledge from interesting contacts all over the world.

"Oaks on the Web" presentation
  • As some of you already know, my personal interest focuses on the ability of oaks to hybridise easily amongst different species, so that interesting forms can be found when acorns from a cultivated source are planted. Also I explained what happens when you plant the acorns of a hybrid, and that it is possible to find out parentage of a hybrid oak, by using the progeny test method, sowing as many acorns as possible from a hybrid in order to get the answer. Actually my nerves were nothing to worry about, because it went really well, and was complimented by many. Thank you!
  • After some good feedback from Beatrice, who asked interesting questions, some of which I couldn’t answer, we headed back into the gardens to see more oaks again, this time on the other side of the road, a part called ‘De Overtuin’, which means ‘the garden on the other side.’ We saw yet again some great oaks, like the Cambridge oak (Q.×warburgii), the closest you could get to a hardy Mexican Oak, (before the hardy species were tested).
    Dr. Li-Ping Ju


  • Back in the tea house it was time for the lecture by Prof. Fuh-Jiun Pan and Dr. Li-Ping Ju, an interesting lecture which was in two parts. In the first part, Dr.Li-Ping-Ju talked about Fagus hayatae, and the inability of this species to reproduce itself. This tree bears seeds only once every four years, and its seedlings have a very low success rate. She explained that if you have 100 seedlings, after one year, you’ll have about 25, the second year maybe 10, and after three years you are lucky with one or two surviving seedlings. She explained that F. hayatae is also threatened by typhoons, and a dense covering of a fast-spreading species of bamboo, so the seedlings won’t develop because of the lack of sunlight.
  • In the second half of the presentation, Prof. Fuh-Jiun Pan explained the range and diversity of the genus Fagaceae in Taiwan, where several genera unknown to us occur in various different types of ecosystems. He also explained that a lot of their native Castanopsis are grown for their edible nuts. Castanopsis is a
    Prof. Fuh-Jiun Pan 
    semitropical genus resembling Castanea. Very little is known about these very nice and ornamental trees. Some species of Lithocarpus are very difficult to separate from Quercus, as he explained.
  • After the great lectures we headed back to the entrance building where the Dutch Wood Collectors had a small exhibition on oak wood samples, also for sale.
  • As is tradition, a small-scale oak sale was organised, and also some acorns were exchanged, but as I mentioned before it was a bit too early to collect acorns at that time of year. Some members bought some plants from Dirk Benoit, Gert Fortgens and me , which I hope will grow on to become magnificent trees!

The Oak Open Days in Trompenburg was a great event, and it was really nice to meet you all.

Jeroen Braakman

(Photos by Gert Fortgens)

Oak sale at Trompenburg OOD