Invasive Aliens After an incredible sequence of misadventures he was finally reunited with what remained of his plant collections in Leiden, The Netherlands, in 1842. There he set about forming his Royal Society for Opening Pandora’s Encouragement of Horticulture. Preserved in its journal the Jaarboek van de Koninklijke Nederlandsche Maatschappij tot Aanmoediging van den Tuinbouw , are a complete series of seed packet dated and priced catalogues of Von Siebold & Co. Anyone who has ever worked on the history of plant introductions will appreciate what a stroke of fortune this was, since Japanese knotweed arrived as a sought-after exotic plant plant catalogues of this date are extremely but is now a proscribed alien. John Bailey explores some difficult to come by. In the 1848 edition of the Siebold & Co of the unpredictable outcomes that have arisen for these catalogue, the category ‘plants newly indestructible plants. imported from Japan’ includes a range of species with prices from 300-600 francs. Polygonum sieboldii (Japanese knotweed) was available only as a collection of one mother plant and 25 strong plants for the apanese knotweed (Fallopia japonica) had sum of 500 francs. There is a seven-line been minding its own business in Japan footnote extolling the virtues of this and China for millennia. On volcanoes in J wonderful plant, which can do practically Japan the dwarf form of the plant (F. japonica anything, short of bringing back the dead! var. compacta) had the habitat to itself, and Given that 500 francs spent in the same was the primary coloniser of volcanic ash catalogue would have filled the barouche fields. Long association with sulphurous landau to overflowing with choice emissions and sudden depositions of hot ash ornamentals - this was an extremely endowed it with certain tenacity. The high expensive plant. altitudes meant a much restricted growing Siebold was, of course, nobody’s fool. In season, early flowering and dwarf habit. Key order to make money on a plant as readily to its survival was the woody rhizome that propagated as this, you needed a high initial went vertically downwards, where stored price. Indeed by 1856 24 plants could be had nutrients and dormant buds were beyond for only 6 francs! the reach of the next deposit of hot ash. In The next step in 1850, was to send a such habitats, plants are characteristically package of plants, including Japanese separate clumps not connected by knotweed to Kew Gardens in the hope of underground rhizomes. extracting further novelties in exchange. The tall lowland forms of the plant (F. John Bailey is Principal Experimental This is all duly recorded in copperplate Officer in the Department of Biology at the japonica var. japonica) faced a different set of handwriting in the Kew Inwards Book, along University of Leicester, where he has been problems. In Japan they were just one with a terse note saying that on account of working since 1977. A colleague in the component of a giant herb community, bad selection only six of them were new to department, Ann Conolly, introduced him either competing with such plants as the gardens. to Japanese knotweed, and after her Miscanthus and bamboo, or trying to find a Contemporary illustrations show that the retirement he carried on from where she space in a forest clearing or riverside. Here Siebold plant is actually male-sterile, with left off. After completing a PhD on it, he the rhizome may have acquired the maintained a strong interest in the plant secondary function of seeking out new and established many international resources of space, light and evasion of collaborations. The adoption of molecular predation. approaches in the 1990s and the hard work of two PhD students greatly extended the scope and impact of the research, resulting Siebold’s plants in his contribution to more than 30 In order to find out how Japanese knotweed scientific papers on the subject. It is his came to end up in Britain and cause such proud boast that he is more interested in problems, one must delve into the currently the sex lives of these plants than he is in rather unfashionable area of the history of eradicating them. Invitations to lecture on botany. Philipp von Siebold was a most the subject have taken him as far afield as Japan and the US. He now has his sights colourful character, whose name is attached set on New Zealand and is currently as the authority to many of the Asiatic looking for funding to take this research species that we now take for granted in our gardens. As a surgeon he was able to travel further. P h o to Japan with the Dutch trading delegation at t o : R o a time when Japan was effectively closed off y a l B from the rest of the world. In spite of being o t a n i c restricted to an artificial island in the G a r d harbour at Nagasaki, his knowledge of e n s K advanced western surgical procedures won e w him many friends in Japan, who in return Manuscript RBG Kew Inwards book 1848-1858 provided him with choice Japanese plants showing the list of plants sent by Siebold in 1850. that gardeners in the West were keen to Item 34 ‘Polygonum Sieboldii’ is more commonly known as Japanese Knotweed (Fallopia japonica possess. var. japonica) . THE HORTICULTURIST APRIL 2010 21 the 1960s and 1970s, and displayed in a series of dated distribution maps. Some of the earliest non-garden records came from Welsh coal-mining valleys and it is possible that, rather than escapes, these were examples of deliberate planting, since one of many claimed benefits of the plant, was stabilisation of loose soil; coal barons no doubt keen to try anything that allowed their e c spoil heaps to be more vertiginous. n e i c s o i B I B A C Cause for concern : o t o h By the late 1970s the true extent of the P spread of Japanese knotweed in the UK was A nymph of Aphalara itadori, the approved bio-control agent for Japanese knotweed . becoming apparent, and clearly some influential people were beginning to get rattled. Accordingly, when the wide-reaching Eradicate… Wildlife and Countryside Act was published P h Overnight the industry of Japanese knotweed o t o in 1981, provision was made for the : R eradication was born, and suddenly o y proscription of alien plants and animals that a l B developers took a serious interest in botany, o t it was felt were particularly harmful to the a n i with knotweed-infested sites selling at c G environment, Japanese knotweed being one a r serious discounts. Guaranteed eradication d e of two land plants so listed. I will not dwell n s was an expensive business, with developers K e on the almost 30 years it has taken for any w fearful equally of prosecution and the of the many other deserving contenders to Contemporary illustration of Siebold’s Polygonum possibility of any of the ‘armour-piercing’ be added to this list, but examine the strange sieboldii (Japanese knotweed). rhizome being left on their sites. Major consequences of Japanese knotweed being sporting venues such as Wembley and many on it in the first place. of the London Olympic venues have been hit cordate leaf bases. The fact that only the The offence to ‘plant or otherwise cause by these costs. Costs, incidentally, that are female form of a dioecious species was the plant to grow in the wild’ was long incurred only in the UK - other European originally imported has had a number of deemed to exclude movement of viable countries apparently being able to survive important consequences. Firstly, it could not rhizome fragments by road works and without such legislation, which is, I reproduce itself by seed. Not a major issue, redevelopment schemes and was perhaps maintain, an entirely unintended when as little as 0.8gm of rhizome could more suited to evil-doers planting it in consequence of including Japanese give rise to a new plant. Secondly any seed nature reserves at the dead of night! This all knotweed in the 1981 Act. collected from it would inevitably be hybrid, changed with the Environmental Protection In the UK press Japanese knotweed so later on when male plants of the related Act of 1990, when the pendulum swung regularly attracts epithets, such as ‘monster’, giant knotweed (F. sachalinensis) became abruptly to the other extreme. It became an ‘barbarian’ and ‘triffid’, but in spite of the available, seed could be collected from offence to move as much as an atom of mythology surrounding it, if caught early Japanese knotweed from one site to another enough, it is readily eliminated by the use of unless it was in specially sealed and “It became an offence a range of herbicides. Problems arise in the decontaminated lorries delivering it to treatment of long established stands, where to move as much as an officially designated deep landfill sites. atom of Japanese decade after decade, the network of woody knotweed from one site to another unless it was in specially sealed and decontaminated lorries delivering it to officially designated deep landfill sites. ” Japanese knotweed and distributed as Japanese knotweed seed. This seed was of course the hybrid now known as Fallopia x bohemica (after its original description in the Czech Republic), and is a widespread, if under-recorded, component of Japanese knotweed populations throughout the West. We now enter the ‘Dark Age’ of Japanese knotweed knowledge where the only evidence of its existence comes from dated n a v herbarium specimens, and the occasional e B d i v published note of where it had become a D : o t abundant.