Iris ensata

The Japanese iris at Marwood Hill Gardens, Barnstaple

It is only recently that the name ensata has been widely used for  these beautiful irises. Formerly they used to be known as kaempferi, named after Engelbert Kaempfer, but the International Code of Nomenclature states that the first published name takes precendence over any other. As ensata was first used by Thunberg in 1794, this is earlier than von Siebold who in 1886 called them kaempheri.

In holding a collection of iris, it would be virtually impossible to collect and grow all known forms and cultivars, so although we have more than 200, this is a fraction of the 4,000 or 5,000 that have been bred and named.

The Americans have taken this species to their hearts and, like hostas, hemerocallis and camellias, they have developed and raised new cultivars in a myriad of colour combinations.

Iris ensata grows wild all over the Japanes archipelago and can also be seen naturalized in northern China, Siberia and Korea. Centuries of intensive cultivation by Japanees collectors and hybridizers have brought this iris to its present state of magnificence.

In ancient times Japan had no calendar and farmers relied on seasonal changes to guide them in growing rice. The appearance of cherry blossoms marked the time to stop hunting in the forests and mountains and begin cultivating the fields. The iris bloom announced the advent of the rainy season during which rice plants were transplanted from seed beds to the fields. In view of the importance this gave wild iris, it is probably that they were transplanted to gardens in very early times.

Over the centuries, three strains or types of Iris ensata have been developed, according to the area in Japan where their development has taken place. The Ise strain comes from the Kyoto area, which was the former capital of Japan, and the Higo strain from Kyushu. The third strain, called Edo, refers to the older and less-developed cultivars. Even today in Japan, the advancement and improvement of the iris continues unabated in the country in which it began.

Compared with five hundred years of active interest in Japan, the history of Japanese irises in the United States of America is short indeed. It is believed that the first cultivars were imported about the year 1869 and it is probable that many also came to Britain. They quickly became popular and by the early 1900s were to be found in almost every garden. Commericial growers became very interested in them and so their numbers increased.

Several people have been responsible for the development of the flower and have raised many cultivars. probably the most outstanding hybridizer was Arlie Payne of Indiana, who introduced more than 170 cultivars over 40 years. The Marx family of Oregon during the 1950s and '60s produced many more. In later years, Arthur Hazzard of Kalamazoo in Michigan, has produced some very good cultivars. All of his raisings are easily recognised because the names all start with 'Prairie'. But probably Currier McEwan of Maine has done most to develop the flower in size and colour combinations. He has developed tetraploid flowers, which have double the number of chromosomes compared with the normal diploid flowers and so produce large spectacular blooms.

During 1992 Dr Smart, the creator of Marwood Hill Gardens, spent two weeks in America visiting several iris nurseries and growers and attending the main show for iris bloooms. He brought back many new cultivars and it is these, together with others we had previously, which have formed our National Collection.

Like Astilbe, our other National Collection, Iris ensata does best in moist conditions, and we have them planted aound the lake sides at the garden. They must have an acid, moist soil at all times otherwise they quickly lose their vigour and die out, and like most herbaceous plants they are best divided after a number of years. They also like plenty of feeding, so a generous mulch of farmyard manure is very beneficial. One way of growing them if the soil is not wet is to use a leaky pipe, which keeps the soil constantly damp. At the Royal Horticultural Society's garden at Wisley, they are able to grow a trial of Iris ensata cultivars on very free draining soil using this method.

Malcolm Pharoah
Marwood Hill Gardens, Marwood, Barnstaple, Devon EX31 4EB

Marwood Hill Gardens is a 20 acre garden with lakes and a stream. The best time to see the National Collection is the first two weeks of July.
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