After having written most of the today’s entry, a rewrite was in order; to censor a quote from one of my favourite movies, “I’ve got information. New (expletive) has come to light!”. It seems like the series on plants of Japan is becoming more of a series on “plants of China and / or Japan influenced by the other country” after yesterday’s Camellia hybrid and today’s Kerria japonica ‘Pleniflora’. Before getting into the details, first of all today’s photographs are courtesy of Jane of Missouri, USA, aka Shotaku@Flickr (original photo 1 | original photo 2 | Botany Photo of the Day Flickr Pool). Dōmo arigatō, Shotaku.
When I first encountered Kerria japonica ‘Pleniflora’ some years ago, I couldn’t immediately tell what family it was a part of. The problem was the lack of flower characteristics due to the ‘Pleniflora’ — in this case, a “doubling” mutation where the stamens instead develop into petals and the plants are sterile (for a different kind of doubling mutation in the same family, see Rubus spectabilis ‘Olympic Double’. Now that I’ve mentioned Rubus is in the same family, I’ve given away that Kerria japonica ‘Pleniflora’ is a member of the Rosaceae.
Kerria is named after William Kerr, noted by Wikipedia as “the first Western professional full-time plant collector active in China” and the person who introduced Kerria into cultivation in Europe by sending Kerria japonica ‘Pleniflora’ to England in 1805. It twigged on me that Wikipedia’s account doesn’t mention Kerr taking a trip to Japan, so I started to question the name japonica, a specific epithet meaning “of Japan”.
Many, many references state that Kerria japonica, or “Japanese yellow rose” is native to China and Japan (and sometimes Korea). A little bit of digging first revealed that Thunberg, during a collecting trip to Japan in 1776, had first collected the species that was to be eventually named as Kerria japonica. However, the specimen was in poor or incomplete condition, so it was initially determined that the species belonged to a different genus (and family). When it was properly recognized as a new genus post-1805 thanks in part to the living material sent by Kerr, it was named after Kerr but retained the japonica specific epithet. What Thunberg (and Linnaeus, who published the original name) didn’t realize, though, was that Kerria japonica is apparently not native to Japan. It seems that it had been introduced as a garden ornamental from China! I haven’t had any luck tracking down the reference that asserts that Kerria japonica was never native to Japan, but a respected source makes the statement: Dr. Susan Hamilton of the University of Tennessee Gardens on Kerria; and Gerald Klingaman, retired horticultural extension agent at the University of Arkansas makes an allusion: Kerria japonica. If anyone knows of the reference, I’d be glad to add a link. Lesson? Always check your assumptions.
For gardening accounts and additional details of both the species Kerria japonica and its cultivated varieties, see Paghat’s page on Kerria japonica (with a small essay of its cultural importance in Japan!) or Tim Wood’s weblog entry on Kerria.