Kirengeshoma palmata is a late-flowering rhizomatous perennial up to 1.2m high with arching stems and is native to the woods and mountain lowlands of Korea and the Japanese islands of Shikoku and Kyushu.
The unusual name? No, it doesn’t come from an obscure Danish botanist called Kirengeshom. It’s really just a Latinised version of the original Japanese name. Palmata, a common specific epithet, means shaped like a hand and refers to the foliage.
Formerly classified in its own family, it is now a member of the hydrangea family, although its flowers, which are around 3cm long, are more reminiscent of those of a single-flowered Japanese anemone. The flowers of most of the plants seen in gardens are a fairly deep yellow, though the colour of wild specimens ranges from white to apricot. While beautiful and graceful, the fleshy-petalled flowers, which are borne in sprays on wiry stems that bend under their own weight, never really open fully. The buds start to burst in early autumn.
While the flowers can be something of a disappointment, it isn’t too great a disadvantage that they don’t open fully as this is a plant grown as much for its foliage as its flowers. The leaves are up to 20cm long and wide with pointed lobes that are deeper on the basal leaves and very shallow on the reduced leaves found on the flower stems.
The generally accepted opinion is that it the only species in its genus, but some botanists prefer to classify the Korean plants separately as Kirengeshoma koreana. As far as gardeners are concerned any differences between the plants are very minor, though there is some suggestion that the Korean plants may eventually be larger than their Japanese cousins and that their flowers open more fully.
As you would expect, considering its origins, Kirengeshoma palmata prefers a moist, leafy, humus-rich soil in partial shade. In other words, typical woodland conditions. In late autumn it dies back to its rootstock, which is extremely hardy and quite capable of withstanding -15?C. It is propagated either by division in winter or early spring, or by raising from seed. The seed prefers cool temperatures, around 12′to 15?C and the germination time is variable, anywhere from 30 to 300 days. I’ve found that sowing fresh seed in the autumn and leaving the seed tray in a shady place for germination in the following spring satisfies any stratification requirements and gives good results.
Kirengeshoma palmata is an ideal companion for any Japanese or Chinese woodland plants and looks magnificent under maples, the leaf shape of which it complements perfectly. Because it needs ample summer moisture it thrives at the edges of a bog garden with candelabra primroses, Rodgersia and irises. Its late flowering habit is invaluable in providing interest at a time of year when other woodland plants may be becoming rather dull.
So why isn’t it far more common? I have absolutely no idea.