Monday, 28 February 2011

Petasites japonicus

Petasites japonicus
 On a rather dry bank under trees at Colesbourne Park grows a plant that stimulates more questions from our visitors than anything else in the garden:  'There's a plant over there... a bit odd... palish...'

The palish plant in question is Petasites japonicus, or rather its inflorescences. I usually ask if the enquirer knows the British native Butterbur Petasites hybridus (most don't), as it makes it easier to explain that this is a Japanese Butterbur, whose inflorescences appear now, to be followed by large 'rhubarb-like' leaves. There's no doubt that it has a very strange appearance, with the inflorescence appearing close to the ground as a cluster of flower-heads surrounded by broad pale green bracts: at this stage it looks rather like a miniature cauliflower, or perhaps, at a distance, a tuft of some odd primrose. Most years they get frosted at this stage, develop a manky black centre and do not develop much further, but this season they have escaped frost and have developed to their full stature, elongated on stems to 20-30 cm, and have thus become even more conspicuous than usual.

A slightly more developed
Viewed close-up they are really rather attractive, with numerous flowerheads making up the 'cauliflower', each packed with numerous small flowers. The combination of creamy white and pale green is attractive, and it's not surprising that it draws attention. Nor is it surprising that I'm quite frequently asked if it's a parasite - the pallor and general leaflessness reasonably suggesting that it could be. It isn't, of course, being a normal green-leaved plant with an extensive system of thick rhizomes, though neither of these organs is visible now. The flowers will fade away presently, and the site will be obscured by a mass of its large leaves, preventing anything growing in summer except ivy (though snowdrops and daffodils can coexist with it).

Petasites japonicus en masse, Colesbourne Park,
February 2011
It has been interesting to read opinions of  the plant given by the comparatively few authors who mention it. Bowles (My Garden in Spring) thought the leaves more attractive than the flowers, in which I cannot agree, while Graham Stuart Thomas (Colour in the Winter Garden) appreciated the 'toby-frill' of the bracts. In Plants for Ground-cover, however, he says of the genus as a whole: 'Rampageous spreaders in damp soil, preferably heavy. Not fit for use in gardens; ideal where large areas are to be covered and where a vigorous colonizer can be given an area to beautify and save all work.' In this he is quite right! The area in which it grows at Colesbourne is stony and dry, under trees, and the plant is undoubtedly stunted by these conditions: given a place in damp ground  it would be an utter thug.

I believe that our plant is normal P. japonicus; more frequently grown, I think, is var. giganteus, which is even larger and has larger inflorescences and bigger leaves on taller stalks. Scary. This also has a variegated version, 'Nishiki-buki', with leaves ' irregularly sectored and streaked with white to yellow' (but apt to revert),according to Graham Rice's Encyclopaedia of Perennials. More attractive-sounding is f. purpureus, with purplish leaves  - but how purple are they, and do they stay purple? (I suspect this is more alluring in name than in reality).

Petasites japonicus foliage at Birtsmorton Court, June 2010
A final point of interest about this plant is that in Japan, where it is known as fuki,  it is eaten as a vegetable. The petioles are cooked somewhat like rhubarb, or preserved, and the inflorescence bud  is regarded as a delicacy 'with a slightly bitter but agreeable flavour' (Plants for a future). I am sorry to say that I have never ventured to try any part of the plant, but really must give it a go.


  1. John,

    The foliage to me is more prettier than the flowers. Never heard of this before. Thanks for sharing!

  2. You should post some recipes for Butterbur delicacies, John. Should we be expecting to find for sale Butterbur preserves at Colesbourne, soon? How about some recipes for Japanese Knotweed, too.

    I can vouch for Butterbur's thug qualities in moist soils. In a friend's garden here in Medina, near Seattle, the arm size roots went down at least five feet he discovered when he tried to dig it out of a large border near Lake Washington.

    In my old garden (which you saw in the dark) we used it near a winter wet pond, summer dry shade area. Beneath it I planted Cyclamen hederifolium and C. coum, both did well as the Butterbur leaves started dying down about August first.


  3. We have a pretty large clump of Japanese Butterbur in our woodland growing in shallow soil atop limestone. It's always a treat to see it flower and well worth the walk to the top of the wood.

  4. We have a butterbur growing in our garden, a present from a gardener in an Oxford Museum, years ago - it grows in its place, in another plant's place, through the hedge and the fence, along the lane and into someone else's garden. A thug indeed! Now and again I have the time to pull some of it up - but the perfume! - on a warm, February afternoon, rare this year, it can be located from yards away. But I did ask the gardener what the lovely scent was, so I brought it on myself! Does yours have any perfume?

  5. What an amazing plant, I dont think I have ever seen one of those before. The flowerhead looks like a posy. I suspect it would be too big for my suburban garden, even under my Maple tree.

  6. @Randy: the foliage is handsome when fresh and vigorous in early summer; it soon becomes very weary-looking, and gets worse as summer drought sets in.

    @June: your scented species is probably P. fragrans. No scent worth mentioning on P. japonicus.

    @Patientgardener: very much too big!

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  8. Hello... I admired this plant at the gardens of the Stratford Festival in Stratford, Ontario. I was given a small plan in 2007 and planted it in my new garden. This plant looks great in the garden... but... make sure you plant it in a damp area. It is a very attrative plant, especially if planted under trees/pines, etc. It does not do well in dry areas and in direct sun. It is great plant is you need to cover large areas under trees because if grows very quickly and the large leaves can cover large areas (if needed). I receive several requests each year for a cutting/small plant from friends and people who visit our garden. WARNING: this plant very colonizes quickly and can be very aggressive.... truly!

  9. I have just cleared our riverbank of this monster!! Totally invasive at a startling rate to the exclusion of all other species. Took a lot of digging. If you do elect to grow Butterbur, ensure that you have a huge area that you no longer have use for.


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