The Allure of The Kalopanax

Kalopanax septemlobus, the Prickly Castor Oil tree, and a sole species in its genus is one of my favourite plants, so much so that we have several in the garden. Even now, whenever I spot some in the nurseries we visit I still find myself gravitating towards them, admiring the overall form of the plant with it's lush leaves on spiny stems, gorgeous! Mind you, I say that about a lot of plants and I have loads of other favourites too, but there is something special about the inherently unique Kalopanax.

Lush leaves....

...with prickly stems, irresistible combination!

This plant is deciduous in the winter and is apparently hardy down to minus double digits in celsius, thriving in parts of continental Northern Europe. Certainly at least it's been hardy enough in our garden. It can grow into a huge tree but is easy enough to keep juvenile by regular pollarding and pruning in the spring to keep it into a more manageable size, and as an added bonus can respond to the treatment by producing even bigger leaves in the summer. Virtually pest and disease free, it has very little special requirements apart from occasional supplemental feeding in the growing season, as well as being watered on dry spells. I do suggest though that it only gets pollarded every so often, letting a year or two pass by in between them, as well as siting on a well drained site that doesn't get waterlogged but doesn't dry out either. It prefers a full sun to a partial shade aspect.

There are several leaf forms available of essentially the same plant, at least three that I know of and possibly even more,  including ones that are 'in between' these leaf shapes. There is no reliable or standardised naming for these various leaf forms which makes sourcing rather tricky, especially if you're after a particular form.

As a fan of this plant I regard all of the leaf forms of Kalopanax as beautiful in their own right and worthy additions to the garden, but for some one leaf form would be more desirable over the others and would only go for that one. Makes sense too especially if space is limited. Some nurseries sell plants that have different variety names attached to it, while others carry on using variety names that have been used before (like the name var. maximowickzii). This is a grey area and I'm aware that at one point all of the variety names used before were deemed not valid for use, and that whatever the shape or form of the leaf this, they are all just Kalopanax septemlobus. I'm not updated if things have changed and if the older names can be officially used again (as well as new ones) but I would highly suggest that this is one of those plants that are best bought in person. You purchase if you like what you see in front of you rather than rely on whatever variety name it has.

As I've mentioned earlier I'm aware of at least three leaf forms of this plant and we have them in the garden. As a rough guide here they are using my unofficial names for them, based mainly on the general shape of the leaf and what I associate them with. The names may be unofficial but it will give you an idea on what to look for (and what's available) especially if you decide to source for one (or more!). Another thing worth noting is that juvenile leaves do vary in appearance compared to the more mature ones on the same plant, but the difference in leaf shape amongst the other forms (juvenile and mature) are still very discernible from each. Whatever leaf form they may, they are all very prickly so caress the stems with care.... or caution.

The 'Acer' leaf form
The leaves of this form remind me of Acer palmatum or Liquidambar leaves, palmate in appearance but not as deeply lobed. When in full leaf it can be easily confused as a Japanese Acer but much faster growing, and a glimpse of the spines will quickly indicate that it is definitely not. I think it's equally at home to lush planting schemes, minimal Japanese style gardens, or gardens with a general oriental theme.

Juvenile leaves

Mature leaves at the top of the plant (not to be confused with the Fatsia japonica leaves beneath)

The 'Fatsia' leaf form
The leaves of this form remind me of nothing else but the leaves of good old Fatsia japonica, with its palmate shape that are much more lobed than the previous leaf form. And the leaves are much bigger too, probably the biggest of all the forms. Also of all of them it has the most traditional 'Castor Oil' plant in appearance.

Juvenile leaf

Mature leaf

Mature leaves at the top of the plant

The 'Duckfoot' leaf form
Ok, I can't really think of many plants are called duckfoot (apart from one variety of Hedera) but with it's distinctively well dissected leaves and shape, they remind me of the webbed feet of ducks. And funny enough this unofficial name is more widely used than I thought (as an easy adjective when making enquiries on nurseries). This seems to be the most desirable of all the leaf forms, with availability constantly low hence can be tricky to find. 

Juvenile leaves

older but still juvenile leaves

Mature leaves, note that the leaves are no longer as dissected as the juvenile ones but the form and habit is still distinctive from the 'Fatsia' form

This form is supposed to be the one referred to as var. maximowickzii but the validity of this name is still hanging on a balance, although some nurseries still persist in using it. Just be careful when buying online of plants still labelled as this, you may not get a form that looks like these photos but rather get something more similar to the other ones.

A newer specimen, only planted out last year but I consider it under this same leaf form...

or could it turn out to be another variation, a fourth leaf form?? Time will tell!

Because of the confusion with the naming, it's best to buy this plant in person, so you can actually pick up the leaf form you wish to acquire. If doing so by mail order, it's worth asking for a photo of the actual plant they will sending (or stock), so you know what will be coming. If you're not that fussed, then consider it a lucky dip! After all, I think they are all lovely :-)

Mark

Posted in: Kalopanax , Plant profile