Botany Photo of the Day

Acer shirasawanum is an excellent, if poorly recognized species for the Vancouver area. Most people (save a few maple nuts like myself) wouldn't recognize the differences between it and the morphologically variable A. palmatum. The cultivar 'Aureum' is a standout, however, displaying wonderfully pleated golden leaves, with red stains on their tips. In my experience, A. shirasawanum is slightly less spreading than the typical Japanese maple (again, this is exemplified by the branching habit of 'Aureum' and is evident in Daniel's image above), and the brownish bark tends to have dark striping. The easiest way to separate them, though, is to see them in fruit. Acer shirasawanum holds its samaras above the foliage, while in A. palmatum they (at least eventually) hang down.

I think it unfortunate that other forms of A. shirasawanum are not widely available. Two that are seen on occasion are 'Palmatifolium' (green leaves with narrow, forward pointing lobes) and 'Green Trompenburg' (the edges of these leaves are rolled over handsomely). 'Green Trompenburg' is still listed almost universally as an A. palmatum cultivar, but seeing a mature specimen is to have little doubt of its true affiliation. The cultivar 'Trompenburg' is a purple-leafed A. palmatum with similarly convex leaf lobes.

Eight years ago, my wife and I purchased a townhouse outside Vancouver. Because we were among the first buyers in the complex, we moved in before any landscaping had been started, and I had an opportunity to see the plans and made arrangements with the landscape contractor to check out some of the plants before planting. About a dozen Japanese maples were specified for the site and I visited the supplying nursery to see how they looked. Much to my surprise, I found a number of 6-7' B&B A. shirasawanum seedlings (labeled as A. palmatum) while I was snooping around. Naturally, I made arrangements for the contractor to ask for these when it came time to order the plants.

Unfortunately, the site landscape architect rejected them in favour of slightly larger A. palmatum seedlings. To understand my enormous frustration (and my original cunning plan), the reader needs to appreciate that green A. palmatum seedlings are inexpensive because nurseries grow them to use as grafting stock (more distinctive cultivars are grafted on them). Such stocks are grown, not because they will eventually grow into attractive trees, but because they grow rapidly. And while any Japanese maple is generally attractive, fast growing individuals often suffer from a variety of problems, most particularly, weak branch-attachments. Last week, for example, a 12-foot branch broke out of the top of the specimen outside of our townhouse after a heavy rainfall. Without my regular (albeit surreptitious) summer thinning, more branches would have broken by this time.

I don't think of myself as a sentimental man, but I sometimes dream of those lonely, mis-labeled shirasawanums at that nursery, and wonder who the lucky people are, appreciating them now.

Hello

I also have an Aureum as per my web page.

For some unknown reason, this year it has been very poor with foliage.

Only a few branches have sprouted leaves and the remaining buds look as though they will not grow any further.

This said there are a number of very small sprouters poping out directly on the main trunk.

Have you ever met this problem.

thanks
Don
in the UK.

Don - this sounds like a great question to post to the UBC Maples Forum. A lot of great people on there + it will give your question more visibility.