Sunday, October 28, 2012

The maple with gold paper bark

Species name: Acer griseum

Common name: paperbark maple

Location: Ontario

This species of tree is native to China, and is used there extensively as an ornamental plant. It has recently taken hold of landscapers' attention in North America (recently as in approximately 60 years ago), and is becoming more and more common here. While being non-native it is incredibly tolerant of cold, harsh Canadian winters and survives well; it reproduces on its own incredibly poorly here and so there is very little chance of it becoming invasive.

The bark of the paperbark maple is very similar to the bark of a birch tree; the outer layers of the bark, instead of being heavily suberized (waterproofed) and hardened onto the tree's surface as scales, are instead gradually sloughed off in almost transparent layers that are only a few cells thick. This gives the tree almost a shimmery appearance under the right light conditions, one of the reasons why this plant is so favoured for its ornamental value. The leaves are also quite spectacular, at least as far as maple leaves go. The leaves are so heavily lobed that the lobes with the main veins actually turn into leaflets like you would see in the Manitoba maple. The main difference between the leaflets of the Manitoba maple and the paperbark maple is that the Manitoba maple shows a huge amount of phenotypic plasticity: the ability for a structure to show very different morphology based on growing condition. The newest leaves only have three leaflets (which sometimes fuse together under unusual circumstances to make one full simple leaf) to as many as nine leaflets in the older leaves. The paperbark maple only has three leaflets per leaf, no matter how old the leaf is.

The leaves of the paperbark maple deserve just as much mention as the bark, since they're quite pretty no matter the season. In the spring when they first start to grow out of the buds they're almost white and furry, then towards the late spring and during the summer the tops of the leaves are a dark green while the undersides are almost a pure white. In the fall, the leaves turn my favourite colour: pink. They almost end up the colour of pink strawberry candy before falling off the tree. It might be a non-native species, but it's certainly one of my favourites!