Trees Behaving Badly...

Picture Source: https://daily.jstor.org/why-learning-the-names-of-trees-is-good-for-you/

Sometimes in the course of our work we come across the novel, the unusual, or the curiously bizarre. Such was the case this week, when we stumbled upon this two-tiered oddity in a local landscape.

With differently sized and differently colored needles, as well as a completely different growth habit, it gave the appearance that another species had set up residence atop the original plant. To understand what caused this unique bi-level effect, we first have to understand the specie the owner had originally planted.

At the bottom of the photo, we can see a fairly common landscape tree, the Dwarf Alberta Spruce, AKA Picea glauca 'Conica'. This was the tree intended for the site. The Dwarf Alberta is a novelty among landscape plants in that it was almost entirely man-made. Here is how.

Certain types of conifers, and some deciduous trees as occasionally develop tightly clustered and deformed masses of twigs and foliage that are generally stunted, or dwarfed. These misshapen growths are called 'Witch's Broom's, and can be caused by a number of different things; insect activity, infection, injury, even lightning. When plant enthusiasts come upon a witch's broom that appeals to them, they begin to try to propagate it, and if the propagation proves successful, a new plant appears on the market.

In the case of the Dwarf Alberta, a Witch's Broom that was found several years ago on a White Spruce, AKA Picea glauca, proved not just viable, but hardy and attractive as well, and quickly found its way into gardens across the country. As mutated dwarves go, it has been quite successful.

So what then accounts for the topknot?

In periods of stress, trees' foremost instinct is to survive; all else is discarded, even the physical form of the plant. Nature reverts to its first choice, the original parent plant, and this is what we are seeing here. P. glauca 'Conica' has decided it would be better off as a full sized P. glauca, and has begun the process of reversion. Unfortunately for the homeowner, this tree, if left to grow, will soon dominate the space allowed for its smaller version, and a choice fo whether to remove the entire tree or live with a large specimen will have to be made.

The Dwarf Alberta is not the only variety to show reversion; variegated maples, globe blue spruce, and some color selections of hosta may also revert at some point, and tulips are famous for being planted in one color, only to come up a few years later in the standard red and yellow.

But don't let this information discourage you from planting any of the above varieties, such reversion is very rare, and who knows, your garden mutation may become tomorrow's best selling garden plant.