Bud scales & the most adorable leaf ever

What: The forest is mostly green now that all the buds have opened or are opening. While out in Centennial Woods the other day I was collecting leaves of all different sizes from Norway maple (Acer platanoides). Like other maples, the scales on Norway maple buds open and form these elongate leaves that subtend the normal leaves (seen as the plus sign in the photo below). Buds are made out of modified leaves and these are deciduous once the normal leaves (there's probably a technical name for these) are more fully developed.

Something must have gotten messed up somewhere along the way on one of the branches I was looking at. It appeared that the bud scale decided that it was going to get back to its roots and form a leaf. In the photo above, the mini leaf was actually attached to the tip of the bud scale leaf.

Norway Maples in the US and Centennial Woods

Posted by Maxwell Siegel- A junior in the Rubenstein School at UVM who is interested in environmental studies, and specifically sustainability studies. Forests and nature in general has always been a passion of his worth pursuing.

The Norway maple (Acer platanoides) is an extremely common species of tree across the United States, whether they line urban avenues, or make up large portions of deciduous forest. One begins to wonder, “Why is a Norway maple growing in North America?” Most Americans are accustomed to the look of the Norway maple and do not question their presence in the United States. In fact, the leaf of the species is the trademark icon for my hometown of Maplewood, New Jersey. The Norway Mmaple is the maple that suburban and urban Americans think of. But when did this species make its way from Europe to North America, and how did it become so popular and widespread?

According to the USDA Forest Service Norway maple is the most widely distributed native maple in Europe, existing in locations with elevations ranging from 0-6000 feet. The first Norway maples made it to the United States in 1756 but were relatively rare until the late 1800s when their popularity exploded. There are several reasons for the cultivation and spread of Norway maples throughout the Untied States. The first being the aesthetically pleasing color and shape the species presents, as well as its extremely immediate and sustained accelerated growth patterns. The species is well adapted to urban environments as it can withstand “moderate pollution, dusts, pavement and dry soil” (USDA forest service), making it an ideal species for lining urban and suburban streets and landscaping properties. They provide ample shade and can quickly become the centerpiece of a yard.

The true boom to the U.S Norway maple population came after Dutch Elm Disease decimated the Elms across the nation, including all of the Elm that had previously lined roads. The urban landscaping niche needed to be filled, and thus the Norway maple stepped into the batter’s box and has taken over the continent’s maple distribution and make-up. Here in urban Vermont these trees are quite common and fill their new niche rather well, making up for the disappearance of Elms along roadsides and in yards. Because they are fully capable of reproducing, the have spilled out of the concrete and are filling our forests as well. It can be estimated that Norway maples entered our state between 1860-1900 and “blossomed” between 1925 and 1950. In Centennial Woods, here in Burlington, the Norway maple thrives. It can live in varying soils because moisture is not a limiting factor. The largest Norway maple I have personally seen in Centennial Woods is in the North-Western section of the woods, and can be approximated to an age between 90-110 years old, dating it back to somewhere between 1902-1922. Another stand fills the gaps in an area that was selectively logged in the late 60s, regeneration from those first Norway maples that had since matured.

It is difficult to determine whether or not the species should be considered “invasive” or not, only because it can out compete native maples such as sugar (A. saccharinum) and red maples (A. rubrum). The diversity of maple species in Centennial Woods seems evenly distributed, however with more research a more accurate depiction of the impact of Norway maples could be determined. But that is for another time!

Little leaves

What: Quiz Time! This seems to be the hardest part of the year for telling which trees are which: the buds are bursting, becoming unrecognizable, and the little leaves, just emerging, haven't quite yet taken full shape. It's like looking baby photos of friends and trying to guess who they are. The leaves in the photos below are some of the early ones to come out. Roll over each to test your ID skills (there are both shrubs and trees). 

Ecological notes: You can compare the male boxelder shown above to the female boxelder from my post on boxelder bugs. Also, the last photo shows the seeds from an ornamental Siberian elm in Centennial Woods. Ryan Morra and I were pondering over greenness of the seeds. One possibility is that they're actually photosynthetic when they're young (boxelder, white pine, oaks, walnuts, and probably other seeds that invest a lot in endosperm are also green when young). I would imagine that this would take away pressure on the leaves to produce energy for the developing seed. In the elm photo it's a fly on the seed, but other pests can destroy a seed. If leaves were producing energy for growth, winter storage, and the seed, they might be more likely to be at a net loss each year. Having seeds responsible for their own growth is energy insurance for the rest of the plant.

Spoiler alert: The species above are, in order, Populus tremuloides, Cornus alternifolia, Rhamnus cathartica, Acer rubrum, Rhus typhina, Acer platanoides, Acer negundo, Acer negundo, Ulmus pumila.

Other notes: Just a pattern I noticed - willow family and maple family seem to be among our earliest trees to leaf out. Big-tooth isn't out yet, birches are barely opening up, and the buds on some of our more southern species are only beginning to open (e.g. walnut, oak, hickory)