By Marilyn Loser: 2012 January 4
Oh yes you can – it’s fairly easy in Alamosa!
I sometimes grumble about Alamosa’s limited tree palette. But, when it comes to identifying local trees in winter, our task is not as challenging as identifying the more than 100 species on Denver’s recommended street-tree list.
We’ll explore four clues: branching structure, bark, twigs, and nuts/seeds/fruits.
Branching structure: Take a look at a tree. How do the sub-branches grow? Are the branches opposite each other on the parent branch? Or do branches alternate up the stem? Trees with alternate branching structure include elm, aspen, cottonwood, crabapple, Russian olive, hackberry, and oak. Those with opposite branching include ash, maple, box elder (really a maple), and dogwood (only shrubs here).
Bark: Bark is a bit trickier as young trees and branches may differ from older trunk bark. However, it’s another clue. Young aspens and new aspen growth has very white bark. There are a few birches in town and their bark tends to be less white and shaggier than aspen.
Ash bark is smooth grey in young trees and often pale grey-brown in saplings. Older trees display fissured bark with interwoven, almost diamond-shaped ridges that can resemble that of oak. Elm bark acts a bit like cork – when you press it with a finger nail it bounces back. Crab Apple bark is somewhat flaky and mottled.
Although I haven’t seen any young boxelders in Alamosa, there are a few older specimens downtown. The mature bark often has a noticeable yellowish tinge compared to other tree species. Honey locust bark is slate gray and tends to split to one side as it ages. Hackberry bark is gray and becomes very corky looking with age – the specimens I’ve seen in Alamosa are too young to have warty looking trunks.
As cottonwoods age they develop thick, brown bark divided into thick rounded to angular sided ridges. New limbs have a whitish cast while willows are more yellow or orange.
I never gave much thought to lenticels before. They are the openings found in bark that allow gas exchange between the atmosphere and the inner tissues of a plant. As I walked around my winter yard, I noticed my young, oak-leafed ash tree has reddish bark with little white spots. The spots are the lenticels.
Twigs: Get up closer to a tree and examine its twigs. In winter, Siberian elms are a dead giveaway. As you look at the crown against the winter sky, you’ll notice the twigs have a zigzag structure and that there are a lot of very dark, small, round leaf buds along the stem.
As I look out my window at the ash trees in Jardin Hermosa, I can see that their limbs arch to the sky looking a bit like pitchforks. No other trees around have that appearance.
The Kentucky coffee tree usually looks dead in winter. We planted two in Cole Park in September 2010 and last winter I figured they hadn’t made it. They have thick twigs and sparse branching and only tiny nubs for buds.
Natural growing honey locusts, ‘gleditsia triacanthos’, are extremely thorny, with long dagger-like, branching thorns. The thorns have three points for which it is named – triacanthos meaning three spined. It was once called the Confederate Pin tree as soldiers would use the thorns to pin their clothes together. In cities you see more thorn less varieties these days.
Cottonwood twigs have large buds which are long and pointed, up to ½ inch in length. They’re the longest buds I’ve seen in Alamosa. Russian olive twigs and buds are covered in dense whitish hairs, giving it a silvery appearance.
Some leaf scars (the little scar a leaf leaves when it falls off) are very distinctive. Some are heart shaped, like the Kentucky coffee tree. Maple tree leaf scars have three dots that often look like a crescent. Ash scars have tiny dots in a row that look like little smiles.
Nuts/seeds/fruits: Often you can see signs of nuts, seeds, or fruits in winter. I mentioned before that smashed crabapples on wet sidewalks are a hazard. You often see crabapples still clinging to trees in winter looking like shriveled cherries. My shrubby Gambel’s oak has a few acorns still attached. However, I haven’t seen any acorns on the young Bur oaks around town.
Perhaps the most distinctive seed pods you see in Alamosa in winter are the long, spiraling pods of honey locusts.
Take a look around town. You’ll be surprised how much winter trees have to offer. For a more complete chart of Alamosa winter tree identification features, visit AlamosaTrees.net, click the Tree Lists tab and select Winter Tree ID.
"Of winter's lifeless world each tree Now seems a perfect part; Yet each one holds summer's secret Deep down within its heart." Charles G. Stater