Identifying Trees and Shrubs in Winter: a PEEC Plant Walk (Shallow Thoughts)

Akkana's Musings on Open Source Computing and Technology, Science, and Nature.

Fri, 02 Feb 2024

Identifying Trees and Shrubs in Winter: a PEEC Plant Walk

[Craig shows a more common one-seed juniper] Last week Craig Martin led a tree and shrub identification walk for PEEC around Kinnikinnick (yes, I had to look up the spelling) Park in Los Alamos.

It was a very welcome addition to the summer flower walks that Craig and Chick Keller have led in the past. Nothing wrong with flowers, but I get curious about the non-flowering plants I see around me. I guess I'm not the only one who feels that way, because the walk was very well attended despite the mud and snow.

And it was fabulous. I scribbled notes as I could, but I'm sure they won't make any sense to me a week from now, let alone a year. Hence this writeup.

What is a shrub, anyway?

One of the first trees we encountered was a Siberian Elm, Ulmus pumila. Most of us were familiar with that tree, as a very successful invasive species in the area. We have a few growing by the street outside the house; we've tried cutting them down but they grow back, and we'd pretty much decided to let them be since they're a rather pretty (if unfortunately thirsty) tree that does all too well in our changing climate. I was a bit relieved to hear that Craig has come to the same conclusion, and no longer actively seeks and destroys Siberian Elms. (We later encountered another common local invasive, Russian Olive, and this one Craig says he does still try to kill when he sees it.)

We also passed a Gambel's oak, Quercus gambelli, and another oak with slightly less indented leaves, which Craig tentatively called a wavyleaf oak, noted on our plant list as Quercus x undulata. Tentatively because oaks are notoriously hard to identify: they seem to interbreed readily and you'll see oaks that are intermediate between several species, so it's hard to pin an oak down to any one species.

What defines a shrub, anyway? We pondered that. Generally if something smaller than a tree has woody, stiff stems, call it a shrub. Some of the shrubs we examined were obvious, others less so. The tall easter daisy (Townsendia eximia), long past flowering this late in the year, wasn't a shrub, but bore discussion anyway: it turns out Craig is the world's leading identifier of this flower.

Back to shrubs: we examined a wax currant, Ribes cereum, with white horizontal lines called lenticles across its woody stems. (When I look it up now, I see them spelled both as lenticle, which sounds like what Craig said, and lenticel.) These are the same marks you see as the dark horizontal marks in aspen (Populus tremuloides) bark; we didn't see any aspens on our walk, though they were on our plant list. Craig pointed out the lack of thorns on the wax currant: the way to tell currants from gooseberries is that gooseberries have thorns while currants don't. They both have edible berries.

Identifying Conifers

Of course ponderosa pines, Pinus ponderosa, are common around the Nature Center. Craig pointed out how the needles grew in groups of three, with a brown sheath around the base of each trio, called a fascicle (I thought he meant the brown sheath was called a fascicle, but looking it up, I guess it's the whole group of needles that's called that). You can identify pines because their needles are in fascicles. Our local piñon pines, P. edulis, of which we saw plenty of examples later, has fascicles of two needles, but some piñons in Arizona have single needles and even they have this brown sheath around the needle base.

We only saw a few narrowleaf cottonwoods, Populus angustifolia. Rocky Mountain cottonwood has a wider leaf, but there weren't any on this walk.

Leaving the Nature Center grounds, Craig pointed out a shrub: a Viburnum. He calls these "Atomic Energy Commission plants": there's a thriving Viburnum community in Acid Canyon that was planted by the AEC during the postwar years, the only place you'll find it in New Mexico.

[a Rocky Mountain juniper showing its fine, lacy needles] Rounding the turn behind the Swim Center, Craig pointed out a Rocky Mountain Juniper (Juniperus scopularum, left) with its lacy or feathery looking needles, compared to the one-seed juniper (J. monosperma, right) which is more common in this area. I had often seen the lacy junipers on hikes, and wondered if it was a function of age (I see the lacy needles more often on very small, young plants), but now that I know it's a different species, of course I'm seeing lots of tall, mature Rocky Mountain junipers all over.

This kicked off a discussion of the "one-seed" name: apparently if you cut open a berry, most junipers will have more than one seed inside. Someone also asked about a low ground-covering juniper she sees locally; that's called common juniper, J. communis, and according to wikipedia it has the largest geographical range of any woody plant, though its presence is spotty in this area.

More conifers: at a white fir, Abies concolor, Craig pointed out the single short needles growing upward (a sign that it's a fir, not a spruce). Fir cones also grow up, though you can usually only see that at the top of the tree and we couldn't see any cones on this fir. The fir needles are also more rounded while a spruce's are square if you squeeze a bunch of needles in your fingers, spruce needles have sharp edges that hurt, while fir needles don't (remember "fir friendly").

You can identify a Douglas-fir, Pseudotsuga mentziesii (not actually a fir), by its single short needles and the bracts on its cones (little fuzzy things sticking out). David Douglas, for whom Douglas-firs are named, was an interesting guy, a Scottish botanist. He made several trips to North America, particularly the Pacific northwest, bringing back trees to be cultivated and used for timber in the UK. Eventually he visited Hawaii, where he fell into a deer trap that was already occupied by a feral bull, which killed him.

[a limber pine, showing its bottlebrush-like needle tufts] Farther west we saw a pine with fascicles of 5 needles and with its needles clustered in clumps, sort of a "bottlebrush" pattern: a limber pine, Pinus flexilis. They're so named because their branches are extremely flexible: you can tie a branch in a loose granny knot without breaking it. Out on the rim on the canyon there was a dead tree that had grown in a spiral pattern; though it no longer has needles, Craig said that spiral-pattern trees like this are almost always limber pines.

Character trees

[another 'character tree', growing sideways] [Craig Martin points out unusually thick ponderosa bark] The spiral tree is one of the "character trees" of Kinnikinnick Park. Another one is an old ponderosa with unusually thick bark, nicknamed the "radioactive ponderosa". Later in the hike we saw another character tree that has turned a right angle and grown sideways. When people first started building the area up, advocates argued for sparing these character trees and leaving park space around them, a decision for which we're all grateful.

[tall dead ponderosa] There are also some lovely dead trees left standing in Kinnikinnick even aside from the character trees, offering me an opportunity to indulge my hobby of what Dave calls my arboronecrophotography.

Southwest white pine (P. strobiformis) looks similar to limber pines and Craig used to call some of the trees here by that name, but lately there's been a decision among plant experts that there are no southwest white pines in New Mexico, and the trees that used to be called that are actually hybrids, which Craig noted on our plant list as border pines, P. reflexa.


[Craig shows chamisa flowers, which are NOT causing your allergies] A few other shrubs we saw on the walk included cliffbush, Jamesia americana, with its branches and seedpods growing opposite each other on the stem; mountain mahogany, Cercocarpus montanus, and Prunis armediaca, an apricot tree, which many of the locals know for the fruit it bears in summer; and a chamisa, which has the unfortunate scientific name of Ericameria nauseosa, maybe because some people find the smell of its flowers quite objectionable. Craig pointed out its fluff-like flowers, which means it often gets blamed for late summer allergies that are actually caused by ragweed. Chamisa, Craig told us, is nothing to sneeze at.

Looking up chamisa on Wikipedia afterward, I was amused to find a mention of radioactive chamisas in Los Alamos's Bayo Canyon, the next canyon over from where we walked, where the roots reach down to an old LANL toxic dumping site where they mistake radioactive strontium-90 for calcium. I expect the same is true where we walked, on the edge of Acid Canyon, named for the Lab's habit, from WWII up through at least the 1980s, of dumping waste wherever it seemed convenient without any regard for the environment.

[my chaotic notes] We ended the hike near a patch of spurge (Euphorbia), where we all wondered why people like to plant this invasive with its irritating, mildly poisonous sap. One person suggested it's because it's so easy to grow and hard to kill. I can concur: we have some at home that I've been trying to get rid of.

During the hike I was frantically trying to find space on the sheet to take notes (at the beginning, Becky lamented having forgotten to bring a clipboard, which I thought sounded excessive, but quickly I realized one would have been helpful). I'm writing this up largely because I'm sure I'll never be able to make sense out of the notes a week from now, let alone a year or more. There was so much good information, and I know that without notes I'll forget it way too quickly.

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[ 12:34 Feb 02, 2024    More nature | permalink to this entry | ]

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