I took the drive on Highway 20 to Bend last week with my sister for a short getaway. It had been many years since I’d been to Central Oregon, and my dryland botany was quite hazy. While the plants don’t care what we call them, humans seem to connect better to other organisms when we have labels for them.
“Ponderosa pine,” “juniper,” “rabbitbrush,” and “sage” all came readily, but the others were a mystery. I had neglected to bring a key, and the motel clerk wasn’t much help.
Yes, one can flip through pictures looking for a photograph that matches the plant you want to get to know better. But how to be sure?
Flowering plants are divided into families according to the number and arrangement of their reproductive parts—the flowers. For that reason, it’s a good investment to learn a few common/large plant families, such as rose and lily and composite, to immediately narrow the choices.
This was September, however, and there weren’t many flowers.
Complicating identification matters, many plants have similar adaptations to a given habitat: many plants in this dry region seemed to be shrubby, tough, prickly and/or narrow-leaved, and grayish.
Beyond flowers, several field characteristics are helpful in confirming the identity of a plant.
The first aspect I notice is the habitat and setting. Wet/Dry? Sun/Shade? Something unusual, such as growing in a sidewalk crack or on another plant’s branch?
A key aspect to consider is whether the candidate is woody or non-woody. If woody, is it a tree, shrub, or woody vine? (Keep in mind that the distinction between “tree” and “shrub” is not hard fast.)
Leaf arrangement comes next in the detail hierarchy. Are the leaves opposite each other on the twig/branch? …or do they alternate from one side of the twig to the other? …or are they arranged in whorls? …or are all or nearly all of the leaves “basal,” at the bottom of the stem or flowering stalk?
Is each leaf separate, having its own petiole (stem)? …or does each petiole have several or many separate leaflets? Look at the leaf petioles, too, noting their length, shape, and other details. Do the leaves even have petioles? …or do they clasp the stem?
Leaf size, texture, and color are also indicative of the species. Leaf shape can be tricky since not all the leaves of a given plant or plant species are identical and because specific conditions, such as lack of water or abundance of pests or disease, can affect the shape or the texture of the leaves.
In addition to observing the overall shape of the leaf (such as round, oval, lance-shaped, lobed, etc.), it’s helpful to look closely at the shapes of both ends of the leaves. For lobed leaves, such as oaks have, take note of the shapes of the lobes.
Look closely at the margins of the leaves or leaflets: some serrations and underturned edges can be tiny and difficult to notice. Observe other leaf details, as well, such as fuzzy undersides or veins that really stand out.
(And, yes, the needles or scales of conifers are also leaves.)
Bark or twig texture and color, arrangement or angle of the branches/stems, and the location of the leaves/flowers/fruit are all details to observe and take note of for discovering or confirming a plant’s identity.
Happily, cataloging as many details as possible is a great way to deeply observe the plant.
A particular prickle-leaved, common Bend plant caught my interest last week. While I was first drawn to the papery, quarter-inch disks nestled among the small, clasping, spike-shaped leaves along some of the plant’s stalks, closer observation found the stems had pretty purple stripes. The spreading-upright shape of the plant, the slender, prickle-leaved branches, the papery disks, and the stripes were the clincher for later identifying the plant: Russian thistle (Kali tragus or Salsola tragus), an introduced weed in the dryer parts of North America that is also known as “tumbleweed.”
Here’s wishing you an observational adventure on your next trip!