| By David Brandenburg, Ph.D |
Read about some common scenarios and questions we hear about plant and wildflower identification:
You’re hiking along a trail and spot a wildflower that you do not recognize, or you are cleaning up a home garden bed and encounter an unfamiliar weed—how can you find out what these plants are without picking them?
Many of us have cell phones that can double as cameras, and—if taken properly—photographs can be used in lieu of actual specimens for identification (ID) purposes. I stress “properly” because care must be taken to ensure that the digital images contain enough information to identify the plant.
Since you are using photographs to take the place of a physical plant specimen, it is important to take pictures of ALL plant parts that might be needed for the ID process. I recommend the following format:
(1) an overall view of the plant to show its height and habit (e.g., upright, weeping, sprawling).
(2) a shot of just the flower cluster.
(3) several close-ups of a solitary bloom (the top/front, the side and the bottom).
(4) images of the leaves, including how they are attached to the stem. If the undersurface of the leaf differs from the upper surface in color or in degree of hairiness, it’s important to document this.
I’ll share an example with you. In Figure 1 we see a cluster of yellow blooms. The characteristic combination of petal-like rays arranged in circular fashion around a central disc is a tell-tale sign that this plant is a member of the composite family, also called the daisy family or the sunflower family. Included in this large group are a great many yellow flowering plants that resemble the one in Figure 1, but the location (central Ohio), time of year (late spring) and habitat (woods) narrow down the possibilities. See Figure 1
An educated guess is the genus Packera, which is comprised of over four dozen species in North America, but far fewer in Ohio. The three species most common in the central part of the state are butterweed (P. glabella), golden ragwort (P. aurea) and round-leaf ragwort (P. obovata). The bright yellow flower heads of these three common species are quite similar, and vegetative features are needed to make a proper determination.
This is where photographs of the leaves make all the difference. The leaves of butterweed (Figure 2) are more or less similar in shape and only gradually reduced in size from the bottom of the plant all the way up to the top. See Figure 2
In the other two Packera species, the upper stem leaves are much smaller than those on the lower stem; furthermore, the round leaves at the base of the plant are strikingly different from the fernlike stem leaves (Figure 3). See Figure 3
The basal blades of golden ragwort are broadly notched at the point where they attach to the leafstalk (Figure 4). See Figure 4
In contrast, the base of the basal blades of round-leaf ragwort is not notched. See Figure 5
Whether you are going to look up an unknown plant on your own in a field guide or you are going to e-mail pictures to a botanist, recording lots of visual information with your camera will make the identification process easier and more reliable. On a final note: take high-resolution digital images!