By Constance Taylor
If you took a walk around Lake Merritt, how may of the tree species would you be able to identify?
It can be a bit tricky in urban areas because so many of the trees are from different places in the world- you won’t find many Oakland city trees in a “Trees of Western North America” or “Trees of California” guidebook. Most urban California trees are from Asia, Australia, or Europe; in fact, only 6% of commonly planted urban trees are native to California1!
However, there’s a fantastic book called A Californian’s Guide to the Trees Among Us that identifies many of the commonly planted urban trees in the state. It also includes a dichotomous key to help you figure out which species are which so you don’t have to go through the guide page by page to identify a tree you’re standing next to. The funny thing about keys, though, is that they can be notoriously confusing to use. I once heard that keys “are written by people who don’t need them for people who don’t use them”- a joke that usually gets a sympathetic chuckle from anyone who’s ever used a key.
Enter Kristin Tremain, Ivan Parr, and Tammy Lim- Wildlife Society biologists who helped guide us though some key-reading 101! But wait… why would wildlife biologists, who usually deal with studying critters, need to know things about trees? “Trees are nature’s architects,” Kristin explained. “Certain animals- birds and mammals, like to live in certain trees, and to study those animals we have to know where to find them.”
We began with Ivan explaining some basic botanical vocabulary and major features you should look for. For example, is the tree a gymnosperm (conifer), angiosperm (flowering plant), or palm?
Leaves are a really important part of tree identification, so we focused on some of the many words describing very specific attributes of leaves.
Is it a simple leaf or a compound leaf?
Are the leaves on the branches opposite, alternate, or whorled?
Are the leaf veins palmate, pinnate, or parallel?
Are the edges of the leaf smooth, serrated, lobed, or undulate?
After the brief indoor tutorial, we went outside and used the key in the Ritter book to help us identify the trees in front of the Rotary Nature Center. Although we focused on trees for this event, these identification basics (and vocabulary) work for any plant.
Here’s a bit of advice from me to you if you’re just starting out with plant ID… don’t be discouraged by the new vocab. It’s important to know the words, but don’t worry if most of them are unfamiliar to you. Even experienced botanists often need the internet or a botanical glossary near them when they’re keying plants! The more you encounter the words, the more familiar they’ll become.
1M. Ritter, A Californian’s Guide to the Trees Among Us (Heyday, 2011), xv