- A ruler — marked with inches as well as metrics. Some field guides use only metric measurements while others use inches. And some field guides use both measuring systems.
- Hand lens — approximately 10x allows you to get the really close-up view of a plant’s leaves, stems, etc. Especially useful when looking at a fern’s spores.
- Binoculars — helpful when looking at plant parts some distance from you, such as leaves on a tall tree.
- Camera — either on a cell phone, pocket digital camera or a larger SLR type of camera. Allows you to make “field notes” to assist later in identifying a plant.
Here’s an excellent post from the folks at “Through Handlens and Binoculars” which provides information about both hand lenses and binoculars. The article includes suggestions for the most useful hand lens or binoculars to acquire.