Identifying Geraniums without flowers or fruits

The foliage of Geranium species can vary considerably within and across species depending on environmental conditions such as water, temperature, light, soil type, and season. Leaf structure can even vary on the same plant; upper leaves tend to be more finely divided in all species and often differ in shape from the lower leaves. In addition, Geranium foliage is often misidentified as Delphinium, Mallow, Hydrocotyle, or Sidalcea. The Jepson key uses flowers and fruits to differentiate Geranium species. It does not use leaf structure in the key at all, except to differentiate G. bicknellii vs. G. rotundifolium: https://ucjeps.berkeley.edu/eflora/eflora_keys.php?key=9884. It’s difficult, if not impossible, to identify Geranium species from leaves alone, so it's best to leave foliage-only observations at the genus level.

Note: The pictures in this journal posting were taken from iNaturalist photos of flowers and/or fruits of Geranium species that have been verified as Research Grade. I cropped the photos to remove the flowers and fruits, leaving only the leaves and stems.