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Eflora.org - Flora of North America: key it out, and find what species you have
Calflora: if you're in California, look to see which species is native (and then leave it alone!)
Wikipedia: For everything else
In the San Francisco Bay Area, where I live, work, and play, mallow is common everywhere from sidewalks and back yards to open space and trails. Most of the mallow species I see are non-native, and therefore on my collection list. With its palmately veined and sometimes lobed leaves, eye-catching (though small) flowers, distinctive seed pods, plant size (often waist high or more), and ubiquitous distribution, it's an easy plant for me to ID as a beginning naturalist and forager.
The whole plant is edible, roots to tips, and the leaves don't become bitter with age, so use them any time. It's a relative of Okra and Marsh Mallow, and has the characteristic mucilaginous (slimy) quality of those plants. Whatever you make with any part of the plant will gain a bit of that texture - which can be either good or bad. The plant has a very mild flavor, and the leaves have an odd texture, even when they're cooked. They're not my favorite wild food, but they're super abundant here during spring, so I do eat them a lot.
I like the seed pods best. Eat them raw by themselves, toss them raw into salads, or quickly fry with garlic, oil, butter, and salt (I leave the sepals on for this one - it catches more of the garlicky sauce). If you're eating them raw, wash them right before you eat them. If they soak, the slime starts to come out.
Make a tea with torn leaves. (This is my second favorite use.)
Add raw leaves, flowers, and seed pods (cheeses) to salad.
Add chopped leaves to soup 15 minutes before the soup is done.
Chop the leaves finely, mix into a batter and fry them as patties, or deep fry them and make fritters. (The only way my kids will eat them.)
Chop and saute the greens and use as you would spinach, add a runny egg for a yummy breakfast.
Add to any stir fry or cooked greens.
Use them as wraps for tacos, lettuce cups, or as you would use cabbage, fig, or grape leaves
Because of the slime, they make a reasonable egg substitute: boil 2 large mallow leaves or 2 Tbs chopped mallow root in 1/2 cup of water to sub for 1 egg
Use leaves as wound dressings, crush for a poultice
Treat sore throats, cold, and flu symptoms with tea or soup. The mucilaginous qualities of the plant are soothing.
I am on the lookout but haven't yet seen our California Native species Malva assurgentiflora, common name Island Mallow. Its flowers are larger. They are more hot-pink than purple. Also, the leaf margins are much more dentate (toothed) than the non-native species. The non-natives are much (much!) more common around me. When I do find M. assurgentiflora, I'll take pictures and nothing else. Since I'm a hobbyist forager and not relying on the calories from foraged plants, I try very hard not to forage California natives. I'm still a beginner, so I'm learning which species are on my ethical 'do' list, and I'm trying to pay a lot of attention to the distinguishing features of natives.
Photo thanks to all the awesome iNaturalist users that provide photos under the CC0 license. (And in particular, thanks to this one!)