The burning sensation is part of the arthritis. I have it too. 3 drops eucalyptus oil in tablespoon light virgin olive oil makes a good pain numbing remedy. I use it myself, and am surprised at the results. Test it in a small spot to make sure her skin can handle it. Hope it helps her like it helps me. BB
The easiest way to identify herbs is to grow them yourself/buy them from a store and keep them labelled. Obviously you can collect wild herbs but until you gain experience with telling the difference, you run the risk of picking the wrong plant. Depending on your area and local herbs, this can be quite dangerous.
Alternatively, you could make simple identification charts to help you tell the difference between similar plants. The charts aren't full-proof but they're a good way to start until you get the hang of it.
When studying and using herbs you need to learn and use the official name of the herb (Latin binomial) as there are many plants with the same common names that are completely different plants with completely different properties. Even some species' of the same plant will have different properties, like the various lavenders. I would recommend the book 20,000 Secrets of Tea by Victoria Zak. It has information on a lot of herbs as well as their uses and when they are contraindicated. If your mother is taking pharmaceuticals you will have to check what their actions are before introducing herbs because there could be reactions or they could enhance or nullify each other. For identification you can look them up in field guides. There are several that are specific to edible and medicinal plants. The field guides will have the latin binomial as well as the common names. When you order herbs, online or otherwise, use the latin binomial to make sure you are getting the correct herb for what you need or want. Any good herbal will have the official name of the herbs.
Plants take from their environment--air, soil, and water/rain that nourish them. This becomes apart of them and many times is a big factor in the constituent makeup of their medicinal value. What this means is, if you want good German Chamomile, you want it to come from Germany. Rose hip oil from Spain will be superior in healing burns to rose hip oil from China. You can grow it elsewhere but it may not be as potent for the use it is so revered for. This is what makes herbalism tricky. For minor problems like cuts, scrapes, tummy aches, insomnia, etc. an herb is an herb as long as it is that herb. But for serious conditions you need to research well, find the herbs origin, and get it from that region.
As for learning herbalism, it's a long process. I suggest beginning with the German Commission E for the modern uses in practice today and use that as a basis. Then research each individual herb in science journals and studies made by universities through the web.
Look up classes in your area, find out if they have a store where herbs can be bought. you can study the plants in order to either grow your own or find them in their natural habitat. If your interested in the medicine side getting a hold of a pdr for medical herbs. any books that all in that area are often a good thing to collect. As far as your mother's arthritis pain and her walking, i don't know what she is taking or it but devil's claw works amazing with inflammatory conditions like that. I have suggested it to a lot of people who struggle, and they all tell me it's a huge help. you can talk with her doc nd see i it interacts with whats she's on but doesn't hurt to try. i hope she feels better!!