Hi & welcome to Gardenweb! Agree with the above. If this was mine, I would scoop it out and leave the root ball sitting loosely on the surface to dry more quickly, maybe even laying it on some newspaper if it's very moist. Then snip the stem below the concentration of aerial roots and sit it atop another pot with a more chunky, porous mix that is barely moist, burying the aerial roots just enough so they don't spring back up, without packing them down at all. That looks like it will leave about 4 leaves and a couple aerial roots on the original plant. See if you can get those aerial roots to make contact with the soil and stay that way. Put both in the sunniest spot you have and let them dry out. Then go very lightly with the water for the removed top part, until the roots have a chance to go throughout the pot, just moisten the surface the first few times. If/when the original part perks back up, gently knock the old soil off of its' roots and put in the chunkier mix that dries out quickly, then finally give it more water. If the soil for these types of plants does not dry quickly, they can rot. Even just after watering, having tiny air pockets throughout the pot is good so the roots can get some air as well as moisture. So avoiding fine particles like peat and sand, and actual soil is best since these small particles fill up all of those spaces, suffocating roots and harboring too much moisture.

You could try a number of penstemon species such as penstemon eatonii, penstemon barbatus coccineus, or penstemon pinifolious. All of which are great drought tolerant/heat resistant hummer plants. Although in Phoenix i would give them part shade since it gets so hot. Another possibility could be red-hot poker which is relatively drought tolereant as well. Im sure aloe sp. would also thrive in Phoenix, i had a huge aloe plant in my front yard when i lived in california(Zone 9 as well) and it drew in the hummingbirds when it was in bloom.

Peperomia glabella Looks like yours might have in addition been one of the forms sold as "red stem" or "red stemmed".

Thank you all for the responses. It looks like Wild Radish has hair on the early leaves while Mustards do not. I don't recall hair on any leaves so Mustard it is (I think) : )