Dermatitis

Tall Grass prairie:

Witch Hazel

• Hamamelis virginiana
• found in woods
• active chemical ingredient is Tannin(Source) 
• Tannin: Chemistry. any of a group of astringent vegetable principles or compounds, chiefly complex glucosides of catechol and pyrogallol, as the reddish compound that gives the tanning properties to oak bark or the whitish compound that occurs in large quantities in nutgalls(Source)

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• Used in European phytomedicine for treatment of burns, dermatitis, hemorrhoids, local inflammation of mucous membranes, minor skin injuries, vercose veins, and venous conditions, among others.(Peterson Field Guide)

Deiduous:

Phlox

• Phlox pilosa(Source)
• found in flat clusters that grow out not up
• active chemical ingredient mupirocin(Source)
• an antibacterial derived from Pseudomonas fluorescens, effective against staphylococci andnon-enteric streptococci; used in the treatment of impetigo and, as the calcium salt, in the treatment of nasal colonization by Staphylococcus aureus. (Source)

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• Tea from leaves used internally and externally as an eczema treatment(Source)

Chicory

• Cichorium intybus
• found on roadsides 
• active chemical ingredient is alpha-amyrin(Source)
(Picture Source)
• alpha-amyrin: A pentacyclic triterpenoid that is ursane which contains a double bond between positions 12 and 13 and in which the hydrogen at the 3β position is substituted by a hydroxy group.(Source)
• Use one ounce root in one pint of water for diuretic, laxative.folk use i jaundice, skin eruptions, fevers.