Toxicodendron radicans Urushiol

Ginkgo leaf contains ginkgolic acids (urushiol type alkylphenols), compounds that are related to those found in poison ivy Toxicodendron radicans) and associated with contact allergies, especially dermatitis. Ginkgolic acids are found in relatively high concentrations in ginkgo seed coats and in low concentrations in the leaf (Blumenthal 1997). 

Craig J C, Waller C W, Billets S, El Sohly M A 1978 New GLC analysis of urushiol congeners in different plant parts of poison ivy Toxicodendron radicans. J Pharm Sci 67 483-485... 

N.A. Rhus radicans L. R. glabra L. R. toxicodendron L. Toxicodendrol, urushiol, 3-n-pentadecylcatechol.102 Sympathetic stimulant, restore nerve function, facial neuritis, ulcerated sores on the bps, mouth, and nasal membrane. 

Poison oak Rhus toxicodendron or Toxicodendron toxicaria Anacardiaceae) is nearly always found as a low-growing shrub, and has lobed leaflets similar to those of oak. It is also common throughout North America. There appears considerable confusion over nomenclature, and Rhus radicans may also be termed poison oak, and R. toxicodendron oakleaf poison ivy. Poison oak contains similar urushiol structures in its sap as poison ivy, though heptadecylcatechols (i.e. C17 side-chains) predominate over pentadecylcatechols (C15 side-chains). 

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