American Sweetgum tree seed pods

(Question)

I am just about to purchase a sweetgum tree and I was wondering if its seed pods were considered nuts or fruit, as I am allergic to nuts and legumes, so I want to know if it will be safe for me to handle the seed pods.

(Answer)

I located no information linking the sweetgum tree seed pods (or other plant components) with nuts or legumes.

By way of background, female flowers of the American sweetgum tree or sweet gum tree (Liquidambar styraciflua) yield hard, round, bristly fruiting clusters that are often referred to as “gumballs”. Each gumball can contain up to 50 seeds; these are eaten by birds, squirrels and other animals.

The tree is associated with a few chemicals that may be of interest, although I found little concerning allergies related to any part of the plant:

  • The fruit seeds contain shikimic acid, which is used as the basis of an anti-flu medication (oseltamivir or Tamiflu®) [this chemical is usually obtained from the Chinese star anise]. It may be possible to be exposed to this chemical if you handled seeds, although this would likely only be in very low concentrations. I found no reports of allergy to shikimic acid.
  • Wounds in the tree exude a “gum” or sap that has been used for chewing gum and flavourings, among other things; this gum is the only part of the tree that is edible.
  • Storax, a chemical present in the sap of the tree, has been reported to cause skin sensitization and contact allergy.  This is not related to your nut/legume allergies, although should you touch the tree’s sap, you may experience skin symptoms. Remember, though, that the sap is used for chewing gum, so the storax concentration would be very low and unlikely to provoke a reaction.
  • The only information I found concerning allergens and the sweetgum relates to the wind-borne pollen it produces, which has been reported to cause allergic sensitization, although the evidence appears anecdotal and is very limited, with few actual cases documented. See Thermo Scientific’s Sweet gum  for more details.

Another issue to consider before purchasing the sweetgum tree is its “nuisance factor”. The gumballs turn dark brown in colour and generally stay on the tree throughout the winter, although from December through April, they often clutter the ground below the tree and can be hazardous to pedestrians, e.g., if the tree overhangs a sidewalk.

Finally, note that there is a gumball-free (fruitless) cultivar of the sweet gum tree, Liquidambar styraciflua ‘Rotundiloba’ .