On our Walk on Wednesday at Wabasso Scrub Conservation Area on July 28 2021 we saw a stand of young Toothache Trees (Zanthoxylum clava-herculis), alias Hercules Club or Prickly Ash. The sheer number of different names this tree has been given speaks to its many historical and current uses. One of its more recent names is Florida Szechuan Tree.
As a member of the citrus family, Rutaceae, this plant’s crushed leaves have a strong lime odor and, together with the fruits, find use in spicy Asian cuisine, hence the name Florida Szechuan. All parts of the tree can potentially be used as a numbing agent as well. The pinnately compound leaves, with their clearly visible pellucid dots (see picture), contain a citrus oil that numbs your mouth when chewed, which comes in handy in extra spicy dishes. No wonder this tree was intensively used by Native Americans for numerous medicinal purposes as well.
Toothache Tree in general is a very protective plant. The base of each leaflet is armed with two spines growing on the rachis (leaf stem) of the compound leaf. The trunk is covered in prickles that give this tree its distinct vicious look.
The terms spine, thorn and prickle are in everyday use interchangeable and in general have no other meaning than “sharp protrusion”. In botanical terms, however, they have distinct definitions based on plant morphology. A spine is a modified leaf, whereas a prickle is a protrusion from the epidermis (the outermost layer) and can technically occur on all parts of the plant. Thorns are modified stems and can be simple or branched. Regardless, all three serve the same function: to protect the plant.
Why should you consider planting such a vicious looking tree in your yard? If not for its general use for humans as described above, then for its special use as a source of nectar and fruit for wildlife such as bees, butterflies, moths, beetles, birds, and more. Specifically, it is the larval host plant for Florida’s largest butterfly, the Giant Swallowtail (Papilio cresphontes).
Beauty certainly lies in the eye of the beholder, but obtaining a better understanding of the ecological context of this plant allows one to better appreciate its unique beauty!