Ask Mr. Smarty Plants

Washingtonia filifera (California fan palm), native to California

Phoenix canariensis (Canary Island Date Palm), a native of the the Canary Islands

Phoenix spp. (other date palms), various nativities

Brahea edulis (Guadalupe Palm), native to Mexico and Guadalupe Island

Brahea armata (Mexican blue palm), native Baja California

Howea forsteriana (Kentia palm), native to Lord Howe Island, Australia

Archontophoenix cunninghamiana (Bungalow palm), another Australian species

I don't know which species your father was 'attacked' by, but you can read about the dermatological effects caused by various species of palms in the Botanical Dermatology Database (BoDD) from Cardiff University in Wales. They offer an assessment of many of the palms in the Family Arecaceae (syn. Palmae). You will note that their introduction page cites a study in Panama from 1943 that says palm frond thorn injuries (palm species not named) are noted for causing infections. Their entry for Phoenix loureiri (pigmy date palm) says:

"The spine-tip may be broken off and serve as a foreign body but a chemical irritant may also be present in the thorns..."

According to Forests Factsheet. a publication of the State of Victoria, Australia the fronds of Phoenix canariensis (Canary Island Date Palm) are poisonous.

So there is a good chance that the thorn of whichever palm entered your father's leg has some chemical irritant in it. However, whether it does or not, puncture wounds of any kind are notorious for becoming infected. This is why it is important to remove the thorn as soon as possible and thoroughly clean the wound. Read what the Mayo Clinic has to say about puncture wounds.

Washingtonia filifera

Washingtonia filifera