The Guadalupe palm, Brahea edulis, grows wild in only one place: Guadalupe Island, a volcanic island about seven million years old that lies 260 km west of the Baja California peninsula in Mexico. Researchers call it the Guadalupe fan palm. It is not a date palm. This page sticks to what three published research papers report about it.
A palm with a very small home
Guadalupe Island covers about 240 km². The palm occupies only about 0.8 km² of it, at the foggy northern end of the island. Botanists describe it as spread across the northwestern side, with small patches along the bottoms of arroyos elsewhere on the island.
That tiny range is worth keeping in mind when you read the genetic results below.
What the DNA work found
In 2017 a team from the Centro de Investigaciones Biológicas del Noroeste in La Paz and Bielefeld University in Germany sequenced chloroplast and nuclear DNA from 169 samples of five native palm species, collected in Baja California, Sonora and on Guadalupe Island (Klimova et al., Ecology and Evolution 2017, PubMed 28690819). Seventeen of the Brahea samples came from Guadalupe palms.
The island palms had very low levels of chloroplast and nuclear diversity. In their nuclear DNA they were fixed for a single haplotype of their own, which set them clearly apart from the Brahea populations on the peninsula. In their chloroplast DNA, though, they could not be told apart from the northern peninsula populations. The authors found the overall pattern consistent with the more recent colonisation and isolation of the island’s palms.
A follow-up in 2018 used genotyping by sequencing on 190 leaf samples, covering all five native Washingtonia and Brahea species of the peninsula and the island (Klimova et al., Ecology and Evolution 2018, PubMed 29938100). It resolved three main clades, and the Guadalupe palm made up the third on its own. The authors took this as support for its status as a separate species. Because the island is generally believed never to have been joined to the mainland or the peninsula, they suggest the first palms got there by long-distance dispersal.
A leaf-spot test in Sicily
The Guadalupe palm also turns up in a short plant pathology note from the University of Catania (Polizzi et al., Plant Disease 2007, PubMed 30780444). In April 2006 a fungus, Calonectria pauciramosa, caused leaf spots on two-year-old seedlings of Mexican blue palm, Brahea armata, in a private garden in eastern Sicily.
The team then sprayed the fungus onto one-year-old plants of several other palms, Brahea edulis and Phoenix canariensis among them. Within seven to ten days, spots developed on both Brahea species and on Chamaerops humilis. The other palms, Phoenix included, stayed healthy, as did the control plants. The authors note it was the first report of this fungus on Arecaceae.
How it differs from the date palm
Dates come from a different plant altogether. The FAO’s date palm handbook gives the botanical name as Phoenix dactylifera, and says the species name comes from a Greek word for finger, after the shape of the fruit. The same handbook says the genus Phoenix holds about a dozen species, all native to tropical or subtropical Africa or Southern Asia. So the Guadalupe palm, a Brahea from an island off Mexico, sits in a different genus from the date palm.
The handbook adds two details about the date palm that are easy to picture. Its adult leaves are pinnate, and it is dioecious, with male and female flowers on separate palms.
Where dates come in
This site is about the fruit of Phoenix dactylifera, not the Guadalupe palm. The blog lists the other articles here, and the About Us page introduces the site. If you have a question about buying dates, use the contact page. Another site in the same network, kurmamazafati.com, is about dates too.