This year, Southern California’s renowned Joshua tree has started blooming significantly earlier than usual, which has raised concerns for scientists attempting to understand what’s going on.
Usually, these Mojave succulents begin their blooming season between February and April, during which they attract yucca moths. These moths play a crucial role in pollinating the flowers, leading to the production of fruit that eventually falls to the ground and is consumed by rodents. As these animals migrate, they help disperse the plant’s seeds.
This year, however, something unusual has happened: the familiar white and yellow flowers began to bloom in late October. This unanticipated timing has left scientists wondering about the potential effects on the Joshua trees’ fruit production and the implications for their reproduction.
These early blooms come at a time when these iconic trees are already facing challenges due to wildfires and extreme weather conditions.
Jeremy Yoder, an associate professor of biology at California State University, Northridge, pointed out that if the yucca moths, the exclusive pollinators of the Joshua tree, can’t adjust to this early blooming, it might pose a problem. Traditionally, the lifecycle of the moth is tightly aligned with the flowering schedule of the Joshua trees.
Yoder mentioned that these moths not only pollinate by depositing pollen, but their larvae also develop inside the fruit, feeding on some seeds before emerging and burrowing into the ground, where they form cocoons—essentially continuing the cycle.
“The moths are completely reliant on the trees,” Yoder explained. “They do such an effective job that there aren’t other pollinators.” The pressing concern now is whether the moths will show up in response to the early blooms, and preliminary observations suggest they haven’t.
Yoder believes that this year’s early rains might have been a factor contributing to the unexpected flowering. His lab is encouraging public participation to document this phenomenon by sharing photos of blooming Joshua trees. This effort aims to gather more data to understand the effects of early flowering on fruit production.
A similar early bloom was noted in 2018, but that mostly impacted trees within Joshua Tree National Park—this year’s blooming seems to be affecting trees across all habitats.
The data collected could provide invaluable insights as scientists compare public photos from 2018 with those from this current year to assess the potential impacts of early blooming on the Joshua trees.
“If the trees are blooming more frequently without the moths coming around to pollinate, it might lead to an energy drain for the trees,” Yoder noted. “This could make them less resilient during stressful times, which can be concerning for the overall population.” Yet, he conceded, “That’s just a possibility. We really don’t know.”
