Joshua trees are rock stars in the plant world when it comes to the ability to survive in scorching heat, freezing cold and with little water.
U2 is celebrating the 30-year anniversary of its best-selling album, The Joshua Tree and touring Southern California this weekend. The band will come and go but these trees will continue to stand tall in the harshest of environments.
Joshua trees are the largest plants in the high desert, some reaching more than 40 feet tall, but they would not grow without the help of a tiny moth less than an inch long. In short, the tree is a nest and food source for the insect and the insect (only the females) pollinates the tree’s flowers. There is no other plant the insect can utilize and there is no other insect that can help the Joshua trees reproduce.
Not a tree
Technically Joshua trees are not trees, they are plants. In 2011, The American Journal of Botany published a report confirming that there are two distinct varieties of Joshua trees, brevifolia and a smaller plant, jaegeriana McKelvey. The plant is a member of the Agave family.
Plenty of names
It’s unclear how the Joshua tree got its name, though it could have originated with Mormon settlers naming it after the Biblical figure Joshua, seeing limbs outstretched and guiding travelers. The Native Americans call them “humwichawa” among other names. They are also referred to as yucca palms and in Spanish they are izote de desierto “desert dagger.”
As far as plants in the desert are concerned Joshua trees grow rapidly when they are young. They can grow about three inches a year for the first 10 years and slow to about half that rate the following years. That means a Joshua tree seed planted in 1987 when U2’s album came out would be about 60 inches tall.
A cross section of the tree’s fruit where its seeds are kept. New plants can grow from seed, but in some populations, new stems grow from underground rhizomes that spread out around…