Young saguaro cactus were peeking out from its bursage nurse plant.

As you walk through the desert, there are many opportunities to view some of the striking cacti and their unique shapes.  What is not initially apparent, are the many examples of plants helping young cacti survive.  However, if you look closely, it is all around you – desert shrubs and trees sheltering growing cacti from the harsh desert climate. 

 Young barrel cactus underneath a bursage nurse plant

Despite their tough, prickly appearance, cactus are quite vulnerable.  Of the thousands of seeds that are released by each cactus, only a tiny fraction grow into new cactus plants.  Most would not survive if it were not for “nurse plants.”   These plants provide much-needed protection from the sun, cold temperatures and predators (including humans).  Nurse plants also provide much needed additional moisture for the new cacti.

 Mammillaria microcarpa 

It is easy to walk by and not even notice the presence of the small cacti growing underneath nurse plants.  Most of the year, the fishhook cactus (Mammillaria microcarpa), pictured above, are almost impossible to see.  It is only in the spring when they are blooming that you can spot them.

 Hedgehog cactus outgrowing it’s bursage nurse plant.

For the smaller cacti species, bursage (Ambrosia deltoidea) most often serves as the nurse plant.  It also often serves as the first nurse plant for saguaro cacti.

 Two young saguaro cacti outgrowing their creosote and bursage nurse plants

Creosote (Larrea tridentata), palo verde, mesquite or ironwood trees often serve as the nurse plants for larger species of cacti.  As it grows larger, it requires more water and nutrients from the soil, which leaves little for the nurse plant.  So frequently, the nurse plant will decline and die as you can see from the photo above.

 Young buckhorn cholla emerging from its bursage nurse plant.

So next time you have the opportunity to take a walk in the desert, look around….you will most likely see examples of this unique relationship of plants helping young cactus survive.

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