Why is Rudolp's nose red?
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Desert Fruits Rock!

By John Alcock
Illustrated by Sabine Deviche

show/hide words to know

  • Brilliant: very bright.
  • Lure: attract.
  • Mace: a spiked ball-shaped weapon used in medieval battles to crush armor.
  • Mammal: warm-blooded animal with fur.
  • Scarlet: bright red or reddish orange color.
  • Sonoran Desert: a desert located in the southwestern corner of the United States and the northwestern tip of Mexico including Baja California... more
  • Spectacular: outstanding, dramatic, thrilling.

Saguaro flowers and fruitsWhen you or I go walking in the desert and see a saguaro cactus with its gorgeous big white flowers or a brittlebush covered in hundreds of smaller but very cheerful, bright yellow flowers, we applaud what we are seeing (or at least I do).  In fact, most people only pay attention to plants when they are in flower. But let’s face it. The season of the flower for any given desert plant is usually fairly short and if we were to limit ourselves to just that period we would miss some remarkable things.

Take the spectacular fruits of saguaro cacti. As they ripen, the big green plum-sized fruit of this species splits open, revealing brilliant red interior panels.These panels spread apart to form a stunning advertizement for the popsicle-shaped mass of black seeds and dark red pulp in the middle of that big red star. These popsicles are wildly popular with desert house finches and white-winged doves, which come to feast on the fruit. After consuming the pulp and seeds, the birds will later pass some of the seeds through their gut and out onto the desert ground, where they will have a chance to grow into a new saguaro.

Saguaro fruits are hard for doves to ignore and they are so big and showy that even people are usually willing to take a look at them. But this is not the case for most other desert plants.

Pincushion cacti flower and fruitConsider the little pincushion cactus, which is only a few inches tall, not 20 or 30 feet high like an adult saguaro. The pink flowers are small but they are so attractive that some people may glance their way. However, after the flowers have been pollinated by tiny bees, the tiny fruits generally get ignored. But if you take the time to look at them, you will see that these fruits are not only quite pretty, they also can make us stop and think: why are pincushion fruits so red? The scarlet fruits are so close to the ground that you might guess that they must be harvested by small desert mice and rats. But wait a minute. Most small mammals cannot see colors but birds can, and so I wonder if pincushion cacti are “trying” to lure a ground-dwelling bird, perhaps a curve-billed thrasher or mourning dove, to come have a bite to eat, the better to disperse the seeds within their tiny but brilliantly red fruits.

It’s not just cacti fruits that repay a closer look after the flowering season is over and done with. Take white ratany, a scruffy little shrub that in spring produces some amazing red-purple flowers, which really are prettier than the follow-on fruits. These fruits look rather like the head of a medieval mace, a heavy round weapon studded with iron spikes. But the spikes on white ratany fruits are not hard or spiky. Instead, they are flexible devices tipped with two tiny little hooks. By coating the surface of the fruit, the hooked spikes create a Velcro-like surface that clings to whatever comes in contact with the fruit, such as a passing rabbit or the leg of a coyote.  So this fruit does not “try” to attract a seed disperser but instead invests in structures that help it hitch a ride on an involuntary seed carrier.

Each and every one of our Sonoran Desert flowering plants produces fruits that have their own stories, a complement to those associated with the often eye-catching flowers of these species. Take a look after the flowering season and maybe you too will be surprised and entertained by what you see.

Ratany flower and fruit

About the author and photographer: John Alcock is a behavioral ecologist and an emeritus faculty member of the School of Life Sciences. He is also the author of more than a half dozen books including: When the Rains Come: A Naturalist's Year in the Sonoran Desert.

Catclaw acacia

Catclaw acacia fruit

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