Species Driven Restoration – Tumamoc globeberry

Healthy Tumamoc globe berry vine and fruits growing in a creosote on Tumamoc Hill.

Healthy Globeberry fruit on vine - about the most likely thing
for one to notice about the plant.

If, near the tail-end of the monsoon season, you find yourself walking among the creosotes and acacias, you may notice a small vine twining its way up through their branches to expose a handful of leaves on the shrub’s surface. Then again, you might not. You might pass by and never notice this spindly vine. If you do spot it, it will probably be the subtle color differences that grab your attention—a blue-green vine against the yellow-green creosote or the bright red of their small fruits (that is, if you can catch them before they’re eaten by bird or beast).

Dormant Globeberry fingerling

What you do not see are the underground tubers of the Tumamoc globeberry (Tumamoca macdougallii Rose). These amazing Sonoran Desert natives are in the same family as gourds and melons. They were historically common through the Avra Valley where they grew among the creosote flats. However, with the spread of agriculture the globeberries disappeared, residing finally in just a few known refuges including Sabino Canyon, the Painted Hills, and Tumamoc Hill. In 1986 they were listed as a federally endangered species. During construction of the CAP canal, many were relocated into a preserve on the eastern side of the Avra Valley, adjacent to the canal. Upon discovery of widely scattered populations in the Waterman Mountains to the west of Avra Valley and remote deserts in Sonora MX, they were delisted in 1993. Although no longer “officially” endangered, their numbers on Tumamoc and in Sabino Canyon continue to decline and the Tumamoc globeberry is remains a species of conservation concern by the Sonoran Desert Conservation Plan. These plants are root perennials, sprouting out a new vine each summer that will dry up after the monsoon season ends. The tuber itself will live for many years…baring predation that is. (See the website maintained by FrankReichenbacher, the leading expert on Tumamoc globeberries, for more details on the listing/delisting and population levels of the globeberry.)

Uprooted tuber ready to plant

Last summer, at our Martin Farm restoration site, we began an effort to reestablish the genetic linkage between the population in the Waterman Mountains and those populations to the east. Pollination for this species is not well understood, however the tiny, non-showy, and relatively unscented flowers make long-distance cross-pollination unlikely. This necessitates a chain of relatively close populations to increase the likelihood of genetic flow. We purchased a flat of 32 tubers, each a year old, from Miles Anderson at Miles' to Go--Cactus and Succulents, about the only nursery in Tucson that sells them. We planted them across the site in a generally linear fashion.

The succulent nature of these tubers makes them a favorite food of many desert mammals, including javelina, ground-squirrels, and jackrabbits. To protect our newly transplanted fingerlings, we planted them in 5-sided cages of hardware cloth, staked deep into the ground.  Nothing would be able to bite into them from the sides or top, they have plenty of room to grow (the tubers can get quite large but the largest are smaller than the cage size), and the vines have plenty of space to stretch out. We planted them under the protective shade and vertical structure of creosote bushes.  These provide a slight filtering of the sunlight that might reach the tuber, and a lattice for the vines to twine among.

Young globeberry vine growing through cage and up into the creosote bush above.

...And it's gone. Hole where 

globeberry tuber used to be.

Last week we went out and checked the plants to see how many had survived from last year. We knew that a few had been eaten last summer by ground-squirrels burrowing under the cage and snacking on the tuber. Quite happily we found that the ground-squirrels had only destroyed four.  The other 28 have pushed out a tiny start of a vine for this year…a tiny start 1” to 8” long awaiting the onset of monsoon rains to take off and grow. If the rains are good, each could produce up to 10m of vines before the end of the season and will hopefully produce fruits to help spread the population.

Given time and financial opportunity we hope to be able to restore more populations across Avra Valley and restore the genetic flow between populations on either side of the valley. If you want to become involved with critical conservation and restoration efforts like this one, please contact us! We’re always looking for more help with ongoing research into the needs of specific species (like our Nestboxes for Urban Birds/Nestbox Experiments – blog coming soon) or optimizing efficiency in restoration techniques (check out pg. 22 of the next issue of the Vermillion Flycatcher).

Finally. if you would like to join the yearly effort surveying for Tumamoc globeberry plants around Tucson, please contact Frank Reichenbacher – especially important this year as the proposed Southline Transmission Projectgoes within 11 yards of the remnant globeberry population on Tumamoc Hill.