The first step for the Horticulture Department was to begin salvaging almost all the plants in the former Horn & Hoof Mesa area. Those 7 acres (2.8 hectares) of the Zoo contained up to 95 percent of the Zoo’s Aloe collection as well as many other succulents and several of the more important specimens of our Cycad collection. For the next several months, the LIMS crew of seven gardeners worked just ahead of the bulldozers to remove and relocate as many plants as we could. Some of the plants were transplanted to improve other parts of the Zoo; the narrow bed at the top of Cat Canyon was re-landscaped with not only plants from the construction zone but also boulders and the display case for our caudiciform plants.

Other plants had to be put in pots and stored until the project has progressed to the point where the plants can be returned to the site. So far, the transplants have gone very well with very few unsuccessful moves.

Whenever accessioned plants are ever moved (or worse, die) they must be recorded. Each plant has an embossed aluminum tag that, with any luck, is the plant’s companion for life. The tag has the plant’s name and accession number embossed on it. For every accessioned plant moved during this project, the paper work was properly updated. In the case of the plants put in storage, the paper work will have to be done again when the plants are returned to Elephant Odyssey. Some of the trees salvaged from the project can be seen in boxes along the north side of Cat Canyon road.

Mike Masterson is a lead gardener at the San Diego Zoo.

Here is more information about Elephant Odyssey…

While the mahoganies were still in #5 pots (sometimes erroneously called “5-gallon” pots), we started pruning them to develop strong structure. We hadn’t worked with this species at the Zoo but noticed right away that the young trees had a tendency to develop “co-dominant stems”; instead of a strong central leader, the trees started to grow several competing leaders. In the forest, a young mahogany would typically be growing with a lot less space around it and probably much less light. It would tend to shoot up a long central leader, reaching for sunlight, rather than using its energy to push out growth in all different directions. Many times, when we use a tree in an urban setting, we give trees a lot of space and a lot of light. While co-dominance isn’t usually an issue with a small tree, if allowed to grow that way unchecked, problems usually develop later.

Co-dominant trunks tend to be weak at the crotch and will break apart easier than trees with a strong central leader. Once the tree is mature, rather than making small corrective cuts that close over easily, we might end up removing very large branches. These large cuts leave large wounds. The open wound leaves a tree vulnerable to all kinds of disease and pest infestation. And many times, removing a large limb leaves the tree looking lopsided, or with a large hole in the canopy. So, for the health of the tree, and for our sense of aesthetics, we know that it is always better to train a young tree to develop into a strong, mature specimen.

When we plant a tree, we try to project out perhaps 25 to 100 years. Many of the trees we plant will be around longer than those of us planting them. We ask ourselves lots of questions before we plant a tree: How big will this tree get? Will it be in the way of vehicles or pedestrians? How invasive will the roots become and what structures may be affected by the roots?

Trees in our communities and parks make us feel good. They create shade, screening, healthier air. They trap particulates, sequester carbon, and make our surroundings feel more natural and pleasing. They can also create problems when we don’t pay attention to what the tree will be like when it is mature. The first five years of pruning a tree takes discipline, but it can save countless hours of corrective pruning in the future and possibly even save us from the heartache of having to remove a beautiful, mature tree.

Keep an eye on those trees in Monkey Trails and all around the Zoo. These young trees will tower above us in no time, keeping us cool in the summer and making Monkey Trails become even more “the place where every monkey would love to live.”

Mychael McNeeley is a lead gardener and certified arborist at the San Diego Zoo.

Read Mychael’s previous blog, A Perfect Way to Start the Day.

Succulent plants also have ways of storing water, but what sets them apart from caudiciforms is that succulents store water in their thick, green leaves, while caudiciforms store it in their caudex, or base, which is not green and does not produce chlorophyll. On most caudiciforms, the foliage is usually small and brittle. This is because, in times of drought, many caudiciforms will become dormant, drop their leaves, and live off stored water reserves. In these times, the plant’s main goal is to make it through the dry period, so little energy is spent on producing vegetative growth. When the rains return, the plant is happy and produces a mass of greenery and flowers freely, while also storing up water for future dry spells.

Probably the most famous of all caudiciforms is the ponytail palm Nolina recurvata, formally known as Beaucarnea recurvata. Ponytail palms come from southeastern Mexico and are grown all over the world as house plants. They look a lot like palms, but they’re not: they are in their own family. In climates like ours, they can be grown outside and get to be very large. Here at the San Diego Zoo, we are lucky enough to have at least 60 ponytail palms on grounds, and some very old specimens measure over six feet across at the caudex (base)! In our Madagascar Garden, one can find an assortment of caudiciforms being grown, as Madagascar is home to a large number of these exotic plants. Hawaii is also home to a few of them, and in our Hawaiian Native Plant Garden, a grouping of the cabbage on a stick Brighamia insignis (pictured above) can be seen growing among lava rocks.

While many caudiciform plants are grown all around the Zoo, the Horticulture Department has a display box at the north end of Horn & Hoof Mesa filled with some exotic, caudex-forming plants. Next time you visit the Zoo, stop by the camels, but also keep your eyes out for the camels of the botanical world, caudiciform plants.

Seth Menser is a gardener at the San Diego Zoo.

Read Seth’s previous blog, New Browse Hill.

Jo collected well over 300 different plant species during this time. One copy of each species is kept in the National Herbarium of Cameroon in the capital, Yaoundé, and the rest are to be sent overseas to the herbarium at the Royal Botanic Gardens, Kew, where they are available to the rest of the botanic world for taxonomic identification purposes and to document their existence in this part of Africa.

Victor Nana, National Herbarium of Cameroon, with an amazing flowering Rubiaceae plant

CRES has had a long-standing relationship in Cameroon with specialist botanists from both Yaoundé and Kew for more than five years, and we host regular visits from international experts. In April, we hosted botanists from Yaoundé, Kew, and Wageningen, in the Netherlands. I joined their search as an enthusiastic amateur: I have been collecting plant species eaten by gorillas, chimpanzees, forest elephants, and drills for many years now but have little knowledge of other species, whose fruits may be eaten and thus dispersed by smaller animals (such as bats), or may disperse with air currents.

Barbara Mackinder takes a sample of the new legume tree species

There was one species in particular that Drs. Barbara Mackinder and Jan Wieringa wanted to find desperately: a large tree that has only been collected once, decades ago, but in the same region as the Ebo forest. It is a member of the Fabaceae (Bean Family). There is only one collection of the species known to science, and it had not even been named yet because insufficient flowers and fruits had been collected to allow for a full scientific description. Imagine our delight to find it on day one of the five-day trip within 300 meters of our research station! Not only that, but within a 10-yard radius of the tree were four other leguminous tree species, one of which is another unnamed species! This species will be named after the Ebo forest, one of what we anticipate to be many new species to be found in this forest, one of the last remaining gems of rain forest found in this biodiversity rich area of Africa.

Meanwhile, we are currently arranging for our second botanist volunteer to join our team starting in July, when she finishes her undergraduate degree. Emma Fenton has visited Ebo once before, with a team from Kew in 2005, and so knows a little of what to expect in the coming months of documenting and discovering the diversity of plant species in the Ebo forest.

Dr. Bethan Morgan is a Conservation Research Fellow for the San Diego Zoo’s CRES.
Read Bethan’s previous blog, Recording the Primates of the Ebo Forest

The canopy in the area consists of two large Moreton Bay figs Ficus macrophylla. These statuesque specimens are about 70 years old. Many years ago, one of our arborists, Dan Simpson, who is now associate horticulturist, tried out an idea. These trees normally live in a more humid environment and naturally grow “aerial roots” by moisture consistently dripping off of the lateral branches. In this way, the tree puts out new roots which in turn support a broader structure, leading to trees that stretch out for up to an acre. In our dry San Diego climate, these aerial roots don’t tend to develop as easily. So Dan gave the trees a little help. He cut long pieces of timber bamboo Bambusa oldhammii and stuffed them full of sphagnum moss. He then placed these pieces under the scaffold limbs of the Ficus trees where they wanted the tree to grow aerial roots. Then drip emitters were installed along the limbs to trickle into the tubes of bamboo, keeping the moss moist and therefore encouraging the growth of root shoots into the poles. As the roots filled the bamboo poles, they eventually touched ground, thickened, and broke the bamboo open. Voila–aerial roots! Some of these roots are now about two or three feet in diameter.

Now, look under the trees and along the roots and branches. The area is teaming with plant life. Epiphytes cling to the trees everywhere. There is a large mangled old piece of deadfall covered with Cattleya orchids. A month or two ago, mostly white Cattleyas were blooming, and right now yellow ones are starting to burst out.

Above the orchids you will see a large staghorn fern Platycerium suberbum. This is an Australian species and one of the more impressive specimens in the garden. To the right is another of the same species that doesn’t look nearly as nice. However, we moved that one from an area in Reptile Mesa about a year and a half ago where it was just about dead. It is now happy in the north-facing location and pumping out some new fronds. As you glance around in the trees, you will see more species of Platycerium.

Under the trees, we planted dozens of African lilies Clivia miniata about a year ago. These bright orange members of the Amaryllis family grow well in the shade, and are in full bloom now. Tall queen palms Syagrus romanzoffianum grow up into the Ficus trees and small Chamaedorea and Rhapis palms dot the lower understory. On the dining side of the garden, bromeliads abound.

Now that you’ve experienced one of the many delightful gardens in the Zoo, sit down on a bench, finish your coffee, listen to the honking flamingos, check out your map, and plan your route. What a great start!

Mychael McNeeley is a senior gardener at the San Diego Zoo. Read his previous blog, Bog Blog: Winding Down into Winter

The Horticulture Department started the transformation months ago with the removal of many old and dangerous trees (see blog, Reforestation). Some of the logs that were not used in terracing the hillside became perches in Zoo exhibits, while others were utilized in wood-working projects. Very little lumber went to waste. With the hillside cleared and irrigation installed, the new browse plants were ready to be planted.

Logistical details, like easy access for harvest, sun exposure, growth habits, and other elements came into play when choosing plant locations. At the top of the slope, in full sun, we planted a large grove of bananas, pictured, with a half dozen different types. A little further down, a band of the Myrtle family’s shrub, eugenia, will fill in alongside a terraced track. In a large open area halfway down the hill, several species of Ficus were installed with plenty of room to grow up and produce aerial roots. Finally, about a hundred Acacia trees were planted, finishing off the hill all the way to the bottom. Since giraffes enjoy eating many times a day, a large supply of acacia trees should keep them happy.

The hardest part of acquiring, moving, and installing the plants is now done. Next, nature will take over and help our new browse hill grow, and someday down the line, browse gardeners will be harvesting food for some lucky animals.

Seth Menser is a gardener at the San Diego Zoo.

Read Seth’s previous blog, Chocolate, Anyone?

Frank Escobedo is currently responsible for getting all of the horticulture work done. He delegates the necessary work to his employees. Bonnie Duff is assigned to the Wild Animal Park’s front entrance. Together there around 30 horticulturists who work at the San Diego Zoo’s Wild Animal Park. The core functions of the Horticulture Department are to provide environments for the animals, guests, and botanical gardens, whether they are for habitat or decoration. Horticulturists must do all the needed work for shows, collections, and exhibits, such as planting, mowing, supplying, recording, and irrigation work. Supplies are often needed for animal exhibits, which include food and habitat. Certain animals need certain materials: birds need perch material, cats like palm fronds to play with. This requires horticulture and animal keeper interaction. And a tree can never be cut down at the Zoo or Wild Animal Park without a bunch of keepers calling dibs on the limbs and stumps for their animals’ enclosures.

Throughout our lovely walkabout through the beautiful gardens, Frank Escobedo intertwined advice about how to have a happy life, even if you don’t want to hang out with plants for a living. “You should work on what you like best and have fun!” exclaimed Mr. Escobedo. “Don’t let go of your dreams and be the best you can be.” He also emphasized the tremendous amount of job opportunities available in this area whether the position is an arborist, botanist, agronomist, or biologist. Find what you love and you will love what you do!

-Melissa, Zoo InternQuest, Animal Careers Team

Watering Plants Saves Water?
The Wild Animal Park has three accredited botanical gardens: Nativescapes Garden, Baja & Old World Succulent Garden, and Conifer Forest. Because these three botanical gardens are recognized and accredited, the Horticulture Department is entrusted to propagate the species of plants in each of the gardens. It is their duty to conserve the plant diversity that otherwise might be endangered.

In addition to growing plants, horticulturists are responsible for managing and mapping the irrigation that accompanies such a vast area of land. It is estimated that the Wild Animal Park goes through 2 million gallons of water a day from various sources like nearby lakes, ponds, and reservoirs. However, the Wild Animal Park is not the only place tapping into these water sources. In the San Pasqual Valley, farmers also need water for their crops. In an effort to conserve water, the Wild Animal Park has built a reclamation plant. This plant processes used water, runoff from irrigation, and gray water from sanitary sources, and stores it in the reclamation pond; from there it is used for irrigation. In the past, the reclamation plant was able to process 40,000 gallons a day. Due to recent upgrades, it processes nearly 200,000. Although local farmers and the Wild Animal Park have drained much of the water in the Valley aquifers, by using reclaimed water for irrigation, the Park is reducing demand on the aquifer and saving fresh water for other uses.

In addition to being in charge of preserving endangered species of plants like the cycad, a prehistoric and endangered conifer, horticulturists are responsible for maintaining an enriching animal environment. Arborists collect deadfall from trees for use in the animals’ enclosures in order to enhance their habitat. This plant material is known as animal “furniture.” In doing so, they are utilizing what might elsewhere be considered useless dead plants. Recycle, reduce, reuse!

-Keesha, Zoo InternQuest, Conservation Team

I Might Have a Green Thumb After All!
To be perfectly honest, I’ve never really had much of a green thumb. Actually, I would go so far as to say I had a shriveled, dead, and black thumb. I tried to grow raspberries recently and they all died. My grandmother, a skilled gardener, said that killing raspberries was quite a feat, because they won’t die, even if you want them to. I’ve harbored resentment against plants for a long time, never having accomplished my dream of a rain forest-like backyard. After our meeting with Ms. Duff and Mr. Escobedo, my anger has lessened considerably. I know now that it is possible to keep a single raspberry plant alive, since the 30 or so gardeners at the Wild Animal Park keep thousands of plants alive without batting an eye; I’m just not a very good gardener. I was deeply impressed by the enthusiasm with which these two people approach their jobs. Instead of focusing on the common complaints of how terrible life is and why can’t they be rich and famous, Ms. Duff and Mr. Escobedo provide a wonderful contrast. Mr. Escobedo pointed out that once you have a passion for something, all you need in order to be happy is a pair of good pruning sheers and some tough work gloves.

Besides keeping the Park looking nice, the Horticulture Department keeps visitors informed about the plight of many plants, including many endangered plants like the Torrey pine. Although plants may seem like background for the animals, they are complex organisms that contribute so much to our world. Some plants have medicinal properties, others provide food for humans and other animals, and all produce the oxygen we breathe. By keeping guests at the Park informed, Mr. Escobedo and Ms. Duff help foster conservation efforts, and can even turn the most cynical, anti-plant person (like me) into true botanical believers.

-Sarah, Zoo InternQuest, Real World Team

Frank Escobedo, a senior horticulturist at the Wild Animal Park, tells of the dangers of having eucalyptus trees. They have weak trunks and bark, which can cause fractures on the tree and lead to falling branches.

The cycad is a prehistoric conifer that is related to the pine tree, hence the large cones in the center. Mr. Escobedo told us of his passion for growing these huge trees in his backyard.

Growing very tropical plants outside has been tried at the Zoo before, but the problem of cool, damp soils in the winter seems to be the biggest killer. The cacao plant Theobroma cacao, source of chocolate, comes from the tropical rain forests of Central and South America–places that rarely get colder than 60 degrees. How could we create an environment where a cacao tree could survive outdoors in cooler temperatures? An idea came to Mike Letzring, the Zoo’s Horticulture Collection Manager. His plan was to create a heated area in the soil just below the plant, similar to heat benches for seed germination in greenhouses. This would help keep the roots warm all winter long.

With our plan in hand, we began our “chocolate experiment” in an area off-limits to the public. First, what was needed was a chocolate plant; luckily there were several growing in our greenhouse. Next, we built a 30-inch box made of insulation board, the kind you would use to insulate walls in homes and other buildings. After making drainage holes in the bottom of our insulated box, we added a few inches of well-amended soil. Our heat source, heating cables regulated by a control box, was coiled out and laid on top of the soil. Six more inches of soil was placed on top of the heating cables. Once the chocolate plant was planted and backfilled, a layer of mulch was spread over the whole area.

Over the course of the experiment, regular soil and air temperatures will be taken and recorded. This information will come in handy to us if our planting is successful. Although this very cold winter has been uncomfortable, the low temperatures will actually work to the advantage of the experiment, in that they provide an extreme temperature variable. Check back in a few months for an update on how our chocolate plant is doing. Who knows…maybe sometime down the line we’ll be able to make our own chocolate bars!

Seth Menser is a gardener at the San Diego Zoo.

The Zoos’ collection of aloes is comprised of 114 taxa and is one of the largest in California. The plants range from the small 6-inch miniatures to the tree-like Aloe bainesii, of which we have four on grounds that are over 12 feet tall. In their native habitat, they grow in the rocky hills of South Africa, mainly in full sun. They do not take frost but some in hotter areas like partial shade. Water requirements are little, but they will take additional amounts of water if given (see Weblog, The Aloe Tree).

Aloes will grow as solitary specimens or as large clumps like the “tree-like” species Aloe arborescens. If you get an aloe plant, be sure to confirm the species, as certain ones can be a problem of large magnitude if they grow too big for your space. They can take over an entire area by their spreading habit. Always keep in mind that they are armed and working with them can be hazardous and painful if you are punctured. However, looking at them can bring great pleasure–come to the Zoo and enjoy our bloomin’ aloes!

Mike Bostwick is the horticulturist for the San Diego Zoo.