Director Lew Feldman

Historical Origins and Medical Discovery

Flowering each autumn in the Garden’s Medicinal Herb Collection, Colchicum autumnale is easily recognized by its striking, purple-pink flowers. Known as autumn crocus or wild saffron, C. autumnale is the source of colchicine, one of the oldest medicinal drugs still used today worldwide. Medicinal applications of colchicine to treat pain and swelling were first documented more than 3,000 years ago in the Ebers Papyrus (circa 1550 B.C.). By the 1st century A.D., the Greek physician Pedanius Dioscorides described it as a remedy for gout. The name “colchicine”, the term given to the toxic alkaloid produced by the plant, likely stems from its historical reputation as a poison in Colchis, an ancient kingdom situated in modern-day Georgia bordering the Black Sea. According to Greek mythology, the sorceress Medea used C. autumnale to craft deadly potions. Its introduction to colonial America is often credited to Benjamin Franklin. Today, colchicine remains a first-line drug of choice for the treatment of gout. More recently, it was also shown to provide therapeutic benefit for another group of conditions in which inflammation is a key component: cardiovascular disease.

Colchicum autumnale is found in the Herb Garden, bed 702, alongside other medicinal plants. It blooms in the fall.

The plant is believed to be native to Great Britain and Ireland and is now found across mainland Europe. It thrives in meadow grasslands and woodlands in moist, periodically damp soils, similar to its location here in the Garden. However, unlike most plants that flower in the spring or early summer, C. autumnale follows what could best be described as a “reversed seasonal cycle,” remaining leafless in late summer and fall, when it flowers. It relies on a subterranean, irregularly shaped corm filled with starch to survive winters underground.

Chemical Defenses and Toxicity
The highest levels of colchicine occur in the seeds and flowers, and it is likely that this compound forms part of the plant’s chemical defense against herbivores and insects. The production of colchicine and its leaching into the soil have been reported to stunt the growth of nearby, competing plants. Take note: the plant poses a particular threat to domestic cats.

Applications in Plant Breeding and Horticulture
Applications of colchicine extend beyond its use as a curative for gout. Treating plants with colchicine causes a doubling of their genetic material (DNA), a condition known as polyploidy. Polyploidy is frequently linked to developmental changes, including new morphological traits such as larger flowers and leaves. As a result, the use of colchicine has gained the attention of horticulturists.

Banner image: Melina Meza

“Inspired by a childhood in the Chaparrals of Southern California, I found myself hooked on plants. Learning all I could about botany, I came to revere institutions like the UC Botanical Garden for the work they did in such an interesting field. Thus, one of the first things I did after arriving on campus was find work at the Botanical Garden…. As a statistics major, working alongside the amazing botanists in the Curation Department, I am able to apply my knowledge of programming, computer science, and mathematics to streamline tasks involving the Garden’s extensive database.”

Arman came to the Garden as a volunteer during his freshman year. It was clear from the start that he was a total plant nerd (just like us), but when he offered to help us streamline a file-renaming process using some more advanced coding techniques we were really impressed! His technical skills turned out to be exactly what we needed for a massive archival effort. As we embarked on what we called the “Dead Card Project” we realized quickly that Arman would be a big help. Thanks in part to a donation from the Hillside Gardeners of Montclair, we were able to offer Arman a job to help us with this project.

The “Dead Card Project”–Bridging a 40-Year Data Gap

When the Garden transitioned to an electronic database in the mid-1980s, left behind was a legacy card file containing roughly 22,000 4″ x 6″ cards, each one representing a unique accession that had previously lived and died. The Garden worked with Doxie AI (a company that specializes in using artificial intelligence to extract structured data from unstructured formats), to read the cards and create output that will allow us to finally integrate them into the Garden’s Plant Database.

Arman has been working closely with the Garden’s Assistant Curator, Sophia Warsh to edit the outputs from Doxie to make sure that they meet our needs, and collaborated on strategies for approaching the data clean-up process.

Arman helped us make sure that different authority records like taxa and collector are all formatted following our current standards, using tools like coding and AI to standardize fields in the output. Meanwhile, he is getting a crash course in taxonomy, nomenclature, and Garden history as he works through the records, asking our curators clarifying questions when presented with confusing formats.

Unlocking Insights for the Future

Soon, all this information will reside in our online database and can be used for climate and phenology insights, historical collecting patterns, recording our horticultural activities over time, and preserving historical collections that may not be recorded by any other method.

Says Garden Curator and Conservation Officer Clare Loughran: “It’s been a joy to work with him. His thoughtful questions really get at the nitty-gritty of curation that we don’t often get to explore. When we’re working together it feels like a genuine opportunity to learn from each other.”

Award-Winning Contributions

Plus, we’re pleased to announce that Arman was nominated for and received a UC Berkeley SPOT Award. Spot Awards recognize significant contributions to a specific project or task. Congratulations, Arman!

The Power of Community Support

This collaboration beautifully highlights the power of community support: a local garden club investing in a student, who then applies cutting-edge AI tools to solve real-world botanical challenges.

A huge thank you to the Hillside Gardeners of Montclair for their continued support of student projects at the Garden! Their support funds Arman Omidvar, a talented student working with our curators to unlock a massive piece of the Garden’s history.

By Lew Feldman, Garden Director

Many plants display two distinct phases in their lifecycle: a vegetative (juvenile) phase, where the plant focuses on increasing biomass but cannot flower, and a reproductive (adult) phase, where the plant gains the ability to produce flowers, fruit, and seeds.

Identifying Juvenile and Adult Foliage
The two phases can often be distinguished on the basis of leaf type. One common example of plants with distinct juvenile and adult leaf types are ivy (Hedera helix) and many species of Acacia. In ivy, which is probably the plant most studied for its phase transitions, leaf shape changes from a 3-5 lobed heart-shaped juvenile leaf to unlobed, entire, ovate or diamond-shaped leaves in the adult form. In most Acacia species, the feathery, divided juvenile leaves are eventually replaced by an undivided leaf-like organ in the adult, known as a phyllode. Phyllodes are actually modified petioles (leaf stalks) that have become flattened and widened to function like leaves, while the original leaf blades are reduced or disappear entirely.

Juvenile English Ivy (Hedera helix) leaves are lobed and heart-shaped.

The adult phase is characterized by a more oval shaped leaf

In addition to changes in leaf shape and flowering capacity, differences between juvenile and adult phases can involve many other features. In ivy the juvenile stems are prostrate (parallel to the ground surface), whereas the adult stems grow upright. In acacias, depending on the species, thorns are more likely observed in the juvenile stage, but become fewer or disappear entirely in the adult form.

Feathery juvenile leaves of acacia

Acacia foliage (phyllodes) and flowers in the adult phase

The Genetic “Master Switch”
Scientists have long known that gibberellic acid (GA), a plant growth regulator, plays a key role in this process; high levels of GA are typically associated with the juvenile phase. More recent research suggests that as GA levels decrease, the transition to the adult phase is triggered by a genetic “molecular switch.” This switch lowers the levels of specific molecular messengers while boosting others. Interestingly, this mechanism appears consistent across the plant kingdom—from simple mosses to complex flowering plants—suggesting that the “clock” governing plant maturity is governed by a nearly universal biological control.

For home gardeners, this transition has a very practical implication: it is significantly harder—and sometimes impossible—to grow successful root cuttings from the adult phase of a plant compared to its juvenile counterpart.

Director Lew Feldman

The Garden’s Mather Redwood Grove is part of the California collection and contains over 450 coast redwoods (Sequoia sempervirens). Given that the trees in the Grove are planted so densely, I am often asked how the understory plants, such as wood sorrel (Oxalis oregana), are able to capture enough sunlight for photosynthesis. Part of the answer relates to the orientation of the leaves (each leaf consists of three leaflets), with each leaflet positioned horizontally (as pictured below), thereby maximizing the surface area available to capture what little light makes it to the forest floor. This feature, coupled with the adaptation of the photosynthetic machinery to function in low light, makes it possible for Oxalis to thrive in the forest understory.

Leaflets oriented horizontally in the deep shade of the Redwood Grove understory

A Beam of Sunlight
Occasionally, however, a beam of sunlight will be unobstructed by the tree canopy and penetrate to the forest floor, creating a sunfleck, an area of the forest floor illuminated by direct sunlight. In these circumstances, the shade-adapted photosynthetic mechanism, as a consequence of being exposed to very bright light, could be damaged or greatly impaired. But the plant has a mechanism to avoid possible injury. When a sunfleck illuminates a plant, the leaflets are rapidly repositioned from a horizontal to a vertical (downward) orientation, thereby decreasing the amount of surface area available to absorb the potentially damaging, sudden, high intensity light.

Oxalis oregana plants exposed briefly to direct sunlight; leaflets are positioned vertically

Researchers have shown that the mechanism for leaflet collapse results from rapid water loss, similar to wilting. Leaflet orientation is reversible with the passing of the sunfleck, or by moving the plants from bright light to shade.

I invite you to visit the Redwood Grove on a sunny day to see this for yourself!

Director Lew Feldman

Epiphytes are plants that grow on other plants; their roots are not connected to the soil but are instead often in direct contact with the atmosphere. Consequently, the only opportunity these aerial roots have to obtain moisture is during rainfall, which, in the tropics, occurs as intense, short downpours. This means epiphyte roots have a very limited window of time to absorb water—usually too short a time for the living tissue to absorb sufficient moisture. Thus, epiphyte roots have developed a unique and ingenious mechanism for rainwater capture.

You may have seen this mechanism in operation. For those who grow orchids indoors, you likely recall what an aerial root looks like: green at the tip and grayish behind. This grayish tissue, technically known as the velamen, is the starting point for understanding how these roots function. The velamen consists of dead cells, usually several layers thick, covering the outer surfaces of the root, as shown in the diagrams below (microscopic views).

When a downpour occurs, water rapidly moves into these dead cells via capillary action—the ability of liquids to flow into narrow spaces without any input of energy, similar to what happens when a piece of paper is put into water. Following a brief rain, the velamen cells swell quickly, as water continues to move into them via capillary action. Long after the rain has ended, this stored water is gradually moved out of the velamen and redistributed to the rest of the plant. If you mist your orchids, you will notice the velamen change color; this indicates that water has moved into the cells. In this way, the velamen acts as the plant’s own “soil,” holding onto moisture and slowly feeding the living tissue until the cells eventually return to their original gray hue.

Listen in to Director Emeritus Paul Licht’s fascinating talk about the newts mating cycle in the Japanese Pool, then plan your visit to see them through March.

[Transcript]

PAUL LICHT

This is Paul Licht, Director [Emeritus] of the University California Botanical Garden, and I’d like to tell you about one of the fascinating and cute little denizens of the Garden, because this is the season of the newt. It would be an understatement to say that I like plants, but one of my first research projects in an earlier life as a zoologist at Cal dealt with the newt, and I now find myself immersed in them again.

The Japanese Pool here at the Garden is a major breeding site for local newts. And this is the season when the action really gets going. The California newts Taricha are salamanders, a kind of amphibian, They look like lizards, about 5 to 8 in long, with brown backs and yellowish orange bellies and long tails. But unlike lizards, they have the typical moist skin of amphibians. And they breed and lay eggs in the water, which is what they’re doing now.

The Japanese pool actually houses two species of newt. The two look very much alike. And in fact, it’s almost impossible to tell them apart unless you’re an expert. However, they’re very distinctive when it comes to egg-laying. The most familiar species, Taricha torosa, lays its eggs in masses of several dozen.

The eggs look like little yellowish BB’s encased in a gelatinous, clear, golf ball-sized mass. This egg mass is typically attached to a twig or a stem of a submerged plant. Like the water lilies we have. In contrast, the second species, Taricha granulosa, lays eggs singly, wrapping each one in the small leaf of an aquatic plant. The single eggs are not usually seen by visitors.

The eggs of both species hatch into tiny larvae in about a month. Unlike frog tadpoles, these larvae look like little miniature adult newts with four limbs, but they have external gills and translucent skin, unlike the lungs of the adult. They spend the summer in the water feeding on tiny invertebrates—unlike frog tadpoles, which are mostly vegetarians—and in the fall the newts metamorphose into the adult form and leave the pond.

The tiny little newts, about an inch long, disappear into the Garden and hopefully will return after several years to breed again. And this is when you’ll first see them. Amazingly, during the summer, we rarely see these young ones or even the many thousands of older, larger adults that live in the Garden, and we’re still unsure of what they do most of the time.

We become aware of them again in the fall, when they start emerging from their summer hiding places with the rains. This is when they begin searching for food, worms and small invertebrates. We have to put up caution signs on our roads and drive carefully to avoid hurting them. In nearby Tilden Park, some of the roads are closed starting in November and newt crossing signs are posted to protect them.

Most of the movement occurs at night, especially wet nights, but you’ll often see them wandering around during the day as well. When conditions are right, sufficient rain and perhaps warm enough, the newts begin their migration to the pond. First the males return and they’re transformed into a more aquatic form. Their skins get smoother and shiny. Their tail flattens and looks like a fin, which is enlarged for swimming, and their muscles, especially in the front legs, enlarge to enable them to hold on to females during courtship.

The males may spend weeks or even months in the pond waiting for females, and some can usually be found in the water year-round. In contrast, the females return to the pond slightly later and don’t show the dramatic aquatic transformation, and they leave shortly after laying their eggs. Courtship is what most visitors will often observe. A male tries to hold onto the back of a gravid— that is, a female with eggs—rubbing the top of her head with his chin while he releases chemicals that are designed to stimulate her.

In the meantime, they’re swimming around. Often a large mating ball forms, with several males jockeying for the attention of one female. Sometimes it even looks like they can drown the female. But don’t worry, they can all hold their breath for long periods.

Eventually, one male seems to win. He’ll then release the female and then begin slowly walking along the bottom of the pond, enticing her to follow until he deposits a tiny package of sperm on the pond floor. The female has to pick this up and uses it to fertilize her eggs as they are released.

The female then goes off on her own to lay her eggs. You can often observe a female holding on to vegetation as she lays her eggs, and forms the gelatinous egg ball. Hopefully the cycle will repeat itself and one or more of her offspring will return to breed, perhaps five years later.

Newts may live for a long time, 10 to 20 years, maybe longer, and breed almost every year, but evidently they only rarely successfully produce a surviving young. Reason for the longevity of the adults is their very potent toxin produced in the skin. Few predators can eat a newt and live to tell the tale.

An interesting recent discovery show that in some northern parts of the newt range around Oregon, garter snakes are starting to feed on newts because they have apparently evolved the ability to detoxify them. We see lots of garter snakes in and around our pond in Berkeley during the summer, but never eating newts. It turns out that the Berkeley newts are among the most poisonous of any population, and the snakes haven’t caught up with them. In fact, the newt poison here is one of the most potent of any animal toxin.

One aspect of the story that I worked on when I first came to Cal, concerned what made the newts migrate to the water to start breeding. This behavior is called water drive and can be easily demonstrated in a terrarium. Normally, newts will try to stay out of the water, but when water drive sets in, they want to enter the water and it’s hard to keep them out of it.

And then they start transforming as I described. We found that this behavioral change was induced by a hormone called prolactin that was produced in a tiny gland, the pituitary gland at the base of the brain. This hormone is virtually identical to the one produced by mammals, including humans like ourselves. Where it gets its name from its role in inducing milk formation called lactation in females, you can induce water drive in a newt by injecting it with human prolactin. We don’t know if newt prolactin will induce lactation, however. Our hormones have evidently been around for a long time. We just started using them for new purposes.

I hope you’ll have a chance to visit the Garden and stand in front of the Japanese Pool to enjoy the biological spectacle of the newt season. This is one of the best places to watch them in the Bay Area, because of the crystal-clear water that we have.

They can almost always be seen, just stand quietly and watch for their movement, or look around for the egg masses. The newts know they’re safe with us, and will soon be out to put on a show for you.

By Director Lew Feldman

Perhaps one of the most unusual modifications in leaf design occurs in the genus Monstera, more commonly known as the Swiss cheese plant or cut-leaf Philodendron. These plants develop holes and splits in their leaves, a process scientifically termed fenestration (from the French word for window, fenêtre).

Monstera adansonia

Hypothesized Functions of Fenestration
In their native habitat these vines can climb to significant heights by attaching their roots to the trunks and stems of tall-growing plants. With regard to the function of the holes or splits, it is hypothesized that it is an adaptation to this elevated, tree-top location.

For instance, in this scenario, the tree-top location of this plant exposes it to high velocity, potentially damaging winds. Thus, the role of the holes or splits, in part, is suggested to diffuse and redirect the force of the wind.

Additional suggestions as to the function of these leaf modifications include,

• Rain Passage: They may allow rain to pass through to the underlying roots more easily.
• Light Penetration: As the plant climbs, the “windows” may allow light to penetrate to lower leaves, ensuring they receive adequate light.
• Insect Discouragement: An unproven, yet intriguing, suggestion is that the holes trick or discourage insect predation. An insect might view the fenestrated leaf as already “damaged” and thus an unfavorable location to deposit eggs, whose larvae would otherwise consume the leaf.

How Fenestration Forms
While the exact function of these leaf modifications is still unclear, we know much about how they form. The holes appear when the developing leaf is still quite small (less than 1-2 mm in height), as shown below.
The holes form through Programmed Cell Death (PCD), where specific cells within the developing leaf die, leaving a small space that enlarges into the hole or split as the leaf grows.

However, the mechanism underlying the patterning or distribution of the holes—why certain cells are fated to die while others are not—remains largely unknown.

Scanning Electron Microscope view of developing holes in the leaves of Monstera sp., as a result of Programmed Cell Death (from Kaplan, 1984).

Another striking example of fenestration due to programmed cell death is shown by the water plant, Aponogeton, a common aquarium plant, pictured below.

Aponogeton madagascariensis, a common aquarium aquatic plant.