Through the Lens of a Plant Detective

On a cool August 2011 morning in Ulaanbaatar, the capital of Mongolia, Patrick Herendeen, Ph.D., of the Chicago Botanic Garden began a mission. Gathering with a team of international researchers, he set out into the vast countryside in search of rare plant fossils dating back to the time of dinosaurs, a time called the early Cretaceous period. Through this ongoing research project, the team is working to solve mysteries of plant evolution and inform science around the globe.

PHOTO: Dr. Herendeen collects lignite samples at Khuren Dukh, an unusual site with both plant and animal (dinosaur) fossils.

After completing fieldwork on expeditions in 2011 and 2012, Dr. Herendeen, a senior scientist at the Garden, is poised to make major strides in his research this year. He told me more about his work on a recent tour of his laboratory at the Garden.

During fieldwork in the grassland steppes of Mongolia, just north of the Gobi Desert and often at an elevation of nearly 5,000 feet, he picks through lignite coal in active strip mines and looks for fossils of everything from plant parts to pollen. “Mongolia is an area where there has been very little research done on fossil plants,” said Herendeen. Yet, “there is a lot of material there of an age that is very interesting for understanding the evolution of flowering plants.”

Sometimes, he finds leaf imprints in shales between layers of coal, and will spend a day or two in the field splitting rocks to prepare them for study. More often, he places promising chunks of lignite, a flaky black form of coal, into gallon-sized plastic bags and brings them back to his lab at the Garden for closer study.

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Learn more about Dr. Herendeen’s work and watch a video interview.

In the Garden’s Daniel F. and Ada L. Rice Plant Conservation Science Center, Herendeen empties the bags of samples and gently breaks up the lignite pieces to uncover fossils. He often finds 20 or more types of reproductive structures, stems, leaves, and pieces of wood from multiple plants in just one sample. Some pieces are so tiny that they can only be seen through a microscope. He must then determine which parts go together in order to create a picture of what each plant looked like in the days of the dinosaur. “It’s like collecting the litter off the forest floor and then trying to sort out which parts are from the same plant,” he said. Already, he and his collaborators have identified more than a dozen types of extinct plants.

The majority of plants found so far are gymnosperms, mostly members of the pine family and related conifers. These discoveries have yielded some answers as to how plants evolved over the past hundred million or so years—such as how major events like volcanic eruptions, disease, or climate change may have impacted changes in their structure and in plant communities. “You can’t understand the history of those habitats without understanding the history of the plants that make them up,” said Herendeen. Although many answers have been found, many questions have also been opened.

Discover more: Attend a lecture on the gingko tree by Dr. Herendeen’s research colleague, Sir Peter Crane, and the unveiling of his forthcoming book, Ginkgo: The Tree That Time Forgot.

A particularly interesting discovery, according to Herendeen, was a seed plant without a clear connection to any group of plants known today. Its physical structure is unique, and its story is yet unknown. “It doesn’t often happen that we find something that we don’t know what major group of plants it belongs to, so it is quite intriguing,” he said.

Although his findings have been rich so far, Herendeen is still searching for what he considers to be the ultimate treasure. He is particularly interested in the origin and evolution of flowering plants, also known as angiosperms. Fossils of angiosperm pollen grains are present in the Mongolian material, but so far no fossil flowers or other parts of flowering plants have been discovered. He hopes to find better angiosperm fossils when he returns to Mongolia this summer to help document their early existence in central Asia.

The plants Herendeen is researching are the ancestors of many that can be seen at the Garden today, including those in the Dwarf Conifer Garden. Gingko trees, also gymnosperms, may be found in the Elizabeth Hubert Malott Japanese Garden and on the north side of the meadow on Evening Island. Cycads are yet another group of gymnosperms that may be represented in the Mongolian fossil assemblages. Visitors can see a cycad tree with pods, standing about 10 feet tall, in the tropical greenhouse at the Regenstein Center.

©2013 Chicago Botanic Garden and

The Garden Turns 40

Chicago Botanic Garden visitors know that the Garden celebrated its 40th anniversary this year. In looking back over the Garden’s growth since 1972, Garden staff, members, and visitors appreciated the remarkable changes that had taken place. The 40th anniversary website includes a timeline of significant events, historical photos, and opportunities for community members to share their experiences at the Garden.

Fewer Garden visitors are aware of the early years of the Chicago Horticultural Society, which dates back to 1890. At a free talk about The Garden Turns 40: Documenting our Past, Planning for the Future exhibition last week, I shared some of this history with those who attended.

In 1890, the goal of the Horticultural Society of Chicago was “the encouragement and promotion of the practice of horticulture in all its branches and the fostering of an increased love of it among the people.” This is in perfect alignment with the City of Chicago’s motto of Urbs in Horto (Latin for city in a garden). The Society shared this message through flower shows. Currently on exhibition in the Lenhardt Library are a poster from a 1900 flower show and a pamphlet from the 1914 flower show.  Seeing the original, primary source documents from the Garden’s early history is inspiring.

PHOTO: The Garden Turns 40 Exhibition

Also on display as a part of the Garden Turns 40 exhibition is an original record book from 1890–1904. It includes all types of documents including board minutes (many of which were hand scribed), by-laws, financial records, newspaper clippings, magazine articles, meeting notifications, and other materials that were of interest to Society members. This is the only original document from the early period in the archives of the Chicago Horticultural Society.

The record book is open to the first page, which has a list of officers. You can see some names crossed off and others added. This is because it was a working document. As board members changed each year, the names were updated on the list. One civic leader who was involved with the Horticultural Society of Chicago and listed as an officer is Andrew McNally (from the Rand McNally family of maps and atlases).

See these items and more at the Lenhardt Library.  Feel free to ask library staff questions. If you have any family stories about how this Garden got started please share them with us; we’d love to hear from you.

©2013 Chicago Botanic Garden and

Signs of Emerald Ash Borer

It’s sad but true:

As I drive around the north suburbs, I am noticing many roadside trees with a spray-painted mark or a ribbon around the trunk. As an arborist, I know that these are ash trees marked for removal because of the emerald ash borer (EAB). The emerald ash borer is beginning to hit our area hard, and many municipalities are trying to stay one step ahead of this ash-tree-killing insect by proactively removing these doomed ashes.  

woodpecker_damage_3If you have an ash tree on your property you should be monitoring for this pest, as it is only a matter of time before the borer finds your tree. In winter, the easiest way to identify if your tree already has EAB is to look for woodpecker damage. From a distance, woodpecker damage looks like lighter colored patches on the trunk, as you can see in this picture.  Woodpeckers make these marks as they feed on the tasty (to them) borers that are just under the bark. Once you start seeing evidence of EAB activity, your tree will most likely suffer severe dieback within three years. There is an insecticide treatment that can save your tree, but treatments need to begin before your tree is infested.  

For more information on EAB and treatments, please contact the Garden’s Plant Information Service or check out these sources:

©2013 Chicago Botanic Garden and

A Winter Walk Through the Japanese Garden

While many city-dwellers might be noticing a serious lack of snow this season, winter finally arrived at Chicago Botanic Garden last week.

The first significant snowfall of the season gave the Garden a perfect white coat for winter. What better reason for a walk through the Malott Japanese Garden?


Many consider winter to be the Japanese Garden’s most beautiful season. Its design emphasizes nature’s forms like clouds, stones and hills. In winter, pruned magnolias, azaleas, forsythia, quince, as well as smooth lumps of yews and junipers, resemble white boulders or fluffy clouds. Open-pruned pines, wired to maximize long and borrowed views, are natural snow catchers, offering up their own cushions of snow. Even the lanterns are designed to catch and display light snowfall.

To learn more about celebrating winter in Japanese culture, be sure to check out the Three Friends of Winter show, held at the end of January each year. 

©2013 Chicago Botanic Garden and