James Miller and Hannah Stevens of The New York Botanical Garden talking with director of the University of Puerto Rico's Botanical Garden, Rafael Davila.

The greatest challenge to protecting the world’s plant diversity is that while perhaps as many as 100,000 species of plants face some risk of extinction in the next few decades, in most parts of the world, we simply don’t know which species are the most threatened. Little progress has been made toward identifying the list of globally threatened plant species (which is target 2 of the United Nations Global Strategy for Plant Conservation), so NYBG scientists have developed a streamlined method to survey plant species one at a time, to determine which are “At Risk.”

This week, August 8 and 9, a consortium of 19 scientists met at the University of Puerto Rico’s Botanical Garden to review the situation for the 2,032 species of plants that are native to Puerto Rico, 461 of which have been determined to be “At Risk.” Botanists from The New York Botanical Garden conducted the workshop in partnership with colleagues from the Smithsonian Institution; the University of Puerto Rico, Río Piedras; the University of Puerto Rico, Mayagüez; the University’s Botanical Garden; Parque Doña Inés of the Fundación Luis Muñoz Marín; the International Institute of Tropical Forestry; Puerto Rico’s Department of Natural Resources; and the Fideicomiso de Conservación.

The rapid review of Puerto Rico’s plant species demonstrates that 461 of them, or 23%, are at possible risk of extinction in the near future. This figure is consistent with analyses from other parts of the world, where it is frequent that about one quarter of species are threatened. Some of these threatened plant species are so rare that they have not been seen for decades and are possibly extinct, others are known from countable numbers of individuals, some less than 25, and thankfully the situation for others is not as dire, though still serious. Having this list will help guide future conservation efforts to the species that most desperately need our attention to ensure their future survival. Some of the participants from the Puerto Rican institutions plan to propagate the most rare species as a prelude to efforts to re-establish viable populations in the wild. The NYBG is extending these efforts and is aiming to complete a review of the entire West Indies in the next year.

Recently, I had the opportunity to help introduce a group of bright junior high school girls to the science behind the beauty of flowers.

Back in March, I volunteered at the Explore Your Opportunities–The Sky’s the Limit! conference put on by the New York City, Westchester, and Manhattan branches of the American Association of University Women. This conference is open to 7th grade girls from New York City and Westchester schools and is designed to encourage girls to pursue science, technology, engineering, and mathematics (STEM) careers through fun, hands-on activities and by providing them with women role models from these fields. This conference has been run annually in the New York City area since 2004, first at Barnard College and now at the College of Mount St. Vincent, and is based on the Expanding Your Horizons in Science and Mathematics™ (EYH™) conferences, which first started in 1976 and now take place worldwide. During the conference, the girls hear a keynote address and then break up into smaller groups to do two hands-on workshops.

I led a workshop called ‘Flower Hour,’ which explored the science of a flower’s shape. I brought in five different types of flowers for the girls to examine. First, I asked the girls to look carefully at a yellow tulip, to describe what they were seeing in as much detail as possible. I gave them five minutes to write their observations down, and then they took turns sharing them with the group. I was impressed with the responses: One girl knew that the plant from which the flower came was an autotroph, an organism which makes its own food from inorganic compounds, and another observed that the flower had the same number of petals as it did stamens. After each girl shared her observations with the group, I drew a flower on the board and taught them the botanical names for floral parts.

In preparation for our next activity, I put five shapes on the board: an oval, a triangle, a star, a circle, and a square.

I asked the girls how they would group these shapes. Everyone agreed that the circle and oval belonged in one group and the triangle, square, and star belonged in another because circles and ovals have rounded edges and triangles, squares, and stars are pointy. Then I asked them, of the triangle, square, and star, which two were more closely related? There were some differing opinions, but they were all backed up by good reasoning. Some girls thought the triangle and square should go together because a square is made up of two triangles, whereas others thought that the triangle and star were more closely related because a star’s points look like triangles. From these series of groupings, we could create a family tree of these shapes, which shows how the shapes are related to each other.

Next, I gave each pair of girls five different flowers: a yellow lily, a pink lily, a yellow tulip, a red and yellow tulip, and a yellow freesia. I asked them to observe the similarities and differences among the flowers that would allow them to group them in a way that reflects how the flowers are related to each other, like we did with the shapes. I chose these particular flowers for several reasons. The duplicate lily and tulip flowers differed only in color, so were easily grouped as similar based on form and shape. I chose three different types of yellow flower to illustrate that some characteristics are more useful in determining relationships than others. In this case, three flowers share the same color, but have different shapes; therefore, grouping according to shape instead of color gives a more accurate estimation of the relationships among the flowers.

The girls noticed that the lilies and tulips all had six colorful tepals, the term given to the showy, petal-like structures of flowers whose sepals and petals look similar. The freesia, on the other hand, had green sepals and six petals, but the petals were fused to form a tube, which distinguished this flower from the others. The girls also observed that the carpels, the female flower parts, of the lilies and tulips looked similar, whereas that of the freesia was much more delicate and had a different shape. In light of these observations, the girls grouped the tulips and lilies together, while the freesia stood alone as distinct from the rest. Through this exercise, the girls not only learned to closely examine flowers and their specific parts, but also about studying evolution and how shared characteristics can be used to determine the relationships between species. The family tree the girls created was correct. Lilies and tulips are both members of the Liliaceae, the lily family, whereas freesias belong to the Iridaceae, the iris family.

Overall, it was an excellent day. I got to interact with very bright, engaged young women who were inquisitive and eager to learn. They will now look at flowers in a new way, appreciating not only their beauty, but also how scientific observation can be used to estimate the evolutionary relationships between species. I hope that my enthusiasm and love of science and plants promoted their interest in the sciences and encouraged them to view a scientific career–maybe even botany!–as a plausible option for their future. I am already looking forward to next year’s conference!

Cranberries are grown in sunken bogs that can be flooded to harvest the fruit. (photo by Vinson Doyle)

Plants and fungi have an intimate relationship. Some fungi, like mycorrhizal fungi which help a plant’s roots use soil resources more efficiently, are beneficial to plants, while others, like powdery mildew on squash leaves, are obviously harmful. However there are many fungi that exist somewhere on the continuum between friend and foe. To further complicate the matter, whether an individual fungus is beneficial, neutral, or antagonistic may change over time such that apparently harmless fungi can become pathogenic.

Cranberries infected with pathogenic fungi. Many different species of fungi are responsible for causing cranberry fruit-rot, but Colletotrichum is one of the most prevalent in cultivated cranberries. (photo by Vinson Doyle)

Studying these fungi can be difficult; they do not always make their presence obvious. Imagine tracking an elephant through the forests of East Africa to understand what it eats, where it travels, and how it selects a mate. Now, imagine tracking an individual you can’t see in the wild, or if you can see it, you can’t tell it apart from its siblings. Tracking these wild fungi would have been impossible a decade ago, but with the advances being made in modern genetic methods both here at The New York Botanical Garden and around the world, we are finally able to address the big questions surrounding these tiny organisms.

My work focuses on understanding the genetic diversity of a single fungal species, Colletotrichum gloeosporioides. C. gloeosporioides is a sneaky fungus that is capable of shifting its place on the continuum between harmless and pathogenic to cranberry. The main focus of my research involves understanding how the spores of C. gloeosporioides are dispersed, what other plants it is associated with, and how it reproduces. I hope that a fuller understanding of this fungus will help cranberry growers formulate effective management plans.

But before we can find answers we have to find the fungus.

Flowering cranberries. While these plants are healthy, there are fungi living under the surface of the plant tissue. (photo by Vinson Doyle)

A pure isolate of Colletotrichum growing on agar that was isolated from cranberry. Ascospores produced in the laboratory by a Colletotrichum species isolated from cranberry. (photo by Vinson Doyle)

My field work begins in the cultivated and wild cranberry bogs of North America in the hope that by finding the plant, we will find the fungus. In some cases, it is readily obvious that the plants have been infected by a pathogenic fungus. However, we frequently can’t determine which fungus has infected them, so we collect fruits, stems, and leaves and bring them back to the lab for further study. In other cases, we find plants that look perfectly healthy, but we suspect there are fungi lurking beneath the surface. So we take the material back to the Pfizer Plant Research Laboratory for more research. The hunt continues!

In order to study plant-associated fungi, that is, fungi that live within a plant such as C. gloeosporioides does, we must first coax the fungi out of the plant. To do this we place the plant pieces on a suitable growth medium that encourages the fungus to emerge from the plant and to populate the medium; in this way we are able to isolate the fungus and study it more carefully. Inevitably, many different species of fungi emerge onto the growth medium, which means we must isolate and identify each one.

A high elevation cranberry bog in the Monogahela National Forest in West Virginia. Cranberries are in flower along the banks of the stream (photo by Vinson Doyle)

Once we have isolated all the individual fungal strains, we use methods similar to those used in forensics to identify each one. In the Cullman Lab, we use DNA markers that allow us to identify each individual fungal strain within a single species in the same way that forensics specialists use DNA markers to establish whether an individual was at the scene of a crime.

Modern genetic methods have helped us determine that fungal strains are likely moving undetected (disguising themselves as harmless fungi) inside cranberry vines used to establish new farms in disparate regions before revealing themselves as harmful pathogens. This finding will hopefully allow researchers and farmers in the future to better understand the sources of disease epidemics. This knowledge should help farmers implement preventative measures and may lead to new methods for establishing cranberry bogs.

Ed. note: Selena Ahmed, ethnobotanist and author of the gorgeous new book Tea Horse Road will be at the Garden for a book signing this Saturday, May 21 at 3 p.m at Shop in the Garden. I first saw Selena’s book in a colleague’s office. The absolutely stunning photographs, taken by Michael Freedman, drew me in, but it is Selena’s tales that bring this fascinating book to life. We are currently working with Michael, who is traveling China, to put together a post of his photographs, so stay tuned. But why wait? Pick up a copy of Tea Horse Road this Saturday. You won’t be disappointed.

My new book, Tea Horse Road: China’s Ancient Trade Road to Tibet, with photographer Michael Freeman explores lives and landscapes along the world’s oldest tea trading route. Our journey starts in tropical montane forests in China’s southern Yunnan Province. This is the birthplace of the tea plant, Camellia sinensis (Theaceae). The cultural groups of Yunnan including the Bulang, Akha have produced and consumed tea for centuries for its well-being and stimulant properties. They traditionally grew tea plants as trees of several meters tall without the use of chemical fertilizers, pesticides and herbicides.

While tea cultivation spread where climatic conditions allowed, the practice of drinking tea reached far beyond. During the 7th century, the Tibetan kingdom to the north of Yunnan came into contact with tea, and the drink soon became central to the Tibetan people’s diet. Tea functioned to reduce the oxidative stress of Tibet’s high altitudes and as a dietary supplement in an environment with limited fruit and vegetable production. These same extreme conditions mean that tea has remained an imported item from tropical and sub-tropical areas in China’s Yunnan and Sichuan provinces. The demand for tea led to the creation of a network of trails extending more than 3,000 kilometers, carved through forests and mountains, with Lhasa at its core. This network collectively became known as the South West Silk Road or Cha Ma Dao, the Tea Horse Road.

However, tea was only one side of the trade equation: China was in constant search for warhorses that made its armies more mobile allowing the kingdom to maintain control over the empire. Abundant natural resources along with tea and horses were exchanged on the Tea Horse Road over the course of 2 millennia, linking cultures and natural resources beyond their surroundings. In its day, the Tea Horse Road touched the lives of many. These were the tea farmers on the southern mountains, the caravan leaders, the Tibetan lados skilled at traversing high passes and the porters with 100-kilo loads on their backs. This book is their story, narrated against the backdrop of some of the world’s most rugged and powerful landscapes.

Trade along the Tea Horse Road declined in the 20th century as horses ceased to have a major military use. Roads were paved allowing for more efficient transport, and policies and markets transitioned. As the Tea Horse Road acquires a historical presence, it is easy to forget its vital former role of maintaining community health, sustainable agriculture, livelihoods, and cultural exchange.

The research for my new book, Tea Horse Road: China’s Ancient Trade Road to Tibet, is partly based on my doctoral study at The New York Botanical Garden supervised by Dr. Charles M. Peters and guided by NYBG curators Drs. Amy Litt, Michael Balick, and Christine Padoch. My goal for this book was to disseminate findings from my doctoral study to a wide audience. The narrative is accompanied by Michael Freeman’s stunning visual documentation and is published by River Books.