Jim Miller is Dean and Vice President for Science.
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.”
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.
July 15, 2011; Hobart, Tasmania, Australia; final entry
Once again we awoke to a frost, this one so heavy that it almost looked as if it had snowed. We assumed that the frost would not be in the forest, and we were right. Our first scheduled stop was not too far away, along a trail leading to a view of St. Columba Falls. The falls are named for an Irish Catholic saint who copied the Psalms around 500 A.D., which started a war, and who was then exiled to Scotland. The falls were named by an Irish woman who discovered them and who had herself been exiled to Tasmania.
Echidna playing ostrich
On the way to the site we finally saw an echidna, a porcupine-like marsupial. We slammed on the brakes, only to have the only other car we saw all morning blow its horn at us. Nevertheless, we scrambled out of the car to get a better look at this strange little animal. Like an ostrich, it had buried its head in the leaf litter, presumably thinking that if it couldn’t see us then we couldn’t see him. It was great to see this odd Australian animal. The only animal we didn’t get to see that we really wanted to was a wombat.
St. Columba Falls
But duty called, and leaving our new friend behind, we headed up the road to the falls. Because St. Columba Falls is a popular tourist destination (just not first thing in the morning on a winter weekday), we were cautioned not to leave scars from our collecting along the trail. It’s just a short walk to the falls, which is one of the highest in Australia. Although I only found a single moss that I hadn’t seen previously on the trip, I found that many of the mosses I had seen sterile at other sites were fertile here. I collected these judiciously so as to have them as reference material in the herbarium.
Thursday, July 14, 2011; Pyengana, Tasmania, Australia
Bill Buck searching for bryophytes
Winter reared its ugly head again today. Sunrise was at about 7:00 a.m., and as soon as it became light, it was obvious that a heavy frost had whitened the landscape, including our car. So, after thawing out the car, we headed to our first site, the Weldborough Pass Rainforest Walk.
Under the canopy, the frost hadn’t covered everything, and since our primary stop that day would be at a much higher (and thus much chillier) elevation, checking out the forest, which is dominated by large southern beech (Nothofagus cunninghamii) with an understory of large tree ferns (Dicksonia), seemed like a good idea. The multitude of tree ferns at this locality was a special treat. We found a large number of bryophytes and lichens (as well as epiphytic ferns) that prefer the spongy, moist root mantles that comprise the tree fern trunks. We also found quite a large number of mosses that we had not seen before. It took a while for our fingers to thaw from the morning chill but the collecting helped keep us active and warm. In fact the collecting was so good that we ended up staying in the Weldborough Pass Rainforest an hour longer than we had scheduled. We decided to quit at a very good time, though, because as we were packing our collections into the car trunk, two other cars of tourists drove up to use the trail. We cleared out in a hurry before they could see the divots and scars we had left from our collecting!
The rental car travels under a novel underpass in the Blue Tier Nature Preserve
Today was mainly a travel day. Before leaving Hobart we ran by Paddy’s office to spread our still-wet specimens on his floor to dry while we are in the field. We headed north out of Hobart toward St. Helens. This town reminds me of some of the small coastal towns in Florida where I grew up, with touristy stores and lots of retirees. We lunched here and then turned inland to our collecting site of the day, the Blue Tier Forest Reserve.
We were a bit dismayed when we arrived at the road into the reserve only to find a “Road Closed” sign at the entrance. However, the road wasn’t blocked so we decided to chance it, which ended up being not nearly as bad a decision as it could have been; it seemed as if a road crew had preceded us! Many of the trees that appeared to have fallen across the road had already been cleared, and the one tree we found that was still over the road had amazingly fallen so that the large branches held the trunk off the ground and formed a kind of tree overpass.
Bill Buck and the Goblin Forest Walk Sign
Once under the tree, the road got narrower and began showing signs of erosion from previous heavy rains, but it was passable with only a minimal bottoming out of our rental car, though we did seem to be dragging branches under the car almost constantly. When the landscape leveled out, at about 700 meters, we came to a car park for the reserve. The air was decidedly cooler and the area around the parking lot was open, presumably kept so by grazing wallabies, based on the large number of droppings. There were several trail options for leaving the parking lot, and I just couldn’t resist the Goblin Forest Walk.
The rain forest earned its name today! You could tell from first thing in the morning that there would be a light, steady rain all day; and it lived up to expectations. We left Hobart after breakfast and headed south to the “Southern Forests” region on the northern edge of Hartz Mountains National Park. Our first stop was the Arve River Picnic Area. Here a short trail, billed as only a 10 minute walk, winds through an incredibly lush but open rain forest. Almost every surface is mossy: the forest floor is carpeted with particularly large mosses, and the fallen trees, many more than 6 feet in diameter, are covered in a diverse mantle of bryophytes. Even the smallest twigs host even tinier epiphytes. The filtered light, more hues of green than I ever knew existed, and the velvety texture of moss-covered surfaces make the forest almost surreal. It looks like a set from Lord of the Rings. For those who have never seen a Southern Hemisphere temperate rain forest, you couldn’t ask for a better introduction. There is something new at each turn of the trail and it was only the lure of additional sites, plus the sudden darkening of the skies and heavier rain that drove us back to the car.
From here we drove toward Hartz Mountains National Park. As we headed up the dirt road we started seeing patches of snow, and in no time at all, the snow was completely covering the ground, getting deeper and deeper as we headed into higher elevations. In fact, the only reason we even dared venture into the park itself is because some four-wheel drive vehicles had already blazed a track through the snow. Once inside the park, we parked our car in the middle of the road, and slogged through the nearly six inches of wet snow. All along the roadside small waterfalls cascaded down the rock walls, resulting in a rich moss diversity (and wet feet!).
The International Botanical Congress (IBC) is held once every six years, and this time it is being held in Melbourne, Australia in mid-July. I have visited Australia twice in recent years, most recently in 2009 in Western Australia, and in 2007 in Tasmania. Both of these trips were to attend field meetings of an Australia-New Zealand bryological group. My motivation to attend the Tasmanian meeting had been to better acquaint myself with another south temperate moss flora so that I could compare it to my study area in southernmost Chile. Despite the constant threat of leeches, I loved Tasmania and thought attending the IBC would be a good opportunity to return. I shamelessly wrote to the organizer of that 2007 meeting, my friend and colleague, Paddy Dalton, at the University of Tasmania, to see if he would be willing to host my visit there, even though it was only a week before the IBC. He generously agreed and so we planned a week-long collecting trip to Tasmania, along with my two graduate students, James Lendemer, working on a lichen genus for his Ph.D. through the City University of New York, and Mike Tessler, a beginning student in the graduate program at Fordham University.
Prior to the trip I had checked the Australian meteorological website to see what the weather might be in Tasmania (and Melbourne), knowing full well it was the middle of the austral winter. Temperature predictions ranged from a low of 3°C (ca. 35°F) to a high of 13-14°C (ca. 55°F), and so I warned the students to bring warm clothes. A few days prior to the trip I heard from Paddy that there had been snow in the hills around Hobart! Not to be deterred by a little cold weather, especially after my last research trip to southern Chile, when it was the austral summer, we all eagerly anticipated the upcoming trip.
After over 24 hours of travel time, it all became real when we boarded a flight from Sydney to Hobart and the Qantas pilot came on and announced that the weather in Hobart to be slightly above freezing with snow showers. But as we flew down the east coast of Tasmania (where we intended to do our field work), I didn’t see any snow on the ground and was hopeful that we might avoid it. I would soon learn otherwise! Paddy Dalton greeted us at the Hobart airport, a familiar face in a faraway land. We rented a car and I followed Paddy to our hotel, driving for my first time on the left side of the road. We then all went to dinner at a local seafood restaurant (local shrimp and scallops have just come into season), where we discussed the upcoming itinerary.
Gregory M. Plunkett, Ph.D. is Director and Curator, Cullman Program for Molecular Systematics
Giant Hogweed (Image from New York State Department of Transportation’s Dangerous Roadside Plants page)
From the recentnewsreports, you’d think that New Yorkers had better fly south to escape the onslaught of the diabolical giant hogweed. Even its name evokes a sort of dread, and we are reminded of the stories of “killer bees” from the 1990s.
The giant hogweed plant (know scientifically as Heracleum mantegazzianum) is native to the Caucasus, a mountainous region that separates Europe from Asia. Like so many invasive plants, this species was originally imported to North America as a garden ornamental. It’s easy to see why. The plant is an attractive, gigantic herb, reaching up to ten feet tall in just a few months, topped by huge, umbrella-like spreads with hundreds of tiny white flowers. As a consequence, each plant can make hundreds or even thousands of seeds. Inevitably, this exotic species started to jump garden fences. In our region, the plant was first introduced to Rochester, N.Y. sometime before 1920. Since then, it has been steadily colonizing New York State (see the DEC map here) and it is now approaching New York City.
Why all the fuss? Well, it turns out that giant hogweed produces a sap containing some nasty chemicals called “furanocoumarins”. These compounds easily pass into our skin cells and bind to the DNA inside. Once inside the skin, one additional ingredient is needed to activate the toxin: sunlight. Exposed to the sun, these chemicals kill the affected cells, resulting in a reaction called phytophotodermatitis. This is a nasty, itchy rash that causes discoloration of the skin (from red to dark purple) that can last for months or even years. In severe cases, it can progress, turning into large blisters that mimic second-degree burns. If the plant’s sap reaches the sensitive tissue of your eyes, this blistering could result in scarring and blindness. Yet, as bad as this rash can be, furanocoumarins have been used medicinally as a remedy for psoriasis (where it prevents cell proliferation) and vitiligo (where it darkens depigmented skin).
Most victims of giant hogweed are affected while working in weedy patches, where they are exposed directly to the sap while removing plants by hand or cutting them down using a weed-whacker or lawn mower. The good news: we have expert advice from http://www.backyardboss.net/best-string-trimmer-reviews/, their blog gave us real insight. Giant hogweed is easy to see (it’s ten feet tall, after all), and you must be exposed to both the sap and sunlight. As a result, there are two ways to prevent this nasty rash: avoid exposure to the plant, especially its sap by wearing long pants, long-sleeved shirts, and protective eyewear in areas where giant hogweed grows (unlike the NYS DOT workers above), and avoid exposure of your skin to the sun for the next few days if you do accidentally touch it.
As it turns out, giant hogweed is not the only plant that can cause phytophotodermatitis. Many of its relatives in the plant family Umbelliferae also produce furanocoumarins, including carrots, parsnips, fennel, and celery, but the level of toxins in these species are typically lower. The same family includes other toxic plants, such as poison hemlock, as well as many useful herbs and spices like dill, parsley, cilantro/coriander, and caraway. The same class of compound are produced in completely unrelated plants, too, such as the wild relatives of tomatoes and strawberries, and in the rinds of lemons and limes. You may have heard of the dangers of making lemonade in the sunshine!
Finally, before you sell the house in New York and move to Florida, remember that we have already learned to deal with other nasty plants that cause terrible skin rashes and even blindness, including poison ivy and stinging nettles. Even though these native plants are harder to recognize, we have learned to deal with them. And one last reminder before you sell you house and head for Florida: We New Yorkers may have to deal with snow and giant hogweed, but at least we don’t have alligators, fire ants, and killer bees!
Elizabeth McCarthy is a post-doctoral researcher in the Genomics Program at NYBG.
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.
Three Garden scientists participated in an international collaboration that sequenced the genome of the lycophyte Selaginella moellendorffii. Lycophytes, known as ground pines or club mosses, are an ancient lineage of vascular plants with small, scale-like leaves that lack the ability to make seeds but produce copious spores. They represent an intermediate evolutionary stage between mosses, which do not have conducting and support (vascular) tissue, and plants such as conifers or flowering plants, which have vascular tissue and complex leaves and protect their embryo in seeds. The genome project was undertaken to see what clues might lie in the DNA to the increasing adaptation of plants to land and the increasing complexity that came along with it. The results were published last Friday in the prestigious journal Science.
Dr. Amy Litt, Director of Plant Genomics and Cullman Curator, Dr. Barbara Ambrose, Cullman Curator and member of the Genomics Program, and Dr. Ken Karol, of the Lewis B. and Dorothy Cullman Program in Molecular Systematics, were part of a group of scientists that identified and described the genes of this important species. Pinpointing the location and sequence of specific types of genes in the genome allowed them to compare the genes of Selaginella with the genes of other plant species that have had their genome sequenced, which include algae, a moss, and several flowering plants. The group, led by Dr. Jody Banks at Purdue, found that some genes are present only in flowering plants and not in the moss or Selaginella; these genes might be needed for the development of flowers and fruits, which are only found in flowering plants. Other genes are found in Selaginella and flowering plants but not in the moss, and these probably function in the increased adaptation to land shown by vascular plants in contrast to mosses.
Dr. Ambrose is now studying some of these genes in more depth in the Pfizer Lab, focusing on a group that is known to control important developmental processes in flowering plants. We think that changes in these genes may have played crucial roles in land plant evolution, perhaps underlying the evolution of key adaptive features, so it will be very exciting to find out what these genes do in Selaginella.
