By Allen,Sarah E
I spent last week visiting the paleobotanical collections at the University of California Museum of Paleontology (UCMP) on the Berkeley campus. The collections include many specimens that are very similar in age to my Blue Rim material, including the specimens collected and published by H.D. MacGinitie in the 1960s and 1970s. MacGinitie (1896-1987), an influential paleobotanist, received his PhD from the University of California at Berkeley in 1935. He taught at Humboldt State College for over 30 years before retiring to Napa, CA. He was an active research associate at the UCMP and published 7 comprehensive monographs of different Cenozoic floras throughout the west*. These volumes are still used today.
Above: The Valley Life Sciences Building to the left and The Campanile or Sather bell and clock tower to the right on the campus of the University of California Berkeley. The tower is 307 feet tall and even stores a few fossils!
Left: Taking photos in the collections. The paleobotany, invertebrate, and vertebrate fossil collections are all housed in one giant room. Photo by S.R. Manchester.
UCMP has a few small exhibits in the hallways of the Valley Life Sciences Buildings, but the collections are closed to the public. However, the museum serves the public through research and education. I was hosted by paleobotanist and museum scientist Diane Erwin. You can find out more about her research here.
The obligatory dinosaur photos: Triceratops horridus(left) and Tyrannosaurus rex (right).
I also talked to graduate student Dori Contreras, who is studying Cretaceous plants from New Mexico. She is a member of Cynthia Looy’s lab. I also must thank Chris Mejia and Lisa White for helping with some logistics and making sure I did not get locked out of the collections!
I also visited the Jepson (vascular plants of California) and University (worldwide collections) herbaria across the hall. These collections contain over 2 million specimens. Herbaria store pressed and dried plants with identifications and information about the locality from which they were collected. Visiting such a large herbarium is beneficial because of the sheer number of taxa from localities around the world. I looked at extant specimens that might be related to my fossil taxa so I could compare the morphological details more closely. Curatorial Associate Kim Kersh was very welcoming and helpful while I worked in the herbarium.
Left: The entrance to the Jepson and University herbaria.
Above: Two fossil leaves from locality PA 114 in the Wind River Formation in Fremont County, Wyoming. These were collected by H.D. MacGinitie in 1963.
Left: A slab of fossil leaves from the Parachute Creek Member of the Green River Formation in Rainbow, Utah. Collected by Bruce Handley. The black line in the lower right is 5 cm long.
Fossils from the Green River Formation in UT, CO, and WY and the Wind River and Aycross Formations in northwestern Wyoming provide good points of comparison to the Blue Rim material because they are similar in age.
*Details about MacGinitie’s life from: Veatch, S.W. and H.W. Meyer, 2008. History of paleontology at the Florissant fossil beds, Colorado, in Meyer, H.W., and D.M. Smith, eds., Paleontology of the Upper Eocene Florissant Formation, Colorado: Geological Society of America Special Paper 435, p. 1–18, doi: 10.1130/2008.2435(01).
By Allen,Sarah E
Microscopes are used regularly by biologists and paleontologists. They are needed on a daily basis in paleobotany. Dissecting scopes are typically used for macrofossils like leaves, while compound microscopes and scanning electron microscopes are typically reserved for microfossils like pollen, or for thin sections of permineralized fossils like petrified wood.
Dissecting Microscopes: Dissecting scopes are a regular feature in a paleobotany lab. They allow one to study the details of fossils that can be hard to see with the naked eye. Most of the dissecting scopes used in paleobotany are mounted on a vertical pole called a stereo boom. They can be adjusted up and down and allow for the space on the table necessary to examine large (or small) rock specimens. To view opaque rocks, the light needs to come from above, and each dissecting scope has a set of lights on two flexible goosenecks. This differs from the compound scope where the light travels through the specimen from below.
Compound Microscopes: Compound microscopes allow smaller things to be viewed at higher powers than dissecting microscopes. However, in most cases, the objects need to be mounted on glass slides. There are many types of compound microscopes ranging from basic student models to very expensive high powered scopes that can accommodate cameras, different lenses, or filters. The objective lenses on most light microscopes can magnify specimens up to 400 times their normal size with no special treatment. However, most higher level objectives (e.g., 60x or 100x) require oil, which helps prevent the loss of light when the objective is so close to the object. With practice, compound microscopes are easy to use and an essential tool in paleobotany and many other disciplines.
Scanning Electron Microscopy (SEM): Scanning electron microscopy is another tool used regularly by paleobotanists. While light microscopy is a good option for observing basic information about pollen including its size and number of apetures, the surface sculpturing of pollen grains can be hard to resolve without an SEM. Check out this link to learn more about how scanning electron microscopy works: How does a SEM work?
Preparing fossil pollen for microscopy
The hardest thing about viewing fossil pollen using either light microscopy or SEM is getting the pollen out of the rock and ready to be viewed. Pollen and spores can be dispersed throughout a rock sample, or if the preservation is ideal, they can be found in situ in a flower’s stamen (a male flower part). Extracting the pollen from the sediment or directly from a stamen is a laborious and delicate process that cannot be completed without a lab, fume hood, and proper safety gear. Multiple strong acids and bases are usually required to remove the surrounding rock from the pollen grains. Specific protocols have been published that one can follow.
Light Microscopy vs. SEM for pollen: Which is better?
Both light microscopy and SEM have pros and cons for studying pollen. Once a light microscope is initially purchased, the cost of maintaining it is low. New scanning electron microscopes cost upwards of half a million dollars so they are typically only available at large research institutions and often require an hourly fee to use. Using an SEM can be a bit more complicated, but the newer machines and associated software have also gotten more user friendly.
Since light microscopy is limited in its ability to see the surface sculpturing of pollen, SEM is a great tool to observe the surface details of pollen grains, which are often on the order of 1 µm or 0.001 mm. SEM can produce beautiful results, but is more expensive and less accessible than light microscopy. Check out this website for a nice comparison of light microscopy and SEM: Comparison of light microscopy and scanning electron microscopy.
Left: A spore from Blue Rim. Note the smooth surface. Scale bar = 30 µm. Right: Pollen from Blue Rim. Note the bumpy surface. Scale bar = 10 µm.
By Allen,Sarah E
Spores are haploid (1N, having one set of unpaired chromosomes) reproductive units. Vascular plants—that is plants that contain xylem tissue to conduct water and nutrients and phloem to conduct sugars produced during photosynthesis—are either homosporous (all spores identical) or heterosporous (spores of two sizes or morphologies). In heterosporous plants, including all seed plants, a megaspore (female) and smaller microspore (male) are produced. Ferns are plants that rely on spores to reproduce.
The brown dots on the underside of this fern frond are sori. Sori are structures that produce spores.
Pollen is only produced by gymnosperms (e.g., conifers, cycads) and angiosperms (e.g., daisies, oaks, grasses). The largest pollen grains are upwards of 2-3 mm in diameter (e.g., in the seagrass Zostera marina which is pollinated underwater). However most grains are less than 100 µm (0.1 mm). The smallest grains are less than 10 µm (0.01 mm) in diameter.
Most pollen grains have at least one aperture, a thin part of the wall where the pollen tube containing the sperm, exits. Apertures can be round pores, irregular pores, or elongated slits.
Dispersed angiosperm pollen from Blue Rim. Scale bars = 20 µm. Photos by undergraduate researcher Morgan Pinkerton.
Some pollen grains (common in Pinaceae or the Pine Family) have bladders or sacci. These aid in wind dispersal and help orient the grain in the pollination droplet. These grains typically lack apertures and may look different depending on their moisture content. Pollen of the Pine Family can be quickly identified by its “Mickey Mouse” appearance. Scale bar of pollen at right = 20 µm.
How is pollen dispersed?
Wind Pollination (Anemophilous)
Wind pollinated flowers generally produce more pollen than insect pollinated flowers. The pollen typically ranges from 20-40 µm in diameter and has a smooth surface. Flowers of wind pollinated plants also tend to have large anthers (male parts that produce pollen), showy, divided stigmas (female parts that catch pollen), and no petals (since they don’t need to attract insects or other animals). There are more wind pollinated taxa in high latitudes (e.g., in boreal forests). For example, wind pollination is common in the plant families Poaceae (true grasses), Cyperaceae (sedges), and Juncaceae (rushes).
Insect Pollination (Entomophilous)
Flowers can be pollinated by beetles, flies, bees, butterflies or moths. In order to attract these different insect pollinators, flowers use different strategies such as bright colors, markings on the petals, a strong scent, or nectar rewards. Insect pollinated flowers tend to have larger pollen grains than wind pollinated taxa.
Bat and Bird Pollination
Pollen grains can also be transported by birds and bats. Flowers pollinated by birds tend to be showy and red, with lots of sugary nectar and no odor. Bat pollinated flowers often are tough and pendulous. They have wide openings that open at night, a dull coloration, a musky or fermenting type odor, and lots of nectar. Pollen transported by animals (including insects) tends to have an armored or textured surface, and/or a sticky covering to enable the grains to stick to each other and to the animal.
By Allen,Sarah E
Archeologist and fellow blogger, Smiti Nathan Staudt (her blog here) asked how paleontologists name new species. It is a bit more complicated than one might think! Carolus Linnaeus founded the fields of taxonomy and nomenclature in the 1700s. Taxonomy or classification is the process of defining groups composed of organisms that share similar traits. Nomenclature is the field of naming a new taxon or species. Both taxonomy and nomenclature form the field of systematics.
Four separate codes provide rules and recommendations for naming the organisms on earth. There are separate codes for animals, bacteria, and cultivated plants. However, the code that applies in paleobotany is the International Code of Nomenclature for Algae, Fungi, and Plants (ICN). The codes help provide a stable way to name taxa in order to ensure that there is only one name per taxon and that the name reflects a taxon’s accurate classification. The names are always binomials (two names) in Latin. Common names are not universal and are often ambiguous. It is possible for the same organism to have dozens of common names in different languages, alphabets, or in different geographic regions. Furthermore, common names can be misleading about an organism’s nearest “relative” (e.g., Spanish moss is not a moss at all; it is an angiosperm in the same family as pineapples!).
So how does one create a scientific name? In paleontology, the organism often represents a new species. Sometimes a new species does not fit in any modern or previously created genera, so a new genus must be created. Genera are singular nouns, in the nominative case, with a capitalized first letter, written in italics. A species name is always a binomial composed of the genus and the specific epithet. In the ICN code, the specific epithet can be an adjective that agrees in gender with the genus, a noun in apposition, or a noun in the genitive case. The specific epithet is written in lowercase, also in italics, directly after the genus. The epithet may be arbitrarily composed as long as it is in Latin. It can honor a person, indicate the country or locality in which the organism was found, or be a relevant descriptive adjective. In the botanical code, the specific epithet cannot be the same as the genus (this is acceptable under the zoological code). There are additional recommendations in the code, one of which is to avoid specific epithets that are long and difficult to pronounce. While I have only mentioned a few rules about naming a new genus or species, the code regulates names at all taxonomic ranks. All the rules in the ICN can be found here.
Once you have decided on a name following the rules of the ICN, the new species has to be effectively and validly published to be considered legitimate. First, it must be in a printed or pdf formatted journal or book with an ISSN or ISBN number. Furthermore, the name can only be composed of letters of the Latin alphabet with proper grammatical formatting. A description or diagnosis is required as is the designation of a type specimen. A type specimen is a name bearing specimen, one that links the name to the taxon. If you are naming a new fossil species, an illustration or figure is required (this is not true for modern plants, but is recommended). There were less restrictive rules in the past, so many names have been “grandfathered” in. Finally, when needed, the codes also govern name changes.
Information compiled from materials from the course “Biological Nomenclature” taught in Spring 2011 at UF by Drs. Nico Cellinese, Walter Judd, and Norris Williams and directly from the ICN.
Botanical Latin by William T. Stearn
How have the names for the new species I have worked on been determined? Here is the entomology for a few examples:
All these species were assigned to either a fossil or modern genus that had already been established. More information and photos of some of these taxa can be found in blog posts from June and July of 2015.
Phoenix windmillis: This flower had a field name of Windmill as the petals are oriented just like the blades of a modern wind turbine. I Latinized this word to create the specific epithet. Phoenix is a modern genus commonly known as the date palms.
Icacinicaryites lottii: The specimens of this fruit were found by FLMNH paleobotany research assistant and lab manager Terry Lott in the summer of 2013. We honored his find and named the species after him. Icacinicaryites is a fossil genus used for Icacinaceae fossils that do not align with a modern genus.
Iodes occidentalis: Occidentalis translates to “western” in Latin. This seemed appropriate as the species is found in the fossil record of the western hemisphere, but the other (living) members of the genus are distributed in Africa and Asia today.
Goweria bluerimensis: These leaves were documented from the Blue Rim escarpment in the Bridger Formation of southwestern Wyoming, so the specific epithet acknowledges the locality. The genus Goweria is used for fossil leaves assigned to Icacinaceae that have an uncertain placement within the family.
Remember: One can never just use a specific epithet to refer to a species. The full binomial with the genus name is the only correct way to refer to a species.
By Allen,Sarah E
This semester has been busy with outreach events. On Sunday, January 10th, I met with 15 students and two instructors from St. Olaf College who were on a field excursion in Florida. I gave them an overview of the Paleobotany collections area at the Florida Museum of Natural History (FLMNH) and answered questions. I also helped coordinate additional activities for the day, which included a vertebrate fossil identification session led by Dr. Richard Hulbert with help from graduate student Victor Perez. Dr. Gordon Hubbell shared his private shark fossil collection, one of the top collections of this type in the world, with the group. Thanks to Victor for coordinating that visit and to Gordon for hosting the group! After their visit to Gainesville, the St. Olaf students spent ~2 weeks collecting fossils on the Peace River before driving back to Minnesota.
On Saturday, February 20th, I gave an hour long presentation about paleobotany and my research to the Florida Fossil Hunters in Orlando, FL. This group of knowledgeable and enthusiastic citizen paleontologists meets once a month at the Orlando Science Center. They also host numerous field trips and paleontological events for kids. Since plant fossils are rare in Florida, I presented a brief overview of paleobotany and plant fossils through geological time before diving into my own research. I enjoyed meeting many members of the Florida Fossil Hunters and wish them luck with their upcoming events.
Most recently, on Saturday, March 19th I met with the PaleoBlitz group, gave them a tour of the Paleobotany collections at the FLMNH, and answered questions. Participants in the PaleoBlitz were citizen scientists from multiple fossil clubs who were selected to spend the weekend learning about “Best Practices in Paleontology.” I enjoyed interacting with all of these groups of enthusiastic amateur paleontologists.
By Allen,Sarah E
Could you have a traditional Thanksgiving meal 50 million years ago in southwestern Wyoming using what is known about the flora and fauna at Blue Rim?
Here is the target “traditional” Thanksgiving meal: Turkey, Stuffing, Cranberry Sauce, Green Bean Casserole, Mashed Potatoes, Vegetables (carrots), Dinner Rolls, and Pumpkin Pie.
Various geologic time periods will be referenced throughout this post. Here is a geologic time scale for reference. Everything is in the Cenozoic or Mesozoic era.
Turkey: Turkeys (Meleagris gallopavo) appeared relatively recently. There are numerous fossil records of the genus Meleagris in the Pliocene and Pleistocene. However, fossil records assignable to the subfamily Meleagridinae (where turkeys are found) are known from the Early Miocene. The fossil record of birds in general is spotty because their bones are light, hollow, and do not preserve well. Since turkeys were not available, the alternate meat options at Blue Rim ~50 Ma likely would have included: local turtles, crocodiles, clams, and snails, and nearby fish and mammals. Bird fossils have been found, albeit rarely, in the Bridger Formation.
Stuffing & Dinner Rolls: The main ingredient in both is wheat or Triticum aestivum which is in the Poaceae (Grass) family. Poaceae is the fourth largest family in terms of number of species, but it covers the most land area of any plant family and is the most economically important today. Grasses evolved in the Late Cretaceous and were widespread by the Early Eocene, but were rare compared to today. Open, grass-dominated habitats did not spread in North America until the Middle-Late Miocene.
There is some evidence for grass-like plants at Blue Rim, but don’t start baking the rolls just yet! Leaf fragments with parallel venation similar to grasses are present, but they do not preserve any diagnostic characters and could represent one of many other monocotyledonous families. There are some fruit clusters with characters in common with modern grasses, but pollen preserved in the stamens lacks the diagnostic single pore. In addition, grass pollen has not been observed in the sediment. Since grasses are wind-pollinated, the pollen should be present if they were nearby; however, grass pollen often degrades over time, so it may not have preserved. More information about the fossil history of grasses can be found in the following paper: Stromberg, 2011.
Sadly, it likely would have been difficult to gather enough grains from the local Blue Rim flora ~50 Ma to prepare stuffing or dinner rolls.
Two grass-like fossils from Blue Rim. Scale Bar = 1 cm.
Cranberry Sauce: Cranberries (Vaccinium macrocarpon) are in the Ericaceae or heath family along with rhododendrons and blueberries. Based on the evidence available, there were not any cranberries or their relatives present in the Blue Rim flora. The closest fossil relative is likely a specimen assigned to an extinct genus in the Polemoniaceae from the Eocene Green River Formation in Utah (Lott et al., 1998). The families Polemoniaceae and Ericaceae are related and both are found in the order Ericales.
Green Bean Casserole: Green beans (Phaseolus vulgaris) are in the Fabaceae or legume family. Fabaceae is the third largest family in terms of number of species and is the second most important plant family economically. The Fabaceae likely evolved in the mid to Late Cretaceous, but the fossil record is more extensive in the Paleogene, with diversification in the Eocene. No fossil beans have been recovered at Blue Rim. However, it is still possible that legumes were present as the leaf characters often mimic other families making them hard to identify. However, there are definitive fruits assignable to Fabaceae at the Kisinger Lakes site in northwest Wyoming. This fossil site is similar in age to Blue Rim, so if you were willing to take an extended walk (~150 miles) you might obtain some edible beans! More information about the fossil history of legumes can be found in the following book: Herendeen, P.S. and D.L. Dilcher eds. (1992). Advances in Legume Systematics Part 4: The Fossil Record. United Kingdom: The Royal Botanic Gardens, Kew.
Fossil legume from the Kisinger Lakes site in northwestern, Wyoming. Scale bar = 1 cm.
Mashed Potatoes: Potatoes (Solanum tuberosum) are members of the Solanaceae or Nightshade family. This family also includes peppers, tomatoes, eggplants, and tobacco. No fossils assignable to Solanaceae have been observed at Blue Rim. The oldest fossils confidently assigned to the Solanaceae that are approximately the same age as the Blue Rim fossils are found in the United Kingdom. A molecular analysis (Särkinen et al. 2013) placed the stem of Solanceae at ~49 Ma and the crown group (the current suite of genera) at ~30 Ma. Therefore, true potatoes probably did not even exist in the Early Eocene and there would be no mashed potatoes for dinner.
Carrots: Carrots, scientifically known as Daucus carota, are in the Apiaceae or Carrot Family. Few Apiaceae fossils are known. Herbaceous plants, such as carrot do not preserve as easily as woody plants. No Apiaceae fossils or their relatives are known from the Blue Rim flora or any nearby floras of similar age.
Pumpkin Pie: Pumpkin or Cucurbita pepo is a member of the Cucurbitaceae family along with melons. Sadly there are no fossils assignable to Cucurbitaceae at Blue Rim either, so a familiar dessert would not have been served.
If Thanksgiving had begun 50 million years ago instead of the 1600s, the “traditional “ meal everyone looks forward to today would be much different if it were based only on the flora and fauna present in the Blue Rim area of Wyoming at that time. Have a Happy Thanksgiving and enjoy your meal!
By Allen,Sarah E
I recently returned from this year’s Botany conference in Edmonton, Alberta, Canada. It was held in the Shaw Conference Center overlooking the North Saskatchewan River. I presented on Monday during the Paleobotany student session. My talk focused on the leaf flora from the lower stratigraphic horizon at Blue Rim. This horizon has 20 non-monocot angiosperm leaf morphotypes. I used specific leaf characters that have been linked to climate to estimate the paleotemperature and paleoprecipitation. I also attended the Paleobotany Banquet, the ASPT (American Society of Plant Taxonomists) Banquet, and numerous talks. After the conference, I participated in a field trip exploring the post-glacial landscapes, history, and vegetation east of Edmonton. This excellent trip was led by Alwynne Beaudoin and Diana Tirlea from the Royal Alberta Museum.
My travel to Edmonton and participation in Botany 2015 was supported by the ASPT and NSF DEB award number 1404895.
Two of the leaf morphotypes (species) from Blue Rim. The leaf on the left is compound and toothed. The leaf on the right is simple and untoothed. Notice the large size of the leaf on the right. Scale bar for both = 1 cm.
View of the Shaw Conference Center in downtown Edmonton.
Foliage of Populus tremuloides (aspen). Aspen is the dominant tree species in and around Edmonton.
A male bison in Elk Island National Park.
A shallow lake at Elk Island National Park.
The North Saskatchewan River to the east of Edmonton near the site of a former Victorian fort and settlement.
By Allen,Sarah E
Fossil palm flowers have been found at Blue Rim and other sites in the Rocky Mountain region. These flowers, representing a new species named Phoenix windmillis, are related to date palms. Modern date palms are native to Africa and southeast Asia, but are found in the Eocene of Wyoming, Colorado, and Utah. One of the flowers contained in situ pollen, which provided more characters to support the assignment of these specimens to Phoenix. This new species is documented in a paper that was recently published in the International Journal of Plant Sciences.
Two Phoenix windmillis flowers from Blue Rim. Scale bar = 5 mm
A flower from the Barrel Springs site in the Green River Formation. This site is in southern Wyoming to the east of Blue Rim. Scale bar = 5 mm
Pollen extracted from an intact anther of Phoenix windmillis and viewed using a scanning electron microscope (SEM). Scale bar = 23.1 µm. (Note: there are 1,000 µm in 1 mm)
By Allen,Sarah E
The second week focused on the secondary plant body or wood. We studied the anatomical details of wood of both flowering plants and conifers. We also touched on the development, function, evolution, ecology, variability, and uses of wood. Week 2 was taught by Elisabeth Wheeler, Peter Gasson, and Pieter Baas – all experts in wood anatomy.
I would like to extend my thanks to all the instructors, the TA Becky Povilus, Faculty Assistant Jess Gard, and our awesome bus driver, Andrew Brown. Thank you also to Steve Manchester and Christine Davis who wrote letters of recommendation on my behalf.
Here are some photographs from the second week:
A cross or transverse section of Quercus robur (English oak) wood. The annual rings are visible. The larger vessels (for water conduction) are formed in the spring when resources are more plentiful. This is termed “earlywood.” Later in the growing season, when water is less plentiful the vessels are smaller and compose the “latewood.”
Rays and vessels in a tangential section of Dalbergia spruceana (rosewood). Dalbergia is a genus in the pea family, Fabaceae.
Radial section of Ilex aquifolium (holly).
Tangential section of Pinus monticola (Western white pine) with a resin canal in one of the rays. While angiosperms have vessels and tracheids, conifers only have tracheids to transport water and minerals.
When you walk by plants, think of them as living, breathing organisms. Although they don’t move or behave like animals, they are interesting and complex, necessary for the ecosystem to function, and add incredible beauty to our world.
Leaves and fruits of Acer tataricum subsp. ginnala (Sapindaceae family). This specimen, commonly known as the Amur Maple, arrived at the Arnold Arbortum in 1963 from the Kyoto Takeda Herbal Garden in Japan.
By Allen,Sarah E
I recently attended a two week short course in Plant Anatomy at the Arnold Arboretum in Boston. It was funded by the NSF microMorph program (More info here). Week 1 was taught by Ned Friedman and Pam Diggle and focused on the primary plant body. We squeezed weeks of material into 5 jam packed days! We covered apical meristems, the epidermis, ground tissue, vascular tissue, secretory structures, stems, leaves, and roots. In addition to learning about all these topics through engaging lectures, we spent our afternoons in the lab seeing and photographing various specimens.
Here are a few pictures from Week I:
Helical protoxylem from a celery (Apium graveolens) petiole.
Glandular trichomes (hairs) on Drosera capensis. The trichomes secrete mucilage that can be used to catch insects. Drosera is a genus of carnivorous plants commonly known as the sundews.
Water absorbing scales from a bromeliad. Pineapples and spanish moss are also in the bromeliad family.
Stellate (star-like) parenchyma in Juncus. Parenchyma is one of the ground tissues and can be found throughout a plant. Juncus is a genus of monocots commonly called the rushes.
A cross section of a mature root of Ranunculus (buttercup). The four “arms” of xylem (water conducting tissue) are visible in the center of the root.
As an aside, if you have never been to Boston or the Arnold Arboretum (More info here), they are both worth a visit! The Arnold Arboretum is a beautiful park spanning 281 acres with 15,000 labeled primarily temperate woody plants. There is no admission charge. I also enjoyed visiting some of the Boston historic sites with several of the other students who were enrolled in the course with me.
The Hunnewell Visitor Center on the grounds of the Arnold Arboretum.