The Sam Mitchel Herbarium of Fungi is the largest macrofungal collection of mushrooms found along the Southern Rocky Mountains. How did this collection rise to fame? What are its origins?</p> Let us begin with the collection’s namesake, Dr. Duane ‘Sam’ Herbert Mitchel (1917-1993). He earned his M.D. from Harvard in 1943 and briefly served in World War II as a medic. In 1949, he relocated to Denver and was a medical practitioner for over 40 years. Naturally drawn to nature, his mycological interest sparked in 1960 when his sons discovered mushrooms on their ranch in Edwards, Colorado. Unable to identify them, he sought assistance from local universities and state extension services and found minimal mycological expertise in Colorado. Demonstrating his characteristic independence and curiosity, Mitchel decided to undertake his own scientific study of Colorado mushrooms.</p> By 1963, Sam created a community of amateur mycologists, and they were given lab space at the Denver Museum of Nature and Science (DMNS). A year of accumulating and studying specimens pushed Mitchel and his fellow mycologists to their mycological knowledge limits. Determined to expand their expertise, Mitchel, inspired by fellow mycologist Mary Wells, attended the University of Michigan’s Biological Field Station in 1965. </p> By 1967, the mycologists were beginning to run out of space at DMNS. That year, Denver Botanic Gardens board member Dr. James J. Waring invited the group to move their specimens to the Gardens. The collection was housed together with the Kathryn Kalmbach Herbarium of Vascular Plants, an integration that remains today. If you walk through the atrium of the Freyer – Newman Center, peek into the natural history collections. There you will see the Sam Mitchel Herbarium of Fungi</a> next to the Kathryn Kalmbach Herbarium of Vascular Plants</a> housed together.</p> Over the last 45 years, the fungal collections at the Gardens have grown by 300-500 specimens annually. Today, it holds over 25,000 specimens, each contributing to research on fungal diversity and evolutionary relationships. The collection was dedicated to Mitchel as the Sam Mitchel Herbarium of Fungi in 2009 and has remained a vital resource for understanding the role of fungi in the ecosystems of the Southern Rocky Mountain region. </p> Want to learn more? Join a tour of the collections</a> at Denver Botanic Gardens. </p> This article was contributed by Collection's Assistant Matthew Sheik</strong>.</em></p>
There is a debate in the garden world about the best time of year to cut back the spent foliage of herbaceous perennials and grasses. If a gardener is hoping to be sustainable, and benefit pollinators via their gardening practices, leaving debris until the spring is the best option. Spent foliage provides shelter for overwintering insects and their larva as well as seeds for birds. Plus, standing perennials provide winter interest – something beautiful to focus on in the colder months, such as dried flower stalks and attractive textures. Lastly, leaving debris in the garden provides insulation to the crowns of sensitive plants. </p> However, those who garden in Colorado know that sometimes adjustments must be made due to unpredictable weather. A particularly heavy, wet snow may flatten perennials that were still standing through the colder months. If this is the case, knock hefty loads off trees and shrubs to alleviate stress and prevent breakage to limbs. And keep an eye out for any broken branches in small and large trees near and around the garden. These “hangers” can be dangerous and will require intervention from tree-care professionals.</p> It may be tempting to get the shears out and clear cut once the snow melts. However, there may be many weeks left of wintery weather to come, and many pollinators will still require shelter. While not always the case, some plants that may seem completely smothered under the snow can rebound once it melts; just give them some time. </p> If broken stalks and smushed plants aren’t a concern, feel free to leave them be. This won’t hurt the plant; it simply has to do with aesthetics. Head out into the garden once the snow melts to do some repairs if you like but delay any heavy garden work until soil is dry to avoid compacting the soil. As for the herbaceous material on the ground, use pruners to cut broken stalks at the base of the plant and leave those that are still standing alone. Sometimes just a few cuts can be made to recreate a tidier appearance.</p> Heavy snow isn’t necessarily a bad thing for the garden. A lot of moisture and precipitation comes from those big spring snows, and plants receive a much-needed drink as it melts. And it sure is pretty. Certainly, some plants may appear damaged, but in reality, herbaceous perennials start over with fresh stalks in the growing season, so don’t fret. Unless shoveling snow from sidewalks is on the agenda...then maybe some fretting is appropriate. </p>
From sweet and floral to skunky and funky scents, the fragrance of a flower is unique. Certain floral scents are hypothesized to attract pollinators, defend against herbivores or act as a mode of communication between plants. Describing a plant as sweet or skunky is a great start, but with the right training and tools, botanists can more deeply understand the exact chemical reasons as to why a plant smells the way it does. </p> Many botanists are passionate about understanding the biochemistry responsible for plant aromatics and incorporating it into their research, like me! This past month, I took a trip to Cornell University to train with floral scent expert Robert Raguso. Using the Arkansas Valley evening-primrose (Oenothera harringtonii</em>) from the greenhouse, we practiced collecting the floral scent. To do so we needed four elements: a plant of interest, a headspace, an air pump and a method of capture. Together, these tools allow us to concentrate molecules and then move them into our method of capture to take back to the lab. If done carefully and correctly, this data collection can be done without causing any harm to the plant of interest. </p> Once back in the lab, we inject our floral scent cocktail into a machine called a gas chromatography-mass spectrometer (GC-MS), a tool which separates and breaks down samples to identify substances and determine their chemical structures and quantities. These are highly specialized instruments capable of determining even the most cryptic of compounds. After injection, the floral compounds travel through a glass column, by force of an inert gas. Inside this column, compounds are separated from one another. As the isolated compounds exit the other end of the column, they are ionized by a laser beam where their mass to charge ratio (m/z) is determined. We are left with both a chromatogram and a mass spectrum; software is then used to determine which compounds are present in our sample. </p> In the case of Oenothera harringtonii</em>, we identified several dominant compounds, particularly a compound called linalool. Linalool, an acyclic monoterpene tertiary alcohol, is known to manifest as a woody, floral scent in several notable plant genera, such as Coriandrum </em>(known for coriander and cilantro) and Lavandula </em>(known for lavender). Oenothera harringtonii </em>is a night-blooming angiosperm that requires the visitation of hawkmoths for successful pollination. Linalool is observed to attract moth visitors, while simultaneously being a deterrent of other herbivorous invertebrates. </p> Whether studying the delicate emissions of alpine wildflowers or analyzing the complex aromatics of cultivated blooms, each volatile molecule we identify tells a worthwhile chemical story. </p> Special thanks to Robert Raguso and Cornell University for taking the time to share their knowledge about floral biochemistry. Learn more about Professor Raguso’s work</a>.</p> This article was contributed by graduate student Ashlee Kerber</strong>.</em> </p>
You may have noticed that the Boettcher Memorial Tropical Conservatory was closed to the public for several months during 2024. We know it was an inconvenience for visitors, but critical changes and improvements were made during the closure. Most of the changes are not visible to visitors – they involved a complete revamp of HVAC systems that are hidden behind the perimeter walls and repairs to the roof vents that had been completely inoperable for over a decade.</p> Many plants had to be removed to accommodate the demolition and subsequent construction, but cuttings or divisions were saved of almost every plant impacted. We also left a few large specimens in place and protected them from damage during the construction process. Since the HVAC systems were not working during the renovations, supplemental heat came from portable gas-powered unit heaters.</p> Now that the dust has settled, it is time to welcome visitors back in to enjoy the benefits of this lengthy process. While many of the newly planted specimens will take a bit of time to fill in, there are still plenty of old favorites to see.</p> Just inside the lobby doors and to the left is a large specimen of Brownea ariza</em> – a member of the Fabaceae or bean family. Native to tropical South America, this plant exhibits cauliflory – its flowers are born on woody stems or on the trunk. The bright red/orange flowers are short-lived so if you do not notice flowers, look for the glowing buds along the plant’s stems.</p> Speaking of cauliflory, a little further along this path is a nice specimen of Theobroma cacao</em>. Notice how the fruits are born along the tree’s trunk. Native to tropical Central and South America, this tree is the source of cocoa, cocoa butter and chocolate. It takes a bit of processing to make the fruit palatable. The Aztec name – Xocolatl – means “bitter water” but Linnaeus derived this tree’s scientific name from the words “theos” – meaning God, and “broma” – meaning food. Literally food of the gods.</p> Another cauliflorous tree can be found at the west end of the south path. The clown fig – Ficus aspera</em> – is a relative of Ficus benjamina</em>, the common houseplant known as weeping fig. You may notice fruits born along the contorted trunk of this tree which has been in our collections since 1965. Ficus aspera is native to the South Pacific region. </p> If you already miss your poinsettia (Euphorbia pulcherrima</em>), you can see a specimen of a close relative in the northwest corner of the Tropical Conservatory. Euphorbia punicea</em> is native to Jamaica, Cuba and other Caribbean coastal areas. Like most members of the Euphorbiaceae family, the stems exude a milky sap that can be a skin irritant.</p> The Boettcher Memorial Tropical Conservatory is a wonderful place to escape the cold thanks to the newly renovated heating and cooling systems. Enjoy your old favorite plants and come back often to watch the progress of the newer plantings! </p> </p> Gallery photos by Nick Snakenberg</em></p>
