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“The Chemistry of Plants: Perfumes, Pigments, and Poisons” by Dr. Maragreta Séquin

The words “Organic Chemistry” strike fear and loathing into the heart of many a young learner – scientist or not. Dr. Margareta Séquin, known more familiarly as Gréti, is here to help diminish this response. And as the smiling, warm-voiced chemistry teacher describes “to ease us gently” from the plants we love, and the things we love about them – like their scents and oils and colors – into an understanding of their actual chemistry. Photo: Rose foliage turning color in fall. What makes leaves turn color in fall? Dr. Séquin will discuss changes in pigmentation of plants over time and seasons.

Using plants that are familiar to you Gréti discusses general building blocks of chemical process, including revisiting the periodic table of elements, going over how elements join together to form compounds, and ions in the soil. “With a basic knowledge of elements, ions, and compounds in hand, we continue to study how plant compounds interact in chemical reactions that assemble new plant compounds or break them down. Plants must be able to perform these reactions in conditions dictated by their environment. Plants are able to function under myriad conditions thanks to elaborate enzymes and lots of time.” These sometimes familiar and sometimes not so familiar reactions and processes include how they take up nutrients from the soil to the elegance of photosynthesis. Photo: Yummy sweet orange peppers, sport a deep orange color. Pigmentation is one of the aspects of plant chemistry discussed at length by Dr. Séquin.

Following this building block information you get to some of the fun stuff – like the building blocks of pigmentation, of defense mechanisms like toxins, and smell – “what makes a stinking hellebore, stinky?”

If you’ve ever had questions about the basis of many of these things going on all around you in the garden and the great outdoors – as they shift from one season to the next – then this class and this book is for you. You may not be worthy of a PhD in Organic Chemistry, but you will have a deeper understanding of the plants we love and many of the reasons we are so fond of them – from their beauty to their individuality. Photo: Creosote bush (Larrea tridentata) is famous for its creosote smell. Scent, both pleasant and unpleasant, is one of the aspects of plant chemistry discussed at length by Dr. Séquin.


Perfumes, Pigments, and Poisons an Introduction to the Chemistry of Plants
October 13, 2012, Saturday – a workshop presented by Friends of the Chico State Herbarium

Plants have evolved a wealth of fragrances that attract pollinators and scents that repel browsing animals. Colorful pigments in flowers and bright colors in fruits attract insects and birds. Some plant pig- ments harvest energy from sunlight while others have protective functions. Furthermore, highly diverse and intricate defensive substances allow plants to stay alive.

Photo: A sweetly scented rose – what makes it smell so sweet?


This workshop is an introduction to the chemistry of plants, with a focus on plant smells, plant colors, and chemical plant defenses. The workshop will begin with a lecture presentation on families of chemical substances that compose the perfumes, pigments, and poisons. Pictures of California native plants and some non-natives that typically contain the compounds will accompany the chemical structures. We will examine what is characteristic of the structures of plant scents, of molecules that compose plant pigments, and of those that have defensive functions in plants. A couple of hands-on activities will further illustrate the topics. We will then take a walk on Campus to view live plants and talk about their special plant chemistry. During a picnic lunch there will be ample opportunity for questions and further discussions of plant chemistry.

Please wear comfortable walking shoes and bring a picnic lunch.

Photo: Deeply colored rose hips – the fruit of this Rugosa rose.


This workshop will be led by Margareta (Greti) Se?quin. Margareta has a Ph.D. in organic chemistry and is a plant enthusiast. She has taught organic chemistry, natural products chemistry, and chemistry for non-majors at San Francisco State University for more than twenty years, and has also led numerous field seminars on the subject of plant chemistry. She is a docent at the Regional Parks Botanic Garden in Berkeley. Margareta Se?quin is the author of the book “The Chemistry of Plants: Perfumes, Pigments, and Poisons” published by RSC (Cambridge, UK) in April 2012.

This workshop will meet Saturday, October 13, 2012, from 9:00 a.m. to 1:00 p.m. in Holt Hall room 129 at CSU Chico. The registration fee is $45.00 ($40.00 for members of Friends of the Herbarium). Please register in advance; class size is limited to 20 participants (class cancelled without a minimum of 10 participants). For more information about workshop content please contact Margareta at msequin@sfsu.edu. Margareta’s home page is at http://userwww.sfsu.edu/~msequin/. For more information about workshop registration please contact the Biology office at (530) 898-5356 or jbraden@csuchico.edu.

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In a North State Garden is a weekly Northstate Public Radio and web-based program celebrating the art, craft and science of home gardening in Northern California. It is made possible in part by the Gateway Science Museum – Exploring the Natural History of the North State and on the campus of CSU, Chico. In a North State Garden is conceived, written, photographed and hosted by Jennifer Jewell – all rights reserved jewellgarden.com. In a North State Garden airs on Northstate Public Radio Saturday mornings at 7:34 AM Pacific time and Sunday morning at 8:34 AM Pacific time. Podcasts of past shows are available here.