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Herbarium: Medicinal Plants as Information Worthy Worts: Comprehensive Comparison of the Histories, Structures, and Therapeutic Uses of Plants in the Scrophulariaceae and Asteraceae Families In order to better understand the “worts'” categorization, an analysis of the plants within the Scrophulariaceae family (Scrophularia californica, Scrophularia scorodonia, and Galvezia juncea) and two plants within the Asteraceae family (Artemisia douglasiana and Artemisia campestris) was conducted. Through research thus far, it was found that these aforementioned plants share structural similarities in terms of aspects that include venation of the leaves. The most prominent common denominator of the wort category is that they all have therapeutic uses. Among the historical therapeutic uses found in the literature are anti-inflammatory, anti-viral, and antioxidant uses. These benefits have been utilized from societies ranging from the American Indians to the Europeans. -By Chris Leung, Catly Do, Fady Tawfik, and Sean Jamali. Exploring the Sages: Medicinal Properties and Appearances of Artemisia Californica and Salvia Apiana Both plants Artemisia Californica and Salvia apiana under the category of sages play important roles in maintaining the growth of their local ecosystems with similar habitats, medicinal properties, and flowering appearances during the times of collection. However, they also share important differences in their flowering and growth patterns as well as the active agents used for their medicinal properties. In analyzing the similarities and differences between these two plants regarding appearances, climate, medicinal properties, and growth patterns, the similarities in how they are able to provide and support their local ecosystems is the big picture idea that can be understood. - By Stephanie Bottomley, Rasika Obla, Tony Ong, and Balpreet Sond. Tea Time: Exploring the Medicinal Properties of Bark-Use Plants from a Traditional Ecological Knowledge Context This page discusses three different plants that contain significant medicinal properties in their bark and have been historically used by indigenous communities throughout North America: Populus tremuloides, Frangula californica subsp. californica, and Amelanchier alnifolia. These species will be compared on a global scale by examining the bark-based applications of two related species from Africa and East Asia: Dovyalis caffra and Rhaphiolepis umbellata. Despite their phenotypic differences and the differences in their medicinal properties, all five of these plants have been used to help relieve symptoms of communicable and chronic diseases through the direct digestion of tea like remedies made from the boiled bark of these plants. -By Saja Zidan, Maha Ulhaq, Kate Santoso, Gillian, Miller, Anna Jovin, and Luc Lorain The History, Comparison, and Analysis of Parasitic Plants Our project presents the process of collecting and researching the special characteristics of parasitic plants. We explore each plant's respective medical practices and compare them to epiphytic plants that are similar to our original plants of interest. In each project, we individually explain how the plants were collected, identified, translated, and classified. The contextual reasons behind this process are also presented and connected to the general unique characteristics of parasitic plants. Each page provides a collection of media images that visually represent the main plant of interest, the epiphytic plant, the historical materia medica image, and the individual journal observations that we made of our respective plants. We offer comparative analysis and highlight important parts of each specimen throughout these photos. - By Khang Vo, Jessica McLaughlin, Alastair Sterns, and Dania Alkoraishi Combating Coughs: The Respiratory Remedies across North America Bioprospecting and the application of materia medica have played central roles in the remedy of physical ailments in humans throughout history. From ancient cultures utilizing extracts from leaves and roots to modern medicinal practices extracting medicinal properties from plants to put into pills and other therapies, materia medica has and remains a relevant and growing practice. Here, we examine various plants from North America and their varied characteristics, though they share similar medicinal properties.- By Raymond Ko, Mari Williams, Elizabeth Pham, Julia Tang, Cienna Henry Milton, and Emma Barrall Antiseptics in Nature: An exploratory analysis of Coptis trifolia and Larrea tridentata The following research studies common properties of plants used as potential antiseptic medicinal use. Explained more in depth later on, the first page introduces the plant Coptis trifolia, and its common characteristics with a similar plant, Thalictrum fendleri. The second page studies Larrea Tridentata found at the UCLA Herbarium and its living species at the UCLA Botanical Garden. The pages also examine other species found at the UCLA Botanical Garden, with references of possible characteristics which may allude to the specificity and uniqueness of the plants and objects. These three species studied share a common use as an antiseptic. - By Neha Shetty, Simran Athwal, Mariah Ghodrat, Madeline Huttie, and Liam Kordmahale-Izaddoust Plant Specimen and their Alias : Exploring the Identity of Plants with Animal in the Name Lycium torreyi and Equisetum laevigatum, both plant species with an animal in their name, were explored for their characteristics and relationship to their respective animals. Through extensive research, we deduce several similarities and differences between our plants that led us to an understanding of why each plant earned their colloquial name, or alias. Lycium torreyi and Equisetum laevigatum, alias Wolfberry and Smooth Horsetail, respectively, have several commonalities and differences to their corresponding animal including physical and character traits as well as their medicinal qualities. Images, observations and outside research portray the many queries and answers to their common name. By Frieda Anastopulos, Alexa Hernandez, Denise Llera, Chelsea Okoro, Grace Randall Precious Polygonaceae: Insight into the Historical Collection and Therapeutic Uses of Polygonum, Eriogonum, and Rumex Genera This comparative analysis took to exploring six species under the Polygonaceae plant family, half of which are housed in the UCLA Herbarium and half of which are located in the Mildred E. Mathias Botanical Garden at UCLA. Although they shared a meaningful commonality, these plants fell under a total of three genuses, which seems to explain their differences in morphology - as observed in the physical herbarium specimen sheets and the botanical garden visit - and utility, as unveiled by various Materia Medica entries. However, with an understanding of both historical and modern collection processes, this analysis also postulated that such differences could relate to how these plants were collected and their associated metadata. - By Moryel Yashar, Lexie Baughman, Nicole Cohen, Yair Tabibi, Tabetha Sanchez, and Leah Tabibi Bidens pilosa, Crataegus douglasii, and Urtica dioica effects on Cardiovascular System Bidens pilosa, Crataegus douglasii, and Urtica dioica are medicinal plants that have been found to contain a myriad of bioactive compounds, such as flavonoids, antioxidants, and polyphenol compounds. These compounds are known to have significant effects on the cardiovascular system by primarily targeting systolic hypertension. Plant extracts and their derivatives ameliorate oxidative stress, hyperlipidemia, and hypertension associated with cardiovascular disease. This association is due to the characteristics of anti-inflammatory, vasorelaxant, and antiviral activity within the specimen. These medicinal outcomes are elicited to prevent the onset of cardiovascular diseases risk factors. Overall, Bidens pilosa, Crataegus douglasii, and Urtica dioica play a crucial role in cardioprotective effects and health benefits. - By Salma Fawzi, Anaeli Guzman, Rere Huang, Lilliane Martin, Isabel Nakoud, and Sriha Srinivasan A History and Analysis of Antiviral Medicinal Plants Medicinal plants vary wildly among cultures around the world, and proper identification, collections, and bioprospecting of these plants expand upon modern medicine and provide new possibilities of drugs. Exploration of historical materia medica, preserved herbarium specimens, and observation of plants both in adaptations and chosen environment allow for the discovery of new medical leads. Three plants in particular, Eclipta prostrata, Astragalus nuttallii var. Nuttallii, and Sambucus canadensis, have historically been documented and used in medicine for their antiviral properties. Through the process of observation as well as investigation of historic cultural uses, much can be learned about these medicinal plants that carry these critical properties. - By Allison Wang, Joanne Kwak, Nina Do, Nicolo Villasis, Sabrina Huang, and Hamza Mojadidi

Whole Specimen of Amelanchier Alnifolia

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Amelanchier alnifolia: Native uses and Neocolonial Pharmaceutical Potential 48 Amelanchier alnifolia, known alternatively as the saskatoon, serviceberry, or juneberry, is a deciduous-leaved shrub that grows in temperate forests of Western North America and possesses an extensive horticultural and medicinal tradition. A. alnifolia is well-represented in colonial textual sources, praised by Western-bound settlers and horticulturalists alike for its appearance with little regard to traditional Native uses. Cross-analysis of these historical texts with herbarium records, first-hand observations of the plant in-situ, and culturally-informed Indigenous accounts yield a powerful framework to situate a modern understanding of A. alnifolia’s morphology and medicinal properties, including matters of species utility and accessibility. While disparate components of A. alnifolia may possess tremendous economic and pharmaceutical potential, Western biomedical researchers and agricultural operations are ethically bound to respect Indigenous concepts of sovereignty and resource management through collaboration, mutual exchange, and sustainable harvesting. plain 2022-03-09T11:12:11-08:00
Three Sources of Investigation
The UCLA Herbarium, site to roughly 200,000 preserved floral specimens from North America, Europe, and California, presents one fundamental source of knowledge regarding the type morphology of Amelanchier alnifolia. The specimen on record at the UCLA Herbarium was collected by W. J. Cody in situ near Yellowknife in the Northwest Territories of Canada on June 27, 1949, with the help of an additional collector J.B. McCanse. These collectors recorded little information regarding the material conditions present in and around the source plant, however some information may nevertheless be gleamed from the specimen label. The host plant of the preserved clipping was identified in humus-rich soil at the water's edge, relatively rare in its local ecology. Visually, the specimen consists of a branch cutting from a larger specimen, measuring approximately 45 centimeters and possessing multiple, slender sub-branches with leaves and flowers. Leaves are a dark green and ovate in shape, with a noticeable central midrib and sharp serrations beginning from the midline. At the apex of several terminal branches grow clusters of delicate yellow-dried flowers with five petals and intricate venation.

The second collection examined was a digital collection of historical documents dated from the turn of the 19th century, situating Amelanchier alnifolia in the Materia Medica. A related specimen of the same genus, Amelanchier canadensis, was identified from the POWO herbarium database. This specimen was presented by Dr. Hoover in February of 1868 and is housed at the Royal Botanic Gardens. The specimen label in the lower right image of the recorded image signifies important metadata like, the collector, a ruler for measuring, the date, and species identified. This specimen is a smaller bunch of leaves than the Amelanchier specimen housed at UCLA herbarium, but contains many of the same hallmarks such as mature, green, and ovate-shaped leaves and yellow flowers growing at the apex of thin branches. However, the recorded metadata of this specimen is far less robust than the UCLA Herbarium classification, likely a product of the laxer consideration of context given that this specimen was recorded 154 years prior. Another historical documentation of A. alnifolia comes from a 1896 encyclopedia and field guide of the native silva of North America compiled by the American botanist Charles Sprague Sargent. In this treatise, Sargent provides a brief overview of the morphology and observed uses of A. alnifolia, and enlisted the engraver Charles Edward Faxon to produce a representative botanical illustration. Faxon depicts the plant from various angles and times of year, including a flowering and fruiting branch alongside a dormant winter branch, an impossible combination meant to aid naturalists year-round. Curiously, Sargent spends a significant amount of space to describe the established ornamental and woodworking purposes of the plant (signifying that it had been fairly familiar to Americans by the turn of the century), while devoting only one sentence to how the Indigenous peoples of North America interacted with it.
A tertiary resource explored was the UCLA Mildred E. Mathias Botanical Gardens, where a living specimen of a related species, Rhaphiolepis umbellata, could be observed to find common distinguishing features across the family Rosaceae. This set documented the growth habit and ecological relationships surrounding a plant within the same family (Rosaceae), Raphiolepis umbellata. This species, unlike Amelanchier alnifolia, is native to the Old World, with a range throughout Korea, Japan, and Taiwan. The cultivated specimen is roughly 5 feet in height and 2-3 feet in width, growing as a dense thicket of wooden branches and deciduous leaves. R. umbellata is morphologically similar to A. alnifolia in several regards: both species share similar leaf size, growth distribution, and overall shape; flowers on R. umbellata are white and cup-shaped (likely the same as a fresh specimen of A. alnifolia); and both plants produce morphologically similar indigo berries. The Rhaphiolepis umbellata ‘Minor’ specimen found in the CCH2 data portal was collected by L. Haines on April 21th, 1950. It is located near the amphitheater in the UCLA Botanical Garden in Los Angeles, California.
Medical Practice and Bioprospecting
A majority of modern research into A. alnifolia focuses on the nutrient content and possible metabolic activity of its berries, which have been touted as a “superfood” by celebrities and various nutraceutical companies. Serviceberries have long been used by settler-colonists in a culinary context in the form of preserves, pastries, and various brewed beverages, but new research highlights their free radical scavenging ability and high mineral content. Several compounds extracted from the berries of A. alnifolia belong to the larger family of polyphenols implicated in lipid regulation and storage, including anthocyanins, catechins, and tocopherols (Vitamin E). Most advertisers of the saskatoon elevate its supposedly miraculous weight-loss properties while ignoring its far more storied history in Indigenous communities across North America, each of which developed unique relationships to A. alnifolia. The dried berries of this plant were a staple component in Northern plains diets in the production of pemmican, a non-perishable blend of dried meats, carbs, and foraged fruits that helped populations weather out times of winter scarcity. Across tribes of the Pacific Northwest, the Great Plains, and the subarctic, A. alnifolia has been used as a key ingredient in tonics meant to alleviate symptoms of viral respiratory infections, aid in childbirth, and as a curative laxative. Both the plant leaves and bark were utilized to meet these ends; for example, thin strips of bark were boiled as part of a “10-bark medicine” for treatment of tuberculosis, venereal disease, and stomach ulcers. Bark-based medicine in particular sometimes carried a spiritual aspect as well: according to two elder women of the Coast Salish tribe explain, as the cut from which bark was taken began to callous and heal, patients in turn were expected to begin their recovery. Use of these natural medicines required adherence to a strict code of collection, requiring a specific confluence of natural conditions, seasonality, and regalia to achieve effect.
Some biomedical researchers have investigated the therapeutic potential of Amelanchier alnifolia, observing moderate effects in vitro. While these findings should not overshadow the living Indigenous history involving this plant, their implications for new forms of curative medicine cannot be ignored. Methanolic extracts of axial branches were shown to possess highly active antiviral properties against enteric coronaviruses (such as the common cold) by McCrutcheon et al (1995), suggesting their potential for prophylactic or antiviral therapeutics.

Citations
1. Abe, Tetsuto, and Michio Matsunaga. 2011. “Geographic Variation in Germination Traits in Melia Azedarach and Rhaphiolepis Umbellata.” American Journal of Plant Sciences 02 (01): 52–55. https://doi.org/10.4236/ajps.2011.21007.
2. Curtis, Edward. n.d. “Ethnobotany and Native Plant Production,” 9.
3. Gottesfeld, Leslie M. Johnson. 1992. “The Importance of Bark Products in the Aboriginal Economies of Northwestern British Columbia, Canada.” Economic Botany 46 (2): 148–57. https://doi.org/10.1007/BF02930629.
4. Lavola, Anu, Reijo Karjalainen, and Riitta Julkunen-Tiitto. 2012. “Bioactive Polyphenols in Leaves, Stems, and Berries of Saskatoon (Amelanchier Alnifolia Nutt.) Cultivars.” Journal of Agricultural and Food Chemistry 60 (4): 1020–27. https://doi.org/10.1021/jf204056s.
5. McCutcheon, A. R., T. E. Roberts, E. Gibbons, S. M. Ellis, L. A. Babiuk, R. E. W. Hancock, and G. H. N. Towers. 1995. “Antiviral Screening of British Columbian Medicinal Plants.” Journal of Ethnopharmacology 49 (2): 101–10. https://doi.org/10.1016/0378-8741(95)90037-3.
6. Ozga, Jocelyn A, Asma Saeed, and Dennis M Reinecke. 2006. “Anthocyanins and Nutrient Components of Saskatoon Fruits ( Amelanchier Alnifolia Nutt.).” Canadian Journal of Plant Science 86 (1): 193–97. https://doi.org/10.4141/P05-139.
7. Rus Jacquet, Aurélie de, Mitali Arun Tambe, Sin Ying Ma, George P. McCabe, Jay Hansford C. Vest, and Jean-Christophe Rochet. 2017. “Pikuni-Blackfeet Traditional Medicine: Neuroprotective Activities of Medicinal Plants Used to Treat Parkinson’s Disease-Related Symptoms.” Journal of Ethnopharmacology 206 (July): 393–407. https://doi.org/10.1016/j.jep.2017.01.001.
8. Turner, Nancy J. 2001. “‘Doing It Right’: Issues and Practices of Sustainable Harvesting of Non-Timber Forest Products Relating to First Peoples in British Columbia.” Journal of Ecosystems and Management, December. https://jem-online.org/forrex/index.php/jem/article/view/215.
9. Turner, Nancy J., and Richard J. Hebda. 1990. “Contemporary Use of Bark for Medicine by Two Salishan Native Elders of Southeast Vancouver Island, Canada.” Journal of Ethnopharmacology 29 (1): 59–72. https://doi.org/10.1016/0378-8741(90)90098-E.
10. Uprety, Yadav, Hugo Asselin, Archana Dhakal, and Nancy Julien. 2012. “Traditional Use of Medicinal Plants in the Boreal Forest of Canada: Review and Perspectives.” Journal of Ethnobiology and Ethnomedicine 8 (January): 7. https://doi.org/10.1186/1746-4269-8-7.
Tea Time: Exploring the Medicinal Properties of Bark-Use Plants from a Traditional Ecological Knowledge Context This page discusses three different plants that contain significant medicinal properties in their bark and have been historically used by indigenous communities throughout North America: Populus tremuloides, Frangula californica subsp. californica, and Amelanchier alnifolia. These species will be compared on a global scale by examining the bark-based applications of two related species from Africa and East Asia: Dovyalis caffra and Rhaphiolepis umbellata. Despite their phenotypic differences and the differences in their medicinal properties, all five of these plants have been used to help relieve symptoms of communicable and chronic diseases through the direct digestion of tea like remedies made from the boiled bark of these plants. -By Saja Zidan, Maha Ulhaq, Kate Santoso, Gillian, Miller, Anna Jovin, and Luc Lorain
Three prominent North American plants to discuss in the context of their medicinal bark use are Populus tremuloides, Frangula californica subsp. Californica, and Amelanchier alnifolia. In addition, the South African native Dovyalis caffra and the Chinese native Rhaphiolepis umbellata can also be discussed in relation to these North American trees, revealing fascinating histories of neocolonial cooption, commercial exploitation, and indigenous erasure over the past several centuries of European hegemony.

Populus tremuloides, otherwise known as the quaking aspen, is part of the Salicaceae family and is native across much of the North American continent. P. tremuloides can be found across Canada and the United States in states as diverse as New Mexico and New York. This deciduous tree has a long trunk with smooth bark and fluffy catkins that grow from the branches. During the fall, the wide sage leaves may appear orange or yellow before being shed. However, the bark of Populus tremuloides has historically been used for its medicinal properties, as the bark contains salicylates, a property used to create aspirin. Indigenous communities like the Apache, the Blackfoot tribe, and the Navajo tribe rely on the bark of this plant to relieve pain from menstrual cramps, combat digestive issues, treat coughs, fevers, and even arthritis. The bark has further been used for its anti-inflammatory and antiseptic medicinal properties, mainly in treating wounds and respiratory disorders when used externally rather than consumed (Simpson 2010, 55).

Another tree found at the UCLA Botanical garden within the family Salicaceae, Dovyalis caffra or the Kei Apple tree, could be analyzed in its stead. Despite being part of the same family, Dovyalis caffra has many phenotypic differences from Populus tremuloides. For instance, D. caffra has much brighter and narrow green leaves with yellow flowers, is native to South Africa and is much shorter than the tall Populus tremuloides trees in the northern hemisphere. Despite their clear morphological differences, both Populus tremuloides and Dovyalis caffra contain a class of chemicals known as salicylates, a naturally-occurring pain reliever and chemical precursor to modern-day aspirin. When boiled into a tea and ingested, bark from both plants may be used to treat pain from illnesses like rheumatism (Anderton 2011, 4).

Another plant that has been used by indigenous communities for the medicinal properties it serves is Frangula californica subsp. Californica. Frangula californica subsp. Californica also known as the coffeeberry, is an evergreen or semi-deciduous shrub in the buckthorn family that is native to California and can be found in other regions of Western America. This plant can be identified from its small, dark green leaves that range from ¼ - 3 inches in length and the presence of blooming coffee berries in the summertime. As a shrub, the plant ranges in height from 3 to 12 feet. The blooming season begins with small white/green flowers and gradually evolves into small clusters of berries that become deeper in purple hue over the summer. Indigenous tribes of California have been utilizing this plant for centuries, including the Ohlone, Chumash, and Kumeyaay tribes who celebrated and made use of the specie’s healing properties. Indigenous Californian tribes dried the inner bark of Frangula californica subsp. Californica and ground it up to create a tea that's served as a treatment for constipation due to its “purgative effect”, as well as a kidney remedy and influenza treatment as a result of proven antimicrobial properties.

Finally, the serviceberry bush, Amelanchier alnifolia, is a case study in Indigenous cultural erasure for the benefit of Western aesthetics. Classified as a member of the family Rosaceae family and Amelanchier genus, this shrub consists of leaves that are a dark green and ovate in shape with serrated leaf margins. Clusters of radially symmetrical, 5-petaled white flowers grow on racemes that emerge from the terminal branches. This species is commonly found in temperate regions of the Northern hemisphere from eastern Alaska through most of Western Canada and as far south as Oregon and South Dakota, across a wide range of altitudes and soil types.

Due to its expansive range, Amelanchier alnifolia is integrated into the ethnobotanical practices of many Indigenous groups across the Pacific Northwest, the Great Plains, and Canada. The Blackfoot Native America tribe used this shrub for food due to the berries it produces and for its medicinal properties. It has been used for appetite restoration, as a laxative, in the treatment of upset stomachs, for treatment of colds, to treat chest and lung infections, and to induce a fever to restore one back to good health. According to McCutcheon, decoctions of saskatoon bark were commonly employed by “traditionally used to treat respiratory ailments such as colds and coughs, as well as diarrhea, influenza and smallpox” (McCutcheon et al, 1995, 106).

Rhaphiolepis umbellata is a fellow member of the family Rosaceae, sharing many morphological similarities to Amelanchier alnifolia with a vastly different native distribution. Commonly found in subtropical forest regions of East Asia, encompassing vast swaths of China, South Korea, and the Japanese archipelago (Abe and Matsunaga, 2011). Similarly to A. alnifolia, R. umbellata is a dense woodland shrub with glabrous branches and ovate green leaves; unlike its relative, however, this species is incapable of taking on a tree-like growth habit and is evergreen rather than deciduous. Flowers of both species are similar and typical of the family Rosaceae: 5-petaled, white, with a cup-shaped calyx and spirally arranged stamen. This species has attracted significant attention in the 20th century as a low-maintenance ornamental plant in urban landscaping projects across much of the Northern hemisphere. Similarly to Amelanchier alnifolia, R. umbellata has been extensively investigated for the presence of flavonol glucosides sourced from bark-based concoctions, which hold potentially cytoprotective benefits when consumed (Nonaka et al, 1983).

All of these plants that share medicinal properties in their bark that can be consumed through tea are unfortunately subject to modern commodification that threatens to rewrite Indigenous history in the name of commercial interests: for instance, monocrop farming of biomedically-valued tree species involves the elimination of less profitable local species, thus limiting access to these plants as sources of food, raw materials, and medicine (Turner, 2001). In order to protect Indigenous cultural sovereignty, further research and harvesting operations involving traditionally-utilized plants, including all species examined above, must be performed in collaboration with tribal leaders in accordance to community needs and values, creating a coproductive and mutualistic future for all parties involved.

WORKS CITED
Abe, Tetsuto, and Michio Matsunaga. 2011. “Geographic Variation in Germination Traits in Melia Azedarach and Rhaphiolepis Umbellata.” American Journal of Plant Sciences 02 (01): 52–55. https://doi.org/10.4236/ajps.2011.21007.
Anderton, Laurel. 2011. “Native American Uses of Native Utah Forest Trees.” Digital Commons, 2211.
Dyrness, C. T.; Acker, S. A. (2010). "Ecology of Common Understory Plants in Northwestern Oregon and Southwestern Washington Forests." H.J. Andrews Experimental Forest, Oregon State University.
Forlines, David R., Terri Tavenner, Johannes C. S. Malan, and Joseph J. Karchesy. 1992. “Plants of the Olympic Coastal Forests: Ancient Knowledge of Materials and Medicines and Future Heritage.” In Plant Polyphenols: Synthesis, Properties, Significance, edited by Richard W. Hemingway and Peter E. Laks, 767–82. Basic Life Sciences. Boston, MA: Springer US. https://doi.org/10.1007/978-1-4615-3476-1_46.
McCutcheon, A. R., T. E. Roberts, E. Gibbons, S. M. Ellis, L. A. Babiuk, R. E. W. Hancock, and G. H. N. Towers. 1995. “Antiviral Screening of British Columbian Medicinal Plants.” Journal of Ethnopharmacology 49 (2): 101–10. https://doi.org/10.1016/0378-8741(95)90037-3.
Sargent, Charles Sprague. 1892. The Silva of North America :A Description of the Trees Which Grow Naturally in North America Exclusive of Mexico. Vol. v.4 (1892). Boston,: Houghton, Mifflin and company,. https://www.biodiversitylibrary.org/item/52477.
Simpson, Michael. 2010.Salicaceae.Science Direct, 02260.