Trees are pervasive phenomena. They exist in our imaginations, grace long tracts of the forested landscape worldwide, and emerge as obvious and surreptitious partners throughout our lives. In the United States alone, the ratio of trees to people is above 200 trees per person. Trees are beings which are both older and larger than humans, yet their prolific generativity has been used and overused throughout human history. Humans often view trees as nothing more than a resource for board-feet of lumber or as unwanted guests on valuable land. This stems from a paradigm in which only humans inhabit the realm of living beings with both plants and animals as merely mechanisms at our disposal. As this paradigm has reached its extreme ends, the entire planet has been ushered into a time of ecological crisis characterized by a shifting climate, ocean rise and acidification, and deforestation. This crisis is not only environmental, but is deeply intertwined with a crisis of both social justice and spirituality. A widespread paradigm shift is necessary to reimagine a sustainable world.
With the global ecological crisis deepening, our meditations on non-human beings have become essential to invoking a shift in consciousness which will support a sustainable and just future for both humanity and the non-human world. Phenomenology, as both a philosophical discipline and investigative methodology, offers a window into our relationship with non-human beings. It allows us to encounter trees in themselves and articulate that experience in a novel description of the world. A phenomenological investigation into the being of trees opens space for our essential interbeing to be revealed.
This paper, in anticipation of a further arboreal and phenomenological dissertation project, begins with a brief review of current plant science and the history that has led to the Western mechanistic paradigm, then moves into an articulation of phenomenological philosophy by exploring the work of three foundational thinkers: Edmund Hussserl, Martin Heidegger, and Maurice Merleau-Ponty. Each of these three philosophers articulated the phenomenological project and shaped the field of phenomenology. Each both discussed phenomenological methods and entered deeply into their own phenomenological investigations. Once the phenomenological groundwork has been laid, the paper will explore eco-phenomenology to understand how phenomenology has engaged the natural, non-human world directly. The second half of the paper will explore how trees appear in primarily recent literature with a phenomenological lens. Though each writer engages trees as a primary focus of their work, they are not explicit phenomenological analyses of trees or plants. This paper will engage religious studies scholars, anthropologists, psychologists, and activists as well as several scientists including biologists, ecologists, and foresters to uncover phenomenological aspects to their arboreal investigations. By better understanding the response of this wide range of scholars to tree beings, I will be able to explicitly form my dissertation around a phenomenology of trees.
Finally, this paper will address the implications of such engagement, both phenomenological and semi-phenomenological. Several philosophers have addressed plants as an ontological metaphor and reimagined a vegetal philosophy. Other writers reimagine a world of relationality and personhood for non-human beings with implications for our ethical treatment of plants and the planet which closely parallel the conclusions of the scientists reviewed. This final section will help point towards a primary question: once we have deeply engaged with a non-human being what is our ongoing responsibility to both that being and the greater environment which it inhabits?
Understanding phenomenology as a philosophic discipline and as a method for encountering the world allows us to engage differently, and arguably more fully, with trees in themselves as trees. It provides structure and form to our embodied, relational, emotional, and spiritual intuitions about the beingness of others, the non-human entities with actual existence and inhabiting a wholly other worlds from the one in which we reside. Phenomenology allows us to touch that existence, if only momentarily, and return with an articulation of our own experience that hopefully has efficacy for other humans and for active participation in the midst of environmental crisis.
Trees in View
The typical Western botanical view of trees is at best beautiful sylvan pillars and at worst resources for economic lumber. This narrow view has a long philosophic history based on the lack of visible movement in plants which has recently been proven incorrect through recent scientific investigations, unveiling that plants not only move but also have memory and analogous operations to human senses. Biologist and philosopher Matthew Hall has traced botany’s view of plants in the West starting from Greek philosophy through Christianity, as well as addressing alternative views from around the world, in his 2011 Plants as Persons: A Philosophical Botany. Philosophical thinking about plant relationships is first found in Plato’s writings and continues in Aristotle’s work. Both posit plants as soulless beings existing in the world for human’s use due to their lack of mobility, sensationality, and agency. These two philosophers have created the groundwork for Western thought, including thought on plant hierarchy, and their approach, which Hall casts as zoocentric, has persisted through the present day. However, Hall does not critique either thinker for including slaves, women, and children in the same category as plants, an ideological oppression which has also persisted through the present day. This zoocentric view continued through the Christian tradition and plants are so backgrounded in the Biblical text, not a single flowering plant species is included on the ark in the story of God saving humans and animals from a planet-wide flood. Current scientific and lay paradigms draw from and are a continuation of this broad lineage. However, recent science has refuted the basis for these claims about plant livelihood. Biologist Daniel Chamovitz published his book, What a Plant Knows: A Field Guide to the Senses, in 2012 to review recent developments in plant biology for the public. Using current peer-reviewed research, he lays out the arguments for plant sight, smell, touch, hearing, locomotion, and memory. In response to recent arguments about plant intelligence and neurobiology, he claims, “the question should be, ‘Are plants aware?’ and, in fact, they are. Plants are acutely aware of the world around them.” More research continues to emerge proving plants function in ways that are intelligent and exhibit a vegetative agency. It is from this basis in scientific understanding that a new paradigm toward plant beings can grow. Phenomenology compliments the emerging science with its insistence on approaching the world through our embodied senses with awareness of our preconceptions.
The phenomenological method, among other movements and approaches, allowed for exploration of new relationships to the non-human world. Thinkers in almost every discipline have discussed non-human beings with the goal of reforming the ideological underpinnings that have lead to a planetary crisis. Trees are particularly charismatic non-human beings since they are pervasive in many environments worldwide, are both larger and older than human beings, have a profoundly other manifestation in the world as sessile beings, appear constantly both recognizably and unrecognizably in products throughout our lives, and figure prominently in our mythologies and cosmologies. Below, thinkers who address trees or plants directly from disciplines such as biology, anthropology, religious studies, law, and others will be reviewed for their engagement with phenomenology. While none of these authors specifically intended to write a phenomenological treatise, by including stories of their own experience or offering a better understanding of our relationship to trees, their work exhibits phenomenological characteristics. Each has contributed significant work to the academic and popular understanding of the environmental status with a primary focus on trees or plants.
This examination is necessarily limited as it will be focusing only on theoretical and narrative written works. While language is a direct expression of consciousness, many other expressions such as poetry, dance, music, and artwork are possible and have not been included here. This choice maintains a fidelity to the initial phenomenological impulse in focusing on individual, personal descriptions of encounters with trees. The work will be organized into three categories: investigative, creative, and personal. These categories are helpful for understanding how the phenomenological method is apparent in each publication. Authors in the investigative section hail from the sciences and represent biologists, ecologists, and foresters. Though he is often known as a poet and writer, Johann Wolfgang von Goethe is included in this section due to his extensive scientific writings. The creative section shifts focus to spiritual, religious, and cultural treatments of trees, and authors include religious scholars, philosophers, anthropologists, and activists. Finally, the personal section addresses authors who more directly enter phenomenological inquiry. Authors include interdisciplinary thinkers in ecology, religious studies, and psychology. Each author is included in only one section, although several could be viewed from multiple angles.
Many thinkers who work with trees and plants have an investigative approach. This broadly covers the sciences. Any peer-reviewed scientific journal would balk at a phenomenological approach to plants, as science as a field has yet to reconcile consciousness in humans and is far from acknowledging essential being in non-humans. However, some scientists have written for broader audiences and include snippets of their personal narratives that betray phenomenologically inspired underpinnings. Professional scientists are specifically trained not to register their internal states or embodied experience, but they may be the most well equipped to describe it if they did. This section includes the work of poet, writer, and scientist Johann Wolfgang von Goethe, geobiologist Hope Jahren, forester Peter Wohlleben, and biologist Robin Wall Kimmerer.
Johann Wolfgang von Goethe, whose work predates phenomenological philosophy by over a century, developed his unique way of inquiry into the world in his The Metamorphosis of Plants in 1790. In the text itself, Goethe does not describe his methodology in detail, instead applying his method to create a new understanding of plant development. His goal in this work was to explore the hidden relationships of the parts of the plants. Of his project, he states, “I tried to make as clear as possible that the various plant parts developed in sequence are intrinsically identical despite their manifold differences in outer form.” Each part of the plant is generated from the leaf and moves from there into its own purpose. He came to this conclusion by carefully examining plants at every stage of their development, looking closely without pre-conceived ideas about how the drama would unfold. In the appendix, Gordon L. Miller, who developed and introduced the most recent publication of Metamorphosis, quotes Goethe on his method, “if I look at the created object, inquire into its creation, and follow this process back as far as I can, I will find a series of steps. Since these are not actually seen together before me, I must visualize them in my memory so that they form a certain ideal whole.” In his introduction to the work, Miller highlights the part of Goethe’s method that matches the phenomenological. He notes, “starting from sense perception of the outer particulars, Goethe’s scientific approach seeks the higher goal of an illuminating knowledge from within.” This description tracks the phenomenological method closely, well before phenomenology was articulated. Part of the beauty of Goethe’s method is its centralization of wholeness and resistance to dissection and instrumentalization so common in traditional scientific methodology.
Much more recently in 2016, Hope Jahren published her popular work Lab Girl to share her story of becoming a professional scientist and her unique understanding of how plants interact with their worlds. She recounts a story of a blue-tinged spruce tree that stood outside her childhood window, where she, “hugged it and climbed it and talked to it, and fantasized that it knew me and that I was invisible when I was underneath it.” During her formal education, she was taught, “the tree didn’t actually care about me” and that the tree took no notice of her actions. Her initial childhood impulse is phenomenological in nature as she was meeting the tree in itself. While her adult mind characterizes this as fantasy, her childhood relational impulse is strong when she allowed herself to engage the tree prior to learning otherwise. Upon hearing the tree died after a late snow storm in her adulthood, Jahren reflected on the livingness of the tree, “my spruce tree was not only alive; it had a life, similar to but different from my own. It passed its own milestones. My tree had its time, and time changed it.” The death of a being that she had spent time with growing up also created an opening for reflection, even though she was far removed from the tree itself.
Throughout her career, Jahren has worked to redefine the study of plants by suggesting plants can control their environment, rather than the common presupposition that the environment controls the plant. She came to this insight by studying plants, “not from the outside, but from the inside” and trying to use their logic rather than her own. While neither phenomenology nor Goethe is mentioned in her work, her surreptitious methodology is reminiscent of a phenomenological method or delicate empiricism.
Similarly, Peter Wohlleben seeks to invite his readers into the forest world in his 2015 popular book The Hidden Life of Trees: What They Feel, How They Communicate — Discoveries from a Secret World. As a forester, he has a strong relationship with the trees in Germany that he has managed over decades. In his work, he does not directly address his own experience, but the depth of his relationships shows through in his statements such as, “when you know that trees experience pain and have memories and that tree parents live together with their children, then you can no longer just chop them down and disrupt their lives with large machines.” In discussing tree identity, he affirms the similarities between trees and animals and guesses the likeness would be even more clear if those similarities could be scientifically established. He also considers trees’ emotional lives and notes human imagination is necessary for any level of understanding due to the difference between ourselves and plants. One particularly interesting suggestion Wohlleben makes is that we can, “unconsciously register the trees’ state of alarm” in a damaged forest. He claims humans intuitively sense the health of the trees in a forest, and it would be fascinating to ask him to conduct phenomenological reflections with his insights. Throughout his book, he gives agency to trees and forests but could be critiqued for bordering on anthropomorphism.
In her 2013 Braiding Sweetgrass: Indigenous Wisdom, Scientific Knowledge, and the Teachings of Plants, Robin Wall Kimmerer brings forward a paradigm very different than that of the Western philosophic tradition. Through her research as a professional biologist and her lineage, she discusses indigenous worldviews which acknowledge and prioritize the living essence of non-human beings. This discussion will focus on her statements and conclusions in an attempt to respectfully engage indigenous wisdom and knowledge. She recognizes the plants themselves, especially the trees, as her teachers. She also discusses how plants are asked for their lives before harvesting and the plants offer themselves as gifts or refuse. She discusses how she uses both her scientific, analytical mind and her intuitive mind to understand the plants’ answer, both by assessing environmental health and by her inner knowing. This could be characterized as a semi-phenomenological analysis of the plant immediately prior to harvesting. In comparing a hand-made basket from a tree chosen and requested for that purpose to other commercially available sylvan products, she ponders, “what would happen, I wonder, to the mountain of junk mail if we could see in it the trees it once had been?” She seems to be calling here for a phenomenological understanding of junk mail, which would reveal its essential plant nature. She notes, “every once in a while, with a basket in hand, or a peach or a pencil, there is a moment when the mind and spirit open to all the connections, to all the lives and our responsibility to use them well.” Sometimes, it seems, a phenomenological reflection can emerge unbidden for some people. Kimmerer’s call for a relational engagement with plants will be discussed in more detail below.
While the scientists reviewed draw on their formal backgrounds to give their work a foundation, each has semi-phenomenological reflections that emerge from their own stories with plants and trees. Within their investigations arise insights ripe for phenomenological description. New research on plant capacities is pushing the boundaries of strict scientific objectivity as well. Beyond the sciences, humans have created ways to engage with trees and forests in our social and cultural milieus.
Researchers in the humanities have also engaged trees in their work on religion, spirituality, and culture. Trees and forests are highly entangled with our social customs, and scholars have theorized that tree worship characterized early ritual development cross-culturally. These creative expressions of our human-tree relationships have a close kinship with phenomenological inquiry as these thinkers are engaging with individual or cultural experience grounded in spirituality or religiosity. This section will discuss the work of religious studies scholar David Haberman in India, activist and founder of the Green Belt Movement Wangari Maathai in Africa, and anthropologist Eduardo Kohn in Ecuador.
In his work, David Haberman focuses on religious worship of trees in Banaras, a region in northern India. His 2013 publication, People Trees: Worship of Trees in Northern India, is a study of local customs and beliefs in order to both understand the religious beliefs but also to understand how we culturally construct ideas of both nature and religion. Haberman also discusses the necessity of relationship as a key part of religious and spiritual worship, addressed further below. While he primarily focuses on local understandings, he does say of his own experience,
For me the tree was a wonderful expression of nature’s beauty; but for a family that lives nearby it was much more. They had wrapped the trunk of this tree with bright red cloth trimmed with a shiny golden border. Three dark, round river stones had been placed on an old red brick at its base. Every morning a member of the household would bring a blue plastic wicker basket full of offerings and instruments for worship, sit before the tree facing east, and proceed to honor the tree as a life-blessing goddess by offering her water, flowers, incense, red sindur powder, and prayers. Clearly, this family had a different perception and experience of this tree than had I, coming from the United States.
While this is not a phenomenological study, he is reflecting on his own experience of trees and using his research to allow for a new description of trees to emerge in his work.
Trees are variously seen in India as sacred spaces for worship, as abodes of gods and goddesses, and as deities themselves. Haberman extensively reviews local beliefs and rituals surrounding the sacred pipal, neem, and banyan trees. Each sacred tree he studies is associated with various deities and has its own set of sacred practices and healing capacities. The people he interviews throughout the region have various views of the trees and relationships with them based on their own experiences. In his work, Haberman finds a relational model where the humans and trees have a reciprocal connection throughout the region.
Activist and Nobel laureate Wangari Maathai initiated the Green Belt Movement to assist rural women in Kenya through planting trees. Replenishing the Earth: Spiritual Values for Healing Ourselves and the World, published in 2010, is her account of her own spiritual journey and the shifts needed for a flourishing world. The idea for planting thousands of trees in Kenya emerged for her as, “a concrete, doable response” to the problems she was hearing from women throughout the country. In the book, she recounts her own experience as part of a group witnessing a tree felled in a Congo Basin forest by a timber company seeking to gain sustainable forestry credentials. The tree was, “a large sapele tree, about seventy feet tall and perhaps eight feet in diameter, with roots than fanned out from the base and anchored themselves firmly in the ground. The canopy of the tree was broad, shaped like an umbrella, and filled with smallish, dark green leaves.” While the tree took “ten or fifteen minutes” to fall at the insistence of saws, Maathai learned it was over two centuries old and that only 35% of the tree would be used as economically viable lumber with the remainder turned into bricks and charcoal. These facts brought her to tears and, “felt like a wound on many levels.” Her embodied response to the experience of the downed tree and her way of relating her experience is a semi-phenomenological reflection. She also brings the experience into the transpersonal realm by stating, “in its collapse was an echo of the trees and whole forests disappearing all over the world.” She notes that these worldwide wounds are a result of a worldview that sees unlimited resources for human use in the environment. She says, “when we reflect on the sacred groves and the spiritual and symbolic weight we have given to trees and forests, it seems self-evident that not only have trees been our constant companion, but we would quite literally not be human if we didn’t perhaps feel regret when a tree disappears from the landscape.” Her work with the Green Belt Movement directly counteracts the wounding of felled trees, weaves people and trees together, and builds relationship and community.
Eduardo Kohn, author of the 2013 How Forests Think: Toward an Anthropology beyond the Human, seeks to show that non-human beings also think and their thinking affects human thinking. His focus is less on individual trees themselves and instead on the forest as an ecosystem of lived experience in his work with the Runa people of Ecuador. He claims, “the first step toward understanding how forests think is to discard our received ideas about what it means to represent something.” This statement has its roots in a phenomenological method. He argues that we can claim forests think because they do, stating, “it is because thought extends beyond the human that we can think beyond the human.” These living, non-human thoughts lead to enchantment, animation, and meaning. He claims, “allowing [Amazonian] forests to think their ways through us can help us appreciate how we too are always, in some way or another, embedded in such webs and how we might do conceptual work with this fact.” While he is here not doing phenomenological work of the type articulated above, he is clearly within the intellectual lineage of phenomenology and using its ideas while also extending the reflective process to include the impacts of entangled relationships. Further, Kohn extends his argument that forests think to claim that life thinks.
The cultural and religious ways that trees entangle with human beings are a creative response to human experience of trees. This is an exceptionally rich area for further phenomenological study, especially in non-Western cultures as studied by the authors above. While the authors shy away from their own embodied experience, this is the core place of phenomenological inquiry.
While many, if not most, scholars remain in the scientific or academic realm while treating trees as a subject of study, some authors choose to delve more deeply into their own experiences and come closer to a phenomenological study of trees. This also can shift into nature writing, which is not the focus of this section. The authors reviewed are scholars who have allowed their own relationships to trees to take a primary space in their writing. This section includes forest canopy biologist Nalini Nadkarni, environmental studies scholar and Buddhist Stephanie Kaza, and psychologist Michael Perlman.
In her 2008 work, Between Earth and Sky: Our Intimate Connections to Trees, Nalini Nadkarni interweaves her forest canopy work with her own story of discovering trees as well as poetic reflections throughout the book. In a statement resonant with Merleau-Ponty’s thinking, she says, “trees can be as familiar to us as our own bodies.” She recounts planting trees as a young child with her father, who immigrated to the United States from India, and his care with the young saplings, “a near-reverent gentleness.” She recalls tapping the soil after the tree had been planted, and the “slender brown trunk that upheld the pliant limbs, so like mine, ready to grow.” She wonders if her father’s care with the transplanted saplings reflected his own story of transplanting, identifying both herself and her father with the trees. She also, among many other stories, talks about her experiences of urban running near small stands of trees and her curiosity and distress as a child at seeing trimmed bonsai trees, unable to grow to their full potential. She has had deeply felt experiences in the presence of trees throughout her life and allowed herself the space to reflect on their meaning.
In talking about how trees are both strong and fragile, Nadkarni gives a compelling comparison reflecting her sense of shared identity with trees:
We humans exemplify a similar strength and fragility. Our bodies allow us to perform amazing feats — ascending into the canopies of trees, climbing mountains, running marathons. But we are fragile, too. Too often, I rely on the opinion of others to define my sense of self. And although I have given birth to two children, the knowledge that I can protect them from almost nothing makes me vulnerable to every danger, real or imagined, in the world. Whenever I climb a strong-limbed, thick-barked tree that exposes tender new foliage, I see myself in each contradictory limb.
Her identification with trees helps her both as a scientist and as a human being in the world, dealing with life’s challenges. When she talks about climbing the tree and how it brings her back to herself, she is reflecting phenomenologically on her experience.
Stephanie Kaza engages in a study that most closely resembles a phenomenological investigation of all the authors reviewed in her 1993 The Attentive Heart: Conversations with Trees. Coming from a Buddhist and environmentalist perspective, her method employs the Zen shikantaza, or just sitting. She, “spent time in silence, close to trees, doing [her] best to be simply present with the tree as Other, aware of [her] thoughts, moods, and projections.” Throughout her book, she deeply engages both trees in themselves and her own experience with trees. This leads to interesting questions such as, “How does one address such a long being? Should we speak to the crown or the trunk, or to the massive roots?” She also notes her own ignorance of tree biology and taking their resilience for granted. She notes the unsettling feeling of not knowing the names and needs of the trees she is encountering and the inadequacy of common tools like field guides for her reflective work. What is present throughout her writing is a sense of wonder, and she says, “awe is not a transferrable emotion; it must strike each person individually as he or she is moved.” Kaza’s Buddhist practices shine deeply into the essence of tree beings and illuminate her own relationship to the trees she comes to know.
In his The Power of Trees: The Reforesting of the Soul published in 1994, Michael Perlman explores the psychological qualities of trees by speaking with Southern locals after hurricane devastation in their area. He focuses on both similarities and differences between humans and trees, as well as the beauty and pain associated with close relationship to trees. He says, “trees are psychological presences that move the soul — sometimes to right them, sometimes to cut them down, always to somehow imagine them.” In his conversations with people throughout the South, he meets a woman he calls Jane who finds trees to be a mirror of herself due to similar uprightness and explores that relationship in her dance practice. Perlman phenomenologically analyzes her words as a kinaesthetic sense or a “vertical motion, an involuntary perception of a force — upwelling, expansive, and downwardly stabilizing — that is shared by tree and self.” He also finds these embodied experiences spiritual and an, “involuntary experience of the body’s ecological soul.” While he does not examine his own experiences, his study of those he speaks to is intentionally grounded in a phenomenological method. Perlman’s explorations give phenomenological grounding to the psychological experience of trees.
Each of these authors brings an intentional gaze to an embodied and inward experience of trees. This stance illuminates not only their own inner essential being, but also gives information about the essential nature of the trees they speak to in their work. All the works above are brushing against phenomenology in some way. From these encounters, the articulations of these scholars lead us towards a renewed relationship to trees and other non-human beings.
With the ecological, spiritual, and social crises of our times intensifying, phenomenology offers a methodology for engaging personally with non-human beings and for creating pathways for relational paradigms to emerge. Drawing from the foundational work of Husserl, Heidegger, and Merleau-Ponty, the phenomenological project has continued to develop and thinkers have specifically focused phenomenological studies on environmental concerns. Many authors who have written of trees from various perspectives have created works that include phenomenological aspects unintentionally, paving the way for a directed phenomenological study of trees. A study of this type will better articulate the ongoing implications of developing a relationship to non-human beings and the planet in the Western world.
Trees are pervasive, charismatic, and critical species for continued human flourishing on earth, as well as having intrinsic worth in themselves. Relational philosophy can be derived from a respectful engagement with non-Western, particularly indigenous, worldviews and help bring humans into a sustainable relationship to the planet. As Haberman claims, “in the end it comes down to what kind of relationship we humans chose to have with nonhuman beings; the world one perceives is the world one inhabits. And the world may turn out to be more ‘peopled’ than we ever imagined.” We co-create the world we perceive, and we can make a choice to have a mechanistic, instrumental relationship with trees, or we can choose to meet trees as themselves and allow tree people to be a mirror for our own being and humanity.
 Hope Jahren, Lab Girl, (New York: Alfred A. Knopf, 2016), 3.
 Matthew Hall, Plants as Persons: A Philosophical Botany, (Albany, New York: State University of New York, 2011), 7.
 Hall, Plants as Persons, 20. This lack of critique is a major oversight on Hall’s part in his discussion of plant oppression. Also, his focus on zoocentrism lacks a nuanced discussion of either anthropocentrism, which would seem to overpower zoocentrism, or androcentrism.
 Ibid., 59.
 Daniel Chamovitz, What a Plant Knows: A Field Guide to the Senses, (New York: Farrar, Straus, and Giroux, 2012), 137.
 Johann Wolfgang von Goethe, The Metamorphosis of Plants, Intro. by Gordon L. Miller, (Spain: MIT Press, 2009), 56.
 Goethe, The Metamorphosis, Quoted by Miller, 105.
 Gordon L. Miller, introduction to The Metamorphosis of Plants, by Johann Wolfgang von Goethe, (Spain: MIT Press, 2009), xvii.
 Jahren, Lab Girl, 27.
 Ibid., 29.
 Ibid., 151.
 Ibid., 75.
 Peter Wohlleben, The Hidden Life of Trees: What they Feel, How they Communicate — Discoveries from a Secret World, (Vancouver, Canada: Greystone Books, 2016), xiv.
 Ibid., 84.
 Ibid., 244, 227.
 Ibid., 222–223.
 Robin Wall Kimmerer, Braiding Sweetgrass: Indigenous Wisdom, Scientific Knowledge, and the Teachings of Plants, (Canada: Milkweed Editions, 2013), 18, 42.
 Ibid., 178.
 Ibid., 148.
 Ibid., 155.
 David Haberman, People Trees: Worship of Trees in Northern India, (New York: Oxford University Press, 2013), 31.
 Ibid., 2.
 Ibid., 93.
 Ibid., 1.
 Ibid., 103.
 Wangari Maathai, Replenishing the Earth: Spiritual Values for Healing Ourselves and our World, (New York: DoubleDay, 2010), 31.
 Ibid., 39.
 Ibid., 39–40.
 Ibid., 41.
 Ibid., 88.
 Ibid., 43.
 Ibid., 87.
 Eduardo Kohn, How Forests Think: Towards an Anthropology Beyond the Human, (Berkeley, California: University of California Press, 2013), 8.
 Ibid., 22.
 Ibid., 72.
 Ibid., 42.
 Ibid., 78.
 Nalini Nadkarni, Between Earth and Sky: Our Intimate Connections to Trees, (Berkeley, California: University of California Press, 2008), 19.
 Ibid., 262.
 Ibid., 109, 153.
 Ibid., 210.
 Stephanie Kaza, The Attentive Heart: Conversations with Trees, (New York: Shambhala, 1993), 5.
 Ibid., 41.
 Ibid., 21, 35.
 Ibid., 151.
 Michael Perlman, The Power of Trees: The Reforesting of the Soul, (Woodstock, Connecticut: Spring Publications, 1994), 4.
 Ibid., 24.
 Ibid., 41.
 Ibid., 46.
 Haberman, 193