BLOOMING & DYING: WITHIN TUCSON’S BUILT ENVIRONMENT

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Authors McGuire, Grace

Publisher The University of .

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BLOOMING & DYING AGAVE WITHIN TUCSON’S BUILT ENVIRONMENT: PROPAGATION, PUBLIC PERCEPTIONS, AND DESIGN BY GRACE KATHLEEN MCGUIRE

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A Thesis Submitted to The Honors College In Partial Fulfillment of the Bachelors degree With Honors in

Sustainable Built Environments

THE UNIVERSITY OF ARIZONA M A Y 2 0 1 9

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Contents Abstract ...... 3 Introduction ...... 3 Literature Review ...... 4 Urban Landscape Theory – Phoenix, AZ as a Nearby Case Study ...... 4 Ethnobotany of Agave...... 5 Past, Present, and Future Cultivation of Certain Agave Species ...... 5 ...... 7 ...... 7 Some Considerations for Planting ...... 7 Agave Biology and Physiology ...... 8 Growth and Water Use ...... 8 Criteria and Utility of Agave within the Built Environment ...... 9 Methodology ...... 10 Results ...... 11 Conclusion ...... 17 Next Steps ...... 18 Works Cited ...... 18

Table 1 ...... 10 Figures 1-6 ...... 5

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Abstract This study examines one species in order to reveal the historical, biological, and social attachments the plant brings to the public and private landscapes in the city of Tucson, Arizona. The life cycle history, cultural attachment, and biological characteristics of the Agave genus are evaluated in terms the relationship between a native, Sonoran Desert adapted species and its use within the urban matrix. The succulent, rosette form is a characteristic that makes the agave species distinct from all other desert . Six particular agave species are mentioned within this writing, and are connected to the Tucson area’s cultural history, and current application of agave as a landscaping material. symbolize a rich history of human utilization and reliance, especially in the cultures of central/northern . As the industry within the U.S. for mescal products grows, agave on the landscape become distinctly agriculture based. The practices of wild harvesting agave for distillation and not allowing cultivated agaves to bloom impacts the ecosystem functions of northern , Mexico, and the southwestern United States, and severely limits the populations of wild agaves. It is estimated that in the coming years it will be almost impossible to find certain populations of wild agaves.

Introduction Within the flora of many high desert grassland communities, one type of succulent stands out. The distinctive rosette shape, curved, and soft through the petals yet often sharply tipped with dark spines, lends a mesmerizing complexity to the land. A decades-long life cycle means a tall stalks will one day stand as a lone beacon within a sea of grass and mesquite, adding a further vertical element to the savanna-like surroundings. Agave species are iconic elements among the slopes of southern Arizona and northern Mexico. The family; Asparagacae, contains the monocarpic succulents that evolved in these regions and are deeply tied to humans through a culture of human-agave mutualism. Agaves are monocarpic, meaning that they flower once in their lifetime – this is the plant’s one opportunity to reproduce sexually. This sexual reproduction is facilitated through pollination. In the desert grassland, perhaps in the Huachuca Mountains near Sierra Vista, AZ, an Agave parryi var. huachucensis is attached to the relationship that this species has with certain pollinators such as migrating bat species, moths, bees, and numerous other users of their floral nectar resources (England, 2012) . The agave in the natural environment represents a key element to ecosystem function, as a result of the plant providing a nutritious nectar resource to desert pollinator species who will visit several flowering agaves in one feeding cycle. Because of this monocarpic nature, agave species are characterized by low genetic diversity within the genus as well as within species (Rivera-Lugo, García-Mendoza, Simpson, Solano, & Gil- Vega, 2018). Vegetative reproduction is the fastest mode of agave reproduction, and happens via rhizomes produced near the stem base of the adult agave rosette. Low genetic diversity may be associated with a significant risk of disease affecting a large percentage of a population (Rodríguez- 4 | Page

Garay et al., 2009), and prevalence of widespread destruction by pests such as the agave (Waring & Smith, 1986). With a limited opportunity for sexual reproduction, agave species have little chance of producing offspring with stronger or more variable genetic packages. Agaves have become the spirits of and mescal (Zizumbo-Villarreal, Vargas-Ponce, Rosales-Adame, & Colunga-GarcíaMarín, 2013), fibers for clothing (Parker, Trapnell, Hamrick, Hodgson, & Parker, 2010), or feasts of slow-roasted agave “meat” and syrup (Zizumbo-Villarreal et al., 2013), to name a few products. This legacy of agave use is found in ethnological records and cultural heritage knowledge of the indigenous peoples of the southwestern United States (Sheldon, 1980), though mainstream U.S. culture links the plant to virtually one product: margaritas (Bioenergy, 2011). To fuel the thirst for tequila, , Mexico is home to several enterprises where a monoculture of thousands of hectares of Agave tequilana Weber azul , the preferred type for tequila production, is cultivated (Zizumbo-Villarreal et al., 2013). Agave mass production is a difficult endeavor; within the waiting period from seedling to maturity (up to five years), the threat of disease, agave weevil infestation, and fluctuating product value are a reality. Recent studies have been conducted to identify viable tequila byproducts that make the harvest of agaves more profitable. These include the fibrous leaves of the agave plant that are removed from the agave head (center) during harvest, which may be useful as a bio resource for feedstocks and paper production (Rowell, 2001). Agave presence in biotic communities means something different than the plant’s presence in the built environment. Besides being cultivated for one of the remaining products of the human-agave culture, agaves are rarely selected for use in landscapes. Do those who select agaves for use in the built environment do this to maintain some ecosystem function, i.e., provide resources for pollinators, or, perhaps are agave species considered valuable in the built environment for the same visual interest as they provide in the natural environment. Located in the northern extent of agave habitat, Tucson, Arizona will be the city of interest in this study. Conversations with landscapers, nursery owners, and community gardeners will elicit responses to the question of agave presence in current plant palettes of Tucson landscapes, and the impetus behind agave nursery supply and use within landscapes.

Literature Review Urban Landscape Theory – Phoenix, AZ as a Nearby Case Study People choose the plant materials they include in the built environment for many reasons. Whether in the capacity of a landscape architect/designer, landscaper, or homeowner, individuals may follow certain knowledge sets and ecological principles in order to achieve an optimal result. The landscape in question might be a tropical oasis, a transitional edge to a patio, a front yard, or a Mediterranean themed plaza. Plant palettes are selected for their ornamental and ecological function, adaptability, water and maintenance requirements, and aesthetics within a particular urban landscape (Arslan & Yanmaz, 2010). City dwellers are familiar with the scenario in which a group of plantings are found – city landscaping of public thoroughfares and public right-of-ways appear in even distribution. In the desert Southwest, planting considerations are characterized by the wish to achieve an aesthetic biomass, often leaning toward the “oasis” type landscape, while considering the implications of water use, reflective heat, and shade provision (Yabiku, Casagrande, & Farley-Metzger, 2008). Preference for lush landscapes among desert dwellers today has not been the norm throughout human habitation of 5 | Page southern and central Arizona. In the city of Phoenix, a paradox exists wherein 60% of residential water use is dedicated to outdoor application, though the arid conditions would never naturally support such water inputs to the native vegetation (Yabiku et al., 2008). Tucson is commonly lauded for relying less on the lush lawns and more water-intensive plantings that characterize most of Phoenix’s residential districts. However, every urban landscape in the desert can stand to receive criticism for designs which favor palettes that try to recreate a landscape outside of the local geography. Ethnobotany of Agave This study focuses on one native plant genus, Agave, and its existence within the plant palettes of Tucson’s urban landscapes. Agave genus exists within the subfamily , and includes over 200 species, visually characterized by the succulent rosette leaves (Rivera-Lugo et al., 2018). The diversity and richness of agave species decreases at the edges of the Sonoran Desert, which is the extent of the agave’s range. Of the 200 agave species, the highest species richness is found in central Mexico, especially the state of Oaxaca (Parker et al., 2010). The ethnobotanical record and genetic studies of wild and remnant agave populations reveal that humans and agaves have had a long history of co- evolution. The cultivation and selection for certain agave species by Pre-Columbian human populations in the Tucson area is seen through artifacts such as roasting pits, agave knives, and rock pile complexes, which are thought to have made use of landscapes for food production that could not otherwise support much plant growth (Parker et al., 2010). Some of Tucson’s first inhabitants selected agave species in order to create utility out of rocky, volcanic soils.

Past, Present, and Future Cultivation of Certain Agave Species Six species of agave are highlighted within this Literature Review in order to exemplify the morphological diversity within the Agave genus, and to highlight the species that this study focuses on as currently cultivated for agricultural and ornamental purposes. A. murphyii, A. tequiliana, A. americana, A. parryi, A. ocahui, and A. murpheyi are noteworthy within the context of Tucson for unique reasons. These six species represent the morphological diversity within the Agave genus, and represent the past, present, and future of agave cultivation within southern Arizona and central and northern Mexico.

In terms of the pre-Columbian human-agave relationship, the agave species A. murpheyi emerges as one of the most widely documented concerning intentional planting (i.e. on high slopes and in patterns with rock structures) (England, 2012). Because of archaeological evidence stemming from canal systems, rock structures, trincheras, and other modes of manipulating water, agave cultivation can be attributed to a specific period. A study conducted by scholars for the American Journal of Botany, including resident agave expert Wendy Hodgson from the Tucson Botanical Gardens, found that A. murpheyi was cultivated within the time period known as ancient Arizona’s Classical period (A.D. 1100 -1450) by the ancient peoples known as the Hohokam, ancestors to the Tohono O’odham people (Parker et al., 2010). A. murpheyi is a relatively fast-growing agave species, and can be used to create many products. A recent study by Karen Adams for the University of Arizona Desert Plants Journal discusses the timeline of agave cultivation in pre-history, and finds that A. murpheyi can store up enough sugar and starchy biomass to be able to send up a flower stalk within nine years (Karen, Rex, Adams, & Adams, 2019) 6 | Page

The comparatively short period from infancy to maturity of A. murpheyi makes the early cultivar, or varietal of a species selected for specific properties and traits, useful for many products. The wealth of agave products created during Hohokam era history include fiber, paper, soaps, shampoos, medicines, armored fences, fermented beverages (), and food from the roasting of the agave cabeza or heart (Parker et al., 2010).

In the case of A. murpheyi, the human cultivation and selection for certain genetic markers have made the species unable to reproduce sexually on its own. As observed by desert plant propagation specialist for Borderlands Restoration Madrean Archipelago Plant Propagtion nursery Francesca Claverie, the agave does not produce seed when it blooms but instead creates rosette clones that erupt from the panicle during (Claverie, 2019). Selection by humans of the cultivar A. murpheyi and the continued cultivation of the species through vegetative reproduction has resulted in the narrowing of genetic variation within the cultivated populations of the species (Parker, Hamrick, Hodgson, Trapnell, & Parker, 2007).

Similar to the story of A. murpheyi, the A. sisalana retains a unique connection to the human agricultural past of Mesoamerica. A. sisalana is native to central and southern Mexico and Central America, and grows well in other tropical area countries (Nikam, 1997). An article within the Journal of Medicinal Plants Research by scholars in India names sisal the “the miracle plant” because of its uses as a medicine, source of saponin (for soap making), and, most robustly, a fiber material (Debnath, Pandey, Sharma, Thakur, & Lal, 2010). Debnath et al found that during the early 1900s Sisal crops represented 70% of the world’s plant fiber resources (Debnath et al., 2010). The economics of current sisal production is documented in a study by T.D. Nikam which highlights the “high frequency shoot regeneration” characteristics of A. sisalana. Nikam’s study reveals that the slow-growing properties of the agave make planting in densities of 4000 plants per hectare necessary, although the technique of regenerating stem cuttings of the plant lessens the propagation time (21-35 days until roots appear) (Nikam, 1997).

An important note on the topic of large scale agave propagation is the effect that clonal reproduction rather than growing from seed has on the overall genetic diversity within the cultivated populations. Sexual reproduction requires the help of pollinators such as bats to transport pollen from one plant to the other, and also assures a level of genetic diversity greater than cloning would (England, 2012). Since most agave products need the sugary, starchy biomass that the agave stores before sending up its flower stalk, most production scale agave fields are harvested before they are allowed to flower. The process of harvesting before flowering does not allow for any pollination, or the support of other mammals and insects that rely on the nectar resources (Good-avila, Souza, Gaut, & Eguiarte, 2006). Nikam mentions that the barriers to maintaining genetic variation are the irregular flowering of agaves (could occur anywhere between 8-30 years), the uncertainty of a producing fertile seed, and the increased period necessary for growing plants by seed (Nikam, 1997).

Lowered genetic diversity within populations is a reality of agave species grown on a large scale because it is economically more feasible to plant with clones. In the case of agave fields grown for making tequila, it is required by law to use only A. tequiliana, and no other species (Rivera-Lugo et al., 2018). A high proportion of genetic “sameness” can be attributed to the practice of propagating the 7 | Page seedling clones of parent agaves rather than investing years in growing out agaves from seed (Claverie, 2019). A study conducted within the A. tequiliana fields of Jalisco, Mexico revealed that the plant has one of the lowest “levels of polymorphism within a plant species recorded to date” (Min, 2011).

The following images provide a visual representation of the morphological variety of agaves, including the six mentioned previously (A. murphyei, A. tequiliana , A. sisalana, and A. parryi), and one of the most commonly seen ornamental agaves in Tucson, A. americana.

FIGURE 1: FIGURE 2: A. TEQUILIANA FIGURE 3: AGAVE PARRYI (SOURCE: (SOURCE: WORLD OF (SOURCE: AMERICANSOUTHWEST NET WORLDOFSUCCULENTS.COM) SUCCULENTS)

FIGURE 4: A. SISALANA FIGURE 5: AGAVE OCAHUI FIGURE 6: (S OURCE: AGAVEVILLE (SOURCE: (SOURCE: WORLD WONDERS WORLDOFSUCCULENTS.COM) GARDENS)

Some Considerations for Planting Contemporary desert landscape design often focuses on the inclusion of native species based on a necessity of maintaining low water use and ensuring longevity and hardiness (Woodward, n.d.). The most commonly seen agave in the Tucson built environment is A. americana (Figure 8), which can grow to be six feet wide with enough space. According to two landscape designers interviewed during this process, the low water use properties of agave make them trickier to use within a planting of other plants that use more water. Rot can occur along the base of the plant and affect the roots when too much is applied to the plant. Agaves prefer shallow, well drained soils, and do not mind the slightly alkaline pH of Tucson soils, according to the nurseries interviewed. Placement in an environment that mimics the rocky, porous soil of many wild agave population sites is important for delivering the plant with adequate drainage.

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Agave Biology and Physiology A product of evolution in an arid climate, agaves are equipped to be drought resistant for two reasons. Primarily, agaves exhibit CAM photosynthesis (Cerassulacean acid metabolism) which make use of the nighttime to open stomata to uptake CO2. This limits the loss of water due to evapotranspiration, and means that the agave conserves water as a result of this carbon uptake pathway (“176 Franco Nobel 1988 Ecology,” n.d.). Secondly, agaves have shallow, fibrous root systems that respond well to any moisture or rainfall (Pavliscak, Fehmi, & Smith, n.d.). These two characteristics make the consideration of irrigation one that is not high on the list of maintenance; since agave species are well versed in desert survival.

Other characteristics of the agave, however, such as a relatively tall inflorescence (flower stalk structure and flower arrangement), monocarpic reproduction, and growth, are dependent upon the availability of soil moisture. An agave provided with an “average” water supply (around 6 gallons/week) may perform differently than one not irrigated, i.e., grow leaves with a large surface area, allocated water resources towards reproduction more quickly, and gain biomass (“050 Nobel 1977 Bot Gaz,” n.d.). In general, the production of the 3-5 meter inflorescence is the most energy and water intensive event in an agave’s life, if the plant allocates this energy to sexual reproduction (“176 Franco Nobel 1988 Ecology,” n.d.; Pavliscak et al., n.d.). Nearly 4.9 gallons (18.6 kg) of water is required of the agave to produce the inflorescence over 130 days (3.8 oz per day) (“176 Franco Nobel 1988 Ecology,” n.d.). Since the wild agave carefully conserves water in order to produce inflorescence, the agave in the built environment provided with a consistent water resource may result in a shorter life history cycle due to the abundance.

Growth and Water Use In a natural setting, agave seedlings are seen to survive with a higher rate of success when they grow with the help of a nurse plant (“176 Franco Nobel 1988 Ecology,” n.d.). These nurse plants may be a parent agave, or a different plant species that provide adequate shade for the agave seedling. Agave seedlings in a nursery setting are subject to a similar luxury – the threats of herbivory, hot surface soil conditions, and lack of shade may be avoided when seedlings are grown in controlled conditions. A study conducted on Agave deserti by the University of California, Los Angeles reveals that agave seedlings produced vegetatively (“rament” populations) produced root and leaf biomass faster when in relation to their parent agave compared to a lone agave seedling. This is most likely due to the ability of the “pups” to draw upon the moisture and carbohydrate reserves of the parent plant (Hunt, Zakir, & Nobel, 1987). Since faster agave growth is associated with a microclimate that mitigates the effects of intense sunlight, the growing of agave seedlings in the nursery may focus on maintaining parent-seedling relationships for propagation, or try to mimic this relationship with climate and sunlight control.

In terms of a cost/revenue analysis, agaves handle water resources conservatively; their famous low water use is one of their most attractive features within a landscape. An additional study conducted by Park Nobel found that the marginal water revenue (uptake) of Agave deserti established roots was more than the marginal water cost of the plant, with the root dry weight representing merely 4-10% of the total plant dry weight (Hunt et al., 1987; Press, 2018). This finding suggests that agaves are able to 9 | Page maintain the ability to uptake more water than they require to grow. When placed in the built environment, their water requirements stay low based on the continual ability of established roots to reach a large underground surface area (Nobel, 1976). Further studies conducted with A. lechuguilla by the same researchers revealed that under the conditions of 0.6 inches (15 mm) weekly irrigation, which supplemented natural rainfall, the plants grew to double their initial height of 7.8 inches (0.2 m) within a two years. Additionally, the application of a thin layer of nitrogen fertilizer to the agaves resulted in more significant growth of shoots than roots, whereas the increase in soil moisture from irrigation encouraged root growth rather than shoot growth (Press, 2018). These findings maintain that water and soil organic matter are the limiting factors in agave growth within their habitat, and, when supplied with these amendments in a controlled environment, these plants exhibit faster growth above and below the soil.

Agaves are slow growing, which is an important characteristic to note when discussing their landscape image from seedling to maturity. A four-year-old agave rosette can be only 6 inches in diameter, but reach over 2 feet in diameter near the end of its life (Gentry, 1982). Some agave species, Agave americana included, can reach widths of up to 10 feet (~ 3 m) in diameter, and produce a multi- branched panicle that reaches around 16-20 feet (5-6m) tall (Gentry, 1982). Based on the agave species in question, the landscape image and space of an agave can be quite substantial. According to a series of studies done at Arizona State University, the framework for residential landscaping choices in a desert climate follow the factors of cost, ecological constraints, laws, and personal preferences (Yabiku et al., 2008). It is reasonable to expect that some population of residents favors a hierarchy where the costs of a landscape is the primary factor of concern. Costs of the landscape include expenses accrued upon installation, improvement, and the non-monetary cost of time associated with maintenance (Gullino & Larcher, 2013). Since agave species require little to no maintenance other than optional irrigation, and are well suited to desert ecological constraints, the factors of note to investigate concerning the inclusion of agaves in residential landscapes are the initial costs of installation/purchase and the preference of the resident.

Criteria and Utility of Agave within the Built Environment The life cycle of an agave within the built environment includes certain economic, and environmental realities. These realities can be seen as barriers to their inclusion in a Tucson plant palette, or as necessary for the maintenance of agave species within the developed land of their native habitat. Table 1 (below) references qualities of agave researched and applies these characteristics to an application within the landscape. The growth of agave seedlings within a nursery necessitate a time commitment of approximately four years to reach a potential size of maturity. Though hardy to the climate of southern Arizona, agave must be cared for with certain climate and soil moisture conditions so as to ensure growth within a reasonable period. To add to knowledge surrounding social attachments to agave use in the built environment, the following sections develop a criteria for a “good” plant in the urban landscape, and decipher where agaves fit into this criteria. Included in the criteria are the weighing of maintenance efforts and water application, time spent on achieving aesthetic appeal, and timeline of death and replacement of agave.

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Comparing Biological Characteristics of Agaves with Utility in the Built Environment Impact of life-cycle strategy, cultural significance, and longevity on maintenance and aesthetics

TABLE 1 Slow growth Arborescent Monocarpic Shallow root Cultural Identity inflorescence system

Maintenance Resources/cost for Flower stalk rises Dead plant Low water Attention paid to agave as a nursery resources, round 3 m high, over- removal, use,the plant meaningful addition to the higher cost to the story interference? replacement with makes use of landscape buyer the same or rainfall events different plant?

Aesthetics/ Wait time till Iconic ‘century plant’ Ephemeral nature Low water A reminder of agave/human Preference maturity; vegetative appeal, of plant, panicle use. No history and cultivation of the pups tend to landmark/accent changes form of mulching or plant by indigenous of expand plant presence in the the plant, leads to basin needed Central and North America. biomass landscape death and to support Utility in Built Environment Built in Utility desiccation growth

Methodology The emerging questions of this study surround the behavior of agave selection for use in public landscaping and private planting. Why do those who plant agaves choose to use them? Moreover, do these preferences lead to the favoring of largely xeriscape spaces over more lush, oasis type landscapes within Tucson? This study aims to understand the mentality of those invested in the Tucson landscaping scene, specifically concerning their views on implementing and growing monocarpic succulents. There appear to be many barriers to implementing agaves in contemporary Tucson landscapes. Dual characteristics of slow growth and a tall flower stalk ultimately emerging from the rosette could result in a tricky planning situation for landscapers and owners, and a long-term investment for nursery owners who choose to propagate agaves by seed.

This study approaches these questions modeling a critical theory study. A critical theory study has the power to deliver first-hand knowledge of the subject’s perspective, as well as have the support of the researcher’s interest and intent to understand the meaning behind a behavior. Human behavior is not fully understood without specific background knowledge of intent and purpose put forth by a human subject, rather than the physical object (Lincoln and Guba, 2005).

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Informal survey and semi-structured interview techniques were used to formalize anecdotal knowledge about the existence or persistence of agave within the city of Tucson. Selected practitioners include those considered professionals within the fields of horticulture, nursery propagation, and landscape architecture. Non-professionals within the fields of design and community garden and heritage conservation were consulted through surveys and interviews.

The results of the interviews coupled with the knowledge presented in the Literature Review create a basis of understanding the contemporary propagation, implementation, and use within design and landscape architecture applications of agaves within Tucson.

Results Survey Responses: University of Arizona College of Architecture, Planning, and Landscape Architecture (Graduate and Undergraduate Students) A five-question survey gauging agave perception was sent out to the University of Arizona College of Architecture, Planning, and Landscape Architecture listserv. A total of 48 responses were generated, and takers were only able to choose on answer to each question.

A link to the Google Form used for the survey is included here: https://forms.gle/1pB9TJqMicPukN9z9

The five question survey was delivered to a population of individuals affiliated with the University of Arizona College of Architecture, Planning, and Landscape Architecture email listserv. The responses recorded arrived from undergraduate Sustainable Built Environments and Architecture majors, as well as the graduate programs of Master of Landscape Architecture, Master of Science in Planning, and Master Science in Architecture. A total of 43 responses were recorded (See Table 2). The questions on the survey correlated to personal perceptions of agaves within the built environment and certain landscape types within Tucson, i.e. within a desert / lush/ planter-only landscape, or as an accent, screen, or background plant. Questions also assessed the survey-taker’s knowledge on the monocarpic reality of agave life-cycles, and asked whether the individual connects agaves most strongly with the built or natural environment. Survey takers were only able to select one answer for each question.

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TABLE 2 Survey Results: Formalizing general perception and knowledge of agaves within the landscape

Ability to 63.8% distinguish an Can always identify an agave agave within a 27.7% Can almost always identify an agave landscape 8.5% Not confident identifying an agave

Products/entities most commonly 47.9% Tequila / Mescal / Bacanora associated with 39.6% agaves Plant within a landscape 8.3% Plant in the wild, not the built environment

Understanding of agave as monocarpic Agave die after producing seed 91.7%

8.4% Agave continue to grow after producing seed

Preference for agaves within certain landscapes Within a desert landscape 85.4%

14.6% Along a line or corridor

Characteristics of 81.3% Accent plant agaves within a landscape 12.5% Background plant

6.3% Screen plant 27.7%

Individual Interview Responses: Nurseries, Landscape Architecture and Design, and Community/Heritage Conservation Gardens Interviews of individuals within the fields of nursery propagation, landscape architecture and design, and community gardening and cultural stewardship make up the majority of data collection for this study. A total of thirteen individuals were interviewed for approximately twenty minutes each. The goals of these interviews were to formalize anecdotes about agaves, and gauge the extent to which the 13 | Page professionals and practitioners within the Tucson community engage and think about agave within their work. The interviews conducted in person revealed personalized narratives related to the individuals’ experience with agave within the context of a profession or practice.

In-person Interview Peter D. - Desert Survivors Nursery On the subject of consumer preference for agave species: “Agave selection is dependent on how well the gardener or landscaper knows the greater Sonoran desert biome. When people come in knowing they want the plants around their homes to reflect the species they see on hikes around Tucson they usually include species such as Agave utahensis, , and Agave schotti, which can grow large, have spines and teeth on the rosettes. Those who do not want to reflect agaves seen in a natural setting are more inclined to like the agave species that have fewer spines but are attracted to the low water intensity and the durability of species such as vilmoriniana and weberi (octopus agave).”

“I have noticed that when I mention to the customers that the agave will die after it they are immediately put off, even when I follow with the fact that the time till flowering is usually quite long.”

“The growing process from seed is a lengthy one, the seedlings need to stay in the nursery for years before they are big enough for a 5-gallon container to sell. The offshoots (pups) make for the easiest propagation, although that is dependent on the age of the parent plant and the need for holding on to mature plants to produce offspring. This is the primary factor in the price of agaves: the time and energy needed to wait out the slow growth process.”

Interview #2 Daniel Souza – Plants for the Southwest, Tucson AZ Explanation of intersection between cactus and agave, and the perceptions of the public: “Agave grow faster than cactus, which makes them saleable within the first four years. Cactus is much more time consuming, though the two types of plants have the same low intensity water use.”

“The main reason someone would choose and agave for a planting is an obsession over its form; the rosette form is just so different than anything else that it catches your eye unlike a lot of other the desert plant forms.”

“We have had the most success in creating varieties that are colorful and striking through cross- pollinating flowering agaves that we like. This is a process that means we rely on the natural life cycle of the agaves we wish to cross, and then hoping for fertile seeds. The results are amazingly colorful agaves.”

Interview #3 Greg Starr – Starr Nurseries, Tucson, Az 14 | Page

Author of Agaves: Living Sculptures for landscapes and containers expands on the depth of the species diversity and joys of experimentation with species native to central Mexico: “Interestingly when you go out into the desert around Tucson, you rarely see agaves growing. They are not one of the most hardcore desert plants, they need some type of nurse [nurse plant] to establish and some shade, and just enough soil moisture. When you get back in to the urban landscape, though, they become a sort of backbone to the plant palettes.”

“I’m most fascinated by the differences between species that I see in the morphological traits. The variegated stripes and leaf margins, toothy impressions on the unfolded leaves, and the traits of spikete vs. paniculate bloom forms are amazing to observe. Getting the genetic sequences to prove speciation is the next step in identifying new agaves, and there are still many more that I would like study.”

“The difference between offsetting and solitary agaves is important for landscape design, and means a lot in terms of the height of genetic variety found within either type of species. Hybridization is something to think about when talking about public and private gardens using agaves, because outcrossing of species can occur when different species flower at the same time and are cross pollinated. Over time that process would lower the overall diversity within the genus, but that is not the biggest concern, especially knowing the state of diversity within cultivated varietals like A. tequiliana. ”

Interview #4 Margaret Joplin – Design Collaborations, Tucson, Az Landscape architect and sculptor reflects on her attachment to agaves as accents to designs: “I started my education in plant materials and plant physiology working in a nursery in northern Arizona. My first experience with agaves was in the nursery context, learning from long-time propagators the way to grow agave, the differences that people liked within the genus, and how to care for them. They really are very cool plants, and so visually intricate.”

“I construct sculptures to work within my landscapes, and agaves function similarly as accents to a space. When I studies landscape architecture at the University of Arizona, I learned to recognize my own style within the forms that I could mimic from others, and have had a journey of finding my own style and letting that take over. I love visual art, and what better plant to be a living sculpture than an agave. If you compare it’s rosette form to other species like ocotillo (Fouquieria splendens), saguaro (Carnegia gigantea), brittlebush (Encelia farinosa), Creosote (Larrea tridentata), or even aloe (Aloe ferox), the desert plant adaptations create such a different organization of form and function. That is what is fun to highlight within a landscape design – connecting people to the desert through emphasizing the unique form adaptations that characterize the life in the desert.”

Interview #5 Jesus Garcia – Mission Gardens, Tucson, Az Bilingual educator, ecologist, anthropologist and specialist in heritage growing practices “I love to keep up a network of people around town who might have agaves that are near flowering, that way I can harvest them and experiment with roasting the flower stalks [Jesus shared roasted A. 15 | Page

Americana flower stalk], and the hearts Often I gather the mature agave cabezas in preparation for the Agave Heritage Festival presentation that happens at Mission Gardens.”

“Making pulque, the fermented beverage made from agave is a project of mine as well, and a practice that I learned from growing up in Mexico. My father was a Mescalero, so I have the knowledge within my family and myself of how to work with these plants, learn from them, learn how to use them best, and how to wait and be patient for their fruits.”

“I am the only one I know in Tucson or even Arizona that is experimenting with A. sisalana for fibers. I know it is grown in fields for fiber in Mexico, but it has not spread to the U.S. It is an amazingly strong fiber because you can wind it around itself a couple times to form a solid length of rope.”

“An interesting characteristic of agaves that I learned the hard way is that they are caustic if you slice open the leaves and touch them in any way. The burning sensation is quite intense! But of course it is just a reflection of the strength of the plant to survive and protect itself.”

Interview #6 Noah D. – Mesquite Valley Growers, Tucson AZ “It can be tempting to bring agave species from central and southern Mexico up to our nurseries in Tucson, but the number one barrier to including those tropical and sub tropical plants is the cold hardiness that we need for our winters. We select for the most cold hardy agave species, which means a lot of A. americana, A. parryi, A. ovatifolia, A. franzonsinii, A. lopantha quadricolor.”

“The second selection criteria is the size of the mature agave. Some people have room for a 5’ x 6’ agave, but most don’t. We try to carry the 2’x3’ size agave, which are more likely to find a home.”

“The agave weevil targets some of the larger species, and we see the effects of the weevil around Tucson within agave. To target the weevil, we can apply a systemic insecticide around the soil near the roots of the plant. This will save the plant, and can be important because a loss of a huge mature agave is pretty significant in terms of cost, labor to remove, and the investment of time spent growing the plant in the nursery and the landscape.”

Interview #7 Tristan – Civano Nurseries, Vail, Az “I love hearing what people want out of an agave when they come to buy one. We have such a variety that it makes the decision sort of difficult, but also narrows down a selection for what will be best for a particular aesthetic or customer preference.”

“The blue glow (A. ocahui x ‘Blue glow’) agave is my favorite. Based on the angle of your vision and the light, different colors stand out to you when you see the plant.”

Interview #8 16 | Page

Francesca Claverie – Borderlands Restoration Madrean Archipelago Plant Propagation Nursery (MAPP), Patagonia, Az Specialist in propagating species native to the desert grasslands oak woodlands, a horticulturalist focused on wild agave populations and restoration efforts expanded on the necessity for putting more agaves on the landscape, especially near the U.S. Mexico borderlands. “I have been hearing about a lot of wild harvesting within our area (near Rio Rico especially) and this concerns me because it means that the wild populations of mature agaves are being used for distillation without any thought to the repercussions of removing these plants from the ecosystems”

“The migrating bat populations that sweep through this area rely on agaves to be flowering at specific times, and that is dependent largely on the types of species: some flower at different times during the year. Less agaves on the landscape means that the species that rely on them to complete their own breeding and mating cycles are impacted. There is still a lot of research going on in order to better understand the role of the agave within the wild landscape.”

Interview #9 Mary McKay – McKay Custom Designs, Patagonia, Az Plant systems ecologist and landscape designer highlights her personal experience using the plant in designs. “User preference for agaves often doesn’t come with the want to have desert or xeroscape landscape- sometimes people just want to put them in lush landscapes that receive a lot of water. This is a problem because they obviously rot and don’t do well in basically any environment that is not rocky, well- drained soil.”

The table below summarizes the findings from the interviews across the themes found: TABLE 3 Area of Focus Especially Most Further thoughts interested in fascinated by Civano Nursery Only grow plants able Cold hardy species, Learning with Agave ideal for all planting Tristan to thrive within ones most related to customers about good applications within Tucson, Tucson and nearby Catalina placement low maintenance and surrounding areas Mountains unique structure Mesquite Valley Growers Native and nonnative Cold hardy agave A. selmanianna form There are more species of (Noah D.) species, wholesale and species, within 2’ x 3’ and the tropical agave agave that would be cold retail size range varieties hardy enough for Tucson, but have not yet been propagated Desert Survivors Native species, wild Replicating the agave A. Americana varieties Encouraging people to get (Jack) seeds species found in the with many colors to know agaves as desert around indicators of cultural Tucson, bringing practices makes them more those to the nursery likely to plant with them Plants for the Southwest Desert cactus and Hybridization of The short period The growing of cactus and (Peter Souza) succulents, one of especially colorful when two flowering succulents like agave is oldest Tucson agaves species can be cross- special and necessary nurseries pollinated to produce because of the time a hybrid seed investment 17 | Page

MAPP Nursery A. parriyi niche, Propagating plants The wild populations We need more agaves on (Francesca Claverie) grown for restoration from seeds harvested of agave and the the landscape, and in projects in the wild disappearance of a lot restoration projects of these from wild harvesting for mezcal Starr Nurseries Extensive Distinguishing species The multitude of Agaves are the most (Greg Star) propagation of based on certain species within dynamic and versatile rare/exotic agave characteristics Mexico, and trying to elements within a Tucson species bring some species to landscape Tucson from Mexico Margaret Joplin Sculpture and Applying a whimsical The sculptural Agave should stand out (Design Collaborations) landscape design style to plantings elements of singular within plantings agaves used as accents Mary McKay Residential and public Incorporating low- The user preference Agave need to be placed (McKay Custom Designs) space design maintenance plantings for agave outside of within environments that xeriscape landscapes are reflective of their native habitats Mission Gardens Bilingual education, Education of the The products of Respect for agave as an (Jesus Garcia) heritage foods, and public, living museum agave, the learning amazing food source and cultivation techniques process of how to cultural tie to Mexican and grow and use the indigenous heritage plant

Conclusion The beauty and utility of the agave in an urban landscape is dependent on the beholder. Of those who deal closely with agaves, such as those who work to propagate them at nurseries, landscape architects who include them in their designs, and community gardeners who showcase them as ways to explain past agricultural strategies, agaves are important plants to Tucson. According to Fred Barr, nursery owner and author of several books on the subject of agave as ornamentals, “Agave are unlike any other desert plant, their variation and diversity is a product of the conditions and time effect of our desert. When we plant with them in Tucson we are watching a hardy, adapted species thrive in one of its niches” (2019). Once particular agave plants are recognized, it is often impossible to not use them as landmarks within the matrix of streets and stoplights throughout Tucson. These public sculptures reflect the low impact and maintenance cost of roadway and corridor design, but also appeal to those who appreciate the use of agave in these spaces rather than the more often used bush lantana, freeway acacia, or desert spoon. Megan Janis, landscape architect and sculptor remarks, “I note the location of truly spectacular, large and nearing flowering agaves on my daily commute. I will always point them out to either my husband or just myself thinking, that is a beautiful plant. When I use them in my designs, they are always the focal points – the living sculptures that I want to stand out” (2019). The natural history and cultural ties of agave to the Tucson landscape are not mutually exclusive to their current use as a landscape plant within the urban environment. Agaves can be viewed as important plants within the urban setting based on largely three factors. Primarily, agaves are viewed as special plants because they represent a unique pinnacle of the evolution of desert flora; their rosette form is unlike other plants in the classic desert scrub grouping of Mesquite, Palo Verde, , creosote, and saguaro. Secondly, ethnobotanical records of the use of agave by native peoples reveals 18 | Page that the cultivation of agave occurred for thousands of years within Central and northern Mexico, including the Tucson basin. This record places the agave species in the light of living exhibits of past human/agave relationships. Lastly, the life cycle and reproduction strategies of the agave requires careful thought about ecosystem function unlike any other plant used in the landscapes of Tucson. No other species can be counted on to die immediately after flowering, or to perform the feat of producing a flower stalk three times the plant’s size. The agave is one of the most dynamic and versatile elements within a Tucson landscape because of the wide change in form the plant can undertake, and the species variation that lends use to lush, transitional, oasis, and desert landscapes. Whether residents of Tucson maintain a connection to agave through its ties to human cultural identity, appreciation of its natural history and biology, or its role as a unique, eye-catching form amongst desert flora, the species continues to be used within the urban setting.

Next Steps The heart of the discussion on importance of the inclusion of agave in Tucson’s landscaped environment surrounds the issue of planting appropriately for the climate. We can track the stages of era styles through the landscape as well as through buildings and social records. The next trend for landscapes seems to be only planting appropriate water users for the geography. An interesting further study might be the analysis of what is necessary to achieve a hands off (no water, energy inputs) landscape design for the particular climate of Tucson, or any climate.

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