Illegal wildlife trade and the persistence of “plant blindness”

A wide variety of plant species are threatened by illegal wildlife trade (IWT), and yet plants receive scant attention in IWT policy and research, a matter of pressing global concern. This review examines how “plant blindness” manifests within policy and research on IWT, with serious and detrimental effects for biodiversity conservation. We suggest several key points: (a) perhaps with the exception of the illegal timber market, plants are overlooked in IWT policy and research; (b) there is insufficient attention from funding agencies to the presence and persistence of illegal trade in plants; and (c) these absences are at least in part resultant from plant blindness as codified in governmental laws defining the meaning of “wildlife.”


| INTRODUC TI ON
This review considers the ways in which "plant blindness," first described by Wandersee and Schussler (1999, p. 82) (Margulies, Hinsley, & Phelps, 2018). Yet, there is wide, long-standing literature on (legal and illegal) plant trades, including of medicinal and aromatic plant species (MAP species) and Non-Timber Forest Products (e.g., Broad, Mulliken, & Roe, 2003;Cruz-Garcia, Lagunez-Rivera, Chavez-Angeles, & Solano-Gomez, 2015;Flores-Palacios & Valencia-Diaz, 2007;Pauls & Franz, 2013;Rijal, Smith-Hall, & Helles, 2011;Tali, Khuroo, Nawchoo, & Ganie, 2019). Moreover, recent research on illegal plant trade has highlighted the importance of filling these knowledge gaps. Recent studies of trade in orchids, for instance, have shown that little is known about commercial trade in wild orchids, even though the family makes up >70% of all species listed in the appendices of the

Convention on International Trade in Endangered Species of Wild
Fauna and Flora (CITES), the primary governing body which sets international wildlife trade regulations (Hinsley et al., 2017;Phelps & Webb, 2015).
Plant trade makes up a part of IWT: Over 900 species of timber species are threatened by IWT and listed on CITES, including in excess of 200 species of rosewoods (mostly Dalbergia spp.) (CITES, 2017;Willis, 2017). Notably, between 2005 and 2014, 35% of all seizures recorded in the United Nations Office on Drugs and Crime's (UNODC) World Wildlife Seizures database were "rosewood" (although many seizures were other fragrant hardwoods marketed as rosewood), representing the highest proportion of all wildlife recorded as seized in the database (UNODC, 2016). Within the cactus (Cactaceae) family, Goettsch and colleagues (2015) note that upwards of 31% of all cactus species are threatened with extinction, and 47% of these species are impacted by collection for the horticultural trade and for ornamental purposes, much of which is illegal.
Cycads are similarly considered at high risk from illegal trade as ornamental plants (Cousins & Witkowski, 2017), and are now reportedly the most endangered plant group on the planet (Brummitt et al., 2015;IUCN, 2010). As the recent TRAFFIC report on the use and trade in wild plant ingredients highlights, 60%-90% of medicinal and aromatic plants in trade are wild collected, representing an industry currently valued at 3 billion USD annually, yet traceability and documentation within this trade is often opaque (Jenkins, Timonshyna, & Cornthwaite, 2018). While the TRAFFIC report demonstrates a need for greater attention to legal trades in plants regulated by CITES, even less is understood about the patterns, processes, and mechanisms of illegal trade in plants. As a result, plants remain greatly underrepresented in IWT discussion.
This article assesses the present impacts of the privileging of animals over plants in the context of contemporary framing of policy discussion on IWT. It reviews how this imbalance emerges out of similar plant-animal dynamics in the field of conservation biology and across broader society. It then considers ways in which plant blindness has historically affected conservation policy, through a specific example of plant blindness in US wildlife trade law. This is followed by a concise review of current patterns and trends in both IWT research and US and UK government funding, highlighting the ways in which plants are widely excluded. The article concludes by discussing present challenges to overcoming plant blindness in the emerging IWT agenda.

| PL ANT B LINDNE SS AND ITS LEG ACIE S
The tendency to overlook the threat of IWT to plants has a clear historical context. Twenty years ago, Wandersee and Schussler (1999) coined the term "plant blindness" to refer to the cognitive condition of how plants remain in the background of many human conceptions of nature and the environment, particularly within non-indigenous societies (Hall, 2011;Van Sittert, 2003). As Heywood (2017, p. 323) aptly notes: It is somewhat paradoxical that the widespread enthusiasm in many cultures for gardens and gardening, parks and other urban plantings…together with the aesthetic appreciation of flowers in art, literature and society, and in the home as cut flowers and potted plants, is not reflected in a public appreciation of the role and importance of plants in the natural environment.
There is a growing body of research demonstrating the diversity of ways in which plants can be understood as intelligent and/or active beings within socio-ecological systems including across the fields of biology and botany (for reviews, see Cowell, 2018;Hall, 2011), geography (Fleming, 2017;Head & Atchison, 2009;Head, Atchison, & Phillips, 2015;Head, Atchison, Phillips, & Buckingham, 2014), anthropology and indigenous studies (Ellis, 2018;Hall, 2011;Kimmerer, 2013;Kohn, 2013;Rose, 2002), and philosophy (Marder, 2013(Marder, , 2016Plumwood, 1993). This interdisciplinary scholarship challenges basic assumptions that have historically kept plants painted into the backdrop of a livelier animal life. While debate continues within the plant sciences community regarding the capacity of plants to be understood as self-aware, mobile, communicative, and more than mechanistically responsive to environmental cues, research increasingly points to the myriad of ways in which plants are highly complex and adaptive beings (Hall, 2011).
For instance, research has demonstrated means by which trees and other plants signal across individuals within a species in response to herbivory threats, reducing predation rates across populations (Dolch & Tscharntke, 2000;Kost & Heil, 2006). While the nascent field of "plant neurobiology" remains controversial in botany (Alpi et al., 2007), research suggesting ways plants exhibit memory (Garzón & Keijzer, 2011), can distinguish themselves from other individuals (Gruntman & Novoplansky, 2004), and display phenotypic plasticity resulting from "the complex computational capability plants can bring to bear to finely scrutinize the local environment and act upon it" (Trewavas, 2003, p. 13), all suggest ways in which plants display complex indicators of intelligence (Baluška & Mancuso, 2009;Trewavas, 2003Trewavas, , 2005. Despite this emerging body of research on plant intelligence, some strands of science and epistemology-how knowledge is developed and acquired-continue to devalue plant life as evolutionarily beneath that of animal life. As Heywood (2017) evidences, while zoology programs continue to flourish in universities worldwide, botany as a discipline has been in a steady decline for decades (Cowell, 2018).
Within the context of biological conservation, plant blindness remains an ongoing issue (Balding & Williams, 2016). There are significant biases related to which species garner the most research attention as well as most funding within conservation research efforts (Havens, Kramer, & Guerrant, 2013;Martín-López et al., 2009;Metrick & Weitzman, 1996). Animals, particularly charismatic megafauna, are overrepresented both in conservation research efforts, as well as in conservation funding streams compared to all other forms of life (Sitas, Baillie, & Isaac, 2009;Smith, Veríssimo, Isaac, & Jones, 2012). Plants are especially underrepresented on both accounts, demonstrating that even within the conservation science community, plant blindness is pervasive, impactful, and privileges animal life over plant life (Balding & Williams, 2016). Efforts to assess the extinction of plant taxa lags behind that of vertebrates, with only 8% (N = 28,287) of known plant species (N ≈ 310,442) assessed for the IUCN Red List compared to 68% (N = 48,101) of known vertebrate animals (N ≈ 69,903) (IUCN, 2018). And yet, three of the top five most threatened taxonomic groups comprehensively assessed for the IUCN Red List are plants-cycads, cacti, and conifers-listed in order of greatest threat (Goettsch et al., 2015). In the context of endangered species currently regulated in international trade, CITES lists a total of 5,811 registered faunal species (which includes mammals, birds, reptiles, amphibians, fish, and invertebrates), compared to 29,990 species of plants (excluding subspecies) (CITES, 2017). Plants receive proportionately far less research attention and funding in relation to the threats they face compared to animals-an imbalance also mirrored in national endangered species laws. As Havens et al. of North America, Australia, and Asia (and see Hall, 2011;Kimmerer, 2013). Their synthesis concludes that the existence of human cultures in which people develop close and meaningful relations with plants " [...] points to a number of practical ways to implement plant conservation programs grounded in promotion of identification and empathy with plants and anthropomorphism of plants" (Balding & Williams, 2016, p. 1197. Namely, they suggest facilitating direct experience with plants, highlighting human and plant similarities as opposed to differences. They propose promoting empathy with plants through engaged and creative activities such as drawing and writing to promote close observation of plants, gardening to "emphasize diverse functions of plants," and collaborations between artists and scientists to "encourage active empathy with other species" (Balding & Williams, 2016, p. 1,197). In summary, while plant blindness is a global phenomenon, it is not generalizable across all human societies, nor must its existence necessarily remain a permanent feature of these societies where its presence is observed.

| PL ANT B LINDNE SS IN CON S ERVATI ON EFFORTS: A C A S E S TUDY FROM THE US
The persistence of plant blindness in the conservation sciences mirrors broader societal patterns in much of the Global North that The Lacey Act is unique among US legislation in that a person can be found in violation of the Act by violating another foreign government's wildlife laws. It was only in 1981, during a major overhaul of the Lacey Act, that a restrictive definition of plants was incorporated into the legislation's language to specifically protect certain US native species of plants that were threatened with extinction (Anderson, 1995).
Until 2008, the Lacey Act considered plants and wildlife as distinctly different legal entities, with much more constrained application of the Act being applied to plants. Prior to 2008, "fish or wildlife" were defined in the Act as: (A)ny wild animal, whether alive or dead, including without limitation any wild mammal, bird, reptile, amphibian, fish, mollusk, crustacean, arthropod, coelenterate, or other invertebrate, whether or not bred, hatched, or born in captivity, and includes any part, product, egg or offspring thereof. (16 U.S.C. S 3371(a)) As Anderson (1995) notes, "this language encompasses virtually any wild animal, fish, or invertebrate, dead or alive, from any part of the world, and any part of, or product made from, such a specimen" (54). In contrast, the definition of plants under the Law is severely restricted: In practice, this meant that until 2008, while importing tiger parts or ivory became an "automatic felony violation … the Act cannot be used to prosecute the importation of an equally endangered orchid or pitcher plant species taken from a foreign rainforest" (Anderson, 1995, p. 55). In 2008, the Act's definitions of plants and wildlife were again updated (summarised in Figure 1 (Havens et al., 2013). This separation and its consequent effects are mirrored in US and international efforts to combat IWT.

| PL ANT B LINDNE SS AND ILLEG AL WILDLIFE TR ADE
Despite the more recently adopted inclusive language about the threat plants face from IWT in US wildlife law, these amendments were made specifically to better tackle the illegal timber trade While there is growing attention in the research community to the subject of IWT, in-depth, empirical studies examining the patterns, processes, and mechanisms of illicit trade in wild species remain a relatively new area of academic research (Rosen & Smith, 2010). Within the social sciences, studies of IWT span the fields of green criminology (e.g., Lavorgna, 2014;Ngoc & Wyatt, 2013;Wyatt, 2009), geography (Collard, 2014;Massé, 2018;Moore, 2011;White, 2014;Zhu, 2017Zhu, , 2018, and international politics (Duffy, 2014;Duffy, St John, Büscher, & Brockington, 2015;Elliot, 2007). Legal scholars have also engaged with IWT and the role and efficacy of legislation in combating IWT, with particular attention to transnational organized crime (Lee, 1995;Warchol, 2004;Zimmerman, 2003). With the exception of research on the illegal timber trade (e.g., Zhu, 2017Zhu, , 2018, the social sciences have all but ignored illegal trade in plants. There is a larger literature on how IWT affects species conservation efforts within the field of biodiversity conservation, ranging from advances in forensics (e.g., Dormontt et al., 2015;Wasser et al., 2008), assessing the extent of illegal internet trade in wild species (e.g., Harrison, Roberts, & Hernandez-Castro, 2016;Sajeva, Augugliaro, Smith, & Oddo, 2013), demand reduction efforts (e.g., Verissimo & Wan, 2018), and spatiotemporal dimensions of IWT's impacts on species conservation (e.g., Critchlow et al., 2015). And yet, given the scale of  barrier that may be discouraging both policymakers and scholars from tackling plant trade. While tiger skins, rhino horn, and live birds may be concealed by a variety of means by wildlife smugglers, it can be incredibly challenging to accurately and quickly identify plant species and the legality of their status. This is especially challenging for customs agents, as there is evidence that illicitly traded plants are often hidden in shipments of legal plant materials, or those where permits are not required (Lavorgna, Rutherford, Vaglica, Smith, & Sajeva, 2018). Developments in DNA barcoding and other molecular techniques, already used in some cases to identify traded plants (e.g., Cowan, Chase, Kress, & Savolainen, 2006;Gathier, 2013;Staats et al., 2016) may help facilitate more accurate and timely identification of illegal plant trade. However, they are likely to present long-term challenges, especially for mega-diverse plant groups (e.g., orchids) and where capacity for such testing is low (Hinsley et al., 2017).
Another key point of consensus from the workshop was that there is insufficient funding for studying illegal plant trade. F I G U R E 2 Results of peer-review literature search in Web of Science. Total number of studies per plant group may be less than the combined numbers tallied by thematic category, as several studies included multiple thematic dimensions (e.g., consumer and supply side dynamics). Literature search was based on the Boolean search query: TS=(("illegal wildlife trade" OR "IWT" OR "illegal wildlife traffick*" OR "illegal timber trade") AND (plant* OR cact* OR cycad* OR timber OR hardwood OR rosewood OR ebony OR ephiph* OR orchid*)). The Boolean search strategy was iteratively developed based on author knowledge of existing illegal wildlife trade in plants literature, and consecutive search queries utilizing a variety of keywords. Final search strategy aimed for the greatest inclusion of relevant papers (thus, illegal timber trade was included as many illegal timber trade articles do not employ "illegal wildlife trade" as a keyword or in paper titles and abstracts). Literature search was restricted to Web of Science, based on topic search. Therefore, studies which relate to or discuss illegal trade in plants but not as a primary subject (for instance, see Goettsch, 2013), were not captured in this literature search. From an initial set of 38 papers, a total of 26 papers were included in Figure 2  Certain plant taxa have been illegally traded for decades, yet research on these trades is lacking. Cycads, despite being one of the most endangered groups of species on the planet also significantly threatened by illegal trade (Brummitt et al., 2015;IUCN, 2010), have received scant attention in the peer-review literature on IWT.
Similarly, cacti have received little attention from the IWT research community, again despite evidence of a robust illegal trade being the primary threat to many cacti species' survival (Goettsch et al., 2015;Novoa, Le Roux, Richardson, & Wilson, 2017;Oldfield, 1997;Robbins, 2003). There are many other families and species of plants such as MAPs that are known to experience illegal trade that were not captured by this literature review, in part because much of this evidence remains in the gray literature or in non-indexed specialist journals. For instance, wild ginseng and black cohosh from the Appalachian region of the US are both known to experience intense collecting pressure for both domestic and international consumer markets (Lange, 2002;Schippmann et al., 2002). Similarly, a variety of other succulent plants face increasing pressure from illegal wild collection for international sale, including several Dudleya species from the California floristic province, but research to address and better understand the drivers and networks of their trade is lacking. Shading in legend corresponds with order in columns (top to bottom). Many funded projects cover more than one species. Species tallies based on their specific mention in project summaries, so totals are greater than number of individual grants funded. *2018 was the first year projects on illegal wildlife trafficking in plants were eligible for UK Challenge Fund grants, but no plantspecific projects were funded (top chart). Plant projects funded by USFWS included five projects on hardwood timber and one project on cycads (bottom chart) beneficial to determine if this trend is reflected internationally.

| CON CLUS ION
Similarly, the inclusion of plants for the first time in 2018 into the UK Illegal Wildlife Trade Challenge Fund (though limited to cycads, cacti, and orchids) suggests that some policymakers are beginning to address the strong taxonomic biases within the IWT arena. In 2018, plants were also included, for the first time and only peripherally, in one of the global IWT conferences. Given the prominent role of both the UK and the US in shaping international wildlife trade policy and conservation finance, these changes suggest that there is reason for cautious optimism that plants may increasingly find a proportionally more equitable place at the table in conservation policy and research tackling IWT. Given these findings, it is important to consider the way in which the plant trade is taken up as a matter of pressing concern by academics, funding bodies, and the wider general public.
Innovative efforts to bring to light the overlooked impacts of illegal plant trade could bolster interest, and subsequently funding, for further research. While here we highlight and discuss plant blindness in IWT, we hope that these discussions are relevant to other potential blindness in IWT research, for example, fungi or insects. it is more appropriate to consider this "blindness" as symptomatic of a particular sociocultural and historical trajectory rather than a problem of inevitable permanence.

ACK N OWLED G M ENTS
We thank three anonymous reviewers and editor Dawn Sanders for their helpful and constructive comments and suggestions on earlier versions of this manuscript. We also thank Bennett Young for helpfully steering the manuscript through the revision process. Writing