diversity Review Does Phytogeography Change with Shifts in Geopolitics? The Curious Case of Cycads in the United States Benjamin E. Deloso 1 , Ulysses F. Ferreras 2 and Thomas E. Marler 1,* 1 Western Pacific Tropical Research Center, University of Guam, UOG Station, Mangilao, Guam 96923, USA; [email protected] 2 Philippine Native Plants Conservation Society Inc., Ninoy Aquino Parks and Wildlife Center, Quezon City 1101, Philippines; [email protected] * Correspondence: [email protected]; Tel.: +1-671-735-2100 Received: 23 October 2020; Accepted: 23 November 2020; Published: 25 November 2020 Abstract: The United States is currently home to five native cycad species. We provide a discussion on these five cycad species to illuminate how evolutionary and geopolitical processes influence phytogeography and published checklists of threatened plants. The number of threatened species in need of protection within any given country is a product of speciation that is contingent with evolutionary processes. However, this number may change instantaneously along with shifting of geopolitical boundaries brought about by armed conflict between rival states and multilateral negotiations. There are five contemporary cycad species within the United States, and the various historical bilateral and multilateral agreements that have generated this list are reviewed. Three of these five cycad species are threatened and in need of urgent protection. A discussion on the history of United States cycads as a microcosm of worldwide conservation issues is presented, with a focus on how federal conservation endeavors of individual nations may influence the world’s biodiversity crisis. Keywords: conservation science; cycad; Cycadaceae; Cycadales; Cycas; Red List; United States; Zamia; Zamiaceae 1. Introduction Cycads are an ancient group of gymnosperms and are considered the most basal extant group of seed plants [1]. Often referred to as “living fossils”, recent research indicates the extant species of cycads are a result of evolutionary radiations occurring during the Miocene (23–5.3 MYA), although the crown group that constitutes the order Cycadales is much older, having split from Ginkgo in the late Permian (274.5 MYA) [2,3]. These contemporary 350+ species of cycads [4] are distributed among 10 accepted genera in 2 families. Among this expansive list, five extant cycad species are native to the United States and territories. The criteria required to define a species has been the subject of contention for many years since the founding of binomial taxonomy by Carolus Linnaeus [5,6]. Indeed, there is no clear consensus among the scientific community on what defines a species. Taxonomists are constantly in disagreement on what characters merit more consideration in circumscribing and delimiting any given species. Despite subjective preferences, any discrete species can be considered distinct long before the taxonomic authority that formally described it existed. Linnaeus himself understood this concept when establishing the system of naming organisms so that humans could attempt to interpret the innumerable life forms on Earth and their relationships among each other. Our view herein is that the use of the term Diversity 2020, 12, 445; doi:10.3390/d12120445 www.mdpi.com/journal/diversity Diversity 2020, 12, 445 2 of 11 Diversity 2020, 12, x FOR PEER REVIEW 2 of 11 “new species” that precedes the formal description of each added binomial is an anthropocentric bias the use of the term “new species” that precedes the formal description of each added binomial is an and should be cautiously avoided [7]. In this review, we employ a distinction between actual taxa and anthropocentric bias and should be cautiously avoided [7]. In this review, we employ a distinction described taxa. between actual taxa and described taxa. The country in which each taxon resides may change when state boundaries are modified as an The country in which each taxon resides may change when state boundaries are modified as an offshootoffshoot of bilateral of bilateral and multilateral and multilateral negotiations. negotiations. Therefore, Therefore, the number the number of species of species that resides that reside withins a countrywithin during a country a specified during a year specified may increaseyear may or increase decrease or along decrease with along these with geopolitical these geopolitical changes. This reviewchanges. describes This review the history describes of thethe botanicalhistory of and the geopoliticalbotanical and issues geopolitical related issues to the fiverelated cycad to the species five that currentlycycad species occur that in currently the United occur States. in the A thoroughUnited States review. A thorough of the history review of of cycad the history species of within cycad Unitedspecies States within territories United and States occupations territories would and be occupations an expansive would endeavor. be an For expansive example, endeavor. several cycad For speciesexample, would several have been cycad included species in would the unincorporated have been included territory in ofthe the unincorporated Panama Canal territory Zone and of the temporarilyPanama occupiedCanal Zone territories and the withintemporarily Cuba occupied following territories the Treaty within of Paris Cuba or Japanfollowing following the Treaty World of War II.Paris However, or Japan none following of these World species War are currentlyII. However, under none the of jurisdiction these species of the are United currently States. under For the purposesjurisdiction of simplicity of the United and brevity, States. we For restrict the purposes our endeavor of simplicity to the and history brevity, of events we restrict that our have endeavor created the fiveto the cycad history species of events that are that contemporary have created taxa the offive the cycad United species States. that are contemporary taxa of the United States. 2. The Contemporary Species of the United States 2. The Contemporary Species of the United States 2.1. Zamia integrifolia L.f. 2.1. Zamia integrifolia L.f. This species is the only cycad native to the continental United States, ranging from southern Georgia toThis Florida species with is fivethe subspeciesonly cycad currentlynative to the recognized continental [4]. United It was firstStates described, ranging in from 1789 southern by Carl von LinnGeorgiaé d. to y., Florida the son with of Carolus five subspecies Linnaeus. currently His name recognized latinized [4 is]. “ItLinnaeus was first filius described”, meaning in 178 Linnaeus9 by Carl the son,von and Linné the d. standard y., the authorson of abbreviationCarolus Linnaeus. L.f. is His used name to indicate latinized him is as“Linnaeus the taxonomic filius”, authority.meaning In fact,Linnaeus the genus the Zamiason, andwas the named standard by author Linnaeus abbreviation himself, and L.f. thusis used the to naming indicate of him this as taxon the taxonomic could be describedauthority as a. fatherIn fact, and the genus son endeavor. Zamia was named by Linnaeus himself, and thus the naming of this taxon Locallycould be knowndescribed as as coontie, a father thisand son species endeavor. has had 17 synonyms, and prior to its most recent Locally known as coontie, this species has had 17 synonyms, and prior to its most recent circumscription was most recently known as Zamia floridana A.DC. [4]. The International Union for circumscription was most recently known as Zamia floridana A.DC. [4]. The International Union for Conservation of Nature (IUCN) currently gives this cycad a status of Near Threatened from the Conservation of Nature (IUCN) currently gives this cycad a status of Near Threatened from the latest latest assessment performed in 2009 by Dr. Dennis Stevenson, a world authority in cycad biology [8]. assessment performed in 2009 by Dr. Dennis Stevenson, a world authority in cycad biology [8]. Placement in this category means the species may be threatened with extinction in the near future, but Placement in this category means the species may be threatened with extinction in the near future, it doesbut not it does currently not currently qualify forqualify threatened for threatened status. status. ThisThis cycad cycad has ahas long a long history history of beingof being utilized utilized and and processed processed as as food-grade food-grade flour.flour. Unfortunately, entireentire plants plants were we excavatedre excavated for thisfor this purpose. purpose. The The peak peak production production years years were were in in the the latelate 1800s1800s andand earlyearly 1900s, 1900s an era, an thatera that decimated decimated the th wilde wild populations populations of of the the species species [9 [].9] The. The contemporary contemporary threatsthreats to Z.to integrifolia Z. integrifoliainclude include habitat habitat loss loss and and wild wild harvesting harvesting [8 ].[8]. The The showy showy small small plant plant isis anan excellentexcellent horticulturalhorticultural specimen specimen that that requires requires little little care care (Figure (Figure1a). 1a). (a) (b) FigureFigure 1. Two 1. T ofwo the of the cycad cycad species species native native to to the the United United States:States: ( (aa)) the the diminutive diminutive ZamiaZamia integrifolia integrifolia; (b); (b) thethe arborescent arborescentCycas Cycas micronesica micronesica.. Diversity 2020, 12, 445 3 of 11 2.2. Zamia erosa O.F.Cook & G.N.Collins This cycad species is one of three taxa that are native