IOWA'S FRAGILE FLORA
By
Diana Horton

Fragile Flora Database

INTRODUCTION

In this state where natural habitats have been all but obliterated through conversion to cropland, Iowa's endangered species legislation has a vital role to play. However, the information pertaining to rare species legislation comprises a relatively extensive and complex data set that is largely inaccessible because the sources are government publications, unpublished reports and professional correspondence. The purpose of this website and database is to make these data readily available in an interactive format and to include background information that provides a useful context for evaluating revisions of the endangered and threatened plant species list when they are proposed. A second phase of this project is underway and involves development of a database of all the University of Iowa Herbarium Iowa collections' data, particularly distributional information, and to make these available in an interactive format that will include county range maps.

WHAT'S IN THE FRAGILE FLORA DATABASE?

The database is a compilation of information on rare Iowa plants from four sources. These sources include (see Literature Cited for bibliographic details):

• five Iowa Administrative Code lists of endangered and threatened plant species (Iowa Administrative Code 1977, 1984, 1986, 1988, 1994)

• 1998 list proposed to supercede the 1994 Iowa Administrative Code list (J. Pearson, Iowa DNR (Department of Natural Resources), in litt. 1998)

• 1998 candidate list (J. Pearson, Iowa DNR, in litt. 1998)

• lists from three endangered and threatened plant reports (Roosa & Eilers 1978, Roosa, Pusateri & Eilers 1986, and Roosa, Leoschke & Eilers 1989)

Five groups of plants/plant-like organisms -- vascular plants ('higher' plants), mosses, hepatics (liverworts), lichens, and fungi (mushrooms/toadstools) -- are included in the database; however, most of the data pertain to vascular plants, which is the only group included in the Iowa Administrative Code lists of endangered and threatened plants. Organized by plant/plant-like group, the data include:

Vascular Plants

• Latin species name according to source (see above). Source names are abbreviated as follows: Iowa Administrative Code (IA Adm. Code), proposed list of 1998 (DNR Prop. List 1998), candidate list of 1998 (DNR Cand. List 1998), and reports on endangered and threatened plants (E & T Report).
• Latin family name according to Eilers and Roosa (1994), The Vascular Plants of Iowa. If the family name in Kartesz (1999), A Synonymized Checklist and Atlas with Biological Attributes for the Vascular Flora of the United States, Canada, and Greenland, is different, it is included in brackets.
• common name according to Eilers and Roosa (1994), and also Gleason and Cronquist (1991) ), Manual of Vascular Plants of the Northeastern United States and Adjacent Canada, and Kartesz (1999), if the latter two differ from Eilers and Roosa.
• category (e.g., endangered, threatened, special concern, extirpated) assigned in each source (Iowa Administrative Code lists, 1998 proposed list, 1998 candidate list, and reports on endangered and threatened plants).
• Latin species name accepted by Eilers and Roosa (1994)
• Latin species name accepted by Gleason and Cronquist (1991)
• Latin species name accepted by Kartesz (1999)

Mosses

• Latin species name according to source
• Latin family name according to Anderson, Crum and Buck (1990), List of the mosses of North America north of Mexico, and Anderson (1990), A checklist of Sphagnum in North America north of Mexico.
• category assigned in 1998 proposed and candidate lists.
• Latin species name accepted by Anderson, Crum and Buck (1990) and Anderson (1990), except in a few instances when more recent taxonomic and nomenclatural changes have been incorporated.

Hepatics (Liverworts)

• Latin species name according to source
• Latin family according to Stotler and Crandall-Stotler (1977), A checklist of the liverworts and hornworts of North America.
• category assigned in 1998 proposed and candidate lists.
• Latin species name accepted by Stotler and Crandall-Stotler (1977)

Lichens

• Latin species name according to source                     
• category assigned in 1998 proposed and candidate lists.
• Latin species name accepted by Esslinger and Egan (1995)

Fungi (Mushrooms/Toadstools)

•Latin species name according to source
• Latin family according to Miller and Farr (1975), An index of the common fungi of North America.
• category assigned in 1998 proposed and candidate lists.
• Latin species name accepted by Miller and Farr (1975)

FRAGILE FLORA DATABASE SUMMARY

The tables below summarize data in five Iowa Administrative Code lists of endangered and threatened plant species (IA Adm. Code 1977, 1984, 1986, 1988, 1994), a 1998 list proposed by the Iowa DNR (Department of Natural Resources) to supercede the 1994 Iowa Administrative Code list (DNR Prop. List 1998), a 1998 candidate list by the Iowa DNR (DNR Cand. List 1998), and lists from three endangered and threatened plant reports (E & T Report 1978, 1986, 1989). Category abbreviations (e.g., E for endangered, T for threatened, SC for special concern, X for extirpated, etc.) correspond to those in the database.

VASCULAR PLANTS

Mosses

Hepatics

Lichens

Fungi

WHY ARE THERE RARE PLANTS IN IOWA?

One frequently hears the assertion that 'Iowa is the most altered state in the union', in reference to the devastation of natural habitats since the time of European settlement. The validity of this statement is evident at a glance on the NRCS (Natural Resources Conservation Service) map showing Percent of Non-Federal Area in Cropland. Only Illinois, and perhaps Indiana, rival Iowa in the areal extent of cropland. In Iowa, estimates are that less than one-tenth of one percent of the tallgrass prairie (and virtually none of the savanna) that covered approximately 83% of the landscape remains today¹. Similarly, less than three-tenths of a percent of the natural wetlands that comprised perhaps 6% of the surface area remain². On the surface, the forests appear to have fared somewhat better, with approximately fifty percent of the original surface area of 11% still wooded³; however, this figure is misleading since much, if not most, of the natural forests have been altered by logging and other management activities. Analyses of 1998 Landsat images by the Iowa Department of Natural Resources Geological Survey Bureau (ftp://ftp.igsb.uiowa.edu/pub/download/
land_cover/cntytot.xls) reveals that 60% of today's dramatically altered Iowa landscape is comprised of row crops; 31% is pastures/lawns; and 2% is roads/buildings. Manmade wetlands comprise approximately .3% of the surface area⁴.

European settlement marks the beginning of wholesale habitat destruction in Iowa, and also the initiation of alien species introductions. Naturalized alien species, that is, ones that have escaped from cultivation and invaded natural habitats where they wreak havoc on remnants of natural vegetation, are probably as great a threat to native species diversity as habitat destruction. Notable examples in Iowa presently include Garlic Mustard (Alliaria petiolata (Bieb.) Cavara & Grande), Leafy Spurge (Euphorbia esula L.), and Purple Loosestrife (Lythrum salicaria L.), three species that are decimating the native species in woodland, prairie and wetland habitats, respectively. According to Eilers and Roosa (1994), 1,958 species of vascular plants have been recorded from Iowa; however, 442 of these are alien, while 1,516 are native. Lewis (1998) noted that 54 additional species have been recorded since the publication of Eilers and Roosa's checklist (Eilers & Roosa 1994), of which eight are alien and 46 are indigenous. More recently, another 39 alien and 12 indigenous species were recorded (Norris et al. 2001). In addition, there are a few more unpublished records (e.g., Horton, Cady and Madsen, unpublished data). Updating Eilers and Roosa's (1994) figures, the current flora is over 2,063 species, of which 489 are alien and 1,574 native. Thus, 24 percent of the species recorded from Iowa are not native. Kartesz' (1999) total of 2,059 species is very close; however, his figure of 405 alien species is slightly lower, but even so, 20 percent are alien. Either way, one-fifth to one-quarter of the plants recorded from this state are naturalized alien species, some of which are having a dramatic, detrimental impact on populations of native species.

Based on Kartesz' (1999) figures, Iowa's native flora (1,654 species) is slightly larger than those of North and South Dakota, and Nebraska (1191, 1486 and 1496 species, respectively), slightly smaller than Minnesota, Wisconsin and Kansas (1840, 1908 and 1794, respectively), and quite a bit smaller than Illinois and Missouri (2313 and 2136, respectively). However, on the basis of surface area, Wisconsin is slightly smaller than Iowa, Illinois is slightly larger, and larger still are Missouri, North Dakota, South Dakota, Nebraska, Kansas and Minnesota (from smallest to largest). Obviously, floristic diversity reflects other factors in addition to surface area. The two that probably have had the greatest impact are physiography, the contours of the land, and phytogeography, the ecological and historical factors that have shaped the vegetation.

Undoubtedly, Iowa's floristic diversity is influenced by the diversity of landform regions documented by Prior (1991), and particularly by the physiographic complexity of the Paleozoic Plateau in the northeastern part of the state and the Loess Hills in the west. Phytogeographically, Iowa is in a transition zone, the ecotone between deciduous forest and prairie, so both eastern and western elements reach the edges of their ranges here. In addition, boreal/northern hardwoods elements extend into the state, particularly in the Paleozoic Plateau, where the cold air (algific talus) slopes provide cooler microsites. Eilers and Roosa (1994) recognized these same elements and also an Ozarkian woodland element. With the data in Kartesz and Meacham's Synthesis of the North America Flora (1999), it is possible to quantitatively analyze the affinities of the Iowa vascular plant flora relative to that of each state and province in North America north of Mexico. The similarity ranks on the accompanying map represent simplified Sørensen similarity indices⁵ calculated from data in Kartesz and Meacham (1999). Floras with the greatest number of species in common with Iowa have lower numbers and are shaded darker, while those with fewer species in common have higher numbers and lighter shading. As one might expect, the floras of Minnesota, Wisconsin and Illinois are most similar to that of Iowa, but Indiana is equally similar, while Missouri and Nebraska are no more so than Ohio and Michigan. At the next level (similarity rank of three), Kansas is no more similar than Pennsylvania, New York, Connecticut and Ontario, while North and South Dakota are less similar still and equivalent to Kentucky, West Virginia, New Jersey and Massachusetts. Clearly, the strongest affinities of the Iowa flora are to the east and northeast, with strong similarities extending as far as the eastern seaboard. In contrast, there is a relatively abrupt decrease in similarity to the west in Montana, Wyoming, Colorado and New Mexico, and this decline is much greater than that to the south and southeast, where, with the exception of Florida, even the states from Louisiana to North Carolina have higher levels of similarity than western states that are much closer geographically.

Considering that Iowa lies on the eastern border of the Great Plains, and historically over 80 percent of the surface area of the state was prairie, it is noteworthy that the strongest floristic similarities are with states that were dominated by deciduous and boreal/northern hardwoods forest. Almost certainly, these latter elements account, in great part, for the relative richness of the Iowa flora by comparison to North and South Dakota, and Nebraska, even though these states have a greater surface area. In addition, a significant number of the species that are largely restricted (in Iowa) to the Driftless Area in northeastern Iowa also are among the rarest species in the state (see maps in Pusateri, Roosa and Farrar, 1993). Thus, these boreal/northern hardwoods forest elements may account for a significant proportion of the historically rare species recorded from Iowa.

In the reports on Endangered and Threatened Vascular Plants (Roosa & Eilers 1978, Roosa et al. 1986, and Roosa et al. 1989), 91 species are listed as either extirpated, presumed or possibly extirpated, although extant populations of some of these have been found subsequently. It is apparent that a significant number of plants would have been rare in Iowa historically simply because of the phytogeographic position of the state. However, the impact of habitat destruction and naturalized alien species has ensured that naturally rare species have become even rarer. For example, Low Bindweed (Calystegia spithamea (L.) Pursh) has been recorded from nine counties, but only four of these are based on post-1950 records (Roosa, Leoschke and Eilers 1989). And some surely have been extirpated, for example, Pod Grass (Scheuchzeria palustris L. var. americana Fern.). Given the on-going urban sprawl into rural areas, if we are to preserve the dwindling biodiversity and remnants of natural habitats that represent the natural heritage of this state, it is vital that effective legal protection be provided.

HOW DO WE KNOW WHICH SPECIES OCCUR IN IOWA AND WHICH ARE RARE?

Herbarium specimens. Scientists and knowledgeable laypersons preserve collections (samples) of living plants and these are maintained in repositories called herbaria (e.g., the University of Iowa Herbarium was such a repository). Each specimen is labelled with the locality where it was collected and serves as a permanent record of the occurrence of that species at a particular site and point in time. Since each specimen documents a single site, it is necessary to collect one at each locality where the species occurs. Collections make it possible to re-evaluate the data (records of the occurrence of species) at any time by examining a specimen. If a record is based solely on a verbal or written communication, it is impossible to determine whether that record is valid, i.e., whether the identification is correct. In most instances, even a photographic record is insufficient documentation simply because many characters useful for identification are too small to be decipherable (or are obscured) in a photograph or they require accurate measurements that are impossible to obtain from a photograph. Thus, collections are the vital link with the natural world and they provide a sound, scientific foundation for all decisions regarding rare species.

The need for collections presents a conundrum. Are the species we want to preserve going to become even rarer as a result of documenting their occurrence with collections? First, specimens of state (and federal) listed species cannot be taken legally without a Scientific Collector's Permit issued by the Iowa Department of Natural Resources. Beyond that, specimens of rare species should not be collected without careful investigation of the size of the population and making sure the site has not been documented already by another investigator. Size of the population is a judgement call, and it also can be a complicated issue with plants. For one thing, populations of some plants fluctuate markedly from year to year. Also, what appears to be a reasonably large population, for example, one comprised of perhaps 100 individuals, may actually represent just a few genetic individuals because multiple plants are connected below-ground. Another consideration is whether the plant is an annual or perennial. If it is an annual, the long-term impact of removing a plant is less than if it is a perennial because the annual will die at the end of the growing season. Ordinarily, plant specimens should include the entire plant, roots and all; however, the destructive effects of making a collection of a rare, perennial plant can be mitigated by removing only the above-ground parts, because some plants can regenerate from the roots the following year.

WHY PROTECT RARE SPECIES IN IOWA?

Humans are one of 10 to 100 million species that inhabit the earth (Wilson 1992). Fewer than two million species have been described and we know virtually nothing beyond the names of most of those already documented, nothing of the potential economic and medical benefits they might provide (Wilson 1992). While most North American species of plants have been described, even in a state as small as Iowa and with as few natural habitats remaining, we still are finding previously undescribed species (albeit rarely), new state records for some (e.g., a population of Southern Adder's-tongue (Ophioglossum vulgatum L.) was discovered in southeast Iowa in 1994, Horton unpublished data), and county records for numerous species. And we have much to learn about the ecological role of the species that occur here. The remnants of natural habitats and the biodiversity they harbour are the natural heritage of this state and country. Learning about them -- which species are present; which species are rare; why some are common and some rare; the factors that control each species' occurrence; how each influences the occurrence of other species -- enriches our lives.

WHAT PROTECTION IS THERE FOR RARE SPECIES IN IOWA?

In 1973, the United States Endangered Species Act provided federal protection for plants as well as animals, and in 1975, the Iowa Legislature passed the Endangered Wildlife and Plants Act (Iowa Acts and Joint Resolutions 1975), which required the following:

• The State Conservation Commission [presently the Natural Resource Commission] "shall perform those acts necessary for the conservation, protection, restoration, and propagation of endangered and threatened species...". •The Director of the State Conservation Commission [presently the Director of the Department of Natural Resources] "shall conduct investigations on fish, plants and wildlife in order to develop information relating to population, distribution, habitat needs, limiting factors, and other biological and ecological data to determine management measures  necessary for their continued ability to sustain themselves successfully".

• The Commission "shall...promulgate a rule listing those species of fish, plants, and wildlife which are determined to be endangered or threatened within the state" based on the investigations enumerated above, "and other available scientific and commercial data, which may include consultation with scientists and others who may have specialized knowledge, learning, or experience...". • The Commission "shall review the state list of endangered and threatened species at least every two years and may amend the list". • The Director "shall establish programs, including acquisition of land or aquatic habitat, necessary for the management of endangered and threatened species".

Subsequently, the Management and Protection of Endangered Plants and Wildlife (Code of Iowa 1977) mandated preparation of a list of "fish, plants, and wildlife which are determined to be endangered or threatened within the state". The Iowa Administrative Code listings of Endangered and Threatened Plant Species, the first of which was published in 1977, provide legal protection for rare species, and the lists have proven crucial in preventing further destruction. For example, the Iowa Department of Transportation was required to reroute the Highway 63 Bypass around Eddyville because a population of the state threatened, Tubercled Orchid (Platanthera flava (L.) var. herbiola (R. Br.) Luer) was discovered in the path of the proposed bypass.

To date, five lists of endangered and threatened species have been published in the Iowa Administrative Code, in 1977, 1984 and 1986 (the latter two are identical), 1988 and 1994, and a sixth was proposed in 1998, but subsequently cancelled in response to public protest (written comments submitted to the Iowa DNR). In addition, in 1998, a list of 'candidate' species was circulated with the proposed list. There also are three reports on endangered and threatened plants, from 1978 (Roosa & Eilers 1978), 1986 (Roosa, Pusateri & Eilers 1986) and 1989 (Roosa, Leoschke & Eilers 1989), that correspond to the Iowa Administrative Code lists of 1977, 1984-86, and 1988. Only vascular plants were included in the five published lists; however, the 1998 proposed list also incorporated mosses, hepatics (liverworts), fungi (mushrooms/toadstools) and lichens.

WHY DO WE HAVE STATE, AS WELL AS FEDERAL, ENDANGERED SPECIES LISTS?

The federal lists of endangered and threatened species provide a continental perspective. Their focus is on species that are rare if one considers the country as a whole. Some of these species may be locally abundant at individual localities or even in some states; Northern Wild Monkshood (Aconitum noveboracense Gray) is one such species that occurs in Iowa. State lists are, by their very nature, constrained to a provincial focus. Their role is at the local level.

WHICH IOWA PLANTS ARE FEDERALLY LISTED?

Five species are federally listed, all as threatened. They are:

Northern Wild Monkshood (Aconitum noveboracense Gray)
Mead's Milkweed (Asclepias meadii Torrey ex Gray)
Prairie Bush Clover (Lespedeza leptostachya Engelm.)
Eastern Prairie Fringed Orchid (Platanthera leucophaea (Nutt.) Lindley)
Western Prairie Fringed Orchid (Platanthera praeclara Sheviak & Bowles)

HOW ARE RARE SPECIES CLASSIFIED IN IOWA?

Three categories, endangered, threatened and special concern, are used in the Iowa Administrative Code lists, but only species designated endangered and threatened have legal protection in Iowa. Endangered and threatened are defined in Iowa as they are federally. The special concern category was introduced in the 1988 Iowa Administrative Code and provides no legal protection. It is not used in the federal listings. Two other categories, extirpated (including presumed and possibly extirpated) and undetermined, are used in at least one of the three Endangered and Threatened Plant reports (Roosa & Eilers 1978, Roosa, Pusateri & Eilers 1986, Roosa, Leoschke & Eilers 1989), but not the Iowa Code or federal lists.

Endangered Species - "any species of fish, plant life, or wildlife which is in danger of extinction throughout all or a significant part of its range" (Iowa Acts and Joint Resolutions 1975) Threatened Species - "any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range" (Iowa Acts and Joint Resolutions 1975) Special Concern Species - "any species about which problems of status or distribution are suspected, but not documented, and for which no special protection is afforded" (Iowa Administrative Code 1988)

Extirpated (incl.Presumed Extirpated and Possibly Extirpated) - "formerly occurred as a native, reproducing population in Iowa but is no longer found there. However, it is still found in other states" (Roosa et al. 1989) Undetermined - "insufficient information has been compiled to make an evaluation of its status, but is of concern" (Roosa & Eilers 1978). This is replaced by 'special concern' in later reports.

WHAT ARE THE CRITERIA FOR LISTING PLANT SPECIES IN IOWA?

The functional criteria for determining whether a species will be included in the Iowa Administrative Code lists of endangered and threatened species are not given in the Code. It simply is stated that "The natural resource commission, in consultation with scientists with specialized knowledge and experience, has determined the following animal/plant species to be endangered, threatened or of special concern" (Iowa Administrative Code 1994). However, the primary criterion for the five Code plant lists published to date (1977 through 1994) has been rarity; that is, species known from a limited number of sites are listed.

The Code lists from 1977, 1984 and 1986 (the latter two are identical), and 1989 correspond to three reports on rare plants by Roosa and Eilers (1978), Roosa, Pusateri and Eilers (1986) and Roosa, Leoschke and Eilers (1989). All three contain distributional information for each species, and the second and third include county dot maps, with closed circles representing post-1950 records or extant occurrences and open circles representing pre-1950 records or sites known to have been destroyed. The dot maps are based on verifiable herbarium records, literature citations, and also sight records (someone has seen the plant, but there is no specimen record). Species designated endangered or threatened in these reports generally are known from less than five extant sites (~=counties), although a few are known from eight or nine because other factors were taken into consideration.

When the 1994 Code list was proposed in 1993, Dr. John Pearson of the Iowa Department of Natural Resources (DNR) circulated a "Rationale for listing of plant species as Endangered, Threatened, and Special Concern" (J. Pearson in litt. 1993). Again, the primary criterion was rarity: if a species occurred in five or fewer counties based on recent (post-1950) records, it would be considered for listing . Dr. Pearson reported that 387 species met this criterion (as in the rare plant reports cited above, in practice, some species considered for listing actually were known from more than five counties); however, an additional factor, 'Inventory Bias', also was taken into consideration. This was based on the premise that general inventories of sites result in collection bias. That is, species that are problematic taxonomically and those that occur in 'under-inventoried habitats', specifically, disturbed and aquatic habitats, will be under-represented in collections. When species in these categories were removed, a total of 151 species were left(J. Pearson in litt. 1993).

In the Code lists from 1977, 1984 and 1986, and 1989, a noteworthy exception to the rarity criterion is that species listed as extirpated (also presumed extirpated or possibly extirpated) in the rare plant reports (a total of 91 species in the three reports) are not included in the Code. These species are included in the 1994 Code list; however, they are designated special concern, so they have no legal protection if extant populations are found.

In October of 1998, a fifth list of endangered and threatened plant species was proposed, and Dr. Pearson provided a discussion of selection criteria and a list of candidate species (J. Pearson in litt. 1998). Although rarity was a fundamental criterion for placing a species on the candidate list, additional criteria were applied subsequently and these focused on 'natural habitats' and a 'regional perspective'. Species that occur in disturbed habitats were excluded from consideration, on the premise that disturbance-adapted species are more likely to persist. Species that occur only in the outer two tiers of counties were excluded, because they are presumed to be more common in adjacent states.

This 1998 proposed list was cancelled in early 1999 in response to public protest (written comments submitted to the Iowa DNR). Subsequently, Drs. Pearson and Daryl Howell organized a "State Endangered Species Expert Workshop", which was held on April 22, 1999. The Workshop was comprised of a series of presentations, and a short question/discussion period. Subsequently (9/24/99), Dr. Howell distributed a questionnaire (D. Howell e-mail, 9/24/99) to some specialists in the state, soliciting assessment of a list of 22 criteria. A year later (D. Howell e-mail, 9/18/00), he distributed an "Animal Species Evaluation Worksheet" with ten criteria. Species are assigned a score with respect to each criterion and the sum of these scores is used to determine whether a species will be listed.

Further revisions of the plant list have not been proposed; however, an amendment of the list of animal species was proposed recently (October 2001). As with the 1998 proposed plant list, this amended animal list is based on additional criteria, including "regional status, distribution changes since 1930, estimated habitat changes in the next 10 years and population trends" (Iowa DNR News, Natural Resource Commission, October 11, 2001). The criteria used were those on the "Animal Species Evaluation Worksheet" (see above), as well as "information and documentation of various experts" (D. Howell e-mail, 3/6/02).

HOW MANY PLANT SPECIES HAVE BEEN INCLUDED ON THE IOWA LISTS?

Vascular Plants

The number of listed species with legal protection (i.e., endangered and threatened) rose from approximately 150 in 1977 to nearly 200 in 1988, and then declined to 150 in 1994. One of the concerns regarding the list proposed in 1998 was that it would have further reduced the number of legally protected species to just over 100.

HOW FREQUENTLY ARE THE IOWA LISTS UPDATED?

The law (as specified in the Iowa Acts and Joint Resolutions 1975) requires that the endangered species lists shall be reviewed at least every 2 years; however, reviews have been conducted irregularly and less frequently (1977, 1984, 1986, 1988 and 1994).

WHAT SHOULD THE CRITERIA BE?

• The purpose of the state lists should be to focus at the local level and provide protection for any rare species, even though some of these species may be more abundant or even common in other parts of the country. Clearly, that is the intent of the Iowa endangered species legislation, which is to protect species "determined to be endangered or threatened within the state" (Code of Iowa 1977). Balsam Fir (Abies balsamea (L.) Miller) is an example of a species that is rare in Iowa, but relatively widespread and common in parts of Minnesota and Wisconsin.

• Considering how little we have left in Iowa, we should err on the side of caution. If there is any possibility that a species is rare, it should be given legal protection until proven otherwise; the onus should be on demonstrating that a species is not at risk, not that it is. Examples include such aquatics as one of the Duckweeds, Lemna perpusilla Torrey, and a Bur-reed, Sparganium androcladum (Engelm.) Morong. Both are known only from one or two sites, yet on the 1994 Iowa Code list, they are designated Special Concern, a category that gives no legal protection, and they were not on the 1998 DNR Proposed List.

• Endangered species lists should have a sound scientific basis. In the past, herbarium specimens, literature citations, and sight records have been the sources for the Iowa lists. However, on