(1991) What We Need to Know About Scientific Names

Home , Form (botany), Trifolium repens, Variety (botany)

What We Need to Know about Scientific Names: An Example with White Clover

Gary W. Fick* and Melissa A. Luckow

ABSTRACT scientific names add precision to communicationsabout Thereis a shortageof currentinformation on the nomencla- crops, and (iii) whyscientific namesfor a particular kind ture of cropsprepared for the classroom.This article is written of plant can change. Our primary goal is to illustrate and for studentsand instructors in the plantsciences withthe goal clarify the issues related to these three questions. In ad- of illustrating the applicationand usefulness of plant nomen- dition, we hope this article will encourageapplied scien- clature andrelated taxonomicconcepts. White clover (Trifoli- tists to consult taxonomists when they have questions umrepens L.) makesa goodexample. It is familiar to many about plant nomenclature. students,is easily grownfor classroomdemonstrations, and has an interesting nomenclatureto matchits great diversity. Its WHY NAMES CAN BE SO LONG nomenclatureis usedto explaininfraspecific names and authority designations.The history of scientific namesfor whiteclover Most persons with biological training will remember illustrates howand whynames change and howprecision in the rudiments of biological nomenclature. A species name scientific communicationcan be increasedby the use of scien- consists of two words: a genus name, which is capital- tific names.The main example for increasedprecision is the ized, and a specific epithet, whichis not capitalized. Both comparisonof the size groupsof whiteclover cultivars withthe are in Latin and are either underlined or italicized. In scientific namesfor the infraspecificranks of the samegroups. addition, the species name is followed by an authority Typespecimens and the associatedtaxonomic descriptions are designation that refers to the author of the name. In the requiredfor scientific namesand make permanent and objec- species namefor white clover, Trifolium repens L., Trifo- tive reference points. Thescientific namesrecommended for lium is the genus name,repens is the specific epithet, and the three commonsize groupsof white clover are the follow- Linnaeus(abbreviated L.) is the authority. If it is not con- ing: (i) Trifoliumrepens L. f. repens, the smallor wildgroup; fusing, the genus name may be abbreviated and the (ii) T. repensf. hollandicumErith ex Jfiv. &So6, the intermedi- authority deleted in subsequent uses in the same paper. ate or Dutchgroup; and (iii) T. repensvar. giganteumLagr.- Foss., the large or Ladinogroup. For example, the above may be shortened to T. repens once it is given in full. Whenwe need to find and use a scientific name, we trsE of scientific (Latin) names necessary for can look it up in a handy flora or a standard reference TrlEprecise communication of biological information such as Hortus Third (3). The confusion begins when across time (history) and space (languages and regions). find a nameof more than two Latin words or an authority As students, we are usually required to memorizescien- that is long and complicated. For a complexspecies like tific names, but it is more important that we knowhow white clover, additional Latin epithets sometimesfollow to interpret and use the scientific names we encounter. the species nameto indicate infraspecific subdivisions of Unfortunately, taxonomic instruction seems to be fre- the species. Such nameswill have designated ranks, usual- quently slighted in the applied plant sciences. This article ly subspecies (ssp.), variety (var.), or form (f.), and its accompanying appendices are intended to help latter (lower) rank encompassedby the former. A group teachers and students with limited taxonomic training of similar plants at any rank is called a taxon (plural, better understand, interpret, and use the scientific names taxa). The name for a taxon below the rank of genus of plants. should also have an authority that follows the name, e.g., White clover (Trifolium repens L.) was chosen as the T. repens ssp. nevadense (Boiss.) D.E. Coombe.The long example species because most plant science students authority for the subspecies nevadenseindicates that this (Homosapiens L.) will be familiar with this widely dis- kind of white clover was first described by Boissier (ab- tributed and commonplant. It can be easily grownin pots breviated Boiss.) in a different genus, as a separate for interesting classroom demonstrations that illustrate species, or at a different rank. It was later madea sub- various taxonomic concepts. The nomenclature of white species by D.E. Coombe. clover also provides ready examples of three points that The current rules of plant nomenclature (14, 18) allow often puzzle plant science students: (i) why "binomial" the taxonomist to define the factors that separate ranks, names are sometimes so long and complicated, (ii) how and this can cause confusion (4). Subspecies are usually defined as geographically distinct parts of a species, but G.W.Fick, Dep.of Soil, Crop,and Atmospheric Sciences, and Melissa both subspecies and varieties are variously defined as geo- A. Luckow,Bailey Hortorium, Cornell Univ., Ithaca, NY14853. Con- graphic, morphological, or economic(i.e., wild vs. weed tribution fromthe Dep.of Soil, Crop,and Atmospheric Sciences, Cor- nell Univ.Received 2 Feb. 1990.*Corresponding author. vs. crop) groups within a species (4). To avoid confusion, most taxonomists refer to subspecies or varieties but not Publishedin J. Agron.Educ. 20:141-147 (1991). both. Forms usually represent morphologically distinct

J. Agron. Educ., Vol. 20, no. 2, 1991 141 Table 1. Comparisonof citation systems found in the "long style" vated Plants (5) specifies that all infraspecific taxa main- of authority designation used with scientific names and refer- tained only by cultivation should be namedas cultivars ence listings used in society journals. Three taxa of white clover (cultivated varieties). Thus, scientific names for sub- serve as examples. species, varieties, and forms should only be used to refer Example Authorityor reference to wild plant populations. Such populations often Scientific namesand authority designations represent the progenitors of moderncrops, the source of 1. Trifolium repens L., Sp. PL 767. 1753. genes in breeding programs, and specialized populations 2. T. repens L. f. hollandicumErith ex Jhv. & So~, A MagyarnOvdnyvilhg of weeds and forages that have differentiated spontane- kdzikonyve 330. 1951. 3. T. repens L. var. giganteum Lagr.-Foss., F1. Tarn Garonne95. 1847. ously in agricultural situations. As a complexof cultivated and wild kinds, white clover challenges our References capabilities for precise scientific identification belowthe 1. Linnaeus, C. 1753. T. repens p. 767. In Species plantarum. 2. J~vorka, S., and R. Sod. 1951. T. repens L. p. 330-331. In A Magyar species level. n0vdnyvil~gk~zikOnyve. Akaddmiai Kiadd. The cultivated code (5) also allows "groups" of simi- 3. Lagreze-Fossat,A. 1847. T. repens,p. 94-95.In Florede Tam et Garonne.Rethord, Montauban. lar cultivars to be recognized. Agronomists frequently divide white clover cultivars on the basis of plant size into small, intermediate, and large groups (8, 11). The size but minor kinds of variability. Subsequent examples differences are important because they affect adaptation, illustrate infraspecific classification, but it should already productivity, and management options. For example, be clear that more than a binomial name might be needed small kinds are less productive than large kinds, but small with some complex species. kinds tolerate close continuous grazing. Large kinds Authority designations can also get complicated. The should be given recovery periods following close grazing. authority citation is really a reference to scientific litera- Caradus (6) briefly described 232 cultivars of white ture. The science of plant taxonomy has developed its clover namedin the literature, and relative size was one ownconventions of style for citing original references, of the main points of most descriptions. Because of vari- and there are three methods in use: able environments and previous interbreeding, there is 1. The short style in which the citation is reduced to complete overlapping of size amongso manykinds. For the author’s name, often abbreviated, e.g., Trifoo comparison, Caradus (6) used old and widely knowncul- lium repens L. tivars as reference points. Amongthe oldest cultivated 2. The name-and-year style in which the publication kinds of white clover used for size reference are the fol- year is added, e.g., T. repens L. 1753 lowing: 3. The long style in which the full reference is cited, 1. ’Kent Wild White’: a small cultivar certified in e.g., T. repens L., Sp. PI. 767. 1753 England in 1930 (6) The short style is commonlyused in scientific journals. 2. ’Dutch’: a widely exported agricultural ecotype of The name-and-year style is useful when names are being intermediate size that originated in the Netherlands comparedfor priority. The long style is used in taxonomic (6). Records of importation of Dutch white clover references where all possible ambiguities must be elimi- seed to England predate 1750 (8) nated (Table 1). The abbreviations for authors and pub- 3. ’Ladino Gigante Lodigiano’: a large agricultural lications are standardized in reference works consulted ecotype knownin Italy from at least 1760 (6). It was by taxonomists(23, 24) so that even the short style should widely exported, and in the U.S., the term "Ladi- be traceable to its original source. For this to be possi- no" denotes both the old cultivar name and the ble, care must be given to exactly reproduce authority group of large cultivars in general (11) designations. Good scientific writing requires that The above list illustrates the rules for namingcultivars: authority designations be included for species and in- cultivar names are to be capitalized, not in Latin (with fraspecific namesthe first time they are used. It is sim- exceptions), of no more than three words, and enclosed ply a matter of citing one’s sources. (Appendix I gives by single quotation marksthe first time they are used (5). more details about the rules of plant nomenclature.) Unfortunately, many cultivars that are properly named have not been carefully described or formally registered. BEING PRECISE Consequently, comparisons like those of Caradus (6) can be very useful to a plant breeder or farm advisor who Because crop scientists work mainly with species, var- is already familiar with white clover. However,relative ieties, and cultivars of plants, most of their taxonomic comparisons are not clear to someoneunfamiliar with the questions concern the names of species and infraspecific reference cultivar, and a reference cultivar maydisappear groups. White clover is a particularly rich example with when it becomes obsolete. Cultivar nomenclature can be at least 232 namedcultivars (6) and about 200 variations ambiguous because it lacks permanent reference points. of scientific names for wild populations (9, 25). Many Unlike a cultivar name, a scientific nameis based on of the 200 + scientific namesare redundant or illegiti- a preserved specimen (the type specimen) and a published mate under the rules of nomenclature, but recent reviews description that distinguishes that taxon from all other (15, 25, 27, 28) showthat there are about eight varieties kinds (14, 18). Consequently, scientific names provide (or subspecies) in the wild populations (Appendix II). about as precise and permanent a reference point as is The International Code of Nomenclature for Culti- possible. Erith (8) was the first to use scientific names

142 J. Agron. Educ., Vol. 20, no. 2, 1991 Table 2. Measurementsof the size for the three cultivated groups of white clover. believed that the genus Trifolium should be divided, one part becoming a new genus Amoria. White clover thus Plant Small group Intermediate Large group characteristic (Wild) group (Dutch) (Lad/no) becameA. repens (L.) K. Presl. This name is nowregard- ed as a synonym of T. repens by most taxonomists be- mm cause they do not believe the Amoria taxon warrants Petiole length~ mostly 25-65 mostly 50-75 up to 600 species status. If they did, A. repens would be the cor- Petiole length~ mostly 50-180 mostly 75-250 mostly >300 Leaflet length~" 6-16 9-22 up to 55 rect name. The authority designation of A. repens is Leaflet length¶ mostly <25 mostly 25-35 mostly >35 another example of the citation of two authors for one Pedunclelength’f < 120 > small group mostly >300 Stolon diam.¶ about 2.0 >3.3 name. The authority in parentheses (the "parenthetical Inflorescence authority") is retained because the delineation of the tax- diam.t mostly 15-20 mostly 15-25 up to 35§ on and the type of specimenare associated with that refer- FromErith (8). ence. The authority outside the parentheses (the FromHartwig (16). Plant characteristics are repeated for different sources. "combining authority") is added because the taxonom- FromSzab6 (25). Zohary and Heller (28) reported most are 30-35 mm. ic position (the genus or rank) has been changedby place- ment of the taxon into a "new combination" by that to define, in effect, wild progenitors of the three follow- authority and reference. ing cultivar groups: The evolution of taxonomicconcepts leading to several scientific namechanges is illustrated by the development 1. var. sylvestre Alef. ("wild white clover," of small of scientific names for the cultivated groups of white size) clover (AppendixIII). Erith’s system (8) was the first 2. var. sylvestre Alef. race hollandicum Erith ("white recognize three progenitors of the cultivated groups, but Dutch clover," of intermediate size) as far back as 1847, Lagreze-Fossat (19) proposed three 3. var. sylvestre Alef. race giganteum (Lagr.-Foss.) size taxa for white clover: (i) T. repens L. (the taxon of Erith ("Lodi or Italian white clover," of large size) Linnaeus); (ii) T. repens var. giganteumLagr.-Foss. (the These three groups are clearly associated with the old large kind); (iii) T. repens var. microphyllumLagr.-Foss. reference cultivars. However,they provide additional in- (a "very small" kind). formation because they have type specimens for refer- In 1866, Alefeld (1) simplified the concept by splitting ence and published descriptions to distinguish them. In the above groups in half and reducing the number of groups to two: (i) T. repens var. silvestre Alef. (the wild addition, Erith (8), Szab6 (25), and other workers meas- ured the variability in each of the three groups and kinds); and (ii) T. repens var. cultum Alef. (the cultivated recorded actual size ranges (Table 2). Although the size kinds). Ascherson and Graebner (2) and Gams(10) parameters have some inconsistencies and may not be agreed with that approach and formulated a taxonomy completely accurate for all environments where white to represent the degree of relatedness of the taxa in ques- clover is nowgrown, they certainly add quantitative de- tion. All were placed together in T. repens var. typicum tail to relative statements about size. Becausereference (Aschers. & Graebn.) Gamsin Hegi. Within this group standards exist for scientific namesbut not for those of were three forms: (i) f. giganteum (Lagr.-Foss.) Gamsin cultivars, the descriptions of cultivars as well as wild plant Hegi (large kinds); (ii) genuinum (Aschers. & Graebn.) populations becomemore precise if they can be related Gamsin Hegi (small and intermediate kinds); and (iii) to infraspecific taxonomic categories. f. microphyllum (Lagr.-Foss.) Gamsin Hegi (very small kinds). Erith’s 1924 revision (8) mentionedin the previous section replaced var. typicurn with the older name WHY NAMES CHANGE var. sylvestre Alef. She also split f. genuinumto recognize a distinct group of intermediate size, i.e., race hol- One of the main functions of botanical nomenclature landicum Erith. The result was three size-based taxa for is to provide a basis for determining the accepted scien- the progenitors of moderncultivars, with both hollandi- tific namefor each kind of plant. A basic rule is that the cum Erith and giganteum (Lagr.-Foss.) Erith given the accepted name will be the oldest name, beginning with rank of race. Erith (8) stated that f. microphyllum Species Plantarum written by Linnaeus in 1753 (14, 18). represented only environmentally stressed specimens of A scientific name can be changed if an older name with the small kind, var. sylvestre. It appears that no one has a type specimen and properly published description is proven otherwise. found for the same kind of plant. Since T. repens is found The names proposed by Erith (8) have also been in the starting reference, it cannot be replaced because changed, though the taxa she recognized still stand. After of priority. However, it has replaced other names. The Erith’s work, the rules of nomenclature were formalized Russian botanist C. von Steven (26) named a kind and specified that the nameof a taxon should be repeated white clover T. nothum Steven in 1856, apparently be- at lower ranks with the same type specimen. Thus, names lieving that it differed from the species already named such as typicum, genuinum, and sylvestre were replaced by Linnaeus. T. nothum is now regarded as a legitimate by repens in the scientific names for the kinds of white but incorrect name and is said to be a synonymof the clover. J~vorka and Sob (17) used the more standard rank accepted name, which is T. repens. of form (f.) as an alternative to the races of Erith (8), Another reason that a namecan change is the develop- and Zohary and Heller (28) reinstated the older treatment ment of new taxonomic concepts. Botanist K.B. Presl (21) of giganteum as a distinct variety. The three wild pro-

J. Agron. Educ., Vol. 20, no. 2, 1991 143 Table3. Aclassification of the wildprogenitors of cultivatedwhite tional rules that govern how plants are named. Those clover that combinesagronomic and taxonomic perspectives. rules are published in the International Code of Botani- Eachscientific nameis in a column. cal Nomenclature (14) and are revised every 6 yr. The Smallgroup Intermediategroup Largegroup rules apply to taxa that are organized into ranks as fol- Rank lWild~ {Dutch) {Ladinol lows: class, order, family, genus, species, subspecies, var- Trifolium Tdfolium Genus Tdfolium iety, and form. Classes are the largest units (have the Species repensL. repens repens Variety repens repens giganteum highest rank), forms the smallest. The rules of nomen- hollandicum Lagr.-Foss. clature only designate the order of ranks and do not at- Form repens giganteum tempt to define them. The rules at the species level and Erith ex Jhv. &Sod below are emphasized here because they are used most genitors of cultivated white clover maynow be designated frequently by crop scientists. 1. The accepted name for a species or infraspecific as follows: rank is the oldest legitimate ("legal") namefor the rank 1. Trifolium repens L. f. repens (the small kind) published in or after Linnaeus’ Species Plantarum in 2. T. repens f. hollandicum Erith ex Jfiv. & Sob (the 1753. More recent names for the same taxon are called intermediate kind) synonyms. Synonymsresult when an author inadvertently 3. T. repens var. giganteum Lagr.-Foss. (the large gives a new nameto a plant that has already been named. kind) Exceptions to the rule of priority are strictly regulated The names for the intervening ranks of these taxa are by the code. The choice of beginning publication was given in Table 3. purely arbitrary, but it nowserves as the starting point for all botanical nomenclature. FROM THE PRECISE TO THE RIDICULOUS 2. For a nameto be legitimate, it must be both effec- tively and validly published. Effective publication means After all this academic intricacy, someoneis likely to that the name appears in printed matter distributed to ask, "Whynot just say the white clover is a small, inter- the general public and maintained in science libraries. mediate, or large kind, and forget the Latin?" In some Valid publication meansthat the namesatisfies four addi- cases, that maybe adequate, but the adjectives are rela- tional requirements outlined below. tive and the species is highly variable across genotypes 3. To be valid, each name must have a genus and and environments. Scientific names provide well-defined specific epithet that are in Latin (see main text). The reference points that aid communication.The counter ar- names should agree in gender, but correction of gender gument follows that perhaps the desired result could be and modernization of spelling, e.g. silvestre for sylves- accomplished by simply designating a cultivar group tre, are allowed after the nameis published. Additional name, i.e., "Wild, Dutch, or Ladino." This would be Latin epithets for infraspecific ranks are allowed if they appropriate if only cultivated types were involved, but meet the other criteria for validity. Infraspecific ranks in a species like white clover, the scientific namesof the in addition to those designated in the code are allowed, wild progenitors makethe same distinction while adding e.g., "race" and "convariety." the precision of type specimens. Whenprecise scientific 4. To be valid, each scientific namemust have a pub- communication is important, scientific names including lished description that distinguishes that plant from all infraspecific ranks can be very helpful. Of course, culti- others (see main text). For any new name published af- var and cultivar group names should also be used ter 1958, the description must be in Latin. whenever they apply. 5. To be valid, each name must have an identifiable Other infraspecific names for kinds of white clover author. If the name has been changed in rank or genus, have also been proposed, but their use could lead to con- the original author is given in parentheses and is called fusion. Examplesinclude T. repens var. tetraphyllum Lej. the parenthetical authority. The author making the & Cour. (the four-leaf clover), var. fusco-maculatum change follows outside the parentheses and is called the Godet (the bloodwort with purple leaf blotches), and combiningauthority (see main text). Nobis (n. or nob.), roseum (Peterm.) Gams in Hegi (purple-flowered white mihi (m.), and hoc locus (h.c.) are used in place of the clover). Since the characteristics of distinction are under authority to show that the author of the publication is rather simple genetic control (27), a four-leaved, purple- the author of the name. Abbreviation for authors’ names blotched, purple-flowered kind could be found. What follows strict rules. The correct abbreviations for authori- should it be named?For such cases, phenotypic or geno- ties can be found in references (23) and (24). typic codes seem more appropriate than scientific names. 6. To be valid, each name must have a preserved refer- The guiding principle for the use of scientific names ence specimen known as the type specimen (see main should be to increase precision and to avoid confusion. text). The type specimen is the permanentreference point for a name, so if a name is changed in genus or rank, APPENDIX ! the type specimen can be located through the parenthetical authority. Additional Rules of Nomenclature 7. Several other special rules apply to authors’ names. For example, in Trifolium repens L. f. hollandicum Erith The most frequently applied standards of plant nomen- ex J/~v. & Sob, the term ex means that Erith first pro- clature were explained in the main text, but there are addi- posed the name but that J~tvorka and Sob provided the

144 J. Agron.Educ., Vol. 20, no. 2, 1991 valid description. Another commonlyencountered case able in Coombe(7), Gillett (12), and Zohary and Heller is exemplified by T. repens L. f. cultum (Alef.) Gamsin (28). Eight or nine main infraspecific groups are gener- Hegi. The taxon named culture by Alefeld was given a ally recognized, but specialists have not agreed on the new rank by Gamsin a book otherwise written by Hegi. rank of each taxon, and this results in variation in the 8. There are several errors that will cause a validly pub- number of groups. The most authoritative source is the lished nameto be illegitimate (nom. illegit.). One exam- recent monograph on Trifolium by Zohary and Heller ple is a later homonym,i.e., an author inadvertently chose (28), and the following list is based on their eight varie- a name that exactly duplicated a name used earlier for ties, here subdivided to accommodatetwo other widely a different taxon. The error is indicated as follows: T. recognized kinds. Wherethe rank is debated, the accepted macrorrhizum Boiss. non Waldst. & Kit. Bossier cor- name at the alternative rank is included in brackets. rected the mistake himself by altering the rank: T. repens L. var. macrorrhizum Boiss. His name does not occur Trifolium repens L. as the parenthetical authority because the first nameis Taxon1: var. biasolettii (Steud. & Hochst.) Aschers. illegitimate. Graebn. [ssp. prostratum Nym.] 9. A namemay also be illegitimate because it is super- ¯ flowers pale pink, heads mostly 14 to 18 mmdiam. fluous (nom. superfl.). For example, the Italian tax- ¯ petioles densely hairy, leaflets mostly 5 to 10 mm onomist Biasoletto proposed the name T. prostratum long Biasol. as an alternative for T. biasolettii Steud. & ¯ range: dry habitats and sunny slopes in the Mediter- Hochst. named in his honor. Because he knew the earli- ranean zone from France to Turkey er namealready existed for the taxon, the name he pro- Taxon lb: IT. occidentale D.E. Coombe= T. repens ssp. posed was superfluous. Nymanlater altered the rank of occidentale (D.E. Coombe)M. Lainz; treated as the same taxon in T. repens L. ssp. prostratum Nym. synonym of Taxon 1 by Zohary and Heller (28)] Biasoletto is not recognized as the parenthetical authori- ¯ similar to Taxon 1 but with slightly larger flower ty because his namefor the taxon is illegitimate. heads (mostly 20-24 mmdiam.) and sparsely hairy 10. Imprecise descriptions, careless interpretations, or petioles disregard for rules of the code can lead to misidentifica- ¯ range: sand dunes along English Channel and At- tion of a taxon or misapplication of the name, and such lantic coast of southern Europe mistakes may be perpetuated in the literature. The ab- Taxon 2: var. giganteum Lagr.-Foss. [var. repens f. breviation auct. (for authors) is used to showthat many giganteum (Lagr.-Foss.) Gamsin Hegi] authors have repeated the same mistake. The designation ¯ flowers white to pale pink, heads > 30 mmdiam. T. repens L. var. latum, auct. Amer. shows that many ¯ petioles mostly glabrous, leaflets mostly > 35 mm Americanauthors have used that namein error. (In this long case the name was invalid.) ¯ range: wild populations have been reported from 11. The following terms are also used in scientific around the Mediterranean names: Taxon3: var. macrorrhizum Boiss. [treated as synonym hort., hortulanorum: "found in gardens," a cultivar. of Taxon 1 by Greuter et al. (15)] nom. nud., nomen nudum’. "naked name," published ¯ similar to Taxon1 but with white flowers and thicker without description. taproots p. p., pro porte: "in part," only part of a taxon is in- ¯ range: mountains of Turkey and Iran cluded. Taxon 4: vat. nevadense (Boiss.) C. Vicioso [ssp. pro syn., pro synonymo: published "as a synonym." nevadense (Boiss.) D.E. Coombe] s. auct., sine auctorum: published "without author." ¯ flowers white and heads _< 20 mmdiam. This only begins the interesting and intricate details of ¯ petioles mostly glabrous, leaflets _< 10 mmlong botanical nomenclature. Crop scientists maynot need to ¯ range: mountains of Spain and Portugal knowall the rules, but they should be able to cite a valid Taxon 5: var. ochranthum K. Mal~ ex Aschers. & Graebn. [ssp. ochranthum (K. Mal~) Ny~r.] name, including the authority, and recognize the com- ¯ plicated cases where expert advice is needed. To deter- flowers yellowish and heads mostly 25 to 30 mm diam. mine the proper name and authority, two references are ¯ available: Index Kewensis (22), listing all plant names, petioles glabrous, leaflets _< 13 mmlong their authorities, and place of publication; and the Gray ¯ range: mountains of Romania and Bosnia Card Index (13), similar to (22) but containing only Taxon6: var. orbelicum (Velen.) Fritsch [ssp. orbelicum World plant names. (Velen.) Pawl.] ¯ flowers cream colored and heads _< 25 mmdiam. APPENDIX II ¯ petioles glabrous, leaflets mostly 6 to 8 mmlong ¯ range: Carpathians and mountains of Balkan Diversity of the Wild Populations of White Clover peninsula Taxon 7: vat. orphanideum (Boiss.) Boiss. [ssp. or- One of the more convincing arguments of the need for phanideum (Boiss.) D.E. Coombe] infraspecific taxa is the existence of distinct wild popu- ¯ flowers pale pink and heads of < 12 flowers lations within a species. Technical descriptions and keys ¯ petioles glabrous, leaflets mostly 3 to 7 mmlong to the main infraspecific taxa of white clover are avail- ¯ range: Sicily to Asia Minor

J. Agron. Educ., Vol. 20, no. 2, 1991 145 Taxon 8: var. repens L. var. repens f. hollandicum Erith ex Jav. & Soo 1951 • flowers white to pale pink, heads mostly 15 to 25 ("Dutch" white clover.) var. cultum Alef. 1866, p.p. var. giganteum Lagr.- mm diam. • petioles mostly glabrous, leaflets mostly 10 to 30 mm Foss. 1847. var. vulgare, s. auct. 1953, in Hartwig (16). long var. hollandicum, s. auct. 1987, in W.M. Williams (27). • range: temperate zones worldwide Taxon 8b: var. repens f. hollandicum Erith ex Jav. & Soo f. genuinum (Aschers. & Graebn.) Gams in Hegi 1923, p.p. f. repens. • similar to Taxon 8 but with slightly larger leaflets (up to 35 mm long) and longer petioles (up to 250 f. silvestre (Alef.) Gams in Hegi 1923, pro syn. of mm long) above. race hollandicum Erith 1924. • range: spontaneous in agriculture of the Netherlands, convar. hollandicum (Erith) Szabo 1988. now worldwide provar. praecox Szabo 1988. (A subset of convar. hol- The above classification of the infraspecific ranks of landicum above.) white clover may be altered in the future as more is provar. prolificum Szabo 1988. (Another subset of con- learned about ploidy level and hybridization of the vari- var. hollandicum above.) ous taxa. var. giganteum Lagr.-Foss. 1847. ("Ladino" white clover.) ssp. giganteum (Lagr.-Foss.) Ponert 1973. APPENDIX III var. cultum Alef. 1866, p.p. var. repens f. hollandicum Erith ex Jav. & Soo 1951. Synonymy for Cultivated Groups of White Clover var. latum, auct. Amer., s. auct. et nom. nud. 1894, in McCarthy and Emery (20). (Also spelled latus and At present, all cultivars of white clover appear to have lata.) been derived from three taxa (2, 8, and 8b of Appendix f. giganteum (Lagr.-Foss.) Gams in Hegi 1923. II) and their hybrids. The following list illustrates the f. lodigense hort. Gams in Hegi 1923, pro syn. of name-and-year method of citation used to show priority above. and history. Annotations include Latin abbreviations f. cultum (Alef.) Gams in Hegi 1923, pro syn. of above. used by taxonomists to indicate the status of a name. race giganteum (Lagr.-Foss.) Erith 1924. Within each of the three main taxa, names are grouped convar. giganteum (Lagr.-Foss.) Szabo 1988. by rank since priority applies within a rank. provar. bienne Szabo 1988. (A subset of convar. Trifolium repens L. 1753. (See Zohary and Heller [28] giganteum above.) and Szabo [25] for a list of synonyms at the species provar. perenne Szabo 1988. (Another subset of con- level.) var. giganteum above.) ssp. repens L. 1753. A.I. typicum Aschers. & Graebn. 1908. (Ascherson and Graebner's rank is ambiguous.) var. repens L. 1753. var. silvestre Alef. 1866. (Also spelled sylvestre and syl- vestrel.) var. typicum Fiori & Paol. 1900. p.p. ssp. prostration Nym. 1878. var. typicum (Aschers. & Graebn.) Gams in Hegi 1923 non Fiori & Paol. 1900. A.I.a. 1.0.7. genuinum Aschers. & Graebn. 1908. (Ascherson and Graebner's "outlined" rank is ambiguous.) var. repens f. repens L. 1753. ("Wild" white clover.) var. microphyllum Lagr.-Foss. 1847. (Erith [8] con- cluded var. microphyllum was simply a depauper- ate state.) f. genuinum (Aschers. & Graebn.) Gams in Hegi 1923, p.p. f. hollandicum Erith ex Jav. & Soo 1951. f. silvestre (Alef.) Gams in Hegi 1923, pro syn. of above. f. microphyllum (Lagr.-Foss.) Gams in Hegi 1923. (See var. microphyllum above.) convar. arcto-alpinum Szabo 1988. (A subgroup of small, cultivated white clovers.) convar. nanum Szabo 1988. (Another subgroup of small, cultivated white clovers.)

146 J. Agron. Educ., Vol. 20, no. 2, 1991 12. Gillett, J.M. 1985. Taxonomy and morphology, p. 7-69. In N.L. their economic value. Bull. North Carolina Agric. Exp. Stn. Taylor (ed.) Clover science and technology. Agron. Monogr. 25. 98:133-170. ASA, CSSA, and SSSA, Madison, WI. 21. Presl, K.B. 1830. Symbolae Botanicae 1:47. 13. Gray Herbarium of Harvard University. 1968-1986. Gray herbar- 22. Royal Botanic Garden at Kew. 1893-1987. Index Kewensis. Claren- ium index. Harvard Univ. Herbaria, Cambridge, MA. don Press, Oxford. 14. Greuter, W. (ed.). 1988. International code of botanical nomen- 23. Royal Botanic Garden at Kew. 1980. Draft index of abbreviations. clature. Koeltz Scientific Books, Konigstein. Her Majesties Stationary Office, London. 15. Greuter, W., H.M. Burdet, and G. Long. 1989. Trifolium repens. 24. Stafleu, F.A., and R.S. Cowan. 1976-1989. Taxonomic literature. Med-Checklist 4:189-190. 2nd ed. Bonn, Scheltema, and Holkema, Utrecht. 16. Hartwig, H.B. 1953. Legume culture and picture identification. 25. Szabo, A.T. 1988. The white clover (Trifolium repens L.) gene pool. M.S. Hartwig, Ithaca, NY. I. Taxonomical review and proposals. Acta Bot. Hung. 34:225-241. 17. Javorka, S., and R. Soo. 1951. A Magyar nOvenyvilag kezikOnyve. 26. von Steven, C. 1856. Verzeichniss der auf der taurischen Halbin- Akademiai Kiado, Budapest. sel wildwachsenden Pflanzen. Bull. Soc. Imp. Nat. Moscou 18. Jeffrey, C. 1990. Biological nomenclature. 3rd ed. Edward Arnold, 29(3):121-186. London. 27. Williams, W.M. 1987. White clover taxonomy and biosystemat- 19. Lagreze-Fossat, A. 1847. Flore de Tarn et Garonne. Rethore, Moun- ics. p. 323-342. In M.J. Baker and W.M. Williams (ed.) White tauban. clover. C.A.B. International, Wallingford, Oxon, UK. 20. McCarthy, G., and F.E. Emery. 1894. Some leguminous crops and 28. Zohary, M., and D. Heller. 1984. The genus Trifolium. Israel Academy of Science and Humanities, Jerusalem.