Karyosystematic study of Potentilla L. subgen. Potentilla (Rosaceae) in the Iberian Peninsula

Botanical Journal of the Linnean Society (2000), 132: 263–280. With 14 figures doi: 10.1006/bojl.1999.0296, available online at http://www.idealibrary.com on

Karyosystematic study of Potentilla L. subgen. Potentilla (Rosaceae) in the Iberian Peninsula LUIS DELGADO, FRANCISCA GALLEGO and ENRIQUE RICO∗ Departamento de Bota´nica, Universidad de Salamanca, E-37007 Salamanca, Spain Received March 1999; accepted for publication July 1999

Chromosome numbers in 80 populations belonging to 18 species of Potentilla L. subgen. Potentilla from the Iberian Peninsula and two of P. maura, a North African endemic taxon, have been counted. The basic number of chromosomes is always x=7 and these chromosomes are small (between 1 and 2 lm). For three species, the number of chromosomes is reported for the first time and, for another six, this number has been established in Iberian representatives. Moreover, new ploidy levels have been obtained for P. hispanica and P. crantzii with regard to their entire distribution area, and in P. cinerea and P. neumanniana for the Iberian Peninsula. Some taxonomic, phylogenetic and phytogeographic comments are made for several species or groups of species from the West Mediterranean region. In 13 species only one ploidy level has been found, but six species have several ploidy levels. Seven ploidy levels occur in the investigated taxa. The frequency of each ploidy level represented within Iberian Potentilla is analysed and the data are compared with those available for taxa from the rest of the distribution area of the genus.  2000 The Linnean Society of London

ADDITIONAL KEY WORDS:—chromosome numbers – cytotaxonomy – polyploidy – Western Mediterranean. CONTENTS

Introduction . . . . . . Material and methods . . Results and discussion . . Potentilla pensylvanica group Potentilla recta group . . Potentilla pyrenaica group . Potentilla crantzii group . Polyploidy . . . . . Acknowledgements . . . References . . . . . .

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263 265 268 271 272 275 276 277 279 279

INTRODUCTION

The genus Potentilla L. comprises more than 300 species distributed mainly in temperate regions of the northern hemisphere. Most of these belong to subgenus ∗ Corresponding author. E-mail: [email protected] 0024–4074/00/030263+18 $35.00/0

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Potentilla. The most informative monograph of this genus was made by Wolf (1908), who recognized 305 species and divided the genus into two sections, Trichocarpae and Gymnocarpae, and several subsections, series and grex or groups of species. Several divisions into subgenera have been proposed, such as that by Ball, Pawlowski & Walters (1968). According to Guille´n & Rico (1998), in the Iberian Peninsula there are 30 species from four subgenera, Trichothalamus (Spreng.) Rchb., Comarum (L.) Syme, Fragariastrum (Heist. ex Fabr.) Rchb. and Potentilla, the last comprising 22 species and, from a taxonomic point of view, the most difficult. Potentilla is a complex genus; the great variability of some of its characters indicates extensive polymorphism. The existence of inter- and intraspecific hybridization and apomixis frequently gives rise to specimens with intermediate characters. As stated by Eriksson, Donoghue & Hibbs (1998), the genus is comparatively easy to recognize, but the apomorphic character states have not yet been defined. According to these authors and on the basis of data obtained from DNA sequencing studies, Potentilla seems to be a polyphyletic genus. Nevertheless, this study has been made on a small number of species from the genus, many quite isolated, with only eight belonging to subgen. Potentilla. Even this subgenus is polyphyletic, according to the results obtained by Leht (1996) from a cladistic analysis based on those morphological characters used by Wolf. In spite of the great variability and polyphyly displayed by this genus, it shows a constant basic number of x=7 chromosomes throughout its distribution area. Moreover, as suggested by Stebbins (1950) and clearly pointed out by Meˇsı´cˇek & Soja´k (1993), two different groups of species can be recognized within Potentilla. On one hand are those species having a stable number of chromosomes all over their distribution area and, on the other, those taxa which are polyploid complexes, whose chromosome numbers vary inside small areas and even within the same population. Karyological studies of Potentilla began in the early 1930s (Shimotomai, 1930). Many studies in this field are included in wider and more general papers on subjects such as apomixis, polymorphism and sexuality in some northern species, e.g. those by Mu¨ntzing (1931, 1958), Mu¨ntzing & Mu¨ntzing (1941) and Asker (1970). Other relevant and more specific studies are those by Skalin´ska & Czapik (1958) on European species and Meˇsı´cˇek & Soja´k (1992, 1993) on Asiatic species, both using chromosome count data in order to survey hypothetical relationships among several species. Iwatsubo & Naruhashi (1991) have analysed the karyotype of nine Japanese species and have made karyomorphological and cytogenetic studies of them. Nevertheless, in most cases only isolated counts have been made and these are recorded in several general indexes of plant chromosome numbers. There is no detailed cytogenetic study of the subgenus Potentilla in the Iberian Peninsula previous to this one. Evenly spread counts were not frequent and usually concerned species rather isolated phylogenetically from the rest of the Iberian Potentilla. Moreover, before 1950 the origin of the material is quite uncertain, since in many cases it had been gathered from collections growing in botanic gardens (i.e. P. pyrenaica and P. nevadensis). Lo¨ve & Kjellqvist (1974) and Asker (1985) have provided most of the chromosome numbers. In Table 1 previous counts on Iberian material are shown, together with those for P. hispanica, P. × ibrahimiana and P. maura. Neither the number of species (ten) whose chromosome number was found, nor the number of populations in which this number had been surveyed were enough to give a clear idea on the karyology of the subgenus in the Iberian Peninsula. In this paper 18 species are surveyed from the 22 representatives of the subgenus

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T 1. Previous counts in species of subgen. Potentilla in the Iberian Peninsula, and those for three taxa in Morocco n

Species

Authors

P. argentea

Asker (1985)

P. brauniana

Ku¨pfer (1968) Ku¨pfer (1974)

14

14

2n

Localities

14 SPAIN. Huesca, Bielsa, Hospital de Parzan 14 SPAIN. Huesca, Balneario de Panticosa 14 SPAIN. Navarra, Sierra de Leyre ANDORRA. Pic de Casamanya 14 SPAIN. Huesca, Pico de la Garganta de Borau 14 SPAIN. Santander, Picos de Europa

P. cinerea

Ku¨pfer (1968)

P. crantzii

Asker (1985)

28 SPAIN. Huesca, Hecho, Sierra de Agu¨eri 42 SPAIN. Huesca, Anso´, Pen˜a Ezcaurri 42 SPAIN. Leo´n, Pico Espigu¨ete

P. erecta

Lo¨ve & Kjellqvist (1974) Castroviejo (1983)

28 SPAIN. Cuenca, Tragacete-Can˜ete 28 SPAIN. Pontevedra, Ga´ndaras de Porrin˜o

P. hispanica

Galland (1988)

P. x ibrahimiana

Galland (1988)

P. maura

Galland (1988)

P. neumanniana

Lo¨ve & Kjellqvist (1974) Asker (1985)

42 42 42 42

P. nevadensis

Shimotomai (1930) Popov (1939, see Bolkhovskikhet al.1969) Gustafsson (1947, see Bolkhovskikhet al.1969)

28 SPAIN ? 14 SPAIN ?

Shimotomai (1930) Popov (1939, see Bolkhovskikhet al.1969)

28 Pyrenees ? 77 Pyrenees ?

P. pyrenaica

14

SPAIN. Granada, Sierra Nevada

MOROCCO. Amzdour, Siroua 42 MOROCCO. T-n-Targa, Seksaoua 42 MOROCCO. Tirrhist, Masker

14

MOROCCO. Col/Assif-n-Arous, M’Goun 28 MOROCCO. Tichchoukt 28 MOROCCO. Taarbat, Ayachi SPAIN. Teruel, Sierra de Albarracı´n (sub P. reuteri ?) SPAIN. Huesca, Santa Orosia SPAIN. Teruel, El Portillo Guadalaviar SPAIN. Huesca, Barranco de Lapillera (sub. P. guarensis P. Montserrat) 49 SPAIN. Burgos, Lecinana de Mena 63 SPAIN. Huesca, Nocito, Sierra de Guara (sub. P. scoparioides P. Montserrat)

28 SPAIN ?

P. reptans

Lo¨ve & Kjellqvist (1974)

28 SPAIN. Jae´n, Sierra de Cazorla.

P. rupestris

Lo¨ve & Kjellqvist (1974)

14 SPAIN. Teruel, Sierra de Albarracı´n.

in the Iberian Peninsula. It has not been possible for us to study any population of P. brauniana, P. grandiflora, P. aurea or P. frigida. Thus, in the last three the chromosome number remains unknown in the Iberian Peninsula. With the aim of obtaining a better interpretation of the group, several counts on populations from Morocco of P. hispanica and others of the north African endemic P. maura have been carried out.

MATERIAL AND METHODS

Eighty-two populations from the Iberian Peninsula and Morocco have been studied (Table 2). Voucher specimens are kept at the following herbaria: SALA

L. DELGADO ET AL.

266

T 2. Material studied and chromosome numbers found. Localities, collectors and voucher specimens Species

n

P. anserina L. subsp. anserina

2n

Localities, collectors

Voucher

28

SPAIN. Santander: San Vicente de la Barquera, Delgado et al. SPAIN. Zamora: Zamora, Rico ´ vila: Hoyos del Espino, Delgado et al. SPAIN. A ´ vila: Navacepeda de Tormes, Delgado & SPAIN. A Martı´nez Ortega ´ vila: Piedrahı´ta, Puerto de la Pen˜a Negra, SPAIN. A Delgado et al. ´ vila: Hoyocasero, Pinar de Hoyocasero, SPAIN. A Delgado et al. ´ vila: Hoyos del Espino, Martı´nez Ortega & SPAIN. A Rico ´ vila: Hoyos del Espino, Plataforma de SPAIN. A Gredos, Delgado et al. ´ vila: Piedrahı´ta, Puerto de la Pen˜a Negra, SPAIN. A Martı´nez Ortega SPAIN. Palencia: Cardan˜o de Abajo, Espigu¨ete, Gira´ldez et al. SPAIN. Palencia: Santiba´n˜ez de la Pen˜a, Gira´ldez et al. SPAIN. Salamanca: Fuenteguinaldo, Martı´nez Ortega et al. SPAIN. Salamanca: Monleo´n, Delgado & Sa´nchez Agudo SPAIN. Salamanca: Navarredonda, Delgado & Sa´nchez Agudo SPAIN. Salamanca: Navasfrı´as, Martı´nez Ortega et al. SPAIN. Salamanca: Navasfrı´as, El Bardal, Martı´nez Ortega et al. SPAIN. Segovia: Cerezo de Arriba, La Pinilla, Martı´nez Ortega SPAIN. Segovia: Matabuena, Delgado et al. SPAIN. Zamora: Ribadelago, Herna´ndez & Rico SPAIN. Zamora: San Martı´n de Castan˜eda, Herna´ndez & Rico

SALA 94908

14 P. argentea L.

14 14 14

P. asturica Rothm.

14 7

14

7

14

7

14

7

14

7 7

14 14 14

7

14

7

14 14

7

14 14 14 14

P. cinerea Chaix ex Vill.

21 42

P. crantzii (Crantz) Beck ex Fritsch

42 21

42 35

P. erecta (L.) Raeusch.

28

14

28 28 28

7

14 14

7

14

P. hirta L.

SALA 94909 SALA 94910 SALA 95375 SALA 94911 SALA 94917 SALA 94661 SALA 94918 SALA 94659 SALA 59695 SALA 94663 SALA 94924 SALA 94921 SALA 94920 SALA 94660 SALA 94913 SALA 96859 SALA 94923 SALA 94915 SALA 94916

SPAIN. Granada: Baza, Sierra de Baza, Martı´nez Ortega et al. SPAIN. Soria: Abejar, Rico

SALA 94951

SPAIN. Palencia: Puerto de Piedrasluengas, Delgado et al. ´ liva, SPAIN. Santander: Fuente De´, Collado de A Delgado et al. ´ liva, SPAIN. Santander: Fuente De´, Collado de A Delgado et al.

SALA 94968

PORTUGAL. Tras-O-Montes: Mogadouro, Serra da Variz, Herna´ndez & Rico SPAIN. Oviedo: Pimiango, Delgado et al. SPAIN. Salamanca: San Miguel de Valero, Delgado et al. SPAIN. Zamora: Ribadelago, Lago de Sanabria, Delgado

SALA 90814

SPAIN. SPAIN. Ortega et SPAIN. Ortega et

Gerona: La Junquera, Vin˜as et al. Granada: Baza, Sierra de Baza, Martı´nez al. Granada: Puerto de la Ragua, Martı´nez al.

SALA 96415

SALA 94969 SALA 94969

SALA 94926 SALA 94925 SALA 94927 HGI 6434 SALA 94949 SALA 94671 continued

KARYOSYSTEMATICS OF POTENTILLA SUBGEN. POTENTILLA

267

T 2. continued Species

n

P. hispanica Zimmeter

2n

Localities, collectors

Voucher

35 49 42

MOROCCO. Marrakech: Oukaı´meden (I), Aedo et al. MOROCCO. Marrakech: Oukaı´meden (II), Aedo et al. MOROCCO. Taroudant: Jbel Siroua, Amasine, Aedo et al. MOROCCO. Taroudant: Jbel Siroua, Peak Amzdour, Aedo et al. SPAIN. Granada: Alfacar, Sierra de Alfacar, Martı´nez Ortega et al.. SPAIN. Jae´n: Mancha Real, Sierra de Ma´gina (I), Delgado et al. SPAIN. Jae´n: Mancha Real, Sierra de Ma´gina (II), Delgado et al.

SALA 94945 SALA 94946 SALA 94947

35 35 49 49

SALA 94674 SALA 94952 SALA 96319 SALA 97642

P. inclinata Vill.

42

SPAIN. Gerona: La Junquera, Aedo et al.

MA 528781

P. maura T. Wolf

28 28

MOROCCO. Marrakech: Oukaı´meden, Aedo et al. MOROCCO. Taroudant: Jbel Siroua, Peak Amzdour, Aedo et al.

SALA 94675 SALA 94674

49

SPAIN. Granada: Puebla de Don Fabrique, Martı´nez Ortega et al. SPAIN. Jae´n: Hornos, Rico et al. SPAIN. Segovia: Cerezo de Arriba, Delgado et al. SPAIN. Soria: Ucero, river Lobos, Rico SPAIN. Soria: Lodares de Osma, Rico SPAIN. Teruel: Albarracı´n, Monte Ortezuelo, Rico SPAIN. Teruel: Frı´as de Albarracı´n, sources of river Tajo (I), Rico SPAIN. Teruel: Frı´as de Albarracı´n, sources of river Tajo (II), Rico

SALA 94932

14 P. neumanniana Rchb. 28

28

56 42 42 56 56 56 49

P. nevadensis Boiss.

P. pyrenaica Ramond ex DC.

SALA 94928

28 28

SPAIN. SPAIN. SPAIN.

14

28

SPAIN.

Granada: Puerto de la Ragua (I), Martı´nez al. Granada: Puerto de la Ragua (II), Martı´nez al. ´ vila: Solosancho, Delgado et al. A Burgos: Canicosa de la Sierra, Aran Segovia: Lastras de Cue´llar, Delgado et al. ´ vila: Hoyos del Espino, Delgado et al. A

14 14 14

28 28 28

SPAIN. SPAIN. SPAIN.

´ vila: La Herguijuela, Delgado et al. A ´ vila: Piedrahı´ta, Delgado et al. A ´ vila: Santiago del Collado, Delgado et al. A

SALA 94935 SALA 94936 SALA 94937

28

SPAIN. SPAIN. SPAIN. SPAIN. Ortega et SPAIN. SPAIN.

Ca´ceres: Ban˜os de Montemayor, Rico Ca´ceres: Cabezuela del Valle, Rico Ciudad Real: Fuencaliente, Delgado et al. Granada: Alfacar, Sierra de Alfacar, Martı´nez al. Salamanca: La Orbada, Rico et al. Salamanca: Los Santos, Amich & Bernardos

SALA 94940 SALA 94941 SALA 96331 SALA 94960

SPAIN. Salamanca: Mogarraz, Delgado & Sa´nchez Agudo SPAIN. Salamanca: Montemayor del Rı´o (I), Delgado & Sa´nchez Agudo SPAIN. Salamanca: Montemayor del Rı´o (II), Rico & Romero SPAIN. Salamanca: Salamanca, Sa´nchez Agudo SPAIN. Salamanca: San Esteban de la Sierra, Delgado et al. SPAIN. Segovia: Matabuena, Delgado et al. SPAIN. Zamora: Argujillo, Rico

SALA 94964

28 28

P. pensylvanica L.

SALA 94933 SALA 94931 SALA 96414 SALA 94930 SALA 94929 SALA 94943

14

P. recta L. 14 14

28 28

14

42 28 28 28 28 28 28 42 56

SPAIN. Ortega et SPAIN. Ortega et

SALA 94677 SALA 96808 SALA 94938 MA 545632 SALA 94953 SALA 94934

SALA 94681 SALA 94961

SALA 94658 SALA 94980 SALA 95376 SALA 94959 SALA 94962 SALA 94939 continued

L. DELGADO ET AL.

268

T 2. continued Species

n

2n

Localities, collectors

14

28 28 28 28 28

SPAIN. SPAIN. SPAIN. SPAIN. SPAIN.

14

28

14

28

7

14

14

SPAIN. Granada: Baza, Sierra de Baza, Prados del Rey (I), Martı´nez Ortega et al. SPAIN. Granada: Baza, Sierra de Baza, Prados del Rey (II), Martı´nez Ortega et al. ´ vila: Hoyocasero, Cueva del Maragato, SPAIN. A Delgado et al. ´ vila: La Herguijuela, Delgado & Martı´nez SPAIN. A Ortega SPAIN. Zamora: Ribadelago, Herna´ndez & Rico

SALA 94954

28

SPAIN. Ca´ceres: Ca´ceres, Guadiloba reservoir, Rico

SALA 92312

P. reptans L.

P. reuteri Boiss.

P. rupestris L.

7 7 P. supina L.

Jae´n: Hornos, Martı´nez Ortega et al. Leo´n. Mirantes de Luna, Delgado et al. Salamanca: Castellanos de Villiquera, Rico Salamanca: San Miguel de Valero, Delgado et al. Zamora: Argujillo, Rico

Voucher SALA 94967 SALA 94955 SALA 94966 SALA 94956 SALA 94957 SALA 94912 SALA 94950 SALA 94965 SALA 94963

(University of Salamanca, Spain), MA (Real Jardı´n Bota´nico de Madrid) and HGI (Herbario del Collegi Universitari de Girona). Chromosome counts were made mostly using young floral buds, from which very immature anthers were selected, although sometimes mitosis was observed in cells of the gynoecium. Young radicles from seedlings and root tips taken from living plants directly in the field were rarely used, as they usually did not produce good results. Material was fixed in 3:1 absolute ethanol-glacial acetic acid, or sometimes 6:1, which gave quite good results. Fixed material was stored at 4°C until required. It was stained with 2% acetic orcein and squashed in 45% acetic acid. From each population at least five counts were made from which chromosomes were drawn and photographs were taken through a Nikon Optiphot microscope. Drawings and negatives are deposited in the Department of Botany of the University of Salamanca. Concerning nomenclature, delimination and arrangement of taxa, we follow Guille´n & Rico (1998).

RESULTS AND DISCUSSION

The main results are given in Table 2, in which the chromosome numbers of the 82 studied populations are shown. There the species appear in alphabetical order, together with the haploid and/or diploid number, locality, collectors, herbarium and number of voucher. From the 19 studied species, the chromosome number is here given for the first time for P. asturica, P. reuteri and probably for P. hirta s. s. This number has been found for Iberian material in the cases of P. anserina subsp. anserina, P. hispanica, P. inclinata, P. pensylvanica, P. recta and P. supina. We have found new ploidy levels in P. hispanica and P. crantzii throughout their entire distribution area and in P. cinerea and P. neumanniana within the Iberian Peninsula. We intended to study three populations of each species, but in particularly interesting cases such as those of P. asturica (15), P. recta (13) and P. hispanica (7), this

KARYOSYSTEMATICS OF POTENTILLA SUBGEN. POTENTILLA

269

number was increased. Populations of P. hispanica from Morocco were also studied due to the small number of populations known in the Iberian Peninsula. As regards P. hirta or P. reuteri, both taxa of very great interest, only a few populations have been investigated, as their distribution area is very small in the Peninsula or the populations contain few individuals (P. reuteri). All the Iberian populations of subgen. Potentilla, including both those studied by us and by other authors, have a basic number of x=7 chromosomes. Commonly they have a quite uniform karyotype and the chromosomes are small in size (between 1 and 2.5 lm). Where large enough to be determined they are submetacentric. Thus, our observations agree with those by Iwatsubo & Naruhashi (1991), although we did not see the satellites that they reported. In the following discussion of our results we will consider first of all those species phylogenetically isolated from the remaining Iberian Potentilla, then those groups of species including two or more clearly related taxa. We have given a name to these last groups, this corresponding to one of the most representative Iberian species from those investigated which are included in the groups. These groups partially correspond with the grex defined by Wolf (1908), most of them being monophyletic (Leht, 1996). It is our intention to avoid giving to those groups names of non-Iberian species that in some cases correspond to groups that are too wide and heterogeneous, e.g. Grex Multifida. Neither do we follow Wolf in considering the taxa P. grandiflora, P. pyrenaica, P. nevadensis and P. maura as members of the same group. In Wolf’s opinion, the first two taxa should be included into one group (Grex Grandiflorae), while the last two species were considered by him to be members of a different group, Grex Persicae. P. anserina L. subsp. anserina We have studied two populations, both tetrapoid with 2n=28. The tetraploid level dominates throughout the distribution of the species, although in North America and northern Europe a few hexaploid populations have been found (Rousi, 1965). P. rupestris L. The diploid number 2n=14 found by Lo¨ve & Kjellqvist (1974) is confirmed by our results. Counts made on populations from 16 localities throughout the distribution area of this species gave the same result. Only Delay (1947, see Bolkhovskikh et al., 1969) seems to have obtained 2n=16 as a chromosome number for P. rupestris. Nevertheless, this is exceptional and is probably mistaken, due to the constancy of this taxon otherwise. P. argentea L. We have studied three populations from the Iberian Sistema Central, all with the same chromosome number, 2n=14, as also found by Asker (1985) in three populations from the Pyrenees. In northern and central Europe this taxon presents a variable ploidy level, from diploid to enneaploid (9×) (Asker, 1970, 1971; Markova, 1982; Leht & Paal, 1998). In the Iberian Peninsula P. argentea seems to have a unique ploidy level, since in the six populations studied only diploid plants have been detected. It is possible that these are perhaps ancient relict populations conserved in warm southern areas, but it seems more likely that they represent a more or less recent arrival of diploids to the Peninsula in areas favoured by man, as this species

270

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occurs in disturbed places (ditches, roadsides, nitrophilous pastures, wood edges, etc). P. inclinata Vill. This species occupies a very small area in the Iberian Peninsula, as it is found only in the north-east part. The chromosome number here detected is 2n=42, a hexaploid. This finding agrees with studies made in the rest of its distribution area, except for Bulgaria, where there are occurrences of 2n=14, 28, 35 and 84 (Markova, 1982). According to Ball et al. (1968) this taxon seems to be an intermediate species between P. argentea group and P. recta. It is probably an allopolyploid, which has at least one distinctive character of the P. argentea group, the presence of crispate hairs on the abaxial face of the leaf, while among those characters shared with P. recta is the possession of a rugose-cristate fruit. P. supina L. The tetraploid level (2n=28) agrees with that predominant in the species. This is the only known level in Europe and corresponds to subsp. supina according to Meˇsı´cˇek & Soja´k (1992). P. reuteri Boiss. We have obtained 2n=28, which does not agree with the previous count reported for this species. Lo¨ve & Kjellqvist (1974) found 2n=42 in plants collected at the Sierra de Albarracı´n (Teruel Province, Spain), where this species is not known to occur. Vouchers could not be located, so it was not possible for us to check the material. In our opinion this probably be a mistaken determination and this count by Lo¨ve and Kjellqvist corresponds to either of the more frequent species which are found in the Sierra de Albarracı´n, P. neumanniana or P. cinerea—probably the former, as the latter can be easily distinguished by its stellate hairs. P. reuteri is an Iberian endemic species growing in mountain pastures of south-east Spain: Sierra Nevada, Ma´gina, Cazorla-Segura and Baza. We have counted the number of chromosomes in plants from two different populations collected in the Sierra de Baza, where the number 2n=28 (tetraploid) has been obtained. This taxon has been sometimes confused with P. hirta and P. nevadensis, due to an incorrect interpretation of the species and the coincidence of their distribution areas. Nevertheless, in our opinion P. reuteri is probably related to neither of these two species, nor to any of the other Iberian representatives of the genus, as can be seen from its distinctive characters such as unbranched stock, deeply divided leaf segments and rugose hairs. Ball et al. (1968) considered that P. reuteri is a species probably of hybrid origin from P. recta and P. nevadensis. Although from a karyological point of view this hypothesis could be defended, in our opinion it should be rejected considering all the previously-mentioned characters. P. reuteri is a species phylogenetically isolated from the remaining Iberian Potentilla, it has a very small distribution area and the few known populations comprise a small number of individual plants. This makes us think that P. reuteri is maybe a species of ancient origin in spite of its tetraploid level (palaeopolyploid). This is a palaeoendemic taxon according to Favarger & Contandriopoulos (1961).

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P. erecta (L.) Raeusch. The counts of 2n=28, made on three Spanish and one Portuguese population, confirm previous results by Castroviejo (1983) and Lo¨ve & Kjellqvist (1974). This tetraploid level is widespread throughout its distribution area. Nevertheless, two counts differ from the rest, with 2n=18 obtained by Davlianidze (1985, see Goldblatt, 1988) and 2n=35 by Skalin´ska & Czapik (1958). P. reptans L. We found 2n=28, the same number that Lo¨ve & Kjellqvist (1974) recorded in another Spanish population. For this species there are 22 tetraploid counts, one of 2n=42 by Skalin´ska & Czapik and another of 2n=20 by Davlianidze (1985, see Goldblatt, 1988). For these two previous species, P. erecta and P. reptans, those unusual counts reported to be by Davlianidze could have been typographical mistakes (18 instead of 28) or mis-identifications of the plants involved, as both species seem to be very stable from a karyological point of view. The exceptional nature of the counts by Skalin´ska & Czapik (1958) was also commented upon by the authors. Potentilla pensylvanica group The representatives of this group in the Iberian Peninsula are P. pensylvanica and P. hispanica, both with pinnatisect leaves, terminal floral stems and a large number of flowers with yellow petals, but they have differing karyological behaviour. The ploidy level is stable in P. pensylvanica, while P. hispanica is a polyploid complex, not only within the Iberian Peninsula but also in North Morocco. According to Sa´nchez Agudo, Rico & Sa´nchez Sa´nchez (1998) some differences involving pollen characters have been observed between them: P. pensylvanica has a pollen grain very stable in size and shape, while P. hispanica shows great size variability, thus reflecting the existence of several ploidy levels within the taxon. P. pensylvanica L. The chromosome number found in the three studied populations is 2n=28. This species, with small petals and anthers, is almost always tetraploid (Lo¨ve & Lo¨ve, 1982; Goldblatt & Johnson, 1990), although there is the remarkable exception of a diploid count by Ward & Spellenberg (1988) in New Mexico. It would be interesting to check whether this American diploid plant is really P. pensylvanica, as it could be a different taxon closely related to it, being in this case a patroendemic element in the sense of Favarger & Contandriopoulos (1961). There are other counts also referred to P. pensylvanica: 2n=42 (Acharya Goswami & Matfield, 1975) and 2n=35, 84 (Popov, 1939, see Bolkohvskikh et al., 1969). In both cases the original material had been collected from botanic gardens and was of uncertain origin. In our opinion, it is possible to think that these high ploidy levels could correspond to species related to P. sericea and not to the true P. pensylvanica. P. hispanica Zimmeter In spite of the few localities of this plant in the Iberian Peninsula, we were able to study three populations. These have different chromosome numbers: 2n=35 (Fig.

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2) and 2n=49. Four other populations from Morocco have also been studied, in which we found several ploidy levels: pentaploid (2n=35) (Fig. 3), hexaploid (2n= 42) and heptaploid (2n=49) (Fig. 4). Both our results and those of Galland (1988), 2n=28, 42, show that P. hispanica, a plant with large petals and anthers, is a polyploid complex with at least four different ploidy levels. In our opinion, P × ibrahimiana Maire (2n=42, Galland, 1988) should be included under the variability of P. hispanica. This North African taxon has been considered to be an intermediate plant of hybrid origin probably between P. hispanica and P. recta. Nevertheless, from a morphological point of view, P × ibrahimiana does not present significative differences from P. hispanica with respect to more relevant characters, such as leaf division, type of style and fruit ornamentation. Moreover, carefully studying the available specimens of P × ibrahimiana, we could not find any typical taxonomic character of P. recta. Considering not only the available karyological data, but also the morphology of P. hispanica, it is clear that this taxon is very similar to other species with pinnate leaves from south-west and central Asia, such as P. sericea L. (2n=28, 34, 35, 42) and P. [x] agrimonioides Bieb. (P. sericea L. × P. pensylvanica L.?) with 2n=42, 49–50 (Meˇsı´cˇek & Soja´k, 1992). This similarity is so clear that the plant has been sometimes considered to be a subspecies of P. agrimonioides (P. agrimonioides subsp. hispanica (Zimmeter) Soja´k). This supports the opinion of Soja´k (1993), with which we agree, that P. hispanica could have arisen from those Asian species in the west Mediterranean area. This must have taken place long ago, so that nowadays a very clear geographical disjunction exists, although the plant still maintains a polyploid complex in which introgressive hybridizations are probably occurring. We have not found any correlation between ploidy levels and morphological variability or geographical distribution of populations, and cannot agree that different taxa should be distinguished (P. hispanica and P. oreodoxa Soja´k or P. hispanica subsp. oreodoxa (Soja´k) Soja´k).

Potentilla recta group In the Iberian Peninsula this group comprises P. recta, P. hirta and P. asturica. They share characters such as stem position, type and number of leaves, many-flowered inflorescence, subcylindrical styles and rugose-cristate fruits. The species in this group also behave in different ways from a karyological point of view. In Figure 1 their distribution in the Iberian Peninsula is shown, together with the studied populations and their respective ploidy levels. Because of the complexity of this group in the Iberian Peninsula and the west Mediterranean, 31 populations have been studied. P. recta L. In 13 populations of this species the chromosome number has been investigated. This is the only taxon of the group in which several ploidy levels have been found (4×, 6× and 8×), and it is a polyploid complex over its entire distribution range. This cytological variability agrees well with its wide polymorphism and ecological requirements, as it has no preference for any specific substrate and grows not only in habitats disturbed by man (e.g. roadsides and ditches) but also in undisturbed pastures.

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P. asturica 2n = 14 2n = 14 P. hirta 2n = 28 P. recta 2n = 42 2n = 56

Figure 1. Distribution of the species of the Potentilla recta group in the Iberian Peninsula: investigated populations together with chromosome counts.

P. hirta L. We surveyed three populations, all diploid (2n=14, n=7) (Fig. 5). This is the first record of diploidy in this species, as all previous counts on P. hirta were of 2n=28 or higher. Most of them were made more than 50 years ago (cf. Bolkhovskikh et al., 1969). Moreover, no count seems to have been made using material collected in south-west Europe, from where P. hirta s.s. is an endemic according to Ball et al. (1968) and Guille´n & Rico (1998). Considering this set of data, our chromosome count is probably the first for this species. Its ploidy level strongly supports an independence of P. hirta from P. recta and from other taxa from the east Mediterranean region that have been considered to be transitional forms between P. recta and P. hirta (Soja´k, 1993), such as P. pedata Willd., the latter with several ploidy levels from tetraploid onwards (Lo¨ve & Lo¨ve, 1974; Markova & Goranova, 1996). P. asturica Rothm. The 15 studied populations of P. asturica are scattered throughout the Iberian area of the species (north-west Iberian Peninsula). This has allowed us to check that they have a very stable ploidy level, all with 2n=14 (Fig. 6) and n=7 (Figs 7–9). On the basis of the most important morphological characters of the group, P. asturica seems to have a position intermediate between P. recta and P. hirta. The presence of short hairs in the stem and petiole, and of a large number of teeth on the leaflets is shared by P. asturica and P. recta, while that species shares with P. hirta

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Figure 2–12. Figs 2, 3, 4. Potentilla hispanica. Fig. 2. Mitotic metaphase, 2n=35 (Granada: Alfacar, SALA 94952). Fig. 3. Mitotic metaphase, 2n=35 (Marrakech: Oukaı´meden (I), SALA 94945). Fig. 4. Mitotic metaphase, 2n=49 (Marrakech: Oukaı´meden (II), SALA 94946). Fig. 5. P. hirta, Metaphase I, n=7 (Granada: Puerto de la Ragua, SALA 94671). Figs 6–9. P. asturica. Fig. 6. Mitotic metaphase, 2n=14 (Palencia: Cardan˜o de Abajo, SALA 59695). Fig. 7. Metaphase I, n=7 (Segovia: Cerezo de Arriba, SALA ´ vila: Piedrahı´ta, SALA 94659). Fig. 9. Anaphase II, n=7 (A ´ vila: 96859). Fig. 8. Metaphase II, n=7 (A Hoyos del Espino, SALA 94661). Fig. 10. P. maura, Metaphase I, n=14 (Taroudant: Jbel Siroua, SALA 94674). Figs 11, 12. P. neumanniana. Fig. 11. Irregular tetrad with five meiospores (Teruel: Albarracı´n, SALA 94929). Fig. 12. Mitotic metaphase, 2n=56 (Teruel: Albarracı´n, SALA 94929).

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an ascending stem, small number of carpels and large anthers. For these reasons P. asturica has sometimes been included in P. recta as P. recta subsp. asturica (Rothm.) M. Laı´nz, or in P. hirta as P. hirta subsp. asturica (Rothm.) Soja´k. P. asturica has only one ploidy level and that is the lowest known within the genus (diploid). Moreover, having in mind its distribution area which is limited to ancient acidic mountains in the north-west of the Iberian Peninsula, we suggest that it could be a species of quite ancient origin. Karyological data also show that P. asturica and P. hirta are more closely related to each other than to P. recta, as the first two share a stable ploidy level and the same number of chromosomes. P. recta, on the other hand, is a typical polyploid complex with higher ploidy levels. Therefore, P. asturica and P. recta would be schizoendemic taxa (Favarger & Contandriopoulos, 1961). Potentilla pyrenaica group The Iberian representatives of this group are P. grandiflora L., P. pyrenaica and P. nevadensis. It is uncertain whether P. grandiflora grows in Spain (Guille´n & Rico, 1998) and it has not been possible for us to include it in our research. On the contrary, the North African endemic P. maura was studied, due to its very close relationship to the Iberian species. The possession of a conic filiform style is the exclusive character shared by the members of this group, which is very important in order to characterize the group within the Ibero-North African Potentilla. P. pyrenaica Ramond ex DC. Our finding 2n=28 confirms the results of Shimotomai (1930), on material of doubtful origin, and Ku¨pfer (1968), on plants from the French Pyrenees. There is also another surprising count, 2n=77 by Popov in 1939 (see Bolkhovskikh et al., 1969), also of very uncertain origin, that we have not considered because in our opinion the studied material was probably wrongly determined. P. nevadensis Boiss Our results (2n=28) also agree with those by Shimotomai (1930) and Gustaffson (1947, see Bolkhovskikh et al., 1969). Again, other data by Popov (1939, see Bolkhovskikh et al., 1969), reporting 2n=14, cannot be checked easily. P. maura T. Wolf We surveyed two populations and obtained a chromosome number of 2n=28 (Fig. 10) which is the same as that found by Galland (1988) for plants collected in the Moroccan Atlas. Some counts made in alpine populations of P. grandiflora were also of 2n=28 (Favarger, 1969; Scholte, 1977), and a further count was reported in this taxon: 2n=42 (Acharya Goswami & Matfield, 1975), where the original material is said to have been collected in a botanical garden. Thus, these four species, comprising the group in the west Mediterranean region share the same tetraploid level. This karyological homogeneity agrees also with the great morphological similarity existing among them, as just one or two characters can be found to distinguish each one from the others; concerning the remaining

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characters, all these taxa show very similar variability. It may therefore be confirmed that they form a natural group, defined by the shared possession of a particular type of style. From a palynological point of view, this is also a homogeneous group (Sa´nchez Agudo et al., 1998). These data suggest that this is possibly a case of gradual speciation (Valentine & Lo¨ve, 1958) and that they are examples of schizoendemic taxa, as was already indicated by Galland (1988) when she compared P. nevadensis with P. maura. Moreover, their distribution areas show a typical case of endemovicariant species: P. grandiflora grows in the Alps and it is very rare in the Pyrenees; P. pyrenaica can be found only among mountains in the North and Central Iberian peninsula; P. nevadensis in South Iberian mountains (Sierra Nevada) and P. maura in North Africa (Rif and Atlas in Morocco). Potentilla crantzii group There are six species belonging to this group in the Iberian Peninsula: P. crantzii, P. neumanniana, P. cinerea, P. brauniana Hoppe, P. frigida Vill. and P. aurea L. (the last three have not been studied here). A group of characters shared by these species comprise lateral position of the stems, relatively small plant size, inflorescences with small number of flowers and cylindrical or subcylindrical styles. This group is made up of species with a very variable number of chromosomes. Phenomena such as apomixis, pseudogamy, inter- and intraspecific hybridization have been described within the group and many papers have been published on these processes (Mu¨ntzing, 1931; Mu¨ntzing & Mu¨ntzing, 1941). The great complexity of this group over its whole distribution area is also reflected in our own investigations. P. crantzii (Crantz) Beck ex Fritsch We obtained the following counts: 2n=35, 42. Asker (1985) found 2n=28, 42 in three populations. The commonest ploidy levels in P. crantzii over its whole distribution range are the hexaploid, followed by the tetraploid. We have found a new ploidy level for this taxon, the pentaploid, which was obtained from a population (Collado ´ liva) where hexaploid individuals were also discovered. The existence of de A pentaploid specimens in that population most probably results from intraspecific hybridization between hexaploid and tetraploid individuals. P. neumanniana Rchb. In eight populations of this species we found three ploidy levels: hexa-, heptaand octoploid, the last of which is new for the Iberian Peninsula. As noted in Table 1, the counts made by Asker (1985) were of 2n=42, 49 and 63, so that four ploidy levels are now known for this taxon. Therefore, this Potentilla has both the highest number of ploidy levels and the highest chromosome count in material from the Iberian Peninsula. This variability can explain the irregularities observed during the meiotic processes in one population collected in Albarracı´n (2n=56, Fig. 12), where aberrant tetrads with five meiospores were found (Fig. 11). P. cinerea Chaix ex Vill. We obtained positive results in only two populations of P. cinerea. The number of chromosomes obtained for P. cinerea (2n=42) is quite uncommon in the species as a

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T 3. Ploidy levels for species of subgen. Potentilla counted in the Iberian Peninsula Ploidy level

2× 4× 5× 6× 7× 8× 9×

Species with one single ploidy level (13)

Species with several ploidy levels (6)

Total

No.

%

No.

%

No.

%

4 8

31 61

1

8

1 4 2 4 2 2 1

6 25 13 24 13 13 6

5 12 2 5 2 2 1

17 42 7 17 7 7 3

whole and does not agree with another previous count made on Iberian plants (2n= 28; Ku¨pfer, 1968). Although this last number is very frequent outside the area we studied (Goldblatt, 1988), we think that, on the basis of the locality and altitude where the material was collected, the count by Ku¨pfer may correspond to P. nevadensis which is a species known to be tetraploid. It has not been possible for us to check the determination of this material, as the voucher has not yet been seen. Polyploidy In the Iberian Peninsula and Morocco, it is possible to distinguish two groups of species, as was recognized by Meˇsı´cˇek & Soja´k (1993). One is constituted by those species having a stable ploidy level, such as P. asturica (2n=14), P. hirta (2n=14), P. pyrenaica (2n=28) or P. reptans (2n=28). These species can usually be easily identified as they do not show many taxonomic problems. The other group comprises polyploid complexes such as P. hispanica (2n=28, 35, 42, 49), P. recta (2n=28, 42, 56) and P. neumanniana (2n=42, 49, 56, 63). These species show extreme variability and are taxonomically complicated. There are some groups of species where the ploidy level is constant, such as the pyrenaica group (P. pyrenaica, P. nevadensis and P. maura with 2n=28). In other groups, almost all the taxa are polyploid complexes, i.e. the crantzii group (P. crantzii, 2n=28, 35, 42; P. cinerea, 2n=28, 42 and P. neumanniana, 2n=42, 49, 56, 63). Finally, there are other groups such as recta, which comprise both types: constant ploidy level (P. asturica, P. hirta, 2n=14) or several levels (P. recta, 2n=28, 42, 56). With the aim of developing an analysis of which ploidy levels are more frequent in the Iberian species, we have prepared Table 3 and the diagrams in Figs 13 and 14. Because some of the investigated species have several ploidy levels, the total number of species in absolute terms as well as that used to calculate the corresponding percentage, is larger than 19 (those whose number has been counted in the Iberian Peninsula). The tetraploid level is the most frequent in the region (12 species have this level either exclusively or in some of their populations, 42%; Table 3, Fig. 13). Also frequent are both the diploid and hexaploid levels (both five species and 17%). We show separately (Table 3, Fig. 14) the percentages of the different ploidy levels in two groups. One corresponds to those species with a constant number of chromosomes (13 species; 68.4%) and the other to those having several ploidy levels

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8× 7%

9× 3%

2× 17%

7× 7%

6× 17%

4× 42%

5× 7%

Figure 13. Percentages of ploidy levels for all the studied species from subgen. Potentilla in the Iberian Peninsula.

70

A

B

60

Percent

50 40 30 20 10 0

2× 4× 5× 6× 7× 8× 9× 2× 4× 5× 6× 7× 8× 9×

Figure 14. Percentages of ploidy levels for the studied species from subgen. Potentilla in the Iberian Peninsula. Percentages are separately calculated and represented for 13 species with a single ploidy level (A) and for the 6 species with several levels (B).

(six species; 31.6%). It is interesting to comment that among the species with a stable level there are only three ploidy levels represented (diploid, tetraploid and hexaploid), with a clear dominance of the tetraploid level. Species with high ploidy levels do not appear in this group, except P. inclinata (2n=42), neither are there odd ones. On the contrary in the second group seven levels are represented, several being odd ones, and they are frequently high so that they reach the enneaploid level (9×). The tetraploid and hexaploid levels only slightly exceed the rest and the diploid is scarcely present. Considering the information compiled at Bolkhovskikh et al. (1969) for the Potentilla subgen. Potentilla (85% of the genus) throughout its distribution area, it can be seen

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that most species have a single ploidy level (61%). This percentage is probably lower than it appears, if it is noted that some of the species have very high ploidy levels and are based on single counts, so probably they may contain more than one ploidy level. The commonest levels in this subgenus are the hexaploid (28%), followed by tetraploid (22%) and diploid (13%). Comparing world-wide data with those from the Iberian Peninsula, it can be seen that in the latter the number of species with a constant level is larger and that low ploidy levels are more common (especially the tetraploid). We thus conclude that the species included in subgenus Potentilla have probably had a less complex history in the Iberian Peninsula than in the rest of its area, with some stable species or groups of taxa characteristic of the west Mediterranean region, such as P. asturica, P. hirta, P. reuteri or the P. pyrenaica group.

ACKNOWLEDGEMENTS

We are grateful to the curators of the following herbaria: HGI, MA and SALA. We would like also to thank M. Martı´nez Ortega for her assistance and especially for the translation of the manuscript into English and to P. E. Brandham for careful revision and useful comments. This work was supported by the Spanish Ministerio de Educacio´n y Cultura (DGICYT), through the research projects Flora iberica IV (PB 91 0070-CO3-00) and Flora iberica V (PB 96-1302).

REFERENCES

Acharya Goswami D, Matfield B. 1975. Cytogenetic studies in the genus Potentilla L. New Phytologist 75: 135–146. Asker S. 1970. Apomixis and sexuality in Potentilla argentea complex. I. Crosses with other species. Hereditas 66: 127–144. Asker S. 1971. Apomixis and sexuality in the Potentilla argentea complex. III. Euploid and aneuploid derivatives (including trisomics) of some apomictic biotypes. Hereditas 67: 11–142. Asker S. 1985. Chromosome studies in Potentilla. Hereditas 102: 289–292. Ball PW, Pawlowski B, Walters SM. 1968. Potentilla L. In: Tutin TG et al., eds. Flora Europaea. Cambridge: Cambridge University Press, vol. 2: 36–47. Bolkhovskikh Z, Grif V, Matvejeva T, Zakharyeva O. 1969. Chromosome numbers of flowering plants. Leningrad: A. Fedorov (ed.). Castroviejo S. 1983. Nu´meros cromosoma´ticos de plantas occidentales, 211–222. Anales del Jardı´n Bota´nico de Madrid 39: 525–531. Eriksson T, Donoghue MJ, Hibbs MS. 1998. Phylogenetic analysis of Potentilla using DNA sequences of nuclear ribosomal internal transcribed spacers (ITS), and implications for the classification of Rosoideae (Rosaceae). Plant Systematics and Evolution 211: 155–179. Favarger C. 1969. Notes de caryologie Alpine V. Bulletin de la Socie´te´ Neuchaˆteloise de Sciences Naturelles 92: 13–30. Favarger C, Contandriopoulos J. 1961. Essai sur l’ende´misme. Berichte der Schweizerischen Botanischen Gesellschaft 71: 384–408. Galland N. 1988. Recherche sur l’origine de la flore orophile du Maroc. E´tude caryologique et cytogeographique. Travaux Institute Scientifique Che´rifien, Se´rie Botanique Biologie Ve´getale 35: 1–168. Goldblatt P. 1988. Index to plant chromosome numbers 1984–1985. Monographs in Systematic Botany from the Missouri Botanical Garden 23. Goldblatt P, Johnson DE. 1990. Index to plant chromosome numbers 1986–1987. Monographs in Systematic Botany from the Missouri Botanical Garden, 30. Guille´n A, Rico E. 1998. Potentilla L. In: Mun˜oz Garmendia F & Navarro C, eds. Flora iberica Madrid: CSIC, vol. 6: 96–140.

280

L. DELGADO ET AL.

Iwatsubo Y, Naruhashi N. 1991. Karyomorphological and cytogenetical studies in Potentilla (Rosaceae) I. Karyotypes of nine Japanese species. Cytologia 56: 1–10. Ku¨pfer P. 1968. Nouvelles prospections caryologiques dans la flore orophile des Pyre´ne´es et de la Sierra Nevada. Bulletin de la Socie´te´ Neuchaˆteloise de Sciences Naturelles 91: 87–104. Ku¨pfer P. 1974. Recherches sur les liens de parente´ entre la flore orophile des Alpes et celle des Pyre´ne´es. Boissiera 23: 1–322. Leht M. 1996. Cladistic analysis of the data published in “Monographie der Gattung Potentilla” by T. Wolf. Proceedings of the Estonian Academy of Sciences, Biology 45: 171–180. Leht M, Paal J. 1998. Potentilla L. sect. Rivales Wolf and related taxa in the Baltic states. Folia Geobotanica 33: 171–186. Lo¨ve A, Kjellqvist E. 1974. Cytotaxonomy of Spanish plants. III. Dicotyledons: CaesalpinaceaeAsteraceae. Lagascalia 4: 153–221. Lo¨ve A, Lo¨ve D. 1974. Cytotaxonomical atlas of the Slovenian Flora. Lehre: J. Cramer. Lo¨ve A, Lo¨ve D. 1982. Reports. In: Lo¨ve A, ed. IOPB chromosome number reports LXXV. Taxon 31: 344–360. Markova M. 1982. Reports. In Lo¨ve A, ed. IOPB chromosome number reports LXXVII. Taxon 31: 761. Markova M, Goranova V. 1996. Reports 757–761. In: Kamari G et al., eds. Mediterranean chromosome number reports 6. Flora Mediterranea 6: 317–323. Meˇsı´cˇek J, Soja´k J. 1992. Chromosome counts of some Mongolian Potentilla species. Folia Geobotanica et Phytotaxonomica 27: 167–176. Meˇsı´cˇek J, Soja´k J. 1993. Annotated chromosome numbers of selected Asiatic Potentilla species. Folia Geobotanica et Phytotaxonomica 28: 437–446. Mu¨ntzing A. 1931. Note on the cytology of some apomictic Potentilla-species. Hereditas 15: 166–178. Mu¨ntzing A. 1958. Further studies on intraspecific polyploidy in Potentilla argentea (coll.). Botaniska Notiser 111: 209–227. Mu¨ntzing A, Mu¨ntzing G. 1941. Some new results concerning apomixis, sexuality and polymorphism in Potentilla. Botaniska Notiser 94: 237–278. Rousi A. 1965. Biosystematic studies on the species aggregate Potentilla anserina L. Annales Botanici Fennici 2: 47–112. Sa´nchez Agudo JA, Rico E, Sa´nchez Sa´nchez J. 1998. Palynological study of Potentilla subg. Potentilla (Rosaceae) in the Western Mediterranean. Grana 37: 276–284. Scholte G. 1977. Reports. In: Lo¨ve A., ed. IOPB chromosome number reports LVI. Taxon 26: 257–274. Shimotomai N. 1930. Chromosomenzahlen und Phylogenie bei der Gattung Potentilla. Journal of Science of the Hiroshima University, Series B, Div. 2: 1–11. Skalin´ska M, Czapik R. 1958. Studies in the cytology of the genus Potentilla L. Acta Biologica Cracoviensia, Se´rie: Botanique 1: 137–149. Soja´k J. 1993. Taxonomische Bemerkungen zu einigen mediterranen Potentilla-Sippen. Preslia 65: 117–130. Stebbins GL. 1950. Variation and evolution in plants. New York: Columbia University Press. Valentine DH, Lo¨ve A. 1958. Taxonomic and biosystematic categories. Brittonia 10: 153–166. Ward DE, Spellenberg R. 1988. Chromosome counts of angiosperms from New Mexico and adjacent areas. Phytologia 64: 390–398. Wolf TH. 1908. Monographie der Gattung Potentilla. Bibliotheca Botanica 16 (Heft 71): 1–714.