Hereditas 86: 225-236 (197n Chromosomal polymorphism in isolated populations of Elymus (Agropyron) in the Aegean 111. Elymus diae

WAHEEB K. HENEEN Institute of , University of Lund, Sweden

HENEEN,W. K. 1977. Chromosomal polymorphism in isolated populations of Elymus (Agropyron)

in the Aegean. 111. Elymus diae. - Hereditas 86: 225-236. Lund, Sweden. ISSN 0018-0661. Received April 27, 1977 Elymus diae is an octoploid (2n = 56) littoral species that grows in small isolated populations on the . A striking chromosomal polymorphism was found in twenty plants raised from seeds collected from four natural populations. All four populations had unique satellite and marker chro- mosome constitutions. Further chromosomal polymorphism was observed among plants originating from one of these populations. There were similarities in the appearance of the satellite in E. diae, E. rechingeri and E. striatulus which denotes a close relationship between the three species. This is ascertained by a analysis of a polyhaploid individual of E. diae. The genome formula J4J4J141J~4,J5J5J6J6or J4J4J,41J141J~l,Jl,,J6J6was suggested for the species. Analysis of the satellite and marker chromosomes in 33 plants raised from seeds obtained in the greenhouse, following open pollination, inferred a predominance of self-fertilization or intrapopulation crosses. Aneuploids were found among plants raised from seeds collected in nature or obtained in the greenhouse. During , paired chromosomes usually appeared as bivalents and rarely as multivalents. Univalents occurred frequently which might be related to the prevailing chromosomal polymorphism. In the polyhaploid, most of the pollen mother cells had 4-7 bivalents which evidenced the presence of two closely related genomes. During the first pollen mitosis, numbers of 28 and 27 were observed in octoploid plants, whereas in the polyhaploid there were variable chromosome numbers. W. K. Heneen, Institute of Genetics, University of Lund, S-223 62 Lund, Sweden

Efymus diue is a littoral species found by RUNEMARK Materials and methods in the Aegean area. The species belongs to the series Junceae established (within Elytrigia) by NEVSKI The somatic metaphase chromosomes of Elymus diue (1936). On morphological and cytological grounds it were studied in a total of 54 plants. Twenty of these is closely related to Elymus furctus (=Agropyron plants were raised from seeds collected by RUNEMARK junceum), E. striatulus and E. rechingeri (HENEEN from the Aegean islands. This material was from four 1962, 1977a; HENEENand RUNEMARK1962, 1972). small populations found on three different islands. The Aegean species E. striatulus, E. rechingeri and Collections from these populations were given dif- E. diae all grow in small isolated populations and the ferent numbers (R-oo00) by RUNEMARK.The localities latter two species show morphological diversity be- of these populations are as follows (Fig. 1): tween populations and uniformity of morphological R-3617: , Dia, Glaronisi. characters within populations. R-3620 and R-3621: Dodecanisos, , north- E. diae is octoploid and exhibits chromosomal poly- east of Kastello point. It cannot be excluded that morphism expressed mainly in the variable appear- these two small populations are part of a large popula- ance of the satellite chromosomes. Similar poly- tion. morphisms have been described for two other Aegean R-3673: Crete, , north-east point. species: the tetraploid E. rechingeri (HENEENand The other 34 individuals studied were raised from RUNEMARK1962; HENEEN1977a) and the diploid seeds obtained under greenhouse conditions from the E. striatulus (HENEENand RUNEMARK1972). above-mentioned 20 plants. Out of these 34 offspring The present study deals mainly with the cytology of plants, 33 resulted after open pollination and consti- E. diae. A taxonomic and morphological description tuted a sample of the first progeny obtained under of the species will be dealt with elsewhere (RUNEMARK, cultivation. One individual was offspring after isola- in preparation). tion. 226 W. K. HENEEN Hereditus 86 (1977)

u3620 .## 3621

0 M 100 km

Fig. 1, A map of the Aegean area showing the localities of the four populations from which seeds of Elymusdiue were collected.

The method described by OSTERCRENand HENEEN (1962) was used for making Feulgen-squashes from 2. Chromosome morphology root-tips. For meiosis, spikes were fixed in Carnoy A. Chromosomal polymorphism within and between (alcohol, chloroform, acetic acid; 6:3 : 1) and pollen mother cells were stained according to the Feulgen populations method. Lacto phenol-acid fuchsin was used as a stain The chromosomes of E. diae are in a length range of for pollen. 3 to 8.5 pm and have mainly median or submedian (Fig. 2). Three pairs have secondary constrictions and are usually easy to identify. The morphology of these chromosomes, however, varied in the different populations studied. The different Results types of satellite chromosomes found are referred to by the letters A, B, D, E and F (Fig. 4). The designa- I. Chromosome number tions given to the satellite chromosomes of E. diae Elymus diae is an octoploid species with 2n = 56 (Fig. are in accordance with, and are a continuation of the 2). Two plants (R-3620) with 55 chromosomes were numbering given to the variant types found in E. among the 20 individuals raised from seeds collected rechingeri and E. striatulus (HENEENand RUNEMARK in nature. Deviating chromosome numbers were also 1962, 1972; HENEEN1977a). Types A, B and D corre- found in five individuals out of the 34 first progeny spond to, or have similarities with satellite chromo- plants analyzed. The deviating plants were four some types found in E. striatulus and E. rechingeri. aneuploids and one polyhaploid. Two of the aneu- Types E and F are new and, as will be pointed out ploids had the chromosome numbers 54 and 55, later on, probably represent variants of types A and B, whereas the other two had 57 chromosomes. The respectively. The letter C was not used to designate plant with 54 chromosomes was among the offspring any type of satellite chromosomes in E. diae since it of a mother plant with 55 chromosomes. The rest of has been adopted for a specific type that occurs in the deviating plants were offspring of euoctoploids. E. rechingeri. The polyhaploid plant had 28 chromosomes (Fig. 3). Other easily identifiable chromosomes in the com- Deviations in chromosome number thus occurred plement are those that seem to be telocentrics or have among plants raised from seeds, either collected in arm-index values markedly deviating from the rest of nature or obtained in the greenhouse. the chromosomes. Such chromosomes have terminal or subterminal centromeres and are here referred to as marker chromosomes (M). Different constitutions of satellite and marker chro- mosomes were found in the 20 individuals which were raised from seeds collected in nature. The frequencies of the different satellite chromosome constitutions are given in Table 1 and representative Herediias 86 (1977) CHROMOSOMAL POLYMORPHISM IN ELYMUS III 227

c

Fig. 2. Representative metaphase chromosomes of E. dim;upper cell: population R-3620; lower cell: population R-3617. Satellite and marker chromosomes are indicated by arrows; upper cell: A,A2 A,A, BIB, MIMI; lower cell: AZA, EE(A1oAio) FF(B,B,) M,. See Fig. 4. Scale: 10 pm.

15 228 W. K. HENEEN Hereditas 86 (1977)

b Fig. 3a and b. The chromosomes of the polyhaploid individual; a: metaphase spread; b: karyotype. Scale: 10 pm.

cells are shown in Fig. 2. Below is a description of the two populations had only one such pair. One of the different kinds of satellite and marker chromosomes two pairs in population R-3673 was difficult to iden- found (Fig. 4). tify. The satellite in this pair was of a relatively smaller Type A.-This is a satellite chromosome with a small size and was often fused to the rest of the short arm. satellite on the short arm. Two pairs were found in This type will be designated A, whereas the most individuals belonging to two populations (R-3673 and usual type is AZ. R-3620), whereas the materials studied from the other Type B. - The in this satellite

Fig. 4. Photographs and schematic drawings of the different constitutions of satellite and marker chromosomes found in the four populations of E. diae studied. The appearance ofchromosome type E is shown under different degrees ofcontraction. In highly contracted chromosomes the segments in the constriction region fuse with the proximal region. Chromosomes D, E and Fare most likely variant A and B types. The long arm of chromosome F would thus correspond to the short arm of chromosome B. Scale: 10 pm. Herediras 86 (1977) CHROMOSOMAL POLYMORPHISM IN ELYMUS III 229

ii

A2 A2

Br ii II EE FF A2 A2 (AlO) (B,) I ii

A2 A2 35

A2 A2 230 W. K. HENEEN Hereditas 86 (1977)

Table 1. Satellite and marker chromosomes in four Some F a variant B (see below), the constitution populations of Elymus diae. Chromosome types D AAEEFF in population R-3617 would be equivalent and E might be variant types of A, also chromosome to AAAABB. This latter constitution was found in type F might be a variant of B two populations (R-3620 and R-3673) and might also be valid for population R-3621. Chromosome type E Population Satellite and marker chromosomes No. of might thus be a variant A, designated as Ale. plants Twe,. F. - This is an easily identifiable satellite chromosome type, being composed of three about R-3673 A2A2 A,A, BIB1 3 equal segments. The presence of a secondary constric- R-3620 A2A2 A2A2 BIB, 6* tion in about the middle of the long arm divides it into R-3621 A2A2 DD(A,A,) BIBl MlM, 5 R-3617 A2A2 E E (AlOAlo) F F (B7B7) 3 two parts each of which is similar to, or slightly R-3617 A,A, E(A,,) FF(B7B7) M, 2 smaller than the short arm. Chromosome F is found R-3617 AiAi EE(AloAlo) FF(B,B7) M, I only in population R-3617, which is the only popula- Total 20 tion that lacks chromosome type 9. It is probable that ~ ~ chromosome F is a chromosome type B that has lost * Two plants with 55 chromosomes about half of its long arm. If this is true, the long arm of chromosome F would correspond to the short arm of . The two arms in question do not chromosome type divides the short arm into two differ much in length. Chromosome F might thus be about equal parts. Individuals representing three of a 9,. the four populations had a pair BIB1. Type MI.- The centromeric position in this marker Type D.-This satellite chromosome type was found chromosome is subtelocentric and the arm ratio in individuals originating from only one population markedly deviates from what is characteristic for (R-3621). The is nearly median in position the rest of the chromosomes in the complement. and a small satellite is present on the short arm. A pair of MI occurred in the individuals studied from Chromosome D is similar to a satellite chromosome populations R-3620 and R-3621 which were found on type, designated by the same letter, found in E. rechin- the same island. Worth mentioning here is the geri and argued to be a possible variant of the satellite presence of an MI chromosome or a chromosome chromosome type A (As; HENEEN1977a). If this is similar to it in one plant of E. rechingeri resulting from true, two A pairs will be present in population R-3621 an interpopulation cross between parents that lacked which is also the case in R-3620 and R-3673. M, (HENEEN1977a). Type E. - Only individuals belonging to population Type M2.- This is a marker chromosome with an R-3617 had this kind of satellite chromosome. The apparently terminal centromere, alternatively with short arm carries a tandem satellite constituted of a very small short arm. Only one such chromosome three segments. The terminal segment is the largest was found in three out of six individuals derived from and is usually separated from the rest of the short population R-3617. arm by a constriction or a gap. The other two seg- As can be seen in Table 1, the four populations ments appear as chromatic bodies in the constriction studied differed in their constitutions of satellite and region. They are small in size and are usually located marker chromosomes. Variations were further found close to the proximal region rather than the distal among the individuals that represented population satellite segment. The two small segments sometimes R-3617. There is no doubt that the present material fuse and appear as one large chromatic body in the is too limited to determine with certainty the con- constriction. This was observed especially when the stellation of satellite and marker chromosomes which chromosomes were relatively contracted. In still more is characteristic of the species. From the limited contracted chromosomes the two small segments information available and as mentioned above, such fused with the proximal region of the short arm. a constitution might be AAAABB. This would be so The various appearances of this chromosome are if the chromosome types D and E are proven to be demonstrated in Fig. 4. In two of the six individuals variant types of A, and chromosome type F a variant of population R-3617, only one E chromosome was of B. detectable. In the other homologue, the satellite was apparently fused to the rest of the short arm, as has been also found in satellite chromosome type B3 in 9. Progeny plants after open pollination or sepng E. rechingeri (HENEENand RUNEMARK1962; HENEEN The satellite and marker chromosome constitutions 1977a). If chromosome E is a variant A and chromo- were also determined in 34 progeny plants obtained Hrreditas 86 (1977) CHROMOSOMAL POLYMORPHISM IN ELYMUS 111 23 1

Fig. 5. Metaphase spread ofa progeny plant with S7chromosomes. The extra chromosome is indicated by an arrow and is shown at a higher magnification ( x 7000) in the insert. Scale: 10 pm. from the above mentioned material. Out of these Two plants in this material had 57 chromosomes. plants, only one was raised from a seed obtained after The extra chromosomes looked similar and were easy selfing, whereas the rest were raised from seeds to identify since they differed from the rest of the obtained after open pollination. chromosomes in the complement (Fig. 5). They were The types of satellite and marker chromosomes subtelocentric chromosomes with a secondary con- found in this material fitted well with what would be striction near the end of the long arm which gave them expected after self-fertilization or crosses between the appearance of isodicentrics. plants originating from the same population. It is A polyhaploid individual (2n = 28), also found likely that under greenhouse conditions and due to among the progeny plants, had only one chromosome the limited number of plants available, there will be from each type of the satellite and marker chromo- a high degree of inbreeding. By nature the species is somes characteristic of the mother plant (Fig. 3b). a cross-fertilizer,nevertheless it is also capable of self- fertilization. 232 W. K. HENEEN Hereditas 86 (1977)

b

8

C d

Fig. 6a-d. Meiosis in pollen mother cells of E. dine; a: 14 I1 at diakinesis; b metaphase I, four univalents; c: metaphase I, 26 11 + 4 I; d: separation difficulties at anaphase I (See HENEEN1972). Scale: 10 Fm.

C. Karyotype of the polyhaploid individual 3. Meiosis The chromosomes of this plant are presented as Meiosis in pollen mother cells was generally regular in a karyotype in Fig. 3b. It was possible to arrange 14 33 out of the 35 individuals analyzed. The two of the 28 chromosomes as seven pairs. The chromo- individuals with aberrant meiosis exhibited multi- somes within each pair look alike and are probably polar divisions and will be discussed in detail else- homologous or homoeologous. The other 14 chromo- where. At diakinesis, 28 bivalents were usually found somes were not classifiable as pairs. The satellite and (Fig. 6a). The high incidence of chiasmata at dia- marker chromosomes are included in this later group. kinesis and the prevalence of ring bivalents at meta- phase I (Fig. 6b and c) are indications of a high degree of homology between the chromosomes. Because of the high number of the chromosomes Hereditas 86 (1977) CHROMOSOMAL POLYMORPHISM IN ELYMUS 111 233

a

C d

Fig 7a-d. Meiosis in pollen mother cells ofthe polyploid individual; a' 1 11 + 26 I, b probably4 I1 + 20 I, c: a trivalent (arrow); d.anaphasel,a 15. 13distributlon.Scale. 10prn.

and their usual alignment in the vicinity of each other some fragmentation. The tetrads were generally at metaphase I (Fig. 6b), it was difficult to determine normal. The occurrence and frequency of micronuclei accurately the different chromosomal configurations at this stage varied among the different individuals. at this stage. Analyzable cells (Fig. 6c), in spite of Frequencies of morphologically good pollen ranged being few, gave an idea about the extent of chromo- between 80 and 99%. some pairing at this stage. The presence of two uni- A certain degree of chromosome pairing was valents in such cells was frequent (-a%,77 anal- noticed in the polyhaploid individual. As can be seen yses). Higher numbers of univalents (Fig. 6b, c), up to in Table 2, about 72% of the cells had 4-7 bivalents. 11, were recorded largely in the aneuploid plants. Fig. 7a and b show representative cells with one and Multivalents (tri- and quadrivalents) were usually at least four bivalents, respectively. A few cells with rare. a trivalent were also found (Fig. 7c, arrow). In the At anaphase I, it was common to find cells showing majority of the anaphase I cells, the chromosomes separation difficulties (Fig. 6d), bridges and chromo- were about equally distributed to the two poles. 234 W. K. HENFEN Hereditas 86 (1977)

..

a c g, Fig. 8a-c. Pollen mitosis; a: 28 chromosomes; b: 27 chromosomes and a chromatic body most likely constituted of the missing chromosome; c: 14 chromosomes in the polyhaploid individual. Scale: 10 lm,

The distributions 14:14 and 15:13 (Fig. 7d) were the most common ones. Discussion Elymus diae is an octoploid species (2n = 56) which is closely related to the tetraploid and diploid species 4. Pollen mitosis E. rechingeri and E. striatulus, respectively (HENEEN Pollen mitosis was studied in euoctoploid plants and and RUNEMARK1962,1972; HENEEN1977a). Chromo- in the polyhaploid individual. Fig. 8a shows first some numbers that deviate from the euoctoploid pollen mitosis with the expected number of 28 number of 56 were found in materials of E. diae raised chromosomes. Cells with only 27 chromosomes were from seeds collected in nature as well as in offspring found occasionally. Such aberrant cells usually plants obtained under greenhouse conditions. These contained a small micronucleus or a diffuse chromatin numerical deviations comprised aneuploidy for one or mass which most likely is constituted of the missing two chromosomes as well as haploidy. Plants with chromosome (Fig. 8b). numerical deviations were more frequently en- Chromosome numbers in pollen mitoses were vari- countered in E. diae (5 out of 54, 9%) than in able in the polyhaploid individual. A cell with 14 E. rechingeri (5 out of 180, 3%; HENEEN1977a). chromosomes is shown in Fig. 8c. On the diploid level, there were no numerical deviations in a total of 26 E. striatulus plants studied (HENEENand RUNEMARK1972). Numerical variations are evidently better tolerated on the Table 2. Frequencies of pollen mother polyploid level than on the diploid level. As expected cells with different numbers of bivalents the higher the degree of , the more fre- in the haploid individual quently such deviations occur. As in the other two Aegean species E. rechingeri and No. of No. of E. striatulus, chromosomal polymorphism was pre- bivalents cells dominant in E. diae. This polymorphism was expressed in the appearance of the satellite chromo- 1 1 somes and the presence of new chromosome types 2 I (markers). The variations in the appearance of the 3 3 4 19 satellite chromosomes involved not only size rela- 5 19 tionships of the satellite and chromosome arms but 6 10 also the type of the satellite. Satellites were composed 7 9 of either one or more than one segment. Tandem 8 2 9 3 satellites have also been observed in other materials (e.g. MARCHANT 1968, MARCHANTand BRIGHTON Totdl 67 1971, MUGOURDand PARKER 1976). Hereditus 86 (1977) CHROMOSOMAL POLYMORPHISM IN ELYMUS 111 235

From the limited material studied, it was found two nearly similar genomes and two different ge- that each of the four populations analyzed had its nomes. The satellite and marker chromosomes were own constitution of satellite and marker chromo- among the chromosomes of the two dissimilar ge- somes. Further variations were found among indi- nomes. Similarities between two of the genomes were viduals within one of these four populations. This also imaged during meiosis in which 72% of the pollen gives the impression of a strikingly extensive chromo- mother cells had 4-7 bivalents. somal polymorphism. The material studied of E. diae, The four genomes in the polyhaploid might be composed of 20 plants derived from four populations, designated J4J,,,J5J, or J,J,,J(,,J,. The letter J has is thus too small for an exact estimation of the extent been used for genome designations (5,-J3) in other of chromosomal polymorphism in natural popula- closely related Elymus species such as E. farctus ssp. tions. More material needs to be analyzed in order to boreo-atlanticus, E. striatulus and E. rechingeri determine with certainty the constitution of satellite (HENEEN1962, 1977a; HENEENand RUNEMARK1962, chromosomes which is characteristic of the species. 1972). In the polyhaploid individual of E. diae, the Two of the four populations (R-3620 and R-3673) two nearly similar genomes are referred to by J4 and had the satellite chromosome constitution AAAABB. J(4). The designation J5 or J(,) refers to a genome that If this constitution characterizes the species, it might includes two satellite chromosomes, one type A and be argued that in population R-3621, one pair of A one type B. Such a genome has been referred to as J1 was missing, and that instead, there was one pair of D. in E. striatulus and E. rechingeri (HENEENand RUNE- Chromosome type D could be a variant of type A. MARK 1972; HENEEN1977a). All chromosome pairs in A possible substitution of one chromosome A by a J, genome, as described in the latter two species, a chromosome considered to be of type D has been were not possible to discern in E. diae. Therefore, a inferred in a certain individual of E. rechingeri designation J(,) or J, might be more appropriate for (HENEEN1977a). In population R-3617, it could this genome in E. diae. The different genomes in the also be that pairs E and F are variant types octoploid species might thus be expressed as of the missing pairs A and B. Analyses of more J~J,J(~,J(~)J~JSJ,J,Or ...... E. diae is material of E. diae and the application of banding evidently an allopolyploid. techniques on all Aegean Elymus species are necessary The prevalence of bivalents during meiosis of the to obtain conclusive evidence about the similarities octoploid species in spite of the presence of two pairs between the different satellite chromosomes, their of homologous or homoeologous genomes is most possible correspondence to each other and their probably determined by genetic factors. Genetical possible modes of origin. The application of banding control of pairing in polyploids is nicely proven for techniques would also elucidate if similar marker wheat (RILEYand CHAPMAN1958; SEARSand OKA- chromosomes (e.g. MI) in E. diae and E. rechingeri MOTO 1958). really correspond to each other. The predominance of cytological instability and Acknowledgments. - I am indebted to Prof. Hans Runemark (Institute of Systematic Botany, University of Lund) who chromosomal polymorphism and the evolutionary provided me with the plants raised from seeds collected by him consequences of these phenomena in the Aegean in the Aegean, and also for putting the map of Fig. I at my species Elymus diae, E. rechingeri and E. striatulus disposal and for stimulating discussions. Also my sincere are discussed in detail in another publication (HENEEN thanks to Kerstin Nyholm, Berit Rohme, Majlis Olin and Kerstin Hultgren for their appreciated assistance, and to Dr. 1977b). All three species grow in small isolated Gunnar Weimarck for his critical comments. Grants from the populations and might be in an effective phase of Swedish Natural Science Research Council are gratefully evolutionary change. acknowledged. The preservation of the different satellite chromo- some types in progeny plants indicates that the differ- Literature cited ent types are heritable entities. The same conclusion was arrived at when controlled crosses were made BOUGOURD,S. M. and PARKER,J. S. 1976. Nucleolar- between plants exhibiting satellite chromosome ~01~-organizer polymorphism in natural populations Of Allium schoenoprasum. - Chromosoma 56: 301 -307 morphism (STRID1965' 1969; BoUGoURD and PARKER HENEEN,W. K. 1962. Karyotype studies in Agropyronjunceum, 1976; HENEEN1977a). A. repens and their spontaneous hybrids. - Hereditus 48: The acquisition of a polyhaploid individual of 471-502 E. diae favourably allowed a ka,-,,otype analysis of a HENEEN,w. K. 1972. Separation difficulties during anaphase I in Elymus (Agropyron) species. - BOI.Noliser 125: 430-438 relatively low Of chromosomes~ Thus' it HENEEN,W. K. 1977a. Chromosomal polymorphism in became apparent that the four genomes in the Pok isolated populations of Elymus (Agropyron) in the Aegean. haploid could be distinguished morphologically into 11. Elymus rechingeri. - Hereditus 86: 21 1-224 236 W. K. HENEEN Hereditas 86 (1977)

HENEEN,W. K. 1977b. Chromosomal polymorphism in Lolieae. Nardeae, Leptureae und Hordeae der USSR. - Acta isolated populations of Elymus (Agropyron) in the Aegean. Inst. Bot. Acad. Sci. USSR 2: 33-90 IV. General discussion. - Hereditus 86: 237-244 ~STERGREN,G. and HENEEN,W. K. 1962. A squash technique HENEEN,W. K. and RUNEMARK,H. 1962. Chromosomal poly- for chromosome morphological studies. - Hereditas 48: morphism and morphological diversity in Elymus rechingeri. 332-341 - Hereditas 48: 545-564 RILEY,R. and CHAPMAN,V. 1958. Genetic control of the cyto- HENEEN,W. K. and RUNEMARK,H. 1972. Chromosomal poly- logically diploid behaviour of hexaploid wheat. - Nature morphism in isolated populations of Elymus (Agropyron) in 182: 713-715 the Aegean. 1. Elymus striatulus sp. nov. - Bat. Noriser 125: SEARS,E. R. and OKAMOTO,M. 1958. Intergenomic chromo- 419-429 some relationships in hexaploid wheat. - Proc. 10 Int. Cong. MARCHANT,C. J. 1968. Chromosome patterns and nuclear Genet. 2 258-259 phenomena in the cycad families Stangeriaceae and Zami- STRID,A. 1965. Studies in the Aegean flora. VII. Chromosome aceae. - Chromosoma 24: 100- 134 morphology in the Nigella arvensis complex. - Bof. Notiser MARCHANT,C. J. and BRIGHTON,C. A. 1971. Mitotic insta- 118 139-165 bility in the short arm of a heteromorphic SAT-chromosome STRID,A. 1969. Variation in the satellite chromosomes of of tetraploid Ranunculusjcaria L. - Chromosoma 34: 1-18 Nigella doerfleri (Ranunculaceae). - Bot. Notiser 122: 9-19 NEVSKI,S. A. 1936. Verzeichnis der Graser aus den Triben