CC BY
0EXPERIMENTAL STUDIES IN HIERACIUM PI LOS ELLA L.
I. REPRODUCTION, CHROMOSOME NUMBER AND DISTRIBUTION
By GOTE TURESSON and BENEDICTE TURESSON
lund, sweden (Received September 7th, 1960)
INTRODUCTION
THE Linnean Hieracium pilosellu has given its name to several groups and subgroups within the genus. The genus is divided into two subgenera, Pilosella and Archieracium, and the Pilosella group again into a number of subgroups, one of them being the Pilosellina subgroup. The genus is further known to be excessively polymorphic, not least the Pilosellas, where apomixis of the apospory type with facultative sexuality prevails together with, as in some interesting forms of the group, obligate sexuality. The systematic treatment of the great number of "species" within the genus and in the Pilosellas is accordingly a most difficult problem confronting the taxonomist. After the appearance of the imposing monograph of the subgenus Pilosella by Nageli and Peter (1885) mostly Scandinavian botanists have been engaged in the Pilosellu taxonomy, the outstanding names being Dahl-stedt in Sweden, Norrlin in Finland and Omang in Norway. As a result of their diligent and painstaking work taxonomical units have been distinguished and named in this group by the hundred.
Our own studies have been limited to a rather narrow range of types, almost exclusively belonging to the collective species H. pilosella L., whose swarm of "species" makes up the subgroup Pilosellina. Most of these types have long and slender stolons, bearing small distant leaves, decreasing in size towards the stolon apex. The involucres are about 10 mm broad, their bracts up to 1.5 mm wide, acuminate. A smaller group of types differs from the preceding in having short and curved stolons, bearing homophyllous leaves with large apical rosettes. The
gOte turesson and benedicte turesson
involucres are up to 14 mm broad and rounded below, their bracts up to 2.5 mm wide, rather obtuse. This latter group of types has been called H. macrolepidium Norrl. ( = //. peleterianum Auctt.). Accordingly the group Pilosellina is split by the taxonomists into the smaller group Mcicrolepidia and Pilosella in a stricter sense (and a third, viz. Furcata). The main bulk of our material belongs to the two first-mentioned Pilosellina groups.
A second Linnean species, H. auricula, belonging to the subgroup Auriculina, has been studied to a limited extent, while hybrids and intergradation between this species and H. pilosella L. occur in nature. The species has also been used in some of our crosses.
MATERIAL AND METHODS
The collecting work started 1944—45 and about 500 collections from nearly as many localities have been studied through the years. The localities are fairly well spread over the country; only very few collections come from abroad. In the collecting work we have received much help from friends and colleagues, and we wish to express our sincere thanks for this valuable assistance.
The transplants were all grown in the Botanical-Genetics garden of the Royal Agricultural College at Uppsala. They were allowed to grow in plant boxes in the open until new stolon rosettes had been developed. One rosette from each transplant was then potted and put in a cold-house for chromosome counts and crossings, while the remaining rosette material was left in the plant boxes for studies in the following seasons with regard to flower colour, stolon characters, hairiness, time of flowering etc. The chromosome counts, based on root tips, were made in the traditional way; the roots were fixed in Karpechenko, cut, and stained with crystal violet. The staining and the countings did not meet with any difficulties.
The open-ground cultures were also used in the castration experiments. Five to ten flower heads in each transplant number were cut with a razor in such a way that only the lower part of the head remained, while the upper part of the filaments and the styles together with the anthers and the stigmas were removed (cf. Raunki^jr, 1903; Ostknfeld, 1906). The proper time for the castration was found to be 1—2 days before the heads opened, the flower colour having just changed at that time from light green to yellow. In order to prevent any loss of achenes at the ripening the castrated heads were wrapped in thin
gauze bags. It should be added that castration does not seem to damage the flowers. In the apomictic types the castrated heads develop at least as many achenes per head as the unwounded ones. In studying this question, as well as the fertility of the sexual types, where castration has no effect, five to ten flower heads in each transplant number were harvested after free pollination in the open-ground cultures. As soon as these flowers were wiltering they also were wrapped in gauze bags to prevent loss of achenes.
EMBRYOLOGICAL NOTES
From the important work by Rosenberg (1906, 1907) we know, that the apomictic mode of reproduction, occurring in subgenus Pilosella, rests on apospory. The species examined by Rosenberg were H. excel-lens, H. flagellare and H. aurantiacum.
Embryological work in the subgenus was not resumed until 1933 when Christoff and Popoff studied four different types of the subgenus. One of these, H. Pavichii Heuff., closely related to H. florenti-num N. et P., is a diploid amphimict. The other three, according to the authors typical H. pilosella L., do not even belong to the Pilosellina group, as is evident from their own description. The three types represent aposporous pentaploids, however.
Gentscheff (1937) studied, among other species, also H. pilosella. He does not describe the plant, and it remains doubtful, whether it belongs to the subgroup Pilosellina. The embryo development is described for the first time in this subgroup, provided that the determination is correct. Also this type represents an aposporous pentaploid.
Christoff and Christoff (1948) studied H. Hoppeanum Schult., a Pilosellina species with 2n = 45, closely related to H. macrolepidium but not occurring in Scandinavia. By colchicine treatment a C0-plant with 2n = 90 was produced, which in the offspring gave rise to 2n = 90 plants as well as to 2n = 45 plants. The type, as well as the doubled C0-plant, were studied embryologically and were found to develop aposporous embryo sacs, while the original EMC degenerated at an early stage. In the aposporous Hieracia, we know, that certain normal EMC do not degenerate but give rise to chromosome reduced eggcells in need of fertilization. In this connection Ostenfeld (1910) should be mentioned, who obtained hybrids between H. aurantiacum and aposporous H. pilosella as mother. The work of Rosenberg (1907), as is well known, showed the presence of normally developed embryo sacs in H. excellens.
46 — Hereditas Mi
gote turesson and benedicte turesson
Christoff and Christoff are of the opinion, however, that the meiosis found in the chromosome doubled C„-plant takes place in somatic cells from the integument. "These somatic cells, which occupy the cavity of an apparently older ovule, probably appeared after the degeneration of the archesporium." They take for granted "that the embryos which gave rise to the individuals with the reduced chromosome number originate from somatic cells, which have passed through meiosis", while the 2n = 90 plants come from ordinary, aposporous embryo sacs with the unreduced chromosome number.
However, since colchicine treated plants often give rise to chimeras, diploids and tetraploids may be produced from the same C0-plant. In the red clover, for instance, it is not uncommon to find the one half of the head with diploid flowers, the other with tetraploid (unpubl.).
Presuming the chromosome doubled C0-plant of H. Hoppeanum were a chimera no additional commentary is necessary to explain the occurrence of plants with 2n = 45 in the offspring.
Since hardly any forms belonging to the subgroups here treated, viz. Macrolepidia and Pilosella s.str. have been examined in this respect, representatives of these subgroups have been checked embryologically. As was expected, apospory was also found to be typical of these groups. Forms or biotypes, which combine facultative sexuality with apomixis, as is the case in the aposporous Pilosellas, have been called amphiapo-micts by the senior writer (Turesson, 1926), and this term has, therefore, been used in the following.
TYPE, CHROMOSOME NUMBER AND DISTRIBUTION
Before discussing Tables 1—7 it should be observed, that the provinces with reported localities are arranged from South to North, and that the foreign collections are tabulated at the end of the table or chromosome group.
The basic chromosome number in subgenus Pilosella is 9. In the subgroup Pilosella the diploid, 2n = 18, is represented by the sexual or amphimictic H. macrolepidium (see Table 1). Its main distribution in Sweden is in the southern and middle parts, especially in the coastal provinces, where it grows in open, grass-covered hills forming dense mats. The underside of the leaves is bright white through a dense and short coat of stellate hairs. The flower heads are rather large and bright yellow.
In H. macrolepidium also types with 2n = 27, 2n = 36 and 2n==45
TABLE 1. Distribution of amphimictic H. macrolepidium.
Field No. Locality Province or country Collector Year of coll. 2 n
146 Landskrona 1 Scania G. TURESSON 1949 18
148 3 1949 18
180 Vitemolle 33. TURESSON 1949 18
252 Saxtorp 1 G. TURESSON 1950 18
253 „2 „ я 1950 18
254 3 1950 18
331 Ähus 1 „ 1951 18
332 2 1951 18
333 „ 3 1951 18
334 Brösarp „ 1951 18
339 Lomma 1 » 1951 18
340 2 " i " 1951 18
341 3 1951 18
345 Kullen 1 1 1952 18
441 Beddinge 1 1952 18
442 2 1952 18
443 Stavs ten 1 1952 18
444 2 1952 18
510 Kämpinge 1954 18
532 Stenshuvud 3 1956 18
356 Haverdal Halland 1952 18
36 Gisebo Smâland 1945 18
86 Kalmar N. Erlandsson 1949 18
456 Skatelöv G. Tuhesson 1953 18
84 Kastlösa Öland N. Erlandsson 1949 18
421 Vickleby b. turesson 1952 18
424 Resmo 2 1952 18
426 4 „ 1952 18
428 Länge Jan 1952 18
429 Byerum 1952 18
430 Byxelkrok 1952 18
423 Resmo 1 1952 18
224 Gothem Gotland H. Nordenskiöld 1950 18
225 Lickershamn 1950 18
227 östergarn 1950 18
229 Hejnum 1950 18
230 Hoburg „ 1950 18
231 Stenkyrka „ 1950 18
537 Vestergarn 2 G. turesson 1957 18
543 Hoburg 1 1957 18
544 2 „ 1957 18
549 Högklint 2 „ 1957 18
371 Trollhättan 1 Västergötland 1952 18
g5te turesson and benedicte turesson
TABLE 1. Cont.
1'u'lll Province or Year
No. locality country Collector of coll. 2 n
372 Trollhattan 2 Vastergótland G. Tubesson 1952 18
373 3 „ 1952 18
473 Forshem 1953 18
90 Ringstad 2 Ostergotland 1949 18
241 Slroinstad 1 Bohuslan 1950 18
242 2 1950 18
244 4 1950 18
357 Ivareby 1 1952 18
358 2 1952 18
359 3 1952 18
360 4 1952 18
366 Brackan, Orust 1952 18
53 Fiskebiickskil ) i 1948 18
48Ü Sannahed Niirke 1953 18
94 Vik Uppland 1949 18
187 L. Ullsjofjarden H. Nordenskiüld 1950 18
192 Uppsala 3 B. Turesson 1950 18
212 Vik 1 „ G. Turesson 1950 18
214 Funbo 1 1950 18
260 Kvarnberget 2 1951 18
261 3 1951 18
323 Skarplinge 1951 18
440 Ramsta B. Turesson 1952 18
438 Valsgarde 4 „ 1952 18
508 Harg 1 » „ 1954 18
512 Fontainebleau France II. Nordenskiüld 1954 18
268 Stenkyrka Gotland „ 1950 27
475 Mariestad 2 Vastergótland G. Turesson 1953 27
193 Uppsala 4 Uppland B. Turesson 1950 27
194 6 1950 27
213 Vik 2 „ G. Turesson 1950 27
410 Valsgiirde B. Turesson 1952 27
176 Olback Gotland B. Pettersson 1949 36
177 „ 1949 36
223 H. Nordenskiüld 1950 36
TABLE 2. Distribution of amphiapomictic H. macrolepidium.
Field No. Locality Province or country Collector Year of coll. 2 n
141 Ту dinge Scania В. Lüvkvist 1949 36
468 Forseriim Smâland G. Turesson 1953 36
42 Slite Gotland 1947 36
228 Holmhällar II. Nordenskiöld 1950 36
540 Hoburg I g. turesson 1957 36
541 II „ „ 1957 ±36
50 Kristineberg Bohuslän 1948 36
191 Uppsala 2 Uppland B. Tuhesson 1950 36
197 7 1950 36
267 Viiddö H. Nordenskiöld 1951 36
401 Biludden 1 G. Tuhesson 1952 36
402 2 1952 36
403 3 1952 ±36
404 üregrund 1952 36
408 Rimbo „ 1952 36
435 Biludden B. Turesson 1952 36
505 öregrund 1 „ 1954 36
422 Vickleby 2 üland 1952 45
470 Bjurum Västergötland g. Turesson 1953 45
52 Lysekil 2 Bohuslän 1948 ±45
245 Strömstad 5 1950 45
88 Virà Södcrmanland B. Bergman 1949 45
437 Valsgärde 3 Uppland В. Turesson 1952 45
439 1952 45
168 Tällberg Dalarna » 1949 45
TABLE 3. Distribution of amphimictic H. pilosella.
Field No. Locality Province or country Collector Year of col 1. 2n
1 Ljungbyhed Scania G. Turesson 1944 36
6 Hylla 1945 36
8 Dalby 1945 ±36
9 Simrishamn 1945 36
11 Gunnarp „ 1945 36
12 Sätaröd 1945 ±36
14 Kungsmarken 1945 36
15 Ludvigsborg 1945 36
16 S. Rörum 1945 36
20 Ostarp 1945 3fi
21 Stenestad » 1945 36
TABLE 3. Cont.
Field No. Locality Province or conntry Collector Year oi'coll. 2 n
38 Tunbyhoim Scania ci. turesson 1945 ±36
122 Kaffatorp 3 ' N. Ehlandsson 1949 36
134 Brobv 4 B. Lövkvist 1949 36
147 Landskrona 2 g. turesson* 1949 36
150 •> 1949 36
152 Malen i „ 1949 36
183 Hallands Viiderö 1 B. Lövkvist 1949 ±36
278 Axelvold 1 ' H. Nordenskiöld 1951 ±36
279 2 1951 36
280 Knutstorp 1 i 1951 36
281 2 1951 ±36
293 Högestad 1 1 G. Tuhesson 1951 36
294 2 ' i. 1951 36
295 Falsterbo 1 j ,, 1951 36
296 2 1951 ±36
297 1' 3 j „ 1951 36
298 Skanör 1 „ 1951 36
299 o 1951 ±36
311 Broby C B. Lövkvist 1951 36
312 „ 1) 1951 36
315 „ G „ 1951 36
316 „ H 1951 36
317 „ I 1951 36
318 „ K „ 1951 36
329 Sânckulla G. turesson 1951 36
330 Klagshamn 1951 36
335 Skillinge 1951 36
336 Sjöbo j ,, 1951 36
338 Bjerred ,, 1951 36
343 Viktorshög i 1952 36
346 Domsten 1 » 1952 36
347 2 1952 36
445 Hohög 1952 36
446 Frostavallen 1953 36
447 Tjörnarp 1953 36
450 Vankiva 3 1953 36
451 „4 ! 1953 36
483 Barsebäck 1 ,, 1953 36
487 llovs Hallar i 1954 36
488 Bâstad 1 ! 1954 36
489 2 1954 36
529 Simrishamn 1956 36
533 Frostavallen » 1956 36
TABLE 3. Cont.
Field Province or ('ollector Year
No. Locality country of coll. 2 n
534 Havilng Scania G. turesson 1956 36
151 Hogaskog 1 Halland 1949 36
354 2 1952 36
33 Griinna Sm&land 1945 36
467 Forserum 1 1953 36
498 Aby 2 Ostergotland 1954 36
117 Talne 1 Denmark S. 0. Bjorkman 1949 36
118 - 1949 36
285 Rodding H. Nordenskiold 1951 36
286 Viborg „ „ 1951 36
287 Ribe 1 1951 36
288 2 1951 36
290 Skibsted 1951 ±36
289 Logstor „ 1, 1951 36
291 Osterild 1951 ±36
292 Bromsholm 1951 36
257 Sussex 1 England H. G. Baker 1950 36
258 2 1950 36
237 Obermoss, Zugsp. Germany ii. Nordenskiold 1950 36
TABLE 4. Distribution of amphiapomictic H. pilosella.
Field Province or Collector Year 2 11
No. Locality conntry of coll.
3 Gyllebo Scania G. turesson 1945 45
10 Nybro&n b. turesson 1949 45
114 V. Stroo b. l5vkvist 1949 45
127 Kaffatorp 8 N. Erlandsson 1949 45
132 Broby 2 b. lovkvist 1949 45
133 „ a „ 1949 45
135 „ 5 1949 45
136 f> 1949 45
137 „ " 1949 45
138 8 „ 1949 45
139 „ 9 1949 45
153 Skiilderviken G. turesson 1949 45
155 V. Stroo 2 b. lovkvist 1949 45
158 5 1949 45
159 6 1949 45
162 Kungsmarken 1949 45
184 Hollands Vadero 2 » 1949 45
TABLE 4. Cont.
Field Province or i Year
No. Locality country Collector Í)í coll. 2 il
30!) : Broby A Scania В. Lövkvist 1951 ±45
310 „ в 1951 45
313 „ E M 1951 45
314 : „ F 1951 ±45
319 „ L 1951 45
337 Bolleruj) „ g. turesson 1951 45
344 Sibbarp 1952 45
452 Vittsjö 1953 ±45
453 Osby „ 1953 45
282 Brükne-IIoby 1 Blekingc „ 1951 45
283 2 1951 ±45
284 Karlskrona „ 1951 45
525 Tjurkö 1 „ 1956 ±45
527 3 „ 1956 ±45
342 Tolarp Mailand 0. Geijn 1952 45
349 S Urea Strand 1 G. turesson 1952 45
350 2 1952 45
351 „ 3 1952 45 ;
352 Steninge 1 „ 1952 45 !
353 2 1952 45
355 Asa 1952 45
490 Tönnersjö 1954 45
37 Visingsö S m áland 1945 45
78 Viixjö I). Berntman 1948 45
218 Vassmolösa 1 b. turesson 1950 ±45
21!) 2 1950 ±45
274 Jönköping H. Nordenskiot.d 1951 45
275 Tännö 1 1951 45
276 2 1951 ±45
277 Markaryd „ 1951 45
348 Lidniis g. turesson 1952 45
411 Hornsborg ; O. Gelin 1952 45
432 Pataholm b. turesson 1952 --45
454 Älmhult g. turesson 1953 45
455 Räshult 1953 45
457 l'rshult 1953 45
458 Riivamâla 1953 45
460 Lrnlmvda 1953 ±45
461 Hyningsniis 1953 45
462 Oskarshamn 1 1953 45
463 2 1953 45
465 Vimmerby 2 „ 1953 45
466 Eksjö » 1953 ±45
TABLE 4. Cont.
Field No. Locality 1 Province or country Collector Year of coll. 2 n
469 Bankeryd Smäland G. Turesson 1953 ±45
491 Vrä i 1954 45
492 Ljungby " i 1954 45
494 Bellö 1 1954 45
495 Svinhult " i " 1954 45
515 Västervik, Gränsö 1 1 1956 ±45
516 2 1956 45
517 3 1 1956 45
518 , Segersg. 1 " i " 1956 ±45
519 2 1956 ±45
520 , Kuggv. „ 1956 45
521 Oskarshamn, Gunnarsö 1956 45
522 , Rotvik 1 1956 ±45
523 , „ 2 1956 45
524 , Sal tö » 1956 ±45
119 Vickleby öland N. Erlandsson 1949 45
425 Resmo 3 ! B. turesson 1952 45
1 431 Böda 1952 45
| 511 Djupvik, Fora N. Erlandsson 1954 ±45
41 Räby triisk Gotland G. Turesson 1947 45
181 Färösund O. Hedberg 1949 45
| 226 Lummclunda H. Nordenskiöld 1950 45
535 Lojsta Hed G. Turesson 1957 45
542 Hoburg 3 1 „ „ 1957 45
545 Vike 1 1957 ±45
546 2 1957 45
547 „ 3 1957 ±45
89 Ringstad 1 östergötland •> 1949 45
92 Grensholmen 1949 45
112 Omberg 1 S. O. Bjöhkman 1949 45
113 2 „ 1949 45
178 Grensholmen j „ A. Gustafsson 1949 45
217 Borghamn ] » 1949 45
496 Atvidaberg j G. Turesson 1954 45
498 Aby 1 | „ 1954 45
499 Näkna 1 | 1954 45
500 2 \ „ 1954 45
4 Göteborg Vilstergötland C. Blom 1944 45
115 I.iickö „ S. O. Björkman 1949 45
202 Hindas j „ II. Nordenskiöld 1950 ±45
203 Alingsäs | >, „ 1950 45
265 Tivägsboda j B. LüVKVisT 1951 45
300 Falköping | » G. Turesson 1951 45
TABLE 4. Cont.
Pichl No. I.oculity Province or COlUltry O>llcctor 1 Ycai- 1 ol'coli. i 2 n
301 Müsseberg 1 Västergötland G. TUItESSON 1951 45
30'2 2 1951 45
303 Kleva 1 1951 ±45
305 3 1951 ±45
371 Trollhiillaii 4 „ 1 1952 45
375 5 ,, i ,, 1952 45
471 Bjurum 2 ! 1953 45
474 Mariestail 1 1953 45
476 Undeniis 1953 45
477 Granvik 1953 45
51 Lysekil 1 Bohuslan „ 1948 45
56 Munkedal i 1948 45
302 Stenungsund ,, 1 ,, 1952 45
363 Svanesund 1952 45
364 Hârlebv, Orust 1 1952 45
365 2 1952 45
367 Sviilto 1 ,, j ,, 1952 45
368 2 , 1952 45
369 Uddevalla 1 1952 45
370 2 1952 45
269 Laxarby Dalsland S. Odén 1951 ±45
270 Ed, Stora Le 1951 ±45
376 Mellerud l G. TUItESSON 1952 45
377 2 1952 45
381 Bengtsfors 1 j „ „ 1952 45 ,
382 2 1952 45 |
383 3 ! 1952 45
266 | Siibylimd Niirke B. Lövkvist 1951 3:45 |
271 Degerfors ! S. Odén 1951 ±45
478 Olshammar G. turesson 1953 45 i
479 Askersund 1953 45 '
58 Kila 1 Södermanland H. Nordenskiöld 1948 45 !
59 ' 2 1948 45
91 ! Tystberga ! „ G. TURESSON 1949 45
182 ! Sjösa i H. Nordenskiöld 1949 45
259 Vaxâker 2 1 1950 ±45
262 Södertiilje ' „ G. TURESSON 1951 45
273 | Vaxâker ; ,, H. Nordenskiöld 1951 45
307 Hömora, Trosa archip. „ 1951 45
433 Sparreholm 1 B. TURESSON 1952 45
434 I 2 1952 45
501 Simonstorp 1 G. TURESSON 1954 45
502 i 2 1954 45
TABLE 4. Cont.
Field No. Province or ■ Collector Year 2 n
Locality country of coll.
503 Klastorp Södermanland G. turesson 1954 45
504 Slemna ,. ! „ 1954 45
79 Blankheden Värmland Â. Gustafsson 1948 45
234 Noppen 1950 45
272 Bro S. Oden 1951 45
386 Vainas ! G. turesson 1952 45
387 Karlstad ; „ 1952 45
388 Brattfors ! 1952 45
389 Saxâ 1952 45
163 Harbo Västmanland B. Lövkvist 1949 45
390 Hjulsjö 1 G. turesson 1952 45
481 Arboga 1 „ 1953 45
482 „ 2 „ ! >> 1953 45
27 Bäcklösa Uppland 1945 45
46 Lidingö H. Nordf.nskiöld 1948 45
48 Ärna „ 1948 45
95 Uddeboö B. Lövkvist 1949 45
185 Hummeldal g. turesson 1950 45
186 Torslunda „ 1950 45
189 Hjällstaviken II. Nordenskiöld 1950 45
190 Uppsala 1 b. turesson 1950 45
196 » " „ 1950 ±45
205 Bogesund 1 Ä. Gustafsson 1950 ±45
207 2 1950 45
210 „3 „ „ 1950 ±45
215 Funbo 2 g. turesson 1950 ±45
216 Gârdskiir B. Lövkvist 1950 45
220 Hammarby 1 g. turesson 1950 45
221 2 1950 45
222 3 1950 ±45
255 ösby ! „ 1950 45
256 Biludden B. Lövkvist 1950 45
308 Ultuna G. turesson 1951 ±45
320 „ 1951 ±45
321 Vittinge 1 1951 45
322 2 1951 45
324 Mânkarbo 1 1951 45
325 österbybruk 1951 45
326 Älvkarleby V 1951 ±45
406 Norrtälje 1952 45
407 Frötuna 1952 45
409 Gottröra »1 1952 45
413 Grisslehamn » b. turesson 1952 ±45
TABLE 4. Cont.
Field No. Locality Province or country Collector Year of coll. 2 n
41<i Väddö Huvud 3 Uppland B. tuhesson 1952 45
417 4 1952 45
418 » » 5 1952 ±45
419 Gottsundn „ 1952 45
396 Storvik 1 Güstrikland G. turesson 1952 ±45
400 Gävle 1952 45
61 Säter Dularna 1948 45
165 Hedemora B. turesson 1949 45
392 Rämshyttan 1 G. tl'resson 1952 45
393 2 1952 45
395 Hosjö ,, 1952 45
70 Nordanede Medcl]>ad A. Gustafsson 1948 45
72 Änge 1948 45
75 Norrhassel ,, 1948 45
174 Are Jämtland G. turesson 1949 45
44 V&dii Finland H. Nohdenskiöld 1947 45
45 östersundom " 1947 45
63 Nätö, Aland E. Hesselman 1948 45
238 Fischbach, Styria Austria II. Nordknskiöi.d 1950 45
239 Maria Trost, Graz 1950 ±45
485 Katschberg 1953 ±45
448 Vankiva 1 Scania G. turesson 1953 54
528 Tjurkö 4 Blekinge B. turesson 1956 54
464 Vimmerby 1 Sniäland G. turesson 1953 54
! 420 Karlevi öland b. turesson 1952 54
536 Vestergarn 1 Gotland G. turesson 1957 ±54
538 3 1957 54
539 Eksta „ 1957 54
548 Högklint 1 „ 1957 ±54
60 Göteborg Viistergötland 1948 54
; 304 Kleva 2 1951 ±54
378 Mellerud 3 Dalsland 1952 54
379 4 1952 54
26 Bergshamra Uppland 1945 54
77 Bogesund 1948 ±54
I 405 Hallstavik 1952 54
414 VäddöHuvud 1 b. turesson 1952 54
! 415 2 1952 54
399 Forsbacka Gästrikland G. turesson 1952 54
! 166 Hedemora 2 Dalarna B. turesson 1949 54
: 97 Gänsvik 1 Angermanland G. turesson 1949 54
98 2 5 f 1949 54
; 68 ösfavall Medelpad A. Gustafsson | 1947 54
TABLE 4. Cont.
Field No. Locality Province or country Collector Year of coll. 2 n
236 Lanser Aim, Innsbr. Austria H. Nordenskiöld 1950 54
240 Glashütten, Koralpe „ 1950 ±54
249 Stockacher Aim, Innsbr. 1950 ±54
250 Polster, Hochschwab. 1950 ±54
531 Stenshuvud Scania b. turesson 1956 63
131 Broby 1 B. Lüvkvist 1949 63
526 Tjurkö 2 Blekinge B. turesson 1956 ±63
TABLE 5. Distribution of umphimictic H. auricula.
Field No. Locality Province or country Collector Year of coll. 2 n
13 Järarna Scania G. turesson 1945 18
279 Axelvold 3 H. Nordenskiöld 1951 18
154 V. Ströö 1 „ G. turesson 1949 18
156 3 ,, 1949 18
120 Kaffatorp 1 N. Erlandsson 1949 18
83 Kastlüsa öland „ 1949 18
49 Mörbylänga „ II. Nordenskiöld 1948 18
143 Gammelgarn 1 Gotland B. Pettersson 1949 18
145 3 „ 1949 18
201 Hindäs Västergötland II. Nordenskiöld 1950 18
306 Kleva G. turesson 1951 18
54 Munkedal 1 Bohuslän 1948 18
55 2 „ 1948 18
380 Backe Dalsland „ 1952 18
57 Kila Södermanland II. Nordenskiöld 1948 18
62 Vaxäker 1948 18
87 Virä 1 B. Bergman 1949 18
179 2 „ „ 1949 18
81 Medskogen Viirmland A. Gustafsson 1948 18
211 Bogesund Uppland 1950 18
200 Uppsala B. turesson 1950 18
31 Bäcklösa „ G. turesson 1945 18
25 Järläsa 1945 18
397 Storvik 2 Gästrikland 1952 18
40 Tisjön Dalarna 1945 18
167 Hedemora B. turesson 1949 18
164 Älvdalen ,, 1949 18
76 Ljusdal Hiilsingland Ä. Gustafsson 1948 18
71 Ange Medelpad » 1948 18
g5te turesson and benedicte turesson
TABLE 5. Cont.
Field No. Locality Province or country Collector Year of coll. 2 n
.0 Nordanede Medelpad A. Gustafsson 1948 18
71 Ivr&ngedc Jiimtland 1948 18
73 Briicke 1948 18
102 Iiagunda G. Turesson 1949 18
105 Stugun 1949 18
64 Sundmo Angermanland A. Gustafsson 1948 18
99 Gansvik G. Turesson 1949 18
100 Solicit ea 1949 18
67 Ostavall .Medelpad A. Gustafsson 1947 18
80 Skellefte& Viisterbotten 1948 18
235 Lanser Aim, Innsbr. Austria H. Nordenskiold 1950 38
251 Moschkogl, Koralpc 1950 18
328 Patscherkofel, Innsbr. » 1950 18
TABLE 6. Amphimictic H. pilosella with some distinct H. macrolepidium characters.
Field No. Locality Province or country Collector Year of coll. 2 n
19 Brosarp Scania G. Turesson 1945 27
121 Kaffatorp 2 N. Erlandsson 1949 27
123 4 1949 27
149 Landskrona 4 G. Turesson 1949 27
530 Stenshuvud 1 B. Turesson 1956 27
TABLE 7. Amphiapomictic H. pilosella with some distinct H. auricula characters.
Field No. Locality Province or country Collector Year of coll. 2 n
459 Kosta Sm&land G. Turesson 1953 36
42 Slite Gotland 1947 36
497 Norsholm Ostergotland 1954 36
493 Vrigstad 1954 36
263 Berga Fiired 1 Viistergotland B. Lovkvist 1951 36
264 1951 + 36
385 Amal Dalsland G. Turesson 1952 36
172 Vir& Sodermanland B. Bergman 1949 36
TABLE 7. Cont.
Field Province or Year
No. Locality country Collector of coll. 2 n
24 Dalarö Södermanland g. tljresson 1945 ±36
391 Hjulsjö 2 Västmanland ,, 1952 36
30 Notholnien Sthlm archip. 1945 36
384 L:a Ulleviksfjärden Uppland B. turesson 1952 36
505 öregrund „ 1954 36
32 Sifferbo, Gagnef Dalarna G. turesson 1945 36
248 Stockacher Bach, Innsbr. Austria H. Nordenskiöld 1950 ±36
249 Aim, 1950 36
occur. The triploid is amphimictic, although much sterile; only a few achens are formed in each head, and the plant is "thinner" and weaker than the diploid and has difficulty in holding its own in competition. The type, therefore, is rare in nature, although it is readily made artificially. The tetraploids and the pentaploids (see Table 2) are larger and more robust than the diploid. They have also longer stolons, although characterized by the distinctive marks of H. macrolepidium for the rest, viz. homophyllous leaves on the stolons with large, apical rosettes. The tomentum on the underside of the leaves is looser and coarser than in the diploid. They are rather rare in nature and grow in scattered individuals without forming close mats, preferably in crevices and on open stony ground. The tetraploids and the pentaploids are amphiapomictic, with the only exception of the tetraploid collection from Olback on the island of Gotland, which represents a deviating, strictly amphimictic type.
The morphological differences between H. macrolepidium and H. pi-losella have been pointed out in the introduction. The best distinguishing marks are the stolon differences and the flower colour, which is darker yellow in H. pilosella. The long, slender stolons in this species become still longer with increasing chromosome number, the scapes also increase in height, and the hairiness on the underside of the leaves becomes coarser and looser.
The few triploid types found among the collections (see Table 6) have several typical characters of H. macrolepidium and represent, no doubt, hybrids between these species. They are, as in the case of triploid H. macrolepidium, fragile and weak and rather sterile. They are easily produced artificially.
We have not found any typical H. pilosella with lower chromosome
gfite turesson and benedicte turesson
number than 2n = 36, and this tetraploid is composed of strictly amphi-mictic types. All types with higher chromosome number (2n=45, 2n = = 54, and 2n = 63, see Table 4) are found to be amphiapomicts. The only amphiapomictic tetraploids found show, without exception, typical characters of H. auricula (see Table 7), and represent hybrids between these species.
As seen from Table 3 the tetraploids are almost restricted in their distribution to the southernmost province, Scania. A few localities have been found north of this province (from southernmost Halland, from Smáland and Ostergotland) but it is of interest to find that these collections come from road-sides and not from undisturbed habitats. In Scania, however, these tetraploids are common, and they are not, as in the case of amphimictic H. macrolepidium, restricted only to the neighbourhood of the coast, but occur in the interior as well. The foreign material is very limited; two collections have been received from ling-land and nine from Denmark (eight of these collections represent spread localities in Jutland, and the ninth, Bromsholm, comes from the east-coast of Zealand). It seems rather significant that these collections all represent the amphimictic, tetraploid H. pilosella.
Evidently, this type is rather common in Denmark, perhaps the predominating one. It is, then, surprising to find that the Danish material, used by Ostenfeld (1906) in his castration and crossing experiments and sent by him to Rosenberg for cytological investigations, consisted of amphiapomictic tetraploids. Ostenfeld showed by castration its apomictic nature, and Rosenberg (1917), in studying the pollen formation, found the chromosome number to be 2n = 36. In the Copenhagen Botanical Museum dried and carefully numbered specimens are preserved of just the type used by Ostenfeld and sent to Rosenberg. This type, however, is not a H. pilosella but a tetraploid H. macrolepidium, which is at once seen upon inspection.
The investigations of Ostenfeld and Rosenberg, based on this comparatively rare type, have led to the erroneous conception that the "species" belonging to the subgroup Pilosellina are all apomictic and characterized by the chromosome number 2n = 36. The inconstancy of many of these "species", as well as of the intergradation found, due to the presence of sexual types in the Pilosellina group, troubled the Pilosella specialists, knowing nothing of these sexuals, but well acquainted with the constant "species" of the strictly apomictic Archieracia. The false analogy led to the great number of so-called species, distinguished and named in the Pilosellas.
The pentaploid H. pilosella is the most frequent type in the group Pilosellina in Sweden. It occurs from southernmost Scania to Jiimtland to the North, although it becomes rarer towards its northern limit. Contrary to the other types within the group it is also found in woody regions in the interior. The long stolons and the tall scapes, especially marked at fructification, make the pentaploids better fitted to live in somewhat taller vegetation than the other types. They form mats, as the tetraploids, but they are less dense because of the greater stolon length. The variation is also considerable, in leaf shape as well as in hairiness. Sometimes also furcated flowering stems with dark-haired involucres are found among the pentaploids, indicating a probable hybridization with H. auricula.
The 2n = 54 and 2n = (>3 types are rare, and they are usually found as isolated individuals. They are robust in growth, but slow in development, flowering late and dispersing themselves with difficulty.
The amphimictic types of H. macrolepidium and H. pilosella are quite fertile with each other. Pure intermediates are seldom found; usually the forms are either H. macrolepidium with some H. pilosella characters, or vice versa. The rareness of the pure intermediates is probably due to the fact, that the hybrid is a rather sterile and weak tri-ploid. With increasing chromosome number they represent amphiapo-micts, showing a rather low frequency of hybridization in spite of being facultative sexuals and having good pollen.
The two sexual types can also be crossed with H. auricula. The amphimictic H. auricukeforme Fr. is a well known hybrid between H. auricula and H. macrolepidium with 2n=18 as in the parents. It is intermediate in habitus and not infrequently found in nature. A collection from Vira in Sodermanland (coll. B. Bergman) has been studied.
In order to produce hybrids between types of subgroup Pilosellina and H. auricula some collections have been made of the latter species (see Table 5). The species prefer somewhat moisier habitats lhan the members of the Pilosellina group, and has an extended distribution from South to North. Some collections from the Austrian Alps are also included in the table. All are amphimictic and found to have the chromosome number 2n=18 without exception.
SUMMARY
(1) The paper deals with representatives of the "species" of the two Pilosellina-suhgroups of Hieracium pilosella L., viz. Macrolepidia and Pilosella.
-17 — Hercditas 't<>
(iöte turesson and benedicte turesson
(2) In amphiniictic H. macrolepidium Norrl. the types 2n=18 (the most widespread), 2n = 27 and 2n = 36 (from only one locality) are found. In the amphiapomicts the types 2n = 36 and 2n = 45 have been found. The habitats and distribution of the different types are discussed.
(3) The amphiniictic type in H. pilosella s.str. has the chromosome number 2n=36 and is largely distributed in southernmost Sweden. In the amphiapomicts the series 2n = 45 (with the most extended distribution), 2n = 54 and 2n = 63 have been found. The habitats and distribution of the different types are discussed.
(4) The Danish H. pilosella type, used by Ostenfeld and sent by him to Rosenberg for cytological study, preserved in the Copenhagen Botanical Museum, is not a H. pilosella s.str. but a tetraploid M. macrolepidium.
(5) Hybrids with H. auricula found in nature — amphimicts having 2n = 18 and amphiapomicts with 2n = 36 — have also been discussed.
Literature cited
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