558 Cvtolcgia 10 Chromosome Studies on Papaveraceae with Special Reference to the Phylogeny* By T. Sugiura Osaka Higher School, Osaka Received April 19, 1939 Although there are about 600 species of Papaveraceae, there have been chromosome studies made of comparatively few of them, in spite of the majority of them being cultivated in the gardens. It is hoped therefore that it will be of some interest to describe some of the chromosome studies of Papaveraceae which the writer has carried on during the last few years, especially with a view to find the phylogenic relationships between various genera of this family. The first karyological studies of the Papaveraceae were made by Nemec (1910) on Corydalis pumila and later by Tahara on Pa.parer rhoeas, orienta,le and somniferum. Afterwards Ljungdahl (1922-'24), Yasui (1921-'39) on Papaver, Winge (1925) on Eschscholtzia, Kachidze (1926) on Platystemon were the chief ones on karyological studies in Papaveraceae. Here the writer wishes to express his best thanks to the directors of the botanical gardens at Berlin-Dahlem, Graz, Kaunas, Kew, Leyden, Oslo, Paris and Warsaw for the seeds that were kindly sent to him for the present study. Material and Method Only young flower buds were collected for study. The Farmer's aceto-alcohol was used for fixation and Heidenhain's iron-alum haematoxylin for staining in order to be able to compare the present preparations with the former ones, upon which my previous descriptions on chromosomes of higher plants are based. Plants Investigated') Hypecoideae According to Fedde (1936) there are two genera Pteridophyllum and Hypecoum. This work was made possible by a grant from the Japan Society for the Advancement of Cytology, to which society the writer's most appreciative thanks are due. 1) The classification in this family is based chiefly on F. Fedde's "Papa veraceae" in "Pflanzenfamilien", 2nd Ed. 1936. 1940 Chromosome studies on Papaveraceae with special reference etc . 559 Pteridophyllum racemosum (Fig. 1). It is only grown wild in our country. The outer and inner morphological characters in this plant are quite different from those of the latter genus. Murbeck (1912), therefore, has established a new subfamily Pteridophylloideae, and Hayata (1930) also adopted a new family Pteridophyllaceae for the reason that they had simpler stele and different floral structure from those of other Papaveraceae. Prof. Nakai of the Tokyo Imperial University holds the same opinion. Karyological results lead to the same conclusion. Its meiotic number 9. which is almost never found (except in Roemeria) in this family, must be derived from 3, the basic number of Papaver oideae (the writer's Cheridonioideae, cf, p. 574, phylogenic scheme) and trebled. Murbeck said "Pteridophyllum ist auf Grund seiner isolierten Stellung unzweifelhaft ein uralter Typus, und da diese Gattung, obgleich sowohl von den Papaveroideae wie von den Hypecoideae scharf geschieden, doch eine Mittelstellung zwischen ihnen einnimmt, so konnte man sich zu der Annahme versucht fuhlen, daB sick diese beiden Gruppen von dem Pteridophyllum Typus abgezweigt hatten. Wahrscheinlicher ist es jedoch, daB sich die drei Unterfamilien entweder gleichzeitig aus einander sehr nahestehenden Formen entwickelt haben, oder daB die Pteridophyl loideae durch ausgestorbene Gattungen einst naher mit den Papa veroideae verbunden gewesen sind und also eine fruhzeitige Auszwei. gung von diesen darstellen". According to Fedde's description no seeds are seen in this plant. It may be so, as polyspory is observable in it. The Pteridophyllum, being different from other papaveraceous plants not only in outer appearances but also as regards inner anatomical and karyological structure, as stated above, should be established as an independent family Pteridophyllaceae. It is pro bable that Pteridophyllum, having 9 meiotic chromosomes, branched out from very remote ancestors of Papaveroideae (the writer's Cheridonioideae, cf. p. 574, phylogenic scheme) with the basic chromosome number 3, and has now grown quite stable by poly ploidation. Hypeco irn procumbens (Fig. 2). This plant, being different from the previous one both as regards its outer and inner mor phological structure, has 8 meiotic chromosomes. Smith (1934) counted, however, 12 somatic chromosomes. In spite of the size of the meiotic chromosomes being rather larger than those of Pterido phyllum, as stated above, the pollen mother cells are far smaller 560 T. SUGIURA Cytologia 10 than that, the former 7.5ƒÊ in diam. and the latter about 14ƒÊ t in diam. The basic number in this genus is 4. From thee basic number 4 in this genus and 3 in the above mentioned species, it is considered that they have been developed face to face in each other as shown in the phylogenic scheme (cf. p. 574). Papaveroideae Platystemoneae Platystemon californicus (Fig. 3). There has been still no report about the chromosome numbers in this genus. Kachidze (1926) communicated to S. Nawashin that it had 6 meiotic chromo somes. The writer has counted 6 also. The pollen mother cells and meiotic chromosomes are larger than those of Hypecoum procumbens. We agree with Dickson's opinion that the present genus is the most primitive one in the Papaveroideae (the writer's Chelidonioideae, cf. p. 574, phylogenic scheme). Hunnemannia funiaria,efolia. (Fig. 4) The genus Hunner,w' nia has only one species which is half xerophytic. It was originally grown wild in Mexico. The writer counted 28 meiotic chromosomes in 1931. The same number was also counted by Smith (1934). The first metaphase chromosomes, being ellipsoidal, are rather small in comparison with those of other Papaveroideae (the writer's Chelidonioideae and Papaveroideae), while the pollen mother cells are very large, about 25ƒÊ in diam. From the results of my karyo logical observation in Papaveraceae it can be said that these pollen mother cells are the largest of the papaveraceous group. The basic number in this genus may be 7. Probably this plant arose as an effect of crossing between some species like Corydalis or Dicentra (Corydaloideae cf. 574 phylogenic scheme) and some Eschscholtzia (Chelidonioideae cf. p. 574 phylogenic scheme) in very early times. The above suggestion seems to be substantiated because the geographical distribution of above 3 species is almost the same. Eschscholtzia pulchella. (Fig. 5) Formerly Winge (1925) found the meiotic chromosome number in four different species to be 6. Morinaga and alli (1929) and Lawrence (1930) have confirmed that there were 6 meiotic chromosomes in E. californica. Smith (1934) has also counted 6 meiotic chromosomes in E. caespitosa and E. californica. But only Lawrence (1930) has counted eight meiotic chromosomes in E. mollis. The writer has also found 6 meiotic chromosomes in E. pulchella. The pollen mother cells are 9ƒÊ in diam. Thus, generally the basic number of chro mosomes in this genus is 3. The chromosome numbers found up to date are as follows: 1940 Chromosome studies on Papaveraceae with special reference etc. 561 J. Dickson believed that Eschscoltzia was the most highly developed type of Papaveroideae (the writer's Cheridonioideae and Papaveroideae, cf. p. 574 phylogenic scheme) from his studies on the gynaecium of the Papaveroideae, but we can not agree with this from the karyological point of view. Chelidonieae Hylomecon japonica. (Fig. 6) This plant is a unique species which is only grown in temparate East Asia. The pollen mother cells are about 8.5ƒÊ in diam.. Six spherical meiotic chromosomes are found. Dicranostigma Franchetianum. (Fig. 7) It is grown in Sze. Chuan and Yiinnan and has 6 meiotic chromosomes like Chelidonium. The size of the chromosomes is equal to that of Chelidonium majus. M. E. Smith (1934), however, counted 16 somatic chromosomes, which seem to be doubtful. Chelidonium majus. Chelidonium has only one species and some varieties. Since this has already been discussed in a previous paper, only certain interesting karyological figures are described-here. In the first metaphase it is often observed that there is a circular arrangement of chromosomes consisting of 6 at one pole and a 5-1 arrangement at the other. This suggests that the char acters of both daughter nuclei are different. C. majus var. laciniata (Figs. 8 a, 8 b) which was studied anew, has also 6 chromosomes, which are as large as those of C. majus. It is observed that although chromosomes are filar at the second anaphase, they are spherical at the first meta and anaphase. Similar figures are also found in C. majus. Probably this phenomenon may be due to the smaller viscosity of chromosomes at the second anaphase. Von Boenicke (1911) counted 8 meiotic chromosomes in C. majus and C, laciniatum, but to the writer it seems to be a miscount, Winge (1917) and Marchal (1920) also counted 6. 562 T. SUGIURA Cytologia 10 Macleaya In this genus there are only two following species which are grown in Central Asia and temparate East Asia. Eu-Macleaya ................. M. cordata n=10 (Fig. 9) Pseudo-Bocconia ............. M. microcarpa n=10 (Fig. 10) Bocconia In this genus there are 9 species which are grown in Central and South America. I have studied one species, B. frutescens (Fig. 11). Apart from systematic knowledge these three plants are very interesting karyologically. These 3 plants have the same number of meiotic chromosomes of almost the same shape and size of pollen mother cells in spite of the fact that they are grown in different localities of the world. Not only is their meiotic chromo some number 10 quite isolated from those of the, neighbouring genera Chelidonium, Hylomecon etc. which have 6, but also their pollen mother cells are smaller than those of other genera in Chelidoniae. The chromosome number 10 has hitherto not been found in other genera in the Papaveraceae. Thus it is considered from the karyological point of view that Macleaya and Bocconia both branched out from the Chelidonium.