Study of Euryale Ferox SALISB. VI. Cleistogamous Versus Chasmogamous Flowers. by Okada-Yonosuke & Otaya-Tasaku
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Study of Euryale ferox SALISB. VI. Cleistogamous versus Chasmogamous Flowers. By Okada-YOnosuke & Otaya-Tasaku The cleistogamy of Euryale ferox SALISB.was reported already by ARCANGELI1)about half a century ago, and in works with respect to aquatic plants, this is often taken to represent an example of cleisto- gamy in water plants2). The fact, however, that chasmogamous flowers are sometimes produced on this plant was not left unnoticed; according to GOEBEL'Sdescription,3) his example grown at Marburg bore in general only such flowers as did not come upon the water sur- face, while the plant at Muenchen produced some chasmogamous flowers, though not of very conspicuous appearance. In this country also the plant is generally recognized to bear flowers that do not open, and our observation with both cultivated and naturally grown examples corroborates the view in general. In the majority of cases, flowers of this plant come just above the water surface, and remain there for two or three days. During this period the sepals never open wide; they separate themselves only a little at best, so that one can hardly recognize the bluish violet petals within. In Text figure 1, on the right is represented an example of such a flower from the Zyunityogata. After this short period of emersed life, the flowers go down again under water and remain there until the time of the second appearance on the water surface as fully ripe fruits. In some exceptional cases, however, chasmogamous flowers are also ob- served. In the same text figure is depicted on the left an example also from the zyunityogata. In this latter case, both the sepals and the petals are turned externally and the flowers may be regarded to be This act of blooming tokes place in the earlyfairly open. 1) ARCANGELI, A. 1889. Sulla fiolitulla della Euryale ferox SAL. Sep.-Abd. aus Atti della Soc. toscana di scienze naturali, Vol. 3, Fase, 2. Pisa. (ref. JUST Bot. Jahresber., 1887. p. 426) 2) CONARD, H. S. 1905. The waterlilies. p. 121; ARBTR, A. 1920. Water plant, a study of aquatic angiosperms. pp. 34, 234. 3) GoEBEL, K. 1893. Pfianzenbiol. Schilderungen, 2 Teil, 2 Lief., p. 363. 370 THE BOTANICAL MAGAZINE [Vol. XLIV, No. 523 morning, and the closing in the afternoon, a little past midday. This procedure is repeated over two or three days. During the next day dircetly following this, the flower is observed to remain closed, but yet above the water surface. Text fig. 1. A chasmogamousflower as compared with a cleistogamous one. (reproduced from a photograph taken with Zyunityogata samples, August 25, 1928) Thereafter, it begins to submerse itself and the behavior in later days is not substantially different from that of the cleistogamous flowers. A few examples from the observation at Takaoka are shown in the accompanying table. The period of the second submergence, i.e., the time from the sinking of the flower to the second appearance on the water surface as a fully ripe fruit lasts over some six weeks (observation during the later part of the summer of 1928 at Takaoka). During the course of the biological study with this plant , we had occasion to examine some examples of chasmogamous flowers in con- trast to cleistogamous ones, so that we will here report bliefly on this question. It may be mentioned here that the comparison given below, except when otherwise stated, is made with the flowers of the same stage, that is, both the cleistogamous and the chasmogamous flowers July, 1930] O.RADA & OTAYA-STUDY OF EURYALE FEROX 371 Chasmogamous flowers of Euryale ferox, observed at Takaoka. ap., first appearance of the flower bud on the water surface; bl., the actual blooming of the flower; cl., the state of the flower unopennd, yet remaining still on the water surface; sub., the beginning of the submergence. were studied when they first appeared on the water surface. First, it is quite worthy of notice that there is a remarkable differ- ence in the development of the ovarial part between the above described two types of Euryale flowers. While the ovary of the cleistogamous flower is well developed and swollen markedly, that of the chasmoga- mous flower is very poorly established, being by far the inferior both . in size and in development. In Text figure 1 the distinction is repre- sented graphically, and the record of a few measurements given below also reveals the difference. There is given in the accompanying table the width, the length (from the tip of the calyx in a closed condition to the base of the flower) and their ratio in both cleistogamous and chasmogamous flowers. The difference is demonstrated not only in the external appearance, but in the internal structure also. The number of the ovules is, in general, larger in the cleistogamous flowers than in the chasmogamous ones. The difference in the size of the ovule is also remarkable; while the ovules in the cleistogamous flowers measure some 5 .0-9.5mm wide, those of chasmogamous ones range between 2.0-2.8mm. Furthermore, on inspection into the structure of the ovules, we can recognize a still 372 THE BOTANICAL MAGAZINE [Vol. XLIV, No. 523 more fundamental distinction. For in the cleistogamous f lowers, the development of the embryo and the endosperm is quite advanced (in an ovule 5mm wide, we get an embryo and an endosperm of the width of 0.15mm and 0.78mm respectively), while in the chasmogamous flowers , such a high grade of differentiation was never met with. With respect to the latter case, however, examination of free hand preparations was not valid enough to determine the developmental stage clearly; the fertilization may possibly have taken place already, prior to the act of blooming, yet the differentiation of the embryo is, if existent at all , still in the rudimental state at the best. In the nucellus of the cleisto- gamous flowers, the accumulation of starch is already quite remarkable, but in the chasmogamous, the nucellus is almost free from starch grains. Based on the above described observations, we may suggest for the present that the cause of cleistogamy in Euryale may not be ascribed to malnutrition1). Nor does it seem probable that the production of cleistogamous flowers is correlated to the fact that the mother plant is then predominantly vegetative2). On the contrary, insufficient nutri- tion seems to favour the production of chasmogamous flowers, a peculiar and exceptional case to the general conception. Text fig. 2. Later development of chasmogamous flowers . photo. October 2, 1928. at Takaoka. Thus the chasmogamous flower of Euryale is by far inferior to the 1) c.f. GOEBEL, K. 1893. 1.c., p. 363. 2) c.f. SKENE, M. 1924. Biology of flowering plants . p. 37. July, 1930] MORINAGA & FUKUSHINA-CHROMOSOME IN BRASSICA 373 cleistogamous, in almost every point. It is, nonetheless, far from abortive with respect to seed production. It sets as fairly ripe seeds in later days as does the cleistogamous flower. Text figure 2, (I) represents an example of this. This fruit originated from a chasmoga- mous flower opening at Takaoka on August 26, 1928, and was collected fully ripe on October 2. It measured 17cm long inclusive of the calyx and 8cm wide,. 98 seeds were found within. The seeds are also shown in the same text figure, those with arylar coverings in (IV), and those without in (V). Some chasmogamous flowers appearing later in the autumn usually fail to complete ripening. Two examples of such fruit are indicated in (II) and in (III). SUMMARY. 1. The majority of Euryale flowers are cleistogamous, but the production of chasmogamous flowers is not excluded. 2. The chasmogamous flowers open themselves on the water sur- face for two or three days, and sink under water for some period subsequently until the fruit is about to ripen, when they reappear on the water surface. The cleistogamous flowers behave in a similar way, except that they do not open their sepals and petals. 3. The fertilization of the cleistogamous flowers seems to take place before the flower buds appear on the water surface. In the chas- mogamous, the same is probable, but the development of the embryo is far more advanced in the cleistogamous flowers than in the chas- mogamous. 4. The chasmogamous as well as the cleistogamous flower set seeds equally completed. Another New Chromosome Number in Brassica. By Toshitaro Morinaga and Eiji Fukushima In 1928 one of the authors found 19 chromosomes in the pollen mother-cell of Brassica Napella Chaix, and reported it as a new chro- mosome number for the genus Brassica. In 1929 Dr. Sinskaia, of the Institute of Applied Botany, Leningrad, kindly sent us seeds of various.