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The chromosomes and relationships of Welwitschia mirabilis

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Summary

W. mirabilis is unique in the plant kingdom by having a very peculiar habit. Its karyotype is very asymmetrical. Two of the chromosomes in the complement are satellited and this coincides with 2 nucleoli in the metabolic nuclei. The longest pair in the complement is nearly 3.25 times longer than the shortest pair. Between the two extremes there is a gradual transition in size in the karyotype. Such a karyotype has no relation (quantitative or qualitative) with those in Ephedra and Gnetum. Arguments have been advanced against interrelating Ephedra and Welwitschia through hermaphrodite “flowers”. Such flowers appear to be due to the sex polymorphism ensuing as the result of tetraploidy (in originally diploid-dioecious species) and do not represent therefore the ancestral condition. Only after these abnormalities are discovered in diploids they will represent atavistic mutations and then alone phyletic reliance can be placed in them. In view of the strong morphological differences the few resemblances between the three genera are possibly due to parallel evolution, because many of these are also found in other gymnosperms. The best arrangement is to treat the three genera as belonging to three distinct orders under one class.

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Literature

  • Bhaduri, P. N., and P. N. Ghosh: Chromosome squashes in cereals. Stain Technol. 29, 269–275 (1954).

    Google Scholar 

  • Bullock, A. A.: A criticism of Chiguryayeva's identification of a microspore referred to Welwitschia. Kew Bull., Roy. Bot. Gardens 1958 (4), 498–499.

  • Chamberlain, C. J.: Gymnosperms: Structure and evolution. Chicago 1935.

  • Cheadle, V. I.: Independent origin of vessels in the monocotyledons and dicotyledons. Phytomorphology 3, 23–44 (1953).

    Google Scholar 

  • Chiguryayeva, A. A.: On the discovery of a microspore of Welwitschia in eocene beds in Western Kazakhistan. Bot. Ž. 36, 315–316 (1951) [Russian]. Translated by H. K. Airyshaw, Kew Bull., Roy. Bot. Gardens 1953 (4), 497–498.

    Google Scholar 

  • Christiansen, H.: A tetraploid Larix decidua Miller. Kgl. Danske Vidnsk. Selsk. Det. 19, 1–9 (1950).

    Google Scholar 

  • Cleveland, L. R.: The whole life cycle of chromosomes and their coiling systems. Trans. Amer. phil. Soc. 39, 1–100 (1949).

    Google Scholar 

  • Cookson, I. C.: Pollen grains of Ephedra type in Australian tertiary deposits. Nature (Lond.) 177, 47–48 (1956).

    Google Scholar 

  • Coulter, J. M., and C. J. Chamberlain: Morphology of gymnosperms. Chicago 1917.

  • Cronquist, A.: The divisions and classes of plants. Bot. Rev. 26, 425–482 (1960).

    Google Scholar 

  • Darlington, C. D.: Misdivision and genetics of the centromere. J. Genet. 37, 341–364 (1939); - Chromosome botany. London 1956.

    Google Scholar 

  • —, and L. F. La Cour: Hybridity selection in Campanula. Heredity 4, 217–248 (1950).

    Google Scholar 

  • Eames, A. E.: Relationships of the Ephedrales. Phytomorphology 2, 79–100 (1952).

    Google Scholar 

  • Ellerström, S., and J. H. Tjio: Note on the chromosomes of Phleum echinatum. Bot. Not. (Lund) 4, 463–465 (1950).

    Google Scholar 

  • Fagerlind, F.: Bau und Entwicklung der Gnetum-Gametophyten. Kgl. Svensk Vetenskapsakad. Hdl. 19, 1–55 (1941).

    Google Scholar 

  • Fernandes, A.: Sur la caryologie de Welwitschia mirabilis Hook. Bol. Soc. Broteriana 11, 267–282 (1936).

    Google Scholar 

  • Florin, R.: Die Chromosomenzahlen bei Welwitschia und einigen Ephedra-Arten. Svensk bot. Tidskr. 26, 205–214 (1932); - The systematics of the gymnosperms: “A century of progress in the natural sciences 1853–1953”. San Francisco 1955.

    Google Scholar 

  • Foster, A. S., and E. M. Gifford: Comparative morphology of the vascular plants. San Francisco 1959.

  • Geitler, L. (1929): Vide Khoshoo 1961.

  • Hunziker, J. H.: Numero de cromosomas de varias especies sudamerieanas de Ephedra. Rev. Argent. Agron. 20, 141–143 (1953); - Morfologia cromosomica de nueve especies Argentinas del género Ephedra. Rev. Invest. agr. (Buenos Aires) 9, 201–209 (1955).

    Google Scholar 

  • Khoshoo, T. N.: Polyploidy in gymnosperms. Evolution (Lancaster, Pa.) 13, 24–39 (1959); - Chromosome numbers in gymnosperms. Silv. Genet. 10, 1–9 (1961).

    Google Scholar 

  • —, and V. B. Sharma: Structural hybridity in Allium ochroleucum. Curr. Sci. 28, 26–28 (1959).

    Google Scholar 

  • Knaben, G.: En cytologisk analyse av diploid og triploid Larix. Blyttia 11, 105–115 (1953).

    Google Scholar 

  • Kurita, M.: A study of the chromosomes in Nothoscordum fragrans (Vent) Kunth. Mem. Ehime Univ. 1, 55–63 (1953); - Nucleolar chromosome with a long centromere. Rep. Biol. Inst. Ehime Univ. No 9, 1–8 (1960).

    Google Scholar 

  • La Cotjr, L. F.: Compound constrictions. Heredity 4, 243–246 (1950).

    Google Scholar 

  • Levan, A., and S. L. Emsweller: Structural hybridity in Nothoscordum fragrans. J. Hered. 29, 291–294 (1938).

    Google Scholar 

  • Maheshwari, P., and V. Vasil: Gnetum. Bot. Monograph. No 1, CSIR, New Delhi 1961.

    Google Scholar 

  • Marks, G. E.: The cytology of Oxalis dispar. Chromosoma (Berl.) 8, 650–670 (1957a); - Teloeentric chromosomes. Amer. Naturalist 91, 223–232 (1957b).

    Google Scholar 

  • Mehra, P. N.: A study of the karyotypes and the occurrence of diploid male gametophytes in some species of the genus Ephedra. Proc. nat. Acad. Sci. (India) 16, 259–286 (1946); - Occurrence of hermaphrodite flowers and the development of female gametophytes in Ephedra intermedia Schrenk et Mey. Ann. Bot., N. S., 14, 165–180 (1950).

    Google Scholar 

  • —, and K. S. Rai: Cytology of Gnetum ula Brongn. J. Genet. 55, 394–396 (1957).

    Google Scholar 

  • Melander, Y.: Studies on the chromosomes of Ulophysema öresundense. Hereditas (Lund) 36, 233–255 (1950).

    Google Scholar 

  • Nawashin, S. G.: Sur quelques indices de l'organisation interne des chromosomes. Timirijaseffs Festschrift 185–274 (1916).

  • Pearson, H. H. W.: Gnetales. Cambridge 1929.

  • Rhoades, M. M.: Studies of a telocentric chromosome in maize with reference to the stability of its centromere. Genetics 25, 483–520 (1949).

    Google Scholar 

  • Sato, D.: Karyotype alteration and phylogeny. V. New type of sat-chromosomes in Nothoscordum and Nerine. Cytologia (Tokyo) 12, 170–178 (1941).

    Google Scholar 

  • Steeves, M. W., and E. S. Barghoorn: The pollen of Ephedra. J. Arnold Arboretum Harvard Univ. 40, 221–259 (1957).

    Google Scholar 

  • Swanson, C. P.: Cytology and Cytogenetics. London 1958.

  • Takhtajan, A. L.: Phylogenetic principles of the system of higher plants. Bot. Rev. 19, 1–45 (1953).

    Google Scholar 

  • Westergaard, M.: The mechanism of sex determination in dioecious flowering plants. Advanc. Genet. 9, 217–281 (1958).

    Google Scholar 

  • White, M. J. D.: Animal cytology and evolution. Cambridge 1954.

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Authors and Affiliations

  1. Post-graduate Department of Botany, Jammu and Kashmir University, Naseembagh, Srinagar

    T. N. Khoshoo &  M. R. Ahuja

  2. Department of Genetics, University of California, Berkeley

    T. N. Khoshoo &  M. R. Ahuja

  3. The Institute for Cancer Research, 7701 Burholme Avenue, Fox Chase, 11, Philadelphia, Pennsylvania, USA

    M. R. Ahuja

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  1. T. N. Khoshoo
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  2. M. R. Ahuja
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Khoshoo, T.N., Ahuja, M.R. The chromosomes and relationships of Welwitschia mirabilis. Chromosoma 14, 522–533 (1963). https://doi.org/10.1007/BF00321471

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