, Volume 45, Issue 2, pp 244–251

Germination, reproduction and interference in the amphicarpic annual Emex spinosa (L.) Campd

  • P. W. Weiss


A comparison was made of the dimorphic subterranean and aerial achenes of the annual Emex spinosa (L.) Campd. Subterranean achenes were less dormant, had a higher percentage of viability, germinated at a faster rate, were less temperature-dependent in germination and produced larger seedlings than aerial achenes. Subterranean achenes germinated, equally well in light or dark but aerial achenes had a strong light requirement. There was a linear relationship between numbers of weight of aerial achenes and plant size in the field. More resources were allocated to reproduction in plants restricted in size because of environmental conditions. Subterranean achene production was less affected than aerial by density, nitrogen levels, varying field conditions and interference between plants grown, from subterranean and aerial achenes. In mixtures of such plants, those from subterranean achenes had larger leaf area and stems and more aerial achenes. These differences were not apparent in monocultures by the time of harvest. Seed dimorphism is more likely in short-lived fugitive species and the different roles associated with dimorphism (persistence in situ versus dispersal in E. spinosa) are seen as an ecological advantage in such species.


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  1. Baker, H.G.: Characteristics and modes of origin of weeds. In: The genetics of colonizing species (H.G. Baker, G.L. Stebbins, eds.). pp. 147–172. New York-London: Academic Press 1965Google Scholar
  2. Black, J.N.: Seed size as a factor in the growth of subterranean clover (Trifolium subterraneum L.) under spaced and sward conditions. Aust. J. Agric. Res. 8, 335–351 (1957)Google Scholar
  3. Evenari, M., Kadouri, A., Gutterman, Y.: Eco-physiological investigations on the amphicarpy of Emex, spinosa (L.) Campd. Flora 166, 223–238 (1977)Google Scholar
  4. Flint, S.D., Palmbland, I.G.: Germination dimorphism and developmental flexibility in the ruderal weed Heterotheca grandiflora. Oecologia (Berl.) 36, 33–43 (1978)Google Scholar
  5. Frankton, C., Bassett, I.J.: The genus Atriplex (Chenopodiaceae) in Canada. I. Three introduced species: A. heterosperma, A. oblongifolia, and A. hortensis. Can. J. Bot. 46, 1309–1313 (1968)Google Scholar
  6. Galil, J.: Emex spinosa (L.) Campd. and Israeli climate. Teva Waaretz 6 (10), 1–6 (1964)Google Scholar
  7. Gilbey, D.J.: Emex species in Australia with particular reference to Western Australia. J. Aust. Inst. Agric. Sci. 40, 114–120 (1974)Google Scholar
  8. Hagon, M.W., Simmons, D.M.: Seed dormancy of Emex australis and E. spinosa. Aust. J. Agric. Res. 29, 565–575 (1978)Google Scholar
  9. Harper, J.L.: The ecological significance of dormancy and its importance in weed control. Proc. 4th Int. Congr. Plant Prot. Hamburg 415–420 (1957)Google Scholar
  10. Harper, J.L.: Establishment, aggression, and cohabitation in weedy species. In: The genetics of colonizing species (H.G. Baker, G.L. Stebbins, eds.) pp. 243–268. New York-London: Academic Press 1965Google Scholar
  11. Harper, J.L.: Population biology of plants. London: Academic Press 1977Google Scholar
  12. Harper, J.L., Benton, R.A.: The behaviour of seeds in soil. Part 2. The germination of seeds on the surface of a water supplying substrate. J. Ecol. 54, 151–166 (1966)Google Scholar
  13. Harper, J.L., Williams, J.T., Sagar, G.R.: The behaviour, of seeds in soil. I. The heterogeneity of soil surfaces and its role in determining the establishment of plants from seed. J. Ecol. 53, 273–286 (1965)Google Scholar
  14. Keeton, W.T.: Biological science, New York: Norton and Co. (1967)Google Scholar
  15. Koller, D.: The physiology of dormancy and survival of plants in desert environments. Soc. Exp. Biol. Symp. XXIII, 449–469 (1968)Google Scholar
  16. Koller, D., Roth, N.: Studies on the ecological and physiological significance of amphicarpy in Gymnarhena micrantha (Compositae). Amer. Jour. Bot 51, (1), 26–35 (1964)Google Scholar
  17. Machin, D., Sanderson, B.: Computing maximum-likelihood estimates for the parameters of the de Wit competition model. Appl. Statist. 26, (1), 1–8 (1977)Google Scholar
  18. Roberts, E.H.: The viability of seeds. London: Chapman and Hall 1972Google Scholar
  19. Ungar, I.A.: Seed dimorphism in Salicornia europea L. Bot. Gaz. 140, 102–108 (1979)Google Scholar
  20. Weiss, P.W.: Reprodductive efficiency and growth of Emex australis in relation to stress. Aust. J. Ecol. 3, 57–65 (1978)Google Scholar
  21. Weiss, P.W., Julien, M.H.: A comparison of two species of spiny emex (Emex australis and E. spinosa) in north-western Victoria J. Aust. Inst. Agric. Sci. 41, 211–213 (1975)Google Scholar
  22. Weiss, P.W., Simmons, D.M.: Photoperiod and temperature effects on growth and development of Emex australia and E. spinosa. Weed Res. 17, 393–397 (1977)Google Scholar
  23. Weiss, P.W., Simmons, D.M.: Variation in Australian and some overseas populations of Emex australis and E. spinosa. Aust. J. Bot. 27, 631–641 (1979)Google Scholar
  24. Williams, J.T., Harper, J.L.: Seed polymorphism and germination. I. The influence of nitrates and low temperatures on the germination of Chenopodium album. Weed Res. 5, 141–150 (1965)Google Scholar
  25. de Wit, C.T.: On competition. Versl. Landbouwk. Onderz. 66, 8–82 (1960)Google Scholar
  26. Zeide, B.: Reproductive behaviour of plants in time. Am. Nat. 112, 636–639 (1978)Google Scholar
  27. Zohary, M.: Flora Palaestina 1. The Israel Academy of Sciences and Humanities 1966Google Scholar

Copyright information

© Springer-Verlag 1980

Authors and Affiliations

  • P. W. Weiss
    • 1
  1. 1.CSIRO Division of Plant IndustryCanberraAustralia
  2. 2.Department of Environmental Biology, Research School of Biological SciencesAustralian National UniversityCanberraAustralia

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