Summary
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.
Similar content being viewed by others
References
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 1965
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)
Evenari, M., Kadouri, A., Gutterman, Y.: Eco-physiological investigations on the amphicarpy of Emex, spinosa (L.) Campd. Flora 166, 223–238 (1977)
Flint, S.D., Palmbland, I.G.: Germination dimorphism and developmental flexibility in the ruderal weed Heterotheca grandiflora. Oecologia (Berl.) 36, 33–43 (1978)
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)
Galil, J.: Emex spinosa (L.) Campd. and Israeli climate. Teva Waaretz 6 (10), 1–6 (1964)
Gilbey, D.J.: Emex species in Australia with particular reference to Western Australia. J. Aust. Inst. Agric. Sci. 40, 114–120 (1974)
Hagon, M.W., Simmons, D.M.: Seed dormancy of Emex australis and E. spinosa. Aust. J. Agric. Res. 29, 565–575 (1978)
Harper, J.L.: The ecological significance of dormancy and its importance in weed control. Proc. 4th Int. Congr. Plant Prot. Hamburg 415–420 (1957)
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 1965
Harper, J.L.: Population biology of plants. London: Academic Press 1977
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)
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)
Keeton, W.T.: Biological science, New York: Norton and Co. (1967)
Koller, D.: The physiology of dormancy and survival of plants in desert environments. Soc. Exp. Biol. Symp. XXIII, 449–469 (1968)
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)
Machin, D., Sanderson, B.: Computing maximum-likelihood estimates for the parameters of the de Wit competition model. Appl. Statist. 26, (1), 1–8 (1977)
Roberts, E.H.: The viability of seeds. London: Chapman and Hall 1972
Ungar, I.A.: Seed dimorphism in Salicornia europea L. Bot. Gaz. 140, 102–108 (1979)
Weiss, P.W.: Reprodductive efficiency and growth of Emex australis in relation to stress. Aust. J. Ecol. 3, 57–65 (1978)
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)
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)
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)
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)
de Wit, C.T.: On competition. Versl. Landbouwk. Onderz. 66, 8–82 (1960)
Zeide, B.: Reproductive behaviour of plants in time. Am. Nat. 112, 636–639 (1978)
Zohary, M.: Flora Palaestina 1. The Israel Academy of Sciences and Humanities 1966
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Weiss, P.W. Germination, reproduction and interference in the amphicarpic annual Emex spinosa (L.) Campd. Oecologia 45, 244–251 (1980). https://doi.org/10.1007/BF00346465
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00346465