Summary
We examined responses to population density in the commitment of apical meristems to reproduction and clonal growth in a rosette-forming, stoloniferous herb (Hieracium pilosella). Despite close physiological coupling between the evocation of the terminal inflorescence bud and the development of one or more axillary buds into stolons, the allocation of meristems was extremely plastic.
Genets at the higher sowing densities showed density-dependent mortality consistent with self-thinning along a-3/2 trajectory. The probability of inflorescence evocation and associated stolon development was negatively dependent on surviving density. The proportinal distribution of primary stolons amongst genets became strikingly more unequal (expressed as the Gini coefficient) with increasing density. Clonal growth was resolved into the number of primary stolons per stoloniferous genet and the extent of stolon branching (i.e. number of apices per primary stolon); both showed strongly negative density-dependence. Reproduction, expressed as the mean number of flowering capitula per stoloniferous genet, declined 15-fold with increasing density; although theoretically expected to be unity, greater values resulted from capitulum production by attached secondary rosettes and lower values reflected the increasing abortion rate of inflorescence buds with increasing density.
Both the total number of apices produced per unit area and the corresponding number of reproductive apices were maximal at intermediate surviving densities (700–1,000 m-2). The balance between reproductive and clonal growth may be expressed as the probability of an apical meristem producing a capitulum, that also peaked sharply at intermediate density. This finding does not conform with linear models that predict a shift from vegetative growth to sexual reproduction with increasing population density.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Abrahamson WG (1980) Demography and vegetative reproduction. In: Solbrig OT (ed) Demography and evolution in plant populations. Blackwell Scientific Publications, Oxford pp 89–106
Abrahamson WG, Gadgil M (1973) Growth form and reproductive effort in goldenrods (Solidago, Compositae). Amer Natur 107:651–661
Armstrong RA (1982) A quantitative theory of reproductive effort in rhizomatous perennial plants. Ecology 63:679–686
Armstrong RA (1983) On the quantitative theory of resource partitioning in rhizomatous perennial plants: the influences of canopy structure, rhizome branching pattern and self-thinning. Ecology 64:703–709
Armstrong RA (1984) On the quantitative theory of reproductive effort in clonal plants: refinements of theory, with evidence from goldenrods and mayapples. Oecologia (Berlin) 63:410–417
Bishop GF, Davy AJ (1984) Significance of rabbits for the population regulation of Hieracium pilosella in Breckland. J Ecol 72:273–284
Bishop GF, Davy AJ, Jefferies RL (1978) Demography of Hieracium pilosella in a Breck grassland. J Ecol 66:615–629
Bostock SJ, Benton RA (1979) The reproductive strategies of five perennial Compositae. J Ecol 67:91–107
Davy AJ, Bishop GF (1984) Response of Hieracium pilosella in Breckland grass-heath to inorganic nutrients. J Ecol 72:319–330
Delcourt E (1972) Contribution a l'étude cytotaxonomique de Hieracium pilosella L. Bull Soc Bot Fr 119:287–302
Eriksson O (1985) Reproduction and clonal growth in Potentilla anserina L. (Rosaceae): The relation between growth form and dry weight allocation. Oecologia (Berlin) (in press)
Gadella TWJ (1972) Biosystematic studies in Hieracium pilosella L. and some related species of the subgenus Pilosella. Bot Notiser 125:361–369
Gaines MS, Vogt KJ, Hamrick JL, Caldwell J (1974) Reproductive strategies and growth patterns in sunflowers (Helianthus). Amer Natur 108:889–894
Harper JL, Ogden J (1970) Reproductive strategy of higher plants 1. The concept with reference to Senecio vulgaris L. J Ecol 58:681–698
Jefferies RL, Davy AJ, Rudmik T (1981) Population biology of the salt marsh annual Salicornia europaea agg. J Ecol 69:17–31
Lovett Doust J (1980a) A comparative study of life history and resource allocation in selected Umbelliferae. Biol J Linn Soc 13:139–154
Lovett Doust J (1980b) Experimental manipulation of patterns of resource allocation in the growth cycle and reproduction of Smyrnium olusatrum L. Biol J Linn Soc 13:155–166
Makepeace W (1981) Polymorphism and the chromosomal number of Hieracium pilosella L. in New Zealand. New Zealand J Bot 19:255–257
Ogden J (1974) The reproductive strategy of higher plants 11. The reproductive strategy of Tussilago farfara L. J Ecol 62:291–324
Sell PD, West C (1975) Pilosella Hill. In: Stace CA (ed) Hydbridization and the flora of the British Isles. Academic Press, London, New York, San Francisco pp 434–438
Solbrig OT, Simpson BB (1974) Components of the regulation of a population of dandelions in Michigan. J Ecol 62:473–486
Thomas AG, Dale HM (1974) Zonation and regulation of old pasture populations of Hieracium floribundum. Can J Bot 52:1451–1458
Tripathi RS, Harper JL (1973) The comparative biology of Agropyron repens (L) Beauv and A. caninum (L) Beauv. 1. The growth of mixed populations established from tillers and from seeds. J Ecol 61:353–368
Turesson G, Turesson B (1960) Experimental studies in Hieracium pilosella L. 1. Reproduction, chromosome number and distribution. Hereditas 46:717–736
Turner MD, Rabinowitz D (1983) Factors affecting frequency distributions of plant mass: the absence of dominance and suppression in competing monocultures of Festuca paradoxa. Ecology 64:469–475
Watkinson AR (1980) Density-dependence in single-species populations of plants. J Theor Biol 83:345–357
Watkinson AR (1981) Interference in pure and mixed populations of Agrostemma githago. J Appl Ecol 18:967–976
Watkinson AR, Davy AJ (1985) Population biology of salt marsh and sand dune annuals. In: Beeftink WG, Rozema J, Huiskes AHL (eds) Ecology of Coastal Vegetation. Vegetatio 69/70 (in press)
Watson MA (1984) Developmental constraints: effect on population growth and patterns of resource allocation in a clonal plant. Amer Natur 123:411–426
Watt AS (1947) Pattern and process in the plant community. J Ecol 35:1–22
Watt AS (1962) The effect of excluding rabbits from grassland A (Xerobrometum) in Breckland, 1936–60. J Ecol 50:181–198
Weiner J, Solbrig OT (1984) The meaning and measurement of size hierarchies in plant populations. Oecologia (Berlin) 61:334–336
Williams GC (1975) Sex and evolution. Princeton University Press, Princeton, New Jersey, USA
White J (1980) Demographic factors in populations of plants. In: Solbrig OT (ed) Demography and evolution in plant populations, Blackwell Scientific Publications, Oxford pp 21–48
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Bishop, G.F., Davy, A.J. Density and the commitment of apical meristems to clonal growth and reproduction in Hieracium pilosella . Oecologia 66, 417–422 (1985). https://doi.org/10.1007/BF00378308
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00378308