Seed production and seed quality of the dune building grass Panicum racemosum Spreng

Cordazzo, Cesar Vieira; Davy, Anthony John

doi:10.1590/S0102-33061994000200004

Abstracts

Seed production, pollination requirement, seed characteristics related to quality and the relationship between number and mass of seeds were examined for Panicum racemosum in three successional populations in southern Brazilian coastal dunes. The seed production was generally low and declined further between the frontal dunes and the backdunes, dropping from 4.05 seeds per panicle in the former to 1.8 seeds in the latter. However fertility (% fertile florets) did not differ among the three habitats. Plants cross-pollinated in a glasshouse showed an increase in seed production to 41.4 seeds compared to no seed production in self-pollinated plants. Caryopses varied in mass from 3.2 to 12.2 mg with a mean of 7.98 mg. A strong negative correlation was found between mean individual seed mass and the total number of seeds per panicle in a natural population. However, this relationship did not persist in seeds produced by cultivated plants in the glasshouse. The causes of low seed production appear to be mainly pollen self-incompatibility and additionally competition for nutrients between sexual reproduction and allocation to clonal growth. Under conditions of nutrient shortage, Panicum racemosum probably allocates resources more to clonal growth and to fewer, but well-endowed seeds. This would permit emergence from deeper burial sand, faster growth and greater survival of seedlings.

Panicum racemosum; seed production; pollination; seed mass; seed number; coastal dunes

A produção de sementes, polinização, características das sementes e a relação entre o número e peso de sementes foram examinadas em três populações de Panicum racemosum ao longo de um gradiente nas dunas costeiras no sul do Brasil. A produção de sementes foi pequena e decresceu ao longo do gradiente, diminuindo de 4,05 sementes por espiga nas dunas frontais para 1,8 sementes por espiga nas dunas mais estáveis. Entretanto não ocorreram diferenças na fertilidade entre as populações. Plantas cultivadas em casas de vegetação e que foram polinizadas cruzadamente mostraram um aumento na produção de sementes (41,4 sementes) em comparação com as plantas auto-polinizadas (nenhuma semente). As sementes variaram em relação à massa de 3,2 a 12,2 mg com uma média de 7,98 mg. Uma forte correlação negativa foi encontrada entre a massa individual das sementes e o número total de sementes por espiga nas sementes coletadas nas dunas frontais. As causas da baixa produção de sementes parecem ser principalmente devido à incompatibilidade do pólen na auto polinização e, devido à competição por nutrientes entre a reprodução sexuada e crescimento vegetativo. Em condições de deficiencia em nutrientes, provavelmente Panicum racemosum utiliza mais recursos em crescimento vegetativo e baixa produção de sementes, mas de boa qualidade. Isto, poderia permitir que as plântulas originadas destas sementes possam emergir de maiores profundidades na areia, terem maior crescimento e sobrevivência.

Seed production and seed quality of the dune-building grass Panicum racemosum Spreng

Produção e qualidade da semente da gramínea Panicum racemosum Spreng. em um gradiente de dunas costeiras

Cesar Vieira Cordazzo^I,II; Anthony John Davy^II

^IDepartamento de Oceanografia, Universidade do Rio Grande, Caixa Postal 474, CEP 96500-900, Rio Grande-RS, Brasil

^IISchool of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, UK

ABSTRACT

Seed production, pollination requirement, seed characteristics related to quality and the relationship between number and mass of seeds were examined for Panicum racemosum in three successional populations in southern Brazilian coastal dunes. The seed production was generally low and declined further between the frontal dunes and the backdunes, dropping from 4.05 seeds per panicle in the former to 1.8 seeds in the latter. However fertility (% fertile florets) did not differ among the three habitats. Plants cross-pollinated in a glasshouse showed an increase in seed production to 41.4 seeds compared to no seed production in self-pollinated plants. Caryopses varied in mass from 3.2 to 12.2 mg with a mean of 7.98 mg. A strong negative correlation was found between mean individual seed mass and the total number of seeds per panicle in a natural population. However, this relationship did not persist in seeds produced by cultivated plants in the glasshouse. The causes of low seed production appear to be mainly pollen self-incompatibility and additionally competition for nutrients between sexual reproduction and allocation to clonal growth. Under conditions of nutrient shortage, Panicum racemosum probably allocates resources more to clonal growth and to fewer, but well-endowed seeds. This would permit emergence from deeper burial sand, faster growth and greater survival of seedlings.

Key words: Panicum racemosum, seed production, pollination, seed mass, seed number, coastal dunes.

RESUMO

A produção de sementes, polinização, características das sementes e a relação entre o número e peso de sementes foram examinadas em três populações de Panicum racemosum ao longo de um gradiente nas dunas costeiras no sul do Brasil. A produção de sementes foi pequena e decresceu ao longo do gradiente, diminuindo de 4,05 sementes por espiga nas dunas frontais para 1,8 sementes por espiga nas dunas mais estáveis. Entretanto não ocorreram diferenças na fertilidade entre as populações. Plantas cultivadas em casas de vegetação e que foram polinizadas cruzadamente mostraram um aumento na produção de sementes (41,4 sementes) em comparação com as plantas auto-polinizadas (nenhuma semente). As sementes variaram em relação à massa de 3,2 a 12,2 mg com uma média de 7,98 mg. Uma forte correlação negativa foi encontrada entre a massa individual das sementes e o número total de sementes por espiga nas sementes coletadas nas dunas frontais. As causas da baixa produção de sementes parecem ser principalmente devido à incompatibilidade do pólen na auto polinização e, devido à competição por nutrientes entre a reprodução sexuada e crescimento vegetativo. Em condições de deficiencia em nutrientes, provavelmente Panicum racemosum utiliza mais recursos em crescimento vegetativo e baixa produção de sementes, mas de boa qualidade. Isto, poderia permitir que as plântulas originadas destas sementes possam emergir de maiores profundidades na areia, terem maior crescimento e sobrevivência.

Full text available only in PDF format.

Texto completo disponível apenas em PDF.

Acknowledgements

We thank Dr. D.C.Wildon and Dr. G.F. Bishop for valuable critiques of the manuscript and CAPES (proc. 1141/90-5) for financial support to this Ph.D. project.

References

Allen, S.E.; Grimshaw, H.M., Parkinson, J.A., Quarmby, C. & Roberts, J.D. 1976. Chemical analysis. In: Chapman, S.B. (ed.) Methods in plant ecology. Oxford: Blackwell Scientific Publications, p. 411-466.

Bashaw, E.C. & Hanna, W.W. 1990. Apomictic reproduction. In: Chapman, G.P. (ed.) Reproductive versatility in the grasses. Cambridge: Cambridge University Press.

Clary, W.P. 1965. Temperature effects on reproductive processes of Russian wildrye. Agron. J., 57:4-6.

Cordazzo, C.V. & Seeliger, U. 1988a. Guia Ilustrado da Vegetação Costeira no Sul do Brasil Rio Grande: Editora da FURG.

Cordazzo, C.V. & Seeliger, U. 1988b. Phenological and biogeographical aspects of coastal dune plant communities in southern Brazil. Vegetatio, 75:169-173.

Cordazzo, C.V. & Seeliger, U. 1993. Zoned habitats of southern Brazilian coastal dunes. J. Coastal Res. 9(2): 317-323.

Costa, C.S.B.; Seeliger, U. & Cordazzo, C.V. 1984. Aspectos da Ecologia populacional do Panicum racemosum Spreng. nas dunas costeiras do Rio Grande do Sul. In: Lacerda, L.D. et al. (eds.) Restingas: origem, estrutura, processos. Niterói: UFF-RJ. p. 395-411.

Costa, C.S.B.; Seeliger, U. & Cordazzo, C.V. 1991. Leaf demography and decline of Panicum racemosum populations in coastal foredunes of southern Brazil. Can. J. Bot., 69:1593-1599.

Ekanayake, I.J.; De Datta, S.K. & Steponkus, P.L. 1989. Spikelet sterility and flowering response of rice to water stress at anthesis. Ann. Bot., 63:257-264.

Fenner, M. 1985. Seed ecology. New York: Chapman & Hall.

Harper, J.L. 1977. Population biology of plants. London: Academic Press.

Harris, D. & Davy, A.J. 1986. Regenerative potential of Elymus farctus from rhizome fragments and seed. J. Ecol., 74: 1057-1067.

Hawke, M.A. & Maun, M.A. 1989. Interpopulation variation in reproduction and seed mass of a beach annual; Cakile edentula var. lacustris. J. Coastal Res., 5(1): 103-112.

Hester, M.W. & Mendelssohn, I.A. 1987. Seed production and germination response of four Louisiana populations of Uniola paniculata (Gramineae). Amer. J. Bot. 74(7): 1093-1101.

Hubbard, C.E. 1984. Grasses. A guide to their structure, identification, uses and distribution in the British Isles. Harmondsworth: Penguin Books Ltd.

Huiskes, A.H.L. 1979. Biological Flora of the British Isles: Ammophila arenaria (L.) Link. J. Ecol., 67:363-382.

Krajnyk, I. & Maun, M.A. 1982. Reproductive biology of Ammophila breviligulata. Amer. Midl Nat., 108:346-354.

Laing, C.C. 1958. Studies in the ecology of Ammophila breviligulata. I. Seedling survival and its relation to population increase and dispersal. Bot. Gaz., 19:208-216.

Lloyd, D.G. 1980. Sexual strategies in plants. I. An hyphothesis of serial adjustment of maternal investment during one reproductive session. New Phytol., 86: 69-79.

Marks, T.C. & Truseott, A.J. 1985. Variation in seed production and germination of Spartina anglica within a zoned salmarsh. J. Ecol., 73:695-705.

Maun, M.A. 1985. Population biology of Ammophila breviiigulata and Calamovilfa longifolia on Lake Huron sand dunes. I. Habitat, growth form, reproduction, and establishment. Can. J. Bot., 63: 113-124.

Maun, M.A. & Lapierre, J. 1986. Effects of burial by sand on seed germination and seedling emergence of four dune species. Amer. J. Bot., 73:450-455.

Maun, A.M. & Baye, P.R. 1989. The ecology of Ammophila breviligulata Fern, on coastal dune sytems. Reviews in Aquatic Sciences, 1(4):661-681.

Michaels, H.J.; Benner, B., Hartgerink, A.P., Lee, T.D., Rice, S., Willson, M.F. & Bertin, R.I. 1988. Seed size variation: magnitude, distribution, and ecological correlates. Evol. Ecol., 2: 157-166.

Pfadenhauer, J. 1978. Contribuição ao conhecimento da vegetação e de suas condições de crescimento nas dunas costeiras do Rio grande do Sul. Rev. bras. Biol., 38:321-364.

Pfadenhauer, J. 1980. Die vegetation der kustendünen von Rio Grande do Sul, sul brasiliens. Phytoecoenologia, 8: 321-364.

Salisbury, E.J. 1942. The reproductive capacity of plants. London: Bell and Sons.

Schemske, D.W. & Lande, R. 1985. The evolution of self-fertilization and inbreeding depression in plants. II. Empirical observations. Evolution 39: 41-52.

Seeliger, U. 1992. Coastal foredunes of southern Brazil: Physiography, Habitats, and Vegetation. In: Seeliger, U. (ed.) Coastal Plant Communities of Latin America. San Diego: Academic Press, p. 367-381.

Shaw, R.H. & Laing, D.R. 1966. Moisture stress and plant response. In: Pierre, P.W.et al. (eds.) Plant environment and efficient water use. Am. Soc. of Agron., p.73-94.

Silvertown, J. 1989. The paradox of seed size an adaptation. Trends in Ecology and Evolution, 4(1):24-26.

Silvertown, J. & Lovett-Doust, J. 1993. Introduction to plant population biology. Oxford: Blackwell Scientific Publications.

Smith, L.B.; Wasshausen, D.C. & Klein, R.M. 1982 Gramineae. In: Flora Ilustrada de Santa Catarina. Itajai: Herbário Barbosa Rodrigues.

Sokal, R.R & Rohlf, F.J. 1981. Biometry. W.H. New York: Freeman and Company.

Van der Valk, A.G. 1974. Mineral cycling in coastal foredune plant communities in Cape Hatteras National Seashore. Ecology, 55:1349-1358.

Wagner, R.H. 1964. The ecology of Uniola paniculata L. in the dune strand habitat of North Carolina. Ecol. Monogr., 34(1):79-96.

Werner, P. A. & Piatt, W.J. 1976. Ecological relationships of co-occurring goldenrods (Solidago: Compositae). Amer. Nat., 110: 959-971.

Wulff, R.D. 1986. Seed size variation in Desmodium paniculatum I. Factors affecting seed size. J. Ecol., 74: 87-97.

Zhang, J. Maun, M.A. 1991. Establishment and growth of Panicum virgatum L. seedlings on Lake Erie sand dune., Bull. Tor. Bot. Club., 118(2): 141-153.

Recebido em 07.07.93.

Aceito em 07.07.94.

Allen, S.E.; Grimshaw, H.M., Parkinson, J.A., Quarmby, C. & Roberts, J.D. 1976. Chemical analysis. In: Chapman, S.B. (ed.) Methods in plant ecology. Oxford: Blackwell Scientific Publications, p. 411-466.
Bashaw, E.C. & Hanna, W.W. 1990. Apomictic reproduction. In: Chapman, G.P. (ed.) Reproductive versatility in the grasses. Cambridge: Cambridge University Press.
Clary, W.P. 1965. Temperature effects on reproductive processes of Russian wildrye. Agron. J., 57:4-6.
Cordazzo, C.V. & Seeliger, U. 1988a. Guia Ilustrado da Vegetação Costeira no Sul do Brasil Rio Grande: Editora da FURG.
Cordazzo, C.V. & Seeliger, U. 1988b. Phenological and biogeographical aspects of coastal dune plant communities in southern Brazil. Vegetatio, 75:169-173.
Cordazzo, C.V. & Seeliger, U. 1993. Zoned habitats of southern Brazilian coastal dunes. J. Coastal Res. 9(2): 317-323.
Costa, C.S.B.; Seeliger, U. & Cordazzo, C.V. 1984. Aspectos da Ecologia populacional do Panicum racemosum Spreng. nas dunas costeiras do Rio Grande do Sul. In: Lacerda, L.D. et al. (eds.) Restingas: origem, estrutura, processos. Niterói: UFF-RJ. p. 395-411.
Costa, C.S.B.; Seeliger, U. & Cordazzo, C.V. 1991. Leaf demography and decline of Panicum racemosum populations in coastal foredunes of southern Brazil. Can. J. Bot., 69:1593-1599.
Ekanayake, I.J.; De Datta, S.K. & Steponkus, P.L. 1989. Spikelet sterility and flowering response of rice to water stress at anthesis. Ann. Bot., 63:257-264.
Fenner, M. 1985. Seed ecology. New York: Chapman & Hall.
Harper, J.L. 1977. Population biology of plants. London: Academic Press.
Harris, D. & Davy, A.J. 1986. Regenerative potential of Elymus farctus from rhizome fragments and seed. J. Ecol., 74: 1057-1067.
Hawke, M.A. & Maun, M.A. 1989. Interpopulation variation in reproduction and seed mass of a beach annual; Cakile edentula var. lacustris. J. Coastal Res., 5(1): 103-112.
Hester, M.W. & Mendelssohn, I.A. 1987. Seed production and germination response of four Louisiana populations of Uniola paniculata (Gramineae). Amer. J. Bot. 74(7): 1093-1101.
Hubbard, C.E. 1984. Grasses. A guide to their structure, identification, uses and distribution in the British Isles. Harmondsworth: Penguin Books Ltd.
Huiskes, A.H.L. 1979. Biological Flora of the British Isles: Ammophila arenaria (L.) Link. J. Ecol., 67:363-382.
Krajnyk, I. & Maun, M.A. 1982. Reproductive biology of Ammophila breviligulata. Amer. Midl Nat., 108:346-354.
Laing, C.C. 1958. Studies in the ecology of Ammophila breviligulata. I. Seedling survival and its relation to population increase and dispersal. Bot. Gaz., 19:208-216.
Lloyd, D.G. 1980. Sexual strategies in plants. I. An hyphothesis of serial adjustment of maternal investment during one reproductive session. New Phytol., 86: 69-79.
Marks, T.C. & Truseott, A.J. 1985. Variation in seed production and germination of Spartina anglica within a zoned salmarsh. J. Ecol., 73:695-705.
Maun, M.A. 1985. Population biology of Ammophila breviiigulata and Calamovilfa longifolia on Lake Huron sand dunes. I. Habitat, growth form, reproduction, and establishment. Can. J. Bot., 63: 113-124.
Maun, M.A. & Lapierre, J. 1986. Effects of burial by sand on seed germination and seedling emergence of four dune species. Amer. J. Bot., 73:450-455.
Maun, A.M. & Baye, P.R. 1989. The ecology of Ammophila breviligulata Fern, on coastal dune sytems. Reviews in Aquatic Sciences, 1(4):661-681.
Michaels, H.J.; Benner, B., Hartgerink, A.P., Lee, T.D., Rice, S., Willson, M.F. & Bertin, R.I. 1988. Seed size variation: magnitude, distribution, and ecological correlates. Evol. Ecol., 2: 157-166.
Pfadenhauer, J. 1978. Contribuição ao conhecimento da vegetação e de suas condições de crescimento nas dunas costeiras do Rio grande do Sul. Rev. bras. Biol., 38:321-364.
Pfadenhauer, J. 1980. Die vegetation der kustendünen von Rio Grande do Sul, sul brasiliens. Phytoecoenologia, 8: 321-364.
Salisbury, E.J. 1942. The reproductive capacity of plants. London: Bell and Sons.
Schemske, D.W. & Lande, R. 1985. The evolution of self-fertilization and inbreeding depression in plants. II. Empirical observations. Evolution 39: 41-52.
Seeliger, U. 1992. Coastal foredunes of southern Brazil: Physiography, Habitats, and Vegetation. In: Seeliger, U. (ed.) Coastal Plant Communities of Latin America. San Diego: Academic Press, p. 367-381.
Shaw, R.H. & Laing, D.R. 1966. Moisture stress and plant response. In: Pierre, P.W.et al. (eds.) Plant environment and efficient water use.
Am. Soc. of Agron., p.73-94.
Silvertown, J. 1989. The paradox of seed size an adaptation. Trends in Ecology and Evolution, 4(1):24-26.
Silvertown, J. & Lovett-Doust, J. 1993. Introduction to plant population biology. Oxford: Blackwell Scientific Publications.
Smith, L.B.; Wasshausen, D.C. & Klein, R.M. 1982 Gramineae. In: Flora Ilustrada de Santa Catarina. Itajai: Herbário Barbosa Rodrigues.
Sokal, R.R & Rohlf, F.J. 1981. Biometry. W.H. New York: Freeman and Company.
Van der Valk, A.G. 1974. Mineral cycling in coastal foredune plant communities in Cape Hatteras National Seashore. Ecology, 55:1349-1358.
Wagner, R.H. 1964. The ecology of Uniola paniculata L. in the dune strand habitat of North Carolina. Ecol. Monogr., 34(1):79-96.
Werner, P. A. & Piatt, W.J. 1976. Ecological relationships of co-occurring goldenrods (Solidago: Compositae). Amer. Nat., 110: 959-971.
Wulff, R.D. 1986. Seed size variation in Desmodium paniculatum I. Factors affecting seed size. J. Ecol., 74: 87-97.
Zhang, J. Maun, M.A. 1991. Establishment and growth of Panicum virgatum L. seedlings on Lake Erie sand dune., Bull. Tor. Bot. Club., 118(2): 141-153.

Publication Dates

Publication in this collection
10 June 2011
Date of issue
Dec 1994

History

Accepted
07 July 1994
Received
07 July 1993

This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

[1] Allen, S.E.; Grimshaw, H.M., Parkinson, J.A., Quarmby, C. & Roberts, J.D. 1976. Chemical analysis. In: Chapman, S.B. (ed.) Methods in plant ecology. Oxford: Blackwell Scientific Publications, p. 411-466.

[2] Bashaw, E.C. & Hanna, W.W. 1990. Apomictic reproduction. In: Chapman, G.P. (ed.) Reproductive versatility in the grasses. Cambridge: Cambridge University Press.

[3] Clary, W.P. 1965. Temperature effects on reproductive processes of Russian wildrye. Agron. J., 57:4-6.

[4] Cordazzo, C.V. & Seeliger, U. 1988a. Guia Ilustrado da Vegetação Costeira no Sul do Brasil Rio Grande: Editora da FURG.

[5] Cordazzo, C.V. & Seeliger, U. 1988b. Phenological and biogeographical aspects of coastal dune plant communities in southern Brazil. Vegetatio, 75:169-173.

[6] Cordazzo, C.V. & Seeliger, U. 1993. Zoned habitats of southern Brazilian coastal dunes. J. Coastal Res. 9(2): 317-323.

[7] Costa, C.S.B.; Seeliger, U. & Cordazzo, C.V. 1984. Aspectos da Ecologia populacional do Panicum racemosum Spreng. nas dunas costeiras do Rio Grande do Sul. In: Lacerda, L.D. et al. (eds.) Restingas: origem, estrutura, processos. Niterói: UFF-RJ. p. 395-411.

[8] Costa, C.S.B.; Seeliger, U. & Cordazzo, C.V. 1991. Leaf demography and decline of Panicum racemosum populations in coastal foredunes of southern Brazil. Can. J. Bot., 69:1593-1599.

[9] Ekanayake, I.J.; De Datta, S.K. & Steponkus, P.L. 1989. Spikelet sterility and flowering response of rice to water stress at anthesis. Ann. Bot., 63:257-264.

[10] Fenner, M. 1985. Seed ecology. New York: Chapman & Hall.

[11] Harper, J.L. 1977. Population biology of plants. London: Academic Press.

[12] Harris, D. & Davy, A.J. 1986. Regenerative potential of Elymus farctus from rhizome fragments and seed. J. Ecol., 74: 1057-1067.

[13] Hawke, M.A. & Maun, M.A. 1989. Interpopulation variation in reproduction and seed mass of a beach annual; Cakile edentula var. lacustris. J. Coastal Res., 5(1): 103-112.

[14] Hester, M.W. & Mendelssohn, I.A. 1987. Seed production and germination response of four Louisiana populations of Uniola paniculata (Gramineae). Amer. J. Bot. 74(7): 1093-1101.

[15] Hubbard, C.E. 1984. Grasses. A guide to their structure, identification, uses and distribution in the British Isles. Harmondsworth: Penguin Books Ltd.

[16] Huiskes, A.H.L. 1979. Biological Flora of the British Isles: Ammophila arenaria (L.) Link. J. Ecol., 67:363-382.

[17] Krajnyk, I. & Maun, M.A. 1982. Reproductive biology of Ammophila breviligulata. Amer. Midl Nat., 108:346-354.

[18] Laing, C.C. 1958. Studies in the ecology of Ammophila breviligulata. I. Seedling survival and its relation to population increase and dispersal. Bot. Gaz., 19:208-216.

[19] Lloyd, D.G. 1980. Sexual strategies in plants. I. An hyphothesis of serial adjustment of maternal investment during one reproductive session. New Phytol., 86: 69-79.

[20] Marks, T.C. & Truseott, A.J. 1985. Variation in seed production and germination of Spartina anglica within a zoned salmarsh. J. Ecol., 73:695-705.

[21] Maun, M.A. 1985. Population biology of Ammophila breviiigulata and Calamovilfa longifolia on Lake Huron sand dunes. I. Habitat, growth form, reproduction, and establishment. Can. J. Bot., 63: 113-124.

[22] Maun, M.A. & Lapierre, J. 1986. Effects of burial by sand on seed germination and seedling emergence of four dune species. Amer. J. Bot., 73:450-455.

[23] Maun, A.M. & Baye, P.R. 1989. The ecology of Ammophila breviligulata Fern, on coastal dune sytems. Reviews in Aquatic Sciences, 1(4):661-681.

[24] Michaels, H.J.; Benner, B., Hartgerink, A.P., Lee, T.D., Rice, S., Willson, M.F. & Bertin, R.I. 1988. Seed size variation: magnitude, distribution, and ecological correlates. Evol. Ecol., 2: 157-166.

[25] Pfadenhauer, J. 1978. Contribuição ao conhecimento da vegetação e de suas condições de crescimento nas dunas costeiras do Rio grande do Sul. Rev. bras. Biol., 38:321-364.

[26] Pfadenhauer, J. 1980. Die vegetation der kustendünen von Rio Grande do Sul, sul brasiliens. Phytoecoenologia, 8: 321-364.

[27] Salisbury, E.J. 1942. The reproductive capacity of plants. London: Bell and Sons.

[28] Schemske, D.W. & Lande, R. 1985. The evolution of self-fertilization and inbreeding depression in plants. II. Empirical observations. Evolution 39: 41-52.

[29] Seeliger, U. 1992. Coastal foredunes of southern Brazil: Physiography, Habitats, and Vegetation. In: Seeliger, U. (ed.) Coastal Plant Communities of Latin America. San Diego: Academic Press, p. 367-381.

[30] Shaw, R.H. & Laing, D.R. 1966. Moisture stress and plant response. In: Pierre, P.W.et al. (eds.) Plant environment and efficient water use.

[31] Am. Soc. of Agron., p.73-94.

[32] Silvertown, J. 1989. The paradox of seed size an adaptation. Trends in Ecology and Evolution, 4(1):24-26.

[33] Silvertown, J. & Lovett-Doust, J. 1993. Introduction to plant population biology. Oxford: Blackwell Scientific Publications.

[34] Smith, L.B.; Wasshausen, D.C. & Klein, R.M. 1982 Gramineae. In: Flora Ilustrada de Santa Catarina. Itajai: Herbário Barbosa Rodrigues.

[35] Sokal, R.R & Rohlf, F.J. 1981. Biometry. W.H. New York: Freeman and Company.

[36] Van der Valk, A.G. 1974. Mineral cycling in coastal foredune plant communities in Cape Hatteras National Seashore. Ecology, 55:1349-1358.

[37] Wagner, R.H. 1964. The ecology of Uniola paniculata L. in the dune strand habitat of North Carolina. Ecol. Monogr., 34(1):79-96.

[38] Werner, P. A. & Piatt, W.J. 1976. Ecological relationships of co-occurring goldenrods (Solidago: Compositae). Amer. Nat., 110: 959-971.

[39] Wulff, R.D. 1986. Seed size variation in Desmodium paniculatum I. Factors affecting seed size. J. Ecol., 74: 87-97.

[40] Zhang, J. Maun, M.A. 1991. Establishment and growth of Panicum virgatum L. seedlings on Lake Erie sand dune., Bull. Tor. Bot. Club., 118(2): 141-153.