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Floral Biology and Embryological Studies are Important for Conservation of Threatened Plants Having Reproductive Bottlenecks:A Case Study of Illicium griffithii Hook. f. & Thomson


Affiliations
1 Department of Botany, Centre of Advanced Studies in Botany, North Eastern Hill University, Shillong 793 022, India
2 Centre for Biodiversity Studies, Baba Ghulam Shah Badshah University, Rajouri 185 234, India
3 Department of Forest Products, Dr Y.S. Parmar University of Horticulture and Forestry, Solan 173 23, India
 

Information on reproductive biology of threatened plant species could be useful for conservation, particularly when the species fails to perpetuate in nature due to regeneration failure. In flowering plants, the domain of reproductive biology includes structural details of reproductive units such as flower or inflorescence, formation of viable gametes, pollination dynamics, role of pollinators, pollen–pistil interactions as determined through compatibility, breeding system and mating strategies, fertilization and embryogeny, seed development, dispersal and germination. The importance of reproductive biology in species conservation has been demonstrated through a case study of Illicium griffithii Hook f. & Thomson, a threatened plant species from Arunachal Pradesh. I. griffithii (Illiciaceae) is a member of the ANITA clade and a representative taxon of the three most basal angiosperms. The flowers of I. griffithii are obligate xenogamous, and hence compatible pollen grains only germinate on the stigmatic papillae. Esterase and phosphatase enzymatic activities are absent in most stigmatic surfaces. Therefore, stigmatic receptivity is absent in many carpels. The ovules are anatropous and bitegmic with a four-celled/four-nucleate structure of embryo sac at maturity. Antipodals and filiform apparatus are absent. Presence of mucilage cells in the embryo sac facilitates the entry of pollen tubes into it. Embryolike organization of the endosperm is present, with one pole globular having smaller cells and the other pole roughly filamentous with larger cells resembling that of a suspensor. Extragynoecial compitum is not observed in I. griffithii. The flowers are brooding sites for the midges and the young ovules are eaten by larvae of the midges. Only 10% of the flowers mature into 13-seeded fruits and the carpels of the remaining 90% of the flowers have seeds ranging from 1 to 5. The seedling survival rate is only 7%. In addition to the above-mentioned reproductive bottlenecks, the species is also being over-harvested. It is now categorized as endangered. The findings of the present study on reproductive biology of I. griffithii should help in improving its conservation status.

Keywords

Embryological Studies, Floral Biology, Illicium griffithii, Reproductive Bottlenecks, Threatened Species Conservation.
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  • Qiu, Y. L. et al., The earliest angiosperms: evidence from mitochondrial plastid and nuclear genomes. Nature, 1999, 402, 404–407.

  • Qiu, Y. L. et al., Phylogeny of basal angiosperms: analyses of five genes from three genomes. Int. J. Plant Sci., 2000, 161, S3–S27.

  • Renner, S. S., Circumscription and phylogeny of the Laurales: evidence from molecular and morphological data. Am. J. Bot., 1999, 86, 1301–I315.

  • Friedman, W. E. and Ryerson, K. C., Reconstructing the ancestral female gametophyte of angiosperms: Insights from Amborella and other ancient lineages of flowering plants. Am. J. Bot., 2009, 96, 129–143.

  • Williams, J. H., Novelties of the flowering plant pollen tube underlie diversification of a key life history stage. Proc. Natl. Acad. Sci. USA, 2008.

  • Johri, B. M., Recent advances in the embryology of angiosperms. In Embryology and Taxonomy (ed. Maheshwari, P.), International Society of Plant Morphologists, Department of Botany, University of Delhi, Delhi, 1963, pp. 395–444.

  • Cronquist, A., An Integrated System of Classification of Flowering Plants, Columbia University Press, New York, USA, 1981.

  • Tobe. H., Jaffre, T., Raven, P. H., Embryology of Amborella (Amborellaceae): descriptions and polarity of character states. J. Plant Res., 2000, 113, 271–280.

  • Friedman, W. E., Gallup, W. N. and Williams, J. H., Female gametophyte development in Kadsura: implications for Schisandraceae, Austrobaileyales, and the early evolution of flowering plants. Int. J. Plant Sci., 2003, 164(5), S293–S305.

  • Friedman, W. E. and Williams, J. H., Modularity of the angiosperm female gametophyte and its bearing on the early evolution of endosperm in flowering plants. Evolution, 2003, 57, 216–230.

  • Berlyn, G. P. and Miksche, J. P., Botanical Micro-technique and Cytochemistry, Iowa State University Press, Ames, Iowa, USA, 1976.

  • Sass, J. E., In Botanical Microtechnique, Iowa State College Press, Ames, Iowa, USA, 1958.

  • Marbaniang, E. J. and Venugopal, N., A new species of Illicium (Illicium arunachalensis) from Arunachal Pradesh, India. Res. J. Sci. IT Manage., 2015, 4, 36–43.

  • Xia, N. and Saunders, R. M. K., Flora of China. 2008, 7, 32–38.

  • Keng, H., Illiciaceae. The families and genera of vascular plants. II. In Flowering Plants: Dicotyledons, Magnoliid, Hamamelid and Caryophyllid Families (eds Kubitzki, K., Rohwer, J. G. and Bittrich, V.), Springer, Berlin, 1993, pp. 344–347.

  • Qiu, D., L., Liu, X. H. and Guo, S. Z., Effects of simulated acid rain on fertility of litchi. J. Environ. Sci., 2005, 17(6), 1034–1037.

  • Borsch, T. K., Hilu, W., Quandt, D., Wilde, V., Neinhuis, C. and Barthlott, W., Non-coding plastid trnT–trnF sequences reveal a well supported phylogeny of basal angiosperms. J. Evol. Biol., 2003, 16, 558–576.

  • Soltis, D. E., Soltis, P. S., Chase, M. W., Mort, M. E., Albach, D. C., Zanis, M. and Savolainen, V., Angiosperm phylogeny inferred from a combined data set of 18S rDNA, rbcL, and atpB sequences. Bot. J. Linn. Soc., 2000, 133, 381–461.

  • Mattsson, O., Knox, R. B., Heslop-Harrison, J. and HeslopHarrison, Y., Protein pellicle of stigmatic papillae as a probable recognition site in incompatibility reactions. Nature, 1974, 247, 298–300.

  • Ghosh, S. and Shivanna, K. R., Structure and cytochemistry of the stigma and pollen-pistil interaction in Zephyranthes. Ann. Bot., 1984, 53, 91–105.

  • Scandlios, J. G., Genetic control of multiple molecular forms of enzymes in plants: a review. Biochem. Genet., 1969, 3, 37–79.

  • Shivanna, K. R. and Rangaswamy, N. S., Pollen Biology: A Laboratory Manual, Springer Verlag, Berlin, 1992.

  • Johansen, D. A., Plant Microtechnique, McGraw Hill, New York, USA, 1940.

  • Dashek, W. V., Methods in Plant Electron Microscopy and Cytochemistry, Humana Press, New Jersey, USA, 2000.

  • Dey. S., Basu, B. T. S., Roy, B. and Dey, D., A new rapid method of air drying for scanning electron microscopy using tetra methyl silane. J. Microsc. (Oxford), 1989, 156, 259–261.

  • Zou1, F., Yuan, D., Tan, X., Xie, P., Liao, T., Fan, X. and Zhang, L., Megasporogensis and female gametophyte development of Camellia grijsii Hance. J. Chem. Pharm. Res., 2013, 5(11), 484–488.

  • Shabir, P. A., Nawchoo, I. A. and Wani, A. A., Chromosomal stickiness and related meiotic irregularities in Inula racemosa – a critically endangered medicinal herb of North Western Himalayas. Eur. J. Biosci., 2013, 7, 41–46; http://dx.doi.org/10.5053/ejobios.2013.7.0.5).

  • Zou, F., Yuan, De-Yi., Tan, X.-F., Xie, P., Liao, T., Fan, X.-M. and Zhang, L., Megasporogensis and female gametophyte development of Camellia grijsii Hance. J. Chem. Pharm. Res., 2013, 5, 484–488.

  • Shugaeva, E. V., Male sterility of Valeriana officinalis L. s.l. Sov. Genet., 1979, 15, 138–143.

  • Erica, D.-S., André, L. L., Vanzela, J. and Mariath, E. A., Developmental and cytogenetic analyses of pollen sterility in Valeriana scandens L. Sex Plant Rep., 2010, 23, 105–113.

  • Shugaeva, E. V., Abnormalities of microsporogenesis in Valeriana nitida KR polyploids. Sov. Genet., 1972, 8, 37–46.

  • Khajuria, A., Conservation biology of three overexploited medicinal plants of North-West Himalayan region, Ph D thesis, BGSBU, Rajouri, 2013.

  • Raina, R. and Srivastava, L. J., Floral polymorphism in Valeriana jatamansi. Indian J. Plant Genet. Resour., 1992, 5, 93–94.

  • Raina, R., Behera, M. C., Chand, R. and Sharma, Y. P., Reproductive biology studies in Gentiana Kurroo Royle. Curr. Sci., 2003, 85, 667–670.

  • Jennersten, O., Pollination in Dianthus deltoids (Caryophyllaceae): effects of habitat fragmentation on visitation and seed set. Conserv. Biol., 1988, 2, 359–366.

  • Vikas, G. M., Tandon, R. and Mohan Ram, H. Y., Pollination biology and breeding system of Oroxylum indicum in Western Himalaya. J. Trop. Ecol., 2009, 25, 93–96.

  • Sarma, K., Tandon, R., Shivanna, K. R. and Mohan Ram, H. Y., Snail-pollination in Volvulopsis nummularium. Curr. Sci., 2007, 93, 826–831.

  • Tandon, R., Shivanna, K. R. and Mohan Ram, H. Y., Pollination biology and breeding system of Acacia senegal. Bot. J. Linn. Soc., 2001, 135, 251–262.

  • Tandon, R., Manohara, T. N., Nijalingappa, B. H. M. and Shivanna, K. R., Pollination and pollen–pistil interaction in oil palm, Elaeis guineensis. Ann. Bot., 2001, 87, 831–838.

  • Landry, C. L., Mighty mutualisms: the nature of plant–pollinator interactions. Nat. Edu. Know., 3, 37.

  • Rajkumar, K., Keshavanarayan, P. and Sivaram, V., Pollination biology and breeding system of Eugenia discifera Gamble – an endangered species of Western ghats, India. Int. J. Sci. Nat., 2015, 6, 1–11.

  • Sih, A. and Baltus, M. S., Patch size, pollinator behavior, and pollinator limitation in catnip. Ecology, 1987, 68, 1679–1690.

  • Brys, R., Jacquemyn, H., Endels, P., Hermy, F. V. R. M., Triest, L., Bruyn, L. D. and Blust, G. D. E., Reduced reproductive success in small populations of the self-incompatible Primula vulgaris. J. Ecol., 2004, 92, 5–14.

  • Krushelnycky, P. D., Evaluating the interacting influences of pollination, seed predation, invasive species and isolation on reproductive success in a threatened alpine plant. PLoS ONE, 2014, 9, 1–13.

  • Moza, M. K. and Bhatnagar, A. K., Plant reproductive biology studies crucial for conservation. Curr. Sci., 2007, 9, 1207.

  • Agren, J., Population size, pollinator limitation, and seed set in the self-incompatible herb Lythrum salicaria by the Ecological Society of America. Ecology, 1996, 77(6), 1779–1790.

  • Snow, A. A., Spira, T. P., Simpson, R. and Klips, R. A., The ecology of geitonogamous pollination. In Floral Biology: Studies on Floral Evolution in Animal-Pollinated Plants (eds Lloyd, D. G. and Barrett, S. C. H.), Chapman and Hall, New York, 1996, pp. 191–216.

  • Young, A. G., Broadhurst, L. M. and Thrall, P. H., Non-additive effects of pollen limitation and self-incompatibility reduce plant reproductive success and population viability. Ann. Bot., 2012, 109, 643–653.

  • Raina, R., Bhandari, S. K., Chand, R. and Sharma, Y. P., Strategies to improve poor seed germination in Stevia rebaudiana: a low calorie sweetener. J. Med. Plant Res., 2013, 7, 1793–1799.

  • Nautiyal, B., Nautiyal, P., Mohan, C., Khanduri, V. P. and Rawat, N., Floral biology of Aconitum heterophyllum Wall.: a critically endangered alpine medicinal plant of Himalaya, India. Turk. J. Bot., 2009, 33, 13–20.

  • Wafai, B. A., Siddiqui, M. A. A., Nawachoo, I. A., Dar, N. A., Bhat, M. A. and Mohi-Ud-Din, G. G., Studies on reproductive biology of some endangered medicinal herbs as a prelude to their ex situ conservation. J. Indian Bot. Soc., 2005, 84, 88–106.

  • Wan, P. A., Ganaie, K. A., Nawchoo, I. A. and Wafai, B. A., Phenological episodes and reproductive strategies of Inula recemosa (Astersaceae): critically endangered medicinal herb of NW Himalaya. Int. J. Bot., 2006, 2, 388–394.

  • Harder, L. D. and Barrett, S. C. H., Pollen dispersal and mating patterns in animal-pollinated plants. In Flora Biology: Studies on Floral Evolution in Animal-Pollinated Plants (eds Lloyd, D. G. and Barrett, S. C. H.), Chapman and Hall, New York, 1996, p. 140.

  • Heschel, M. S. and Paige, K. N., Inbreeding depression, environmental stress, and population size variation in scarlet gilia (Ipomopsis aggregata). Conserv. Biol., 1995, 9, 126–33.

  • Khajuria, A., Verma, S. and Sharma, P., Stylar movement in Valeriana wallichii DC. – a contrivance for reproductive assurance and species survival. Curr. Sci., 2011, 100, 1143–1144.

  • Verma, S., Kaul, V., Magotra, R. and Koul, A. K., Pollinator induced anther dehiscence in Incarvillea emodi (Bignoniaceae). Curr. Sci., 2008, 94, 1372–1374.

  • Sharma, S. and Verma, S., Male function for ensuring pollination and reproductive success in Berberis Lycium Royle: A novel mechanism. J. Biosci., 2016, 41, 21–25.

  • Raina, R., Mehera, T. S., Rana, R. C. and Sharma, Y. P., Reproductive biology of Picrorrhiza kurrooa – critically endangered high value temperate medicinal plant. Open Access J. Med. Aromat. Plant., 2010, 1, 40–43.

  • Gautam, K. and Raina, R., New insights into the phenology, genetics and breeding system of critically endangered Nardostachys grandiflora DC. Caryologia, 2016, 69, 91–101.

  • Raina, R. and Gupta, L. M., Increasing seed yield in Glory Lily (Gloriosa superba) – experimental approaches. Acta Hortic., 1999, 502, 175–179.

  • Vaughan, M. and Black, S. F., Native pollinators: how to protect and enhance habitat for native bees, Xerces Society for Invertebrate Conservation, Portland, USA, OR97215, 2008.

  • Yao, H. T. P. and Linsenmair, K. E., Seed dispersal mechanisms and the vegetation of forest islands in a West African forest savanna mosaic (Comoe´ National Park, Ivory Coast). Plant Ecol., 1999, 144, 1–25.

  • Ruxton, G. D. and Schaefer, H. M., The conservation physiology of seed dispersal. Philos. Trans. R. Soc. Bot., 2012, 367, 1708–1718.

  • Raina, R., Patil, P., Sharma, Y. P. and Rana, R. C., Reproductive biology of Swertia chirayita – a temperate critically endangered medicinal plant. Caryologia, 2013, 66, 12–20.

  • Shah, I. A., Sharma, Y. P., Raina, R. and Rana, R., Pollination studies in Swertia chirayita: a critically endangered medicinal plant of Western Himalayas. Open Access J. Med. Aromat. Plant, 2011, 2, 14–17.

  • Shah, I. A., Studies on seed germination and seed set in Swertia chirayita (Roxb. ex. Flem.) Karst., M Sc thesis, Department of Forest Products, Dr Y. S. Parmar University of Horticulture & Forestry, Solan, 2008.

  • Patil, P., Studies on morphological variation and breeding system in Swertia chirayita (Roxb. ex. Flem) Karst., M Sc thesis, Department of Forest Products, Dr Y. S. Parmar University of Horticulture & Forestry, Solan, 2011.

  • Wotton, D. M. and Kelly, D., Frugivore loss limits recruitment of large-seeded trees. Proc. R. Soc. Bot., 2011, 278, 3345–3354; doi:10.1098/rspb.2011.0185.

  • Robertson, A. W., Trass, A., Ladley, J. J. and Kelly, D., Assessing the benefits of frugivory for seed germination: the importance of the deinhibition effect. Funct. Ecol., 2006, 20, 58–66.

  • Samuels, I. A. and Levey, D. J., Effects of gut passage on seed germination: do experiments answer the questions they ask? Funct. Ecol., 2005, 19, 365–368.

  • Ramasubbu, R. and Irudhyaraj, F. D., Reproductive biology of Elaeocarpus blascoi Weibel, an endemic and endangered tree species of Palni Hills, Western Ghats, India. Curr. Sci., 2016, 110, 240.

  • Cerabolini, B., De Andreis, R., Ceriani, R. M., Pierce, S. and Raimondi, B., Seed germination and conservation of endangered species from Italian alps: Physoplexis comosa and Primula glaucescens. Biol. Conserv., 2004, 117, 351–356.

  • Agarwal, A. A., Seed germination of Loxopterygium guasango a threatened tree of coastal northwestern south America. Trop. Ecol., 37, 273–276.

  • Butola, J. S. and Badola, H. K., Effect of pre-sowing treatment on seed germination and seedling vigor in Angelica glauca: a threatened medicinal herb. Curr. Sci., 2004, 87, 796–799.

  • Badhwar, B. L. and Sharma, B. K., A note on the germination of Podophyllum hexandrum seeds. Indian For., 1963, 89, 445–447.

  • Bastrenta, B., Ebreton, J. L. and Thompson, J. D., Predicting demographic change in response to herbivory: a model of the effects of grazing and annual variation on the population dynamics of Anthyllis vulneraria. J. Ecol., 1995, 83, 603–610.

  • Huntly, N., Herbivores and the dynamics of communities and ecosystems. Annu. Rev. Ecol. Syst., 1991, 22, 477–503.

  • Walsh, R. P., Arnold, P. M. and Michaels, H. J., Effects of pollination limitation and seed predation on female reproductive success of a deceptive orchid. AoB PLANTS, 2014, 6, plu031; doi:10.1093/aobpla/plu03.1.

  • Williams, J. H., Amborella trichopoda (Amborellaceae) and the evolutionary developmental origins of the angiosperm progamic phase. Am. J. Bot., 2009, 96, 144–165.

  • Batygina, T. B., Shamrov, I. I. and Kolesova, G. E., Embryology of the Nymphaeales and Nelumbonales. II. The development of the female embryonic structures. Bot. Zh. (Leningrad), 1982, 67, 1179–1195.

  • Maheshwari, P., An Introduction to the Embryology of Angiosperm, Tata McGraw Hill Publishing Company Limited, New Delhi, 1950

  • Endress, P. K., The evolution of floral biology in basal angiosperms. Philos. Trans. R. Soc. London, Ser. B, 2010, 365(1539), 411–421.

  • Lau, J. Y., Pang, C. C., Ramsden, L. and Saunders, R. M., Stigmatic exudate in the Annonaceae: Pollinator reward, pollen germination medium or extragynoecial compitum? J. Integr. Plant Biol., 2017.

  • Oh, I. C., Denk, T. and Friis, E. M., Evolution of Illicium (Illiciaceae): mapping morphological characters on the molecular tree. Plant Syst. Evol., 2003, 240, 175–209.

  • Takhtajan, A L., The criteria used in evaluating the relative degree of their advancement. In Flowering Plants: Main Vectors of Evolution in Flowering Plants, Science and Business Media B.V., Springer, 2009, pp. 10–29.

  • Endress, P. K. and Igersheim, A., Gynoecium structure and evolution in basal angiosperms. Int. J. Plant Sci., 2000, 161, S211–S213.

  • Wodehouse, R. P., Pollen Grains. Their Structure, Identification and Significance in Science and Medicine, McGraw Hill, New York, 1935, p. 574.

  • Huang, T. C., Pollen Flora of Taiwan, Taiwan University Press, Taipei, 1972, vol. 143, pp. 10–16.

  • Lin, Q., A study of pollen morphology of genus Illicium L. Bull. Bot. Res., 1989, 9, 115–124.

  • Battaglia, E., Embryological questions: 7. Do new types of embryo sac occur in Schizandra? Ann. Bot., 1986, 44, 69–82.

  • Yoshida, O., Embryogenic studies in Schisandra chinensis. J. Coll. Arts Sci., Univ. Chiba, 1962, 4, 459–462.

  • Tobe, H. and Raven, P. H., Embryology of Onagraceae (Myrtales): characteristics, variation and relationships. Telopea, 1996, 8, 667–688.

  • Friedman, W. E., Madrid, E. N. and Williams, J. H., Origin of the fittest and survival of the fittest: Relating female gametophyte development to endosperm genetics. Int. J. Plant Sci., 2008, 169, 79–92.

  • Endress, P. K. and Sampson, F. B., Floral structure and relationships of the Trimeniaceae (Laurales). J. Arn. Arbor., 1983, 64, 447–473.

  • Solntseva, M. P., Illiciales. In Comparative Embryology of Flowering Plants (ed. Yakovlev, M. S.), Nauka, Leningrad, Russia, 1981, pp. 51–54.

  • Endress, P. K., The reproductive structures and systematic position of the Austrobaileyaceae. Bot. Jahr. Syst., 1980, 101, 393–433.

  • Swamy, B. G. L., Macrogametophytic ontogeny in Schisandra chinensis. J. Indian Bot. Soc., 1964, 43, 391–396.

  • Batygina, T. B. and Vasilyeva, V. E., Plant Reproduction, University Press, St Petersburg, Russia, 2002.

  • Tobe, H. and Raven, P. H., An embryological analysis of myrtales: its definition and characteristics. Ann. Mo. Bot. Gard., 1983, 70, 71–94.

  • Fareglind, F., Vorkommen und entseehung von hakenleisten an synergiden und eizellen. Sevensk Bot. Tidskrif., 1943, 35, 157–176.

  • Friedman, W. E., Developmental and evolutionary hypotheses for the origin of double fertilization and endosperm. C. R. Acad. Sci.–Ser. III, 2001, 324, 559–567.

  • Friedman, W. E., The evolution of double fertilization and endosperm: an ‘historical’ perspective. Sex Plant Reprod., 1998, 11, 6–16.

  • Friedman, W. E., Organismal duplication, inclusive fitness theory, and altruism: understanding the evolution of endosperm and the angiosperm reproductive syndrome. Proc. Nat. Acad. Sci. USA, 1995, 92(9), 3913–3917.

  • Du, W. and Wang, X. F., Intercarpellary growth of pollen tubes in the extragynoecial compitum and its contribution to fruit set in an apocarpous species, Schisandra sphenanthera (Schisandraceae). Am. J. Bot., 2012, 99(5), 961–966.


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  • Floral Biology and Embryological Studies are Important for Conservation of Threatened Plants Having Reproductive Bottlenecks:A Case Study of Illicium griffithii Hook. f. & Thomson

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Authors

E. J. Marbaniang
Department of Botany, Centre of Advanced Studies in Botany, North Eastern Hill University, Shillong 793 022, India
N. Venugopal
Department of Botany, Centre of Advanced Studies in Botany, North Eastern Hill University, Shillong 793 022, India
Susheel Verma
Centre for Biodiversity Studies, Baba Ghulam Shah Badshah University, Rajouri 185 234, India
Ravinder Raina
Department of Forest Products, Dr Y.S. Parmar University of Horticulture and Forestry, Solan 173 23, India
Ankush Khajuria
Centre for Biodiversity Studies, Baba Ghulam Shah Badshah University, Rajouri 185 234, India
Kamini Gautam
Department of Forest Products, Dr Y.S. Parmar University of Horticulture and Forestry, Solan 173 23, India

Abstract


Information on reproductive biology of threatened plant species could be useful for conservation, particularly when the species fails to perpetuate in nature due to regeneration failure. In flowering plants, the domain of reproductive biology includes structural details of reproductive units such as flower or inflorescence, formation of viable gametes, pollination dynamics, role of pollinators, pollen–pistil interactions as determined through compatibility, breeding system and mating strategies, fertilization and embryogeny, seed development, dispersal and germination. The importance of reproductive biology in species conservation has been demonstrated through a case study of Illicium griffithii Hook f. & Thomson, a threatened plant species from Arunachal Pradesh. I. griffithii (Illiciaceae) is a member of the ANITA clade and a representative taxon of the three most basal angiosperms. The flowers of I. griffithii are obligate xenogamous, and hence compatible pollen grains only germinate on the stigmatic papillae. Esterase and phosphatase enzymatic activities are absent in most stigmatic surfaces. Therefore, stigmatic receptivity is absent in many carpels. The ovules are anatropous and bitegmic with a four-celled/four-nucleate structure of embryo sac at maturity. Antipodals and filiform apparatus are absent. Presence of mucilage cells in the embryo sac facilitates the entry of pollen tubes into it. Embryolike organization of the endosperm is present, with one pole globular having smaller cells and the other pole roughly filamentous with larger cells resembling that of a suspensor. Extragynoecial compitum is not observed in I. griffithii. The flowers are brooding sites for the midges and the young ovules are eaten by larvae of the midges. Only 10% of the flowers mature into 13-seeded fruits and the carpels of the remaining 90% of the flowers have seeds ranging from 1 to 5. The seedling survival rate is only 7%. In addition to the above-mentioned reproductive bottlenecks, the species is also being over-harvested. It is now categorized as endangered. The findings of the present study on reproductive biology of I. griffithii should help in improving its conservation status.

Keywords


Embryological Studies, Floral Biology, Illicium griffithii, Reproductive Bottlenecks, Threatened Species Conservation.

References





DOI: https://doi.org/10.18520/cs%2Fv114%2Fi03%2F576-587