Abstract
Staminate flowers, androecium, and pollen of Siparuna aspera (Siparunaceae) were examined by using light and electron microscopy techniques. The presence of three decussate whorls of two stamens in Siparuna, each whorl with two opposite stamens, is reported for the first time. A structure in the floral center was also found that could correspond to a vestigial style. The tapetum of Siparuna is here reported for the first time as being secretory. Pollen of S. aspera is globose and inaperturate. The exine is differentiated into sexine and nexine; the sexine is formed by an undulate, continuous, granulose, thin tectum, and by globose-conical columellae; the tips of the latter project through the tectum and form the echinulate sculpture of the grain. The nexine is continuous and differentiated into a lamellar foot layer and a granulose endexine. The intine is also continuous and its inner border is irregular. All these features reinforce the close phylogenetic relationship between Siparuna and Glossocalyx shown also by molecular data. Floral and palynological characters are extremely variable and conflicting within order Laurales, including Siparunaceae, Atherospermataceae, Gomortegaceae, Hernandiaceae, and Monimiaceae. Therefore, more floral ontogenetic, pollen ultrastructure, and phylogenetic studies of these families are necessary in order to get a better approach on the evolution of such characters in order Laurales.
Keywords
References
Beerhues, L., M. Rittscher, H. Schüpk er, C. Schwerdtfeger & R. Wiermann. 1993. The significance of the anther tapetum in the biochemistry of pollen pigmentation. Plant Syst. Evol. (Suppl.) 7: 117-125.
Bhandari, N.N. 1963. Embryology of Pseudowintera colorata - a vesseless dicotyledon. Phytomorphology 13: 303-316.
Bhandari, 1971. Embryology of the Magnoliales and comments on their relationships. J. Arnold Arbor. 52: 1-39, 285-304.
Brizicky, G.K. 1959. Variability in the floral parts of Gomortega (Gomortegaceae). Willdenowia 2: 200-207.
Doyle, J.A. & P.K. Endress. 2000. Morphological phylogenetic analysis of basal angiosperms: comparison and combination with molecular data. Int. J. Plant Sci. 161 (Suppl.): S121-S153.
Endress, P.K. 1972. Zur vergleichenden Entwicklungsmorphologie, Embryologie und Systematik bei Laurales. Bot. Jahrb. Syst. 92: 331-428.
Endress, P.K. , 1980. Ontogeny, function and evolution of extreme floral constructions in Monimiaceae. Plant Syst. Evol. 134: 79-120.
Endress, P.K. , 1990. Patterns of floral construction in ontogeny and phylogeny. Biol. J. Linn. Soc. 39: 153-175.
Endress, P.K. , 1994. Diversity and evolutionary biology of tropical flowers. Cambridge Tropical Biology Series, Cambridge, U.K.
Endress, P.K. , 1996. Diversity and evolutionary trends in angiosperm anthers. In W.G. D'Arcy & R.C. Keating (eds.), The anther: form, function and phylogeny. Cambridge University Press, Cambridge, pp. 92-110.
Endress, P.K. & D.H. Lorence. 1983. Diversity and evolutionary trends in the floral structure of Tambourissa (Monimiaceae). Plant Syst. Evol. 143: 53-81.
Endress, P.K. & L.D. Hufford. 1989. The diversity of stamen structures and dehiscence patterns among Magnoliidae. Bot. J. Linn. Soc. 100: 45-85.
Endress, P.K. & S. Stumpf. 1990. Non-tetrasporangiate stamens in the angiosperms: structure, systematic distribution and evolutionary aspects. Bot. Jahrb. Syst. 112: 193-240.
Erdtman, G. 1966. Pollen morphology and plant taxonomy. I. Angiosperms. New York, Hafner.
Feil, J.P. 1992. Reproductive ecology of dioecious Siparuna (Monimiaceae) in Ecuador - A case of gall midge pollination. Bot. J. Linn. Soc. 110: 171-203.
Furness, C.A. & P.J. Rudall. 1998. The tapetum in monocotyledons: structure and systematics. Bot. Rev. 64: 201-239.
Furness, C.A. & P.J. Rudall. 1999. Microsporogenesis in monocotyledons. Ann. Bot. 84: 475-499.
Furness, C.A. & P.J. Rudall. 2000. The systematic significance of simultaneous cytokinesis during microsporogenesis in monocotyledons. In K.L. Wilson & D.A. Morrison (eds.), Monocots: systematics and evolution. Collingwood: Victoria, Australia, CSIRO Publishing, pp. 189-193.
Furness, C.A. & P.J. Rudall. 2001a. The tapetum in basal angiosperms: early diversity. Int. J. Plant Sci. 162: 375-392.
Furness, C.A. & P.J. Rudall. 2001b. Pollen and anther characters in monocot systematics. Grana 40: 17-25.
Furness, C.A. & P.J. Rudall. & F.B. Sampson. 2002. Evolution of microsporogenesis in angiosperms. Int. J. Plant Sci. 163: 235-260.
Gabarayeva, N. 1993. Sporoderm development in Asimina triloba (Annonaceae). II. The developmental events after callose dissolution. Grana 32: 210-220.
Gabarayeva, N. , 1995. Pollen wall and tapetum development in Anaxagorea brevipes (Annonaceae): sporoderm substructure, cytoskeleton, sporopollenin precursor particles, and the endexine problem. Rev. Paleobot. Palynol. 85: 123-152.
González, F., P.J. Rudall & C. Furness. 2001. Microsporogenesis and systematics of Aristolochiaceae. Bot. J. Linn. Soc. 137: 221-242.
Heo, K. & H. Tobe. 1995. Embryology and relationships of Gyrocarpus and Hernandia (Hernandiaceae). J. Plant Res. 108: 327-341.
Hesse, M., E. Pacini & M. Willemse (eds.). 1993. The tapetum: cytology, function, biochemistry and evolution. Plant Syst. Evol., Suppl. 7.
Hufford, L. 1996. The origin and early evolution of angiosperm stamens. In W.G. D'Arcy & R.C. Keating (eds.), The anther: form, function and phylogeny. Cambridge University Press, Cambridge, pp. 58-91.
Johri, B.M., K.B. Ambegaokar & P.S. Srivastava. 1992. Comparative embryology of angiosperms. Springer-Verlag, Berlin.
Kubitzki, K. 1993. Gomortegaceae. In K. Kubitzki, J.G. Rohwer & V. Bittrich (eds.), The families and genera of vascular plants, 2: 318-320. Springer-Verlag, Berlin.
Le Thomas, A. 1988. Variation de la région aperturale dans le pollen des Annonacees. Taxon 37: 644-656.
Moseley, M.F., I.W. Bailey & B.G.L. Swamy. 1950. The morphology and relationships of the Monimiaceae. J. Arnold Arbor. 31: 362-404.
Muñoz-Pizarro, C. 1959. Sinopsis de la Flora de Chile. Ediciones de la Universidad de Chile. Santiago de Chile.
Pacini, E. 1997. Tapetum character states: analytical keys for tapetum types and activities. Can. J. Bot. 75: 1448-1459.
Pacini, E. & G.G. Franchi. 1991. Diversification and evolution of the tapetum. In S. Blackmore & S.H. Barnes (eds.), Pollen and spores - patterns of diversification, pp. 301-316. Oxford: Systematics Association. Clarendon Press.
Pacini, E. & G.G. Franchi.1993. Role of the tapetum in pollen and spore dispersal. Plant Syst. Evol. (Suppl.) 7: 1-11.
Pacini, E. & G.G. Franchi. & M. Hesse. 1985. The tapetum: its form, function and possible phylogeny in Embryophyta. Plant Syst. Evol. 149: 155-185.
Perkins, J.R. 1898. Beiträge zur Kenntnis der Monimiaceae. I. Über die Gliederung der Gattungen der Mollinedieae. Bot. Jahrb. Syst. 25: 547-577.
Philipson, W.R. 1993. Monimiaceae. In K. Kubitzki, J.G. Rohwer & V. Bittrich (eds.), The families and genera of vascular plants, 2: 426-437. Springer-Verlag, Berlin.
Pichon, M. 1948. Les Monimiacées, famille hétérogène. Bull. Mus. Hist. Nat. Paris, ser. 2, 20: 383-384.
Pignal, M., B. Lugardon, J. Jérémic & A. Le Thomas. 1999. Morphologie et ultrastructure du pollen de Siparunaceae (Laurales). Grana 38: 210-217.
Renner, S.S. 1998. Phylogenetic affinities of Monimiaceae based on cpDNA gene and spacer sequences. Perspectives in Plant Ecology, Evolution and Systematics 1: 61-77.
Renner, S.S. & A. Chanderbali. 2000. What is the relationship among Hernandiaceae, Lauraceae, and Monimiaceae, and why is this question so difficult to answer? Int. J. Plant Sci. 161 (Suppl.): S109-S119.
Renner, S.S. & F. Feil. 1993. Pollinators of tropical dioecious angiosperms. Amer. J. Bot. 80: 1100-1107.
Renner, S.S. & C. Hausner. 1997. Siparunaceae. In G. Harling & L. Andersson (eds.), Flora of Ecuador, No. 59. Council for Nordic Publications in Botany.
Renner, S.S. , A.E. Schwarzbach & L. Lohmann. 1997. Phylogenetic position and floral function of Siparuna (Siparunaceae: Laurales). Int. J. Plant Sci. 158 (Suppl.): S89-S98.
Renner, S.S. & H. Won. 2001. Repeated evolution of dioecy from monoecy in Siparunaceae (Laurales). Syst. Biol. 50: 700-712.
Reynolds, E.S. 1963. The use of lead citrate at high pH as an electron opaque stain in electron microscopy. J. Cell Biol. 17: 208-212.
Rodríguez, R., O. Matthei & M. Quezada. 1983. Flora arbórea de Chile. Editorial de la Universidad de Concepción de Chile, Santiago de Chile.
Sampson, F.B. 1969. Studies on Monimiaceae. II. Floral morphology of Laurelia novae-zelandiae A. Cunn. (subfamily Atherospermatoideae). New Zealand J. Bot. 7: 214-240.
Sampson, F.B. 1977. Pollen tetrads of Hedycarya arborea J.R. et G. Forst. (Monimiaceae). Grana 16: 61-73.
Sampson, F.B. 1996. Pollen morphology and ultrastructure of Laurelia, Laureliopsis and Dryadodaphne (Atherospermataceae [Monimiaceae]). Grana 35: 257-265.
Sampson, F.B. 1997. Pollen morphology and ultrastructure of Australian Monimiaceae - Austromatthaea, Hedycarya, K ibara, Leviera, Steganthera and Tetrasynandra. Grana 36: 135-145.
Sampson, F.B. 2000. Pollen diversity in some modern magnoliids. Int. J. Plant Sci. 161 (Suppl.): S193-S210.
Sastri, R.L.N. 1963. Studies in Lauraceae. IV. Comparative embryology and phylogeny. Ann. Bot. (Lond.) 27: 425-433.
Schodde, R. 1970. Two new suprageneric taxa in the Monimiaceae alliance (Laurales). Taxon 19: 324-328.
Takhtajan, A. 1997. Diversity and classification of flowering plants. Columbia University Press, New York.
Walker, J.W. 1976a. Comparative pollen morphology and phylogeny of the Ranalean complex. In C.B. Beck (ed.), Origin and early evolution of angiosperms. Columbia University Press, New York. pp. 241-299.
Walker, J.W. 1976b. Evolutionary significance of the exine in the pollen of primitive angiosperms. In J.K. Ferguson & J. Muller (eds.), The evolutionary significance of the exine. Linnean Society Symposium Series No. 1. Academic Press, London. pp. 251-308.
![Creative Commons License](http://i.creativecommons.org/l/by-nc-nd/4.0/88x31.png)
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.