Abstract
Floral ontogeny can assist in understanding formation of mature floral structure and provide taxonomic and evolutionary insights at the species and genus level. In this study, floral ontogeny of Magnolia liliiflora, M. maudiae and M. figo was investigated using scanning electron microscopy. The results showed that tepal primordia of these species are initiated asynchronously in whorls, whereas stamen and carpel primordia are initiated spirally and centripetally. Variation in tepal number in M. maudiae was also observed at the early stage of differentiation. Our study demonstrates that floral ontogeny is remarkably homogenous in Magnoliaceae, and thus it cannot serve as a basis for classification at the genus or lower taxonomic levels. Nonetheless, the transition of floral development from typical spiral flowers to typical whorled flowers is of great significance for understanding evolution of angiosperm flowers.
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<p>De Craene, L.R.D. (2016) Meristic changes in flowering plants: how flowers play with numbers. <em>Flora</em> 221: 22–37. https://doi.org/10.1016/j.flora.2015.08.005</p>
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<p>Dong, X.Y., Liu, Z., Saunders, R.M.K. & Chen, Z.D. (2012) Floral ontogeny of <em>Schisandra chinensis</em> (Schisandraceae): implications for androecial evolution within <em>Schisandra</em> and <em>Kadsura</em>. <em>Plant Systematics and Evolution</em> 298: 713–722. https://doi.org/10.1007/s00606-011-0581-5</p>
<p>Dos Santos, P. & de Craene, L.P.R. (2015) Floral development of <em>Lewisia</em> (Montiaceae): investigating patterns of perianth and stamen diversity. <em>Flora</em> 221: 4–13. https://doi.org/10.1016/j.flora.2015.11.011</p>
<p>Dunn, S.T. (1908) A botanical expedition to central Fokien. <em>Journal of the Linnean Society, Botany</em> 38: 353–354. https://doi.org/10.1111/j.1095-8339.1908.tb00858.x</p>
<p>Endress, P.K. (2001) The flowers in extant basal angiosperms and inferences on ancestral flowers. <em>International Journal of Plant Sciences</em> 162: 1111–1140. https://doi.org/10.1086/321919</p>
<p>Erbar, C. & Leins, P. (1981) Zur Spirale in Magnolien-Blüten. <em>Beiträge zur Biologie der Pflanzen</em> 56: 225–241.</p>
<p>Erbar, C. & Leins, P. (2006) Floral ontogeny and systematic position of the Didiereaceae. <em>Plant Systematics and Evolution</em> 261: 165–185. https://doi.org/10.1007/s00606-006-0432-y</p>
<p>Erber, C. & Leins, P. (1983) Zur sequenz von blütenorganen bei einigen Magnoliiden. <em>Botanische Jahrbücher für Systematik</em> 103: 433–449.</p>
<p>Figlar, R.B. & Nooteboom, H.P. (2004) Notes on Magnoliaceae IV. <em>Blumea</em> 49: 87–100. https://doi.org/10.3767/000651904X486214</p>
<p>Figlar, R.B. (2000) <em>Proleptic branch initiation in Michelia and Magnolia subgenus Yulania provides basis for combinations in subfamily Magnolioideae</em>. <em>Proceedings of the international symposium on the family Magnoliaceae</em>. Science Press, Beijing, pp. 14–25.</p>
<p>Franchet, A.R. & Delavay, J.M. (1889) <em>Plantae Delavayanae. </em>Klincksieck, Paris, 240 pp. https://doi.org/10.5962/bhl.title.10529</p>
<p>Fu, L., Zeng, Q.W., Liao, J.P. & Xu, F.X. (2009) Anatomy and ontogeny of unisexual flowers in dioecious <em>Woonyoungia septentrionalis</em> (Dandy) Law (Magnoliaceae).<em> Journal of Systematics and Evolution</em> 47: 263–272. https://doi.org/10.1111/j.1759-6831.2009.00029.x</p>
<p>Fu, L., Zeng, Q.W., Xu, F.X. & Zhu, J.Y. (2007) Floral organogenesis of <em>Tsoongiodendron odorum</em> Chun. <em>Journal of Tropical and Subtropical Botany</em> 15: 30–34.</p>
<p>Fu, D.L. (2001) Notes on <em>Yulania</em> Spach. <em>Journal of Wuhan Botanical Research</em> 19: 191–198.</p>
<p>Jussieu, A.L. (1789) Magnoliae, les Magnoliers. <em>Genera plantarum</em>, Apud viduam Hérissant et Théophile Barrois, Paris, pp. 280–283.</p>
<p>Kim, S. & Suh, Y.B. (2013) Phylogeny of Magnoliaceae based on ten chloroplast DNA regions. <em>Journal of Plant Biology</em> 56: 290–305. https://doi.org/10.1007/s12374-013-0111-9</p>
<p>Kim, S., Park, C.W., Kim, Y.D. & Suh, Y.B. (2001) Phylogentic relationships in family Magnoliaceae inferred from <em>ndhF</em> sequences. <em>American Journal of Botany</em> 88: 717–728. https://doi.org/10.2307/2657073</p>
<p>Law, Y.H. (1984) A preliminary study on the taxonomy of the family Magnolicaeae. <em>Acta Phytotaxonomica Sinica</em> 22: 89–109.</p>
<p>Li, Y.F., Sylvester, S.P., Li, M., Zhang, C., Li, X., Duan, Y.F. & Wang, X.R. (2019) The complete plastid genome of <em>Magnolia zenii</em> and genetic comparison to Magnoliaceae species. <em>Molecules</em> 24: 261. https://doi.org/10.3390/molecules24020261</p>
<p>Liao, W.F. & Xia, N.H. (2008) Floral organogenesis of <em>Manglietia fordiana</em> Oliv. and <em>Manglietia chingii</em> Dandy. <em>Subtropical Plant Science</em> 37: 7–10.</p>
<p>Lin, R.Z., Li, R.Q., Lu, A.M., Zhu, J.Y. & Chen, Z.D. (2016) Comparative flower development of <em>Juglans regia</em>, <em>Cyclocarya paliurus</em> and <em>Engelhardia spicata</em>: homology of floral envelopes in Juglandaceae. <em>Botanical Journal of the Linnean Society</em> 181: 279–293. https://doi.org/10.1111/boj.12413</p>
<p>Link, J.H.F. (1822) <em>Enumeratio plantarum Horti Regii Berolinensis Altera</em>, vol. 2, Reimer, Berlin, 66 pp. https://doi.org/10.1515/9783112630648</p>
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