Modeling Nymphoides architecture: A morphological analysis of Nymphoides aquatica (Menyanthaceae)

Authors

Jennifer H. Richards, Department of Biological Sciences, Florida International UniversityFollow
Marlene Dow, Department of Biological Sciences, Florida International University
Tiffany Troxler-Gann, Southeast Environmental Research Center and Department of Biological Sciences, Florida International UniversityFollow

Abstract

• Premise of the study: Species in the aquatic genus Nymphoides have inflorescences that appear to arise from the petioles of floating leaves. The inflorescence-floating leaf complex can produce vegetative propagules and/or additional inflorescences and leaves. We analyzed the morphology of N. aquatica to determine how this complex relates to whole plant architecture and whether whole plant growth is sympodial or monopodial.

• Methods: We used dissections, measurements, and microscopic observations of field-collected plants and plants cultivated for 2 years in outdoor tanks in south Florida, USA.

• Key results: Nymphoides aquatica had a submerged plagiotropic rhizome that produced floating leaves in an alternate/spiral phyllotaxy. Rhizomes were composed of successive sympodial units that varied in the number of leaves produced before the apex terminated. The basic sympodial unit had a prophyll that subtended a renewal-shoot bud, a short-petioled leaf (SPL) with floating lamina, and an inflorescence; the SPL axillary bud expanded as a vegetative propagule. Plants produced either successive basic sympodial units or expanded sympodia that intercalated long-petioled leaves between the prophyll and the SPL.

• Conclusions: Nymphoides aquatica grows sympodially, forming a rhizome composed of successive basic sympodia and expanded sympodial units. Variations on these types of sympodial growth help explain the branching patterns and leaf morphologies described for other Nymphoides species. Monitoring how these two sympodial phases are affected by water depth provides an ecologically meaningful way to assess N. aquatica’s responses to altered hydrology.

Comments

This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DBI-0620409 and #DEB-9910514. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Recommended Citation

Richards, J.H., M. Dow, T. Troxler. 2011. Modeling Nymphoides architecture: A morphological analysis of Nymphoides aquatica (Menyanthaceae). American Journal of Botany 97(11): 1761-1771.