Gandolfo, M. A., K. C. Nixon, and W.L. Crepet. 2004. The oldest complete fossil flowers of Nymphaeaceae and implications for the complex insect entrapment pollination mechanisms in early angiosperms. Proceedings of the National Academy of Sciences, USA 101 (21): 8056-8060.
Abstract: Recent cladistic analyses using molecular data have suggested that modern Nymphaeales sensu stricto (excluding the Nelumbonaceae) are remnants of a collateral sister group of the rest of or all remaining angiosperms (possibly excluding only Amborella). The position varies among the analyses, sometimes as a solitary collateral “basal” branch, sometimes as the next collateral branch above Amborella, or with Amborella as a sister group to Nymphaeales, and with or without the Illiciales (Illicium and Schizandra) forming a monophyletic group. This putative basal or near-basal position of the Nymphaeales and Amborella has promoted much interest in these taxa among phylogeneticists. But until recently, evidence from fossils supporting this hypothesis was lacking.
For many years, knowledge of the fossil record for the Nymphaeales has been based on fossil leaves and pollen. The oldest leaves, petioles and stems known with nymphaeoid characters come from the Kurnub Group (Upper Aptian- Uppermost Albian, 97-124 my, Early Cretaceous) of Jordan whereas the oldest record for pollen assignable to Nymphaeaceae is of Maastrichtian (Upper Cretaceous) age and was registered at the Edmonton Formation, Canada. Friis et al (2001) proposed an Early Cretaceous (100-125 my) Portuguese fossil flower with associated pollen grains as a member of the Nymphaeales. This fossil flower, apparently bisexual and perigynous, consists of a receptacle with twenty-four rhombic structures interpreted as remains of stamens that are surrounding twelve basally fused carpels, which encircled a central protrusion. The putative stamens are placed in two whorls; the outer cycle alternates the carpels, whereas the inner one is placed opposite to them. Pollen grains found on the surface of the flower are monocolpate with a coarsely reticulate exine. The carpels form a syncarpus gynoecium, and each carpel contains numerous ovules. Although this Portuguese fossil flower may have preserved characters common to some extant members of the Nymphaeales, unfortunately those features alone are inadequate and insufficient to place this fossil flower unambiguously within the Nymphaeales sensu stricto (Nymphaeaceae+Cabombaceae).
Our goal is to report here newly discovered fossil flowers that have the precise and unique complement of characters of the extant genus Victoria, allowing definitely their placement within the Nymphaeaceae sensu stricto. These new fossil flowers were collected from sediments of the Raritan Formation exposed in the Old Crossman Clay Pit in New Jersey, United States.
Actual width in ( ) unless otherwise noted.
|Side view of flower
(height= 2.4 mm)
|Side view, dissected
(height= 2.4 mm)
|Top view of receptical showing
paracarples and steril tip
|Dissection of receptical,
with steril column in center
(image height= 637 µm)
|Bottom of androecium- stamens at
edge, staminodes in center
|Dissected top showing petaloid
tepals (top) and staminodes
(height= 1.1 mm)