Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9 Canada. Petioles are at least 4 mm wide with 5-7 primary veins that enter the leaf blade. Venation is campylodromous resulting in 21-25 weak primary veins, with three central primaries that remain unbranched to the apex. Secondaries diverge at angles of 45-65 degrees near the midveins and 90 degrees near the leaf margin. Minor, or tertiary veins, alternate with the secondaries.
Tertiaries are usually unbranched but occasional dichotomies and anastomoses are present.
No freely ending veinlets are visible. These leaves were compared to extant leaves of Alismatidae and show closest similarities to those in the genus Caldesia Parl. and fossils described from the Upper Cretaceous and early Tertiary of Eurasia as Haemanthophyllum kamtschaticum Budantsev and H. cordatum Golovneva. The fine-grained sediments at the Cardston locality have enabled a much more detailed description of the fine venation than has been possible in leaves of this type from other localities. A reexamination of previously described species of Haemanthophyllum is needed since this taxon appears to contain a diverse assemblage of leaf types of varying morphology and of different affinities. Furthermore, the Cardston locality shows great potential for the reconstruction of these as well as other aquatic monocots.