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Premise of research. Sixteen compression/impression specimens of a new floating aquatic angiosperm that enrich our knowledge of Late Cretaceous vegetation have been identified from the early Maastrichtian St. Mary River Formation near Cardston, Alberta, Canada. Methodology. Fossils were studied using dégagement and photographed under reflected light. Leaves were morphotyped using methodology in the Manual of Leaf Architecture and compared to other extant and extinct rosette-forming floating aquatic angiosperms. Pivotal results. Stems of this aquatic dicot show determinate growth of floating shoots with opposite/decussate attachment of heterophyllous leaves. Leaves are simple and sessile at the apicalmost node, simple and petiolate at the second node, and compound with three leaflets at nodes 3–6. Compound leaves are petiolate and ternate (trifoliate). Leaflet shape is unlobed, obovate, and symmetrical; base is acute-obtuse; apex angle is obtuse; base shape is convex; petiolar attachment is marginal; apex shape is rounded; and margin is crenate. Primary veins are flabellate to pinnate with three to five basal veins that dichotomize distally. Secondary veins are craspedodromous with uniform spacing and angles. Teeth are of a single order, three per centimeter near apex, and convex-convex; the sinus is angular, and the apex is foraminate. Conclusions. While the basic growth habit of this plant is similar to that of several extant taxa in the Onagraceae, Lythraceae, Plantaginaceae, and Hydrocharitaceae, leaf venation and the presence of compound leaves differ greatly from the living species. In growth habit and the presence of both simple and compound leaves, the new plant is similar to Quereuxia angulata , also found at this fossil site. These fossils are described as a new genus and species, Tolmania aquatica Edmonds, Stockey & Rothwell, which differs from Quereuxia in pattern of heterophylly, venation, larger plant size, stem morphology, and the presence of hydathodes in the leaves. [ABSTRACT FROM AUTHOR]

Premise: Nearly 200 araceous leaves and two spadices have been identified among Paleocene fossils from the Blindman River locality near Blackfalds, Alberta, Canada. Although not found in attachment, these probably represent parts of the same extinct plant species. Methods: Specimens were studied using light microscopy. Phylogenetic analyses using a morphological matrix of living and fossil Araceae were performed using TNT version 1.5 to help establish relationships of the fossil leaves and spadices within Araceae and to each other. Results: Leaves are simple with a broad petiole, entire margin, and elliptic to ovate or oblong blade with an acute to slightly rounded apex. A multi‐veined midrib extends into the basal region of the blade. Parallelodromous primary veins of two orders diverge at acute angles, converging with a submarginal vein or at the apex. Transverse veins are opposite percurrent, producing rectangular to polygonal areoles. Higher‐order veins are mixed opposite/alternate. Spadices are cylindrical, with helically arranged, bisexual, perigoniate flowers, each with six free tepals and a protruding style. Fruits are trilocular, with axile placentation and one seed per locule. Conclusions: Leaves are assignable to the fossil genus Orontiophyllum J. Kvaček & S.Y. Sm. as O. grandifolium comb. nov. Spadices are described as Bognerospadix speirsiae gen. et sp. nov. Leaves and spadices each conform to an early‐diverging lineage of Araceae, increasing the known diversity of Proto‐Araceae (viz., subfamilies Gymnostachydoideae and Orontioideae). Together, they provide strong evidence for extinct Proto‐Araceae with novel combinations of characters shortly after the Cretaceous‐Paleogene floral transition. [ABSTRACT FROM AUTHOR]