Florissantia is an extinct genus of flowering plants in the Malvaceae subfamily Sterculioideae known from western North America and far eastern Asia.

[8][9] A tentative report of the species from the Katalla Formation, Alaska was made by Jack Wolfe (1977) based on a single specimen.

[3] The occurrence is supported by an additional fossil from the lowland floodplain environment preserved in the Huntingdon Formation around Vancouver, British Columbia.

[10] F. quilchenensis has been recovered from four locations in the Okanagan highlands, the Falklands and McAbee sites[11] near Cache Creek, British Columbia, the Coldwater Beds Quilchena site near Quilchena, British Columbia and the Klondike Mountain Formation in Republic, Washington, northern Ferry County, Washington.

[1] The Amgu flora, the type locality for F. sikhote-alinensis, represents outcrops of the Khutsin Formation exposed in the Sikhote Alin mountains on the Russian far-east coast.

The flora was reported by Manchester (1999) as Miocene, however more detailed work on the stratigraphy of the region moved the age to Early Oligocene as noted by Kvaček et al (2005),[16] Peng et al (2011) reported a slightly older late Eocene or Early Oligocene age[17] which was followed by Archibald and Rasnitsyn (2018) who list the site as likely Priabonian or perhaps Rupelian.

[18] The flower reported in 2024 from the Northwestern Indian province of Rajasthan was recovered from the Gurha opencast lignite mine working rocks of the Palana Formation.

Based on palynological data the formation has an estimated Early Eocene age, with dating between 55 to 52 million years ago.

The Formation has been interpreted to preserve a region of ponds, flood plains, swamps, and waterways moderated by a warm wet climate.

[4] Fossils now placed in Florissantia were first reported by Leo Lesquereux (1883) from the Florissant Formation and described as the morning glory family species Porana speirii.

Manchester chose the specific epithet ashwillii as a patronym honoring Melvin S. Ashwill who collected many of the specimens examined.

The flowers are radially symmetrical shallowly bell shaped, with large sepals fused up to 50% of their length and born on long pedicels.

The 20–32 μm (0.00079–0.00126 in) pollen grains are slightly flattened spheres, with three to four short colpi apertures on the outer surface[1] Florissantia ashwillii calyxes are moderate in size with a diameter of 21–31 mm (0.83–1.22 in), those of F. quichenensis are known to be smaller, while those of F. speirii range notably larger.

Due to the smaller size and mix of characters, Ashif Ali and his coauthors did not assign the flower to an existing species.