Permineralized fruits and Seeds from the Princeton chert (Middle Eocene) of British Columbia: Lythraceae

Abstract

Two types of lythraceous fruit and seed remains are described from the Middle Eocene, Allenby Formation of Princeton, British Columbia. Small globose, pedicellate fruits with persistent sepals, four to six locules, septa complete to the fruit apex, axial placentation, a palisade-like endocarp, and pyramidal seeds are referable to the genus Decodon Gmel. Numerous dispersed anatropous seeds of the same morphology show rounded or angular comers, lack lateral wings, and have a raphe that begins near the micropyle, passing through the middle integumentary layer on the dorsal face to the seed chalaza. Integuments are three zoned and seeds bear a ventral germination valve composed of radially elongated rectangular cells similar to the outer integumentary layer. Seeds show a prominent hypostase and dicotyledonous embryos with remains of a suspensor. These fruits and seeds are described as a new species of Decodon, D. allenibyensis Cevallos-Ferriz et Stockey sp.nov., which represents the oldest known species of the genus described to date. One fruit with several large, pyramidal lythraceous seeds is described. Seeds have three integumentary zones, the outer of which appears to have been mucilaginous. These remains most closely resemble the genus Lawsonia L., but additional specimens are needed to confirm this comparison. These lythraceous remains add to our knowledge of the Princeton angiosperm flora and further support the idea that these plants lived along a lake or marsh.