Oldest known fossils of monocotyledons

The monocotyledonous angiosperm clade (class Liliopsida) includes roughly 50,000 species1 of diverse forms. The group comprises such economically noticeable plants as palms, orchids, most of the horticultural bulbs, and grasses, which include some of the most important food crops, such as maize, rice and other grains. Modern monocotyledons are diverse and dominate many habitats, but the fossil record of these plants is meagre, fossils of monocotyledonous flowers are rare, and the earliest putative monocotyledonous fossils (pollen and leaves) are all equivocal2,3. Here we describe the oldest known fossil flowers that can be definitely assigned to the Liliopsida.