Paleoallium billgenseli gen. et sp. nov.: Fossil monocot remains from the latest early Eocene Republic Flora, northeastern Washington State, USA

Document Type

Article

Publication Date

2018

Publication Title

International Journal of Plant Sciences

Abstract

Premise of research. Fossil inflorescences (scapes) producing both pedicellate flowers and sessile bulbils, both covered partially by a persistent spathe, are described from the latest early Eocene Republic flora of north-central Washington. They are associated with an individual specimen of a single bulb with attached roots, and two small flower buds that appear to represent the same plant. The morphology of these fossils closely resembles that of certain bulb-forming monocots, such as some species of the onion genus Allium and other members of Amaryllidaceae. Methodology. Compression-impression fossils preserved in a lacustrine shale were uncovered from the rock matrix to reveal morphological details and were photographed with LM. Specimens were compared morphologically with extant material of related plants, and resulting images were processed minimally with Adobe Photoshop. Pivotal results. Specimens demonstrate an organography that is quite similar to that of modern onions and related forms. To our knowledge, this is the first description of plants showing a combination of bulbils and florets (representing asexual and sexual reproduction) among Paleogene plants. It also represents one of few reports among the fossil record of monocot plants similar to members of Amaryllidaceae. Conclusions. Scapes bearing flowers and bulbils within a spathe similar to those of some modern Amaryllidaceae, associated flower buds, and a root-producing bulb indicate the presence of a distinctive monocot plant in the Republic flora of the latest early Eocene Okanogan Highlands, northeastern Washington. Along with other Republic plants with distinctive morphological features indicative of temperate floras (leaf dimorphism, possible hybridization), these fossils suggest that bulbil-and flower-bearing monocots with a combined asexual and sexual reproductive strategy were already well established among plants of Paleogene.

Department

Biological and Environmental Sciences

Volume Number

179

Issue Number

6

First Page

477

Last Page

486

DOI

10.1086/697898

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