Using Idioblasts to Group Laurinoxylon Species: Case Study From the Oligo-Miocene of Europe

Abstract

Several specimens of Lauraceae fossil wood from the Cenozoic of Greece (southern part of Lesbos), the Czech Republic (Kadaň-Zadní Vrch Hill and Jáchymov), and Hungary (Ipolytarnóc) were studied. When considering whether they belonged to the speciose fossil wood genus Laurinoxylon, we reviewed the literature and data from InsideWood on fossil and modern woods. As a result, we propose criteria for excluding a fossil Lauraceae wood from Laurinoxylon and list the species that should be excluded from this genus. The criteria (filters) proposed to exclude a genus from having relationships with Laurinoxylon are: A. Axial parenchyma features: A1. Marginal axial parenchyma, A2. Aliform to aliform-confluent paratracheal parenchyma. B. Ray features: B1. Rays higher than 1 mm, B2. Exclusively homocellular rays, B3. Rays more than 5 cells wide, B4. Rays storied. C. Porosity features: Ring-porous. D. Idioblasts: Absence of idioblasts. Based on the distribution of idioblasts, we recognize four groups in Laurinoxylon (Type 1 - with idioblasts associated only with ray parenchyma cells, Type 2a - with idioblasts associated with both ray and axial parenchyma, Type 2b - with idioblasts associated both with rays and present among the fibres, and Type 3 - with idioblasts associated with ray and axial parenchyma and also among the fibres) and list the extant genera with features of those groups. Such grouping helps with interpreting the relationships of fossil lauraceous woods with extant genera. We discuss the Oligocene–Miocene European species that belong to these Laurinoxylon groups, noting that some warrant reassignment to different genera or even families. Future studies are needed to determine whether new genera should be established to accommodate these species. We propose the new combination Cinnamomoxylon variabile (Privé-Gill & Pelletier) Mantzouka, Karakitsios, Sakala & Wheeler.

Late Paleocene woods from Cherokee Ranch, Colorado, U.S.A.

“…This wood fits Laurinoxylon Type 2b of Mantzouka et al (2016). According to them, Type 2b's combination of features occurs in only three extant genera: (1) Actinodaphne p.p.…”

“…B. We a lso relate them to the Laurinoxylon groups of Mantzouka et al (2016), groups that are defined by the location of the idioblasts (oil cells). (Fig.…”

“…This combination of features characterizes many Late Cretaceous to late Eocene fossil woods from the Northern Hemisphere. If oil cells are present as well, then the wood can be assigned to the Lauraceae (Laurel family) (Metcalfe and Chalk, 1950;Richter, 1987;Mantzouka et al, 2016;Jud et al, 2017). If the diagnostic feature of oil cells is absent, then it is usually impossible to confidently assign such woods to a single family because this combination of features occurs not only in the Lauraceae (order Laurales), but in other families in other orders, e.g., Anacardiaceae, Burseraceae, Kirkiaceae (order Sapindales), Lamiaceae, and Verbenaceae (order Lamiales).…”

“…Material: DMNH EPI.40935 Comments: Mantzouka et al (2016) used Werff and Richter's (1996) classification scheme for Lauraceae tribes because it included wood anatomical characters. Mantzouka et al (2016) suggested that modern genera resembling their 'Group 1' included members of Tribe Laureae (Laurus, the Litsea chinensis group) and Tribe Perseae: Dicypellium, North American Persea, Systemonodaphne, and Urbanodendron. We did not observe septate fibers in DMNH EPI.40935, so it is unlikely to be in Tribe Perseae, which has "ubiquitous septate fibers" (Werff and Richter, 1996).…”

Reappraisal of Greguss’ Fossil Wood Types and Figured Specimens from the Cenozoic of Hungary: Overview, Corrected Geology and Systematical Notes

“…8., upper arrow) with the former not as pronounced. Following the new classification by Mantzouka et al (2016), this species belongs to Laurinoxylon Type 2a. There are also numerous crystals, mainly associated with axial parenchyma (Pl.…”