Embryology of Gomortegaceae (Laurales): characteristics and character evolution

Abstract

The embryological characteristics of Gomortegaceae, which are poorly understood, were investigated on the basis of Gomortega nitida, the only species of the family, to understand better the evolution of this group within Laurales. Comparisons with other Laurales and Magnoliales (a sister group of Laurales) show that Gomortega has many embryological features in common with the other lauralean families. Notably, Gomortega shares a testa without or with at best only a poorly developed mesotesta as a synapomorphy with all other Laurales. The genus further shares anthers dehisced by valves as a synapomorphy with the other Laurales (except for Calycanthaceae and Monimiaceae), and a non-multiplicative testa and bisporangiate anther as synapomorphies with Atherospermataceae and Siparunaceae (although the non-multiplicative testa occurs as a homoplasy in Monimiaceae, and the bisporangiate anther in Monimiaceae pro parte, Lauraceae pro parte and Hernandiaceae, respectively). Gomortega shows simultaneous cytokinesis to form pollen grains, a one-celled ovule archesporium and non-specialized chalaza, all or part of which may be synapomorphies shared with Atherospermataceae. Gomortega appears to have no embryological autapomorphies, but further comparison with Atherospermataceae is required.

Diversity and Lability of Floral Phyllotaxis in the Pluricarpellate Families of Core Laurales (Gomortegaceae, Atherospermataceae, Siparunaceae, Monimiaceae)

“…A similar function for apparently homologous organs has been described in Calycanthaceae (Staedler et al 2007), which may be either a synapomorphy or a plesiomorphy at the order level, retained only in Calycanthaceae and Atherospermataceae. Number of (inner) staminodes is low in Gomortega (two to four ;Brizicky 1959;Heo et al 2004; this study), Peumus (10-13; this study), and Hortonia (two to seven; Endress 1980a), and in these genera they do not play a role in fruit development or dispersal (Doweld 2001;Heo et al 2004;Romanov et al 2007). The velum of Siparunaceae (Endress 1980b) and the inferior ovary of Gomortegaceae may have evolved to compensate for the loss of the protective function of the persisting staminodes during fruit development.…”

Comparative Gynoecium Structure and Development in Calycanthaceae (Laurales)

“…However, a few character states present in Calycanthaceae are shared by most of the order: ovules anatropous (with the exception of Gomortega, orthotropous; Endress and Igersheim 1997;Heo et al 2004), bitegmic (except for Siparunaceae, unitegmic;Heilborn 1931;Endress 1972;Renner et al 1997;Kimoto and Tobe 2003), and crassinucellar . The outer or the only integument is semiannular or annular, with both character states observed in the same species in Peumus of Monimiaceae and Siparuna of Siparunaceae .…”

Embryology of Illigera and Sparattanthelium (Hernandiaceae, Laurales): Family Characteristics and Relationships

“…References Heo and Tobe 1995; this study Heo and Tobe 1995; this study Heo et al 1998;Kimoto et al 2006Kimoto and Tobe 2008Kimoto and Tobe 2001, 2003Heo et al 2004 Note. Character states were determined by comparison with outgroup (i.e., Siparunaceae, Gomortegaceae, and Atherospermataceae): plesiomorphy (0) and apomorphy (1, 2).…”

“…a In the Lauraceae, an amoeboid tapetum is found in the most basally diverging genus, Hypodaphnis, and in many derived genera, while a glandular tapetum is found in only a few genera of Cryptocaryeae (Kimoto et al 2006). b In the outgroup (Atherospermataceae-Gomortegaceae-Siparunaceae clade), successive cytokinesis occurs in the Siparunaceae (Kimoto and Tobe 2003), simultaneous cytokinesis in the Gomortegaceae (Heo et al 2004), and ''modified simultaneous cytokinesis'' in the Atherospermataceae (Sampson 1969a(Sampson , 1969b. The Calycanthaceae, which are sister to the rest of the Laurales, exhibit simultaneous cytokinesis (Kimoto and Tobe 2001).…”