Vegetative Anatomy of the Haemodoraceae and Its Phylogenetic Significance

Abstract

Premise of research. Haemodoraceae are a relatively small monocot family consisting of 14 genera and approximately 108 species and are distributed in parts of Australia, southern Africa, South and Central America, and eastern North America. The family is divided into two subfamilies, Haemodoroideae and Conostylidoideae. This research focuses on the vegetative anatomy of the family, with an emphasis on leaf anatomical features. The aims of this project are (1) to acquire new vegetative anatomical data for a large selection of Haemodoraceae and (2) to evaluate these data in the context of both phylogenetic relationships and environmental factors. Methodology. Cross sections of roots, stems (scapes), or leaves of 60 species and 63 ranked taxa from all 14 genera of the family were prepared and stained using standard histological methods, and SEMs were made of the leaf surface. Line drawings were prepared of leaf cross sections of an exemplar of each genus. Tissues and cells were examined and photographed, and comparisons were made among taxa. For leaf epidermal cells, the ratio of cell wall transectional area∶cell transectional area was calculated and plotted. Several discrete anatomical characters and character states were defined and plotted on a recently derived cladogram and examined for phylogenetic signal. Correlation of certain anatomical features with environmental factors was also noted. Pivotal results. Leaf anatomy provides several phylogenetically informative traits, including bulliform cells, tannin cells, marginal fiber caps, the relative wall transectional area of epidermal cells, the morphology of palisade cells, the distribution of fibers in the vascular bundle, leaf aerenchyma, mucilage cells, and silica bodies. These features generally correlate significantly with the pattern of phylogenetic relationships in the family. Silica cells, tannin cells, and mucilage cells, all of which may function to deter herbivory, are generally restricted to particular clades. The relative epidermal wall thickness of members of the genus Conostylis is significantly higher than in other members of the family, a feature that may represent an adaptation to their hot, dry environments. Conclusions. The systematic and ecological value of studying plant vegetative anatomy is supported by this study. Vegetative anatomical features of the Haemodoraceae show considerable and significant variation. Numerous anatomical features exhibit a high phylogenetic signal and are apomorphic for specific clades. Some anatomical features are possible adaptations to habitat, climate, or herbivory. However, quantifiable ecological data are needed in future studies for assessing the adaptive significance of these anatomical features.

Morphological phylogeny of Tradescantia L. (Commelinaceae) sheds light on a new infrageneric classification for the genus and novelties on the systematics of subtribe Tradescantiinae

“…Furthermore, most modern taxonomists expect high degrees of incongruence between morphological and molecular datasets (Evans and Faden 1998). Nonetheless, the present study, along with other cases in two other families in the order Commelinales (Haemodoraceae – Simpson 1990, Hopper et al 2009, Aerne-Hains and Simpson 2017; Pontederiaceae – Eckenwalder and Barrett 1986, Graham and Barrett 1995, Kohn et al 1996, Barret and Graham 1997, Graham et al 1998, Simpson and Burton 2006, Ness et al 2011), yield phylogenetically congruent results. Thus, morphological phylogenies reconstructed with properly coded matrixes, and also including different data types (e.g.…”

“…In Commelinales, Haemodoraceae and Pontederiaceae have yielded similar results regarding the congruence between different datasets. In Haemodoraceae, the morphological phylogeny by Simpson (1990) is widely corroborated by the molecular phylogeny by Hopper et al (2009), with recent anatomical data Aerne-Hains and Simpson (2017) further increasing the congruence between morphology and molecular data. In Pontederiaceae the congruence is even clearer, where all phylogenies for the family published so far (i.e.…”

Revisiting the taxonomy of the Neotropical Haemodoraceae (Commelinales)

“… Pyrrorhiza was initially considered as being closely related to Schiekia Meisn. ( Maguire and Wurdack 1957 ), a view supported by the morphological phylogeny of Simpson (1990) , but not supported by the anatomical studies of Aerne-Hains and Simpson (2017) , the molecular phylogeny of Hopper et al (in prep.) and the new morphological phylogeny for the family ( Pellegrini 2019 ).…”

“…The Neotropical species of Haemodoraceae represent morphological outliers in the family that have remained poorly studied for far too long, despite previous comprehensive studies dealing with macro- and micromorphology and the systematics of the Haemodoraceae ( Simpson 1985 , 1987 , 1990 , 1993 , 1998a , 1998b ; Hopper et al 2006 , 2009 ; Smith et al 2011 ; Aerne-Hains and Simpson 2017 ). Furthermore, most of its species dwell deep in the Amazon Forest, and key and enigmatic taxa, like Pyrrorhiza neblinae , are restricted to almost impossible to reach tepuis.…”

“… Haemodoraceae is clearly a monophyletic family, characterised by vascular bundles enveloped by a fibrous layer and a peculiar inferior ovary. They are classified into twosubfamilies: Haemodoroideae and Conostylidoideae ( Simpson 1990 , 1998a ; Hopper et al 1999 , 2009 ; Aerne-Hains and Simpson 2017 ; Pellegrini 2019 ). Members of the family are generally associated with semi-arid to temperate environments due to the diversity of taxa in Australia ( Macfarlane et al 1987 ; Hopper et al 2006 , 2009 ; Smith et al 2011 ).…”