Michael G. Simpson

Reversal in Ovary Position from Inferior to Superior in the Haemodoraceae: Evidence from Floral Ontogeny

Floral anatomy and development were studied in Wachendorfia thyrsiflora and Lachnanthes caroliniana of the monocot family Haemodoraceae in order to evaluate the hypothesis that a superior-ovary position arose from an ancestral inferior-ovaried condition. In Wachendorfia three conduplicate carpel primordia develop at the floral apex, followed by postgenital fusion forming a superior ovary. The lower receptacular tissue at the central floral axis elongates at about the same extent as the peripheral receptacular tissue. In the extended receptacular region, two lateral commissures develop by differential tissue growth, followed by differentiation of inner epithelial cells to form septal nectaries. The receptacular commissures and nectaries are continuous with carpellary commissures of the superior ovary. Junction of the median outer tepal vein and dorsal carpellary vein occurs well below the septal nectaries at the base of the receptacle. In Lachnanthes three small, conduplicate carpel primordia develop at the floral apex. Growth of the lower receptacular tissue at the central floral axis is relatively retarded, such that the peripheral tissues elongate differentially, surrounding the now laterally positioned carpels. Subsequent postgenital fusion results in an inferiorovary position, relative to perianth insertion. Incomplete postgenital fusion of intercarpellary spaces results in the formation of septal commissures. These commissures later mature into septal nectaries, which extend to the apex of the inferior ovary. Junction of the median outer tepal vein and dorsal carpellary vein occurs just beneath the ovary locules. It is proposed that the floral receptacular region of Wachendorfia and of other superior-ovaried Haemodoraceae is homologous with an ancestral inferior ovary with regard to position, development, and vasculature. A superior ovary in the Haemodoraceae arose by the co-option of an ancestral inferior ovary into an elongated receptacle, along with extension of the intercarpellary commissures to the periphery of the receptacular tissue, and modification of those peripheral commissures to nectaries The adaptive significance of this evolutionary event is unclear but apparently related to a shift in pollination mechanism

Familial classification of the Boraginales

The Boraginales are now universally accepted as monophyletic and firmly placed in Lamiidae. However, a consensus about familial classification has remained elusive, with some advocating recognition of a single, widely variable family, and others proposing recognition of several distinct families. A consensus classification is proposed here, based on recent molecular phylogenetic studies, morphological characters, and taking nomenclatural stability into consideration. We suggest the recognition of eleven, morphologically well-defined and clearly monophyletic families, namely the Boraginaceae s.str., Codonaceae, Coldeniaceae fam. nov., Cordiaceae, Ehretiaceae, Heliotropiaceae, Hoplestigmataceae, Hydrophyllaceae, Lennoaceae, Namaceae, and Wellstediaceae. Descriptions, synonomy, a taxonomic key, and a list of genera for these eleven families are provided, including the new family Coldeniaceae (monogeneric) and Namaceae (segregated from Hydrophyllaceae and comprising Nama, Eriodictyon, Turricula, and Wigandia), the latter necessitating a revised circumscription of a more morphologically coherent Hydrophyllaceae.

Pollen Ultrastructure of the Biovulate Euphorbiaceae

Pollen ultrastructure of the biovulate Euphorbiaceae, including the subfamilies Phyllanthoideae and Oldfieldioideae, was investigated with light, scanning electron, and transmission electron microscopy. Pollen of Phyllanthoideae, represented by 12 species in nine genera, was prolate to oblate, almost always 3-colporate, rarely 3-porate or pantoporate, and mostly with reticulate, rarely baculate, echinate, or scabrate, sculpturing. The ektexine showed little variation in ultrastructure; almost without exception it was tectate-columellate with a homogeneous foot layer, columellae continuous with both the tectum and the foot layer, and a perforate, homogeneous tectum. The only major exception was Amanoa guianensis, which was intectate and baculate as the result of the evolutionary loss of the tectum. Pollen of Oldfieldioideae, in which we studied 28 species from 25 genera, and obtained data from the literature for two of the three remaining genera in the subfamily, was globose to oblate, with four or more, rarely only three, apertures that were either equatorial and brevicolporate to porate or pantoporate, and with echinate, rarely scabrate, sculpturing. The ektexine showed considerable variation in ultrastructure. The most widespread structural type consisted of a foot layer that is either thin and irregular or absent, an interstitium composed of irregular to columellate exine deposits that are discontinuous from the foot layer, if present, and a tectum composed of laterally appressed baculate elements that delimit fine microperforations. A second common structural type differed in having a relatively thick, homogeneous foot layer and thin, granular to tabular, microperforate tectum. Isolated genera have a reduced interstitium and/or a homogeneous tectum or show a reversal to a tectate-columellate architecture. Variation in aperture morphology, sculpturing, and exine ultrastructure is phylogenetically significant in the Oldfieldioideae.

Phylogenetic Implications of Pollen Ultrastructure in the Oldfieldioideae (Euphorbiaceae)

The pollen structure of members of Euphorbiaceae subfamilies Oldfieldioideae and Phyllanthoideae was studied using scanning and transmission electron microscopy in order to assess taxonomic relationships. We identified 10 palynological characters that appear to have systematic significance. We also identified 37 characters of vegetative morphology and anatomy, mostly based on data obtained by Hayden, and five characters of reproductive morphology, based on data in the literature. Cladistic analysis of the Oldfieldioideae along with selected genera in the Phyllanthoideae, using various putative relatives of the Euphorbiaceae as outgroups, provided great insight into the phylogeny of the Oldfieldioideae. Synapomorphies of this subfamily are all palynological: brevicolporate to pororate or porate apertures, echinate sculpturing, and exine with the interstitium consisting of columellae discontinuous from the foot-layer (where present)

Geneious! Simplified genome skimming methods for phylogenetic systematic studies: A case study in Oreocarya (Boraginaceae).

Premise of the study: As systematists grapple with how to best harness the power of next-generation sequencing (NGS), a deluge of review papers, methods, and analytical tools make choosing the right method difficult. Oreocarya (Boraginaceae), a genus of 63 species, is a good example of a group lacking both species-level resolution and genomic resources. The use of Geneious removes bioinformatic barriers and makes NGS genome skimming accessible to even the least tech-savvy systematists. Methods: A combination of de novo and reference-guided assemblies was used to process 100-bp single-end Illumina HiSeq 2000 reads. A subset of 25 taxa was used to test the suitability of genome skimming for future systematic studies in recalcitrant lineages like Oreocarya. Results: The nuclear ribosomal cistron, the plastome, and 12 mitochondrial genes were recovered from all 25 taxa. All data processing and phylogenomic analyses were performed in Geneious. We report possible future multiplexing levels and published low-copy nuclear genes represented within de novo contigs. Discussion: Genome skimming represents a much-improved primary data collection over PCR+Sanger sequencing when chloroplast DNA (cpDNA), nuclear ribosomal DNA (nrDNA), and mitochondrial DNA (mtDNA) are the target sequences. This study details methods that plant systematists can employ to study their own taxa of interest.

Ultrastructure of Heterocolpate Pollen in Cryptantha (Boraginaceae)

Pollen of eight species of Cryptantha was studied using scanning electron microscopy. In addition, transmission electron microscopy was used in Cryptantha intermedia to elucidate the ultrastructural basis for their heterocolpate pollen, in which three “true” colporate apertures alternate with three “pseudoapertures.” Both apertures and pseudoapertures are regions of the wall in which ektexine is largely absent. However, apertures have an outer band of verrucate exinous deposits, a central region of inner intine wall material, and a concentration of cytoplasmic vesicles. In addition, apertures are shorter in length and wider at the equator than are pseudoapertures. The exine wall structure in C. intermedia consists of a typical inner, homogeneous endexine and, in regions other than apertures and pseudoapertures, an outer, essentially imperforate, tectate‐columellate ektexine. Curious triangular “polar pseudoapertures,” devoid of ektexine, occur at each pole and resemble the pseudoapertures in sculpturing and wall structure. The described heterocolpate pollen in the Boraginaceae may represent a major apomorphy for the tribes Eritricheae and Cynoglosseae and possibly other taxa. However, further comparative studies within these groups are needed to assess definitively the extent of this putative apomorphy and to identify and characterize palynological features that may be useful within these groups.

Cat's Eyes and Popcorn Flowers: Phylogenetic Systematics of the Genus Cryptantha s. l. (Boraginaceae)

Abstract Cryptantha (Boraginaceae) is a group of approximately 200 annual and perennial species, representing two-thirds of the diversity within subtribe Cryptanthinae. The genus exhibits an amphitropic distribution, occurring in temperate and desert regions of western North and South America. Fifty samples of 45 species of Cryptantha s. l., exemplars of the related genera Amsinckia, Pectocarya, and Plagiobothrys, and four outgroup taxa were sequenced for two gene regions, the nuclear ribosomal gene, ITS, and the trnLUAA intron region of the chloroplast genome. These data were used to assess phylogenetic relationships using parsimony, maximum likelihood, and Bayesian inference methods. Cryptantha s. l. was found to be polyphyletic, with its members placed among several well-supported clades. Based on these analyses, we propose resurrection of the genera Eremocarya, Greeneocharis, Johnstonella, and Oreocarya, and recognition of a newly delimited Cryptantha s. s. The related genera Amsinckia and Pectocarya were resolved as monophyletic and most closely related to various clades within Cryptantha s. l. Plagiobothrys was resolved as polyphyletic in three clades, these clades corresponding to previously named sections or groups of sections. The Cryptanthinae is supported as monophyletic. Character trait analyses support the multiple, derived evolution of perenniality, reduction in nutlet number, nutlet heteromorphism, smooth nutlet sculpturing, heterostyly, and cleistogamy. Although sampling is incomplete, this study generally supports the hypothesis of repeated, unidirectional dispersal events, from North to South America. Genera resurrected include: Eremocarya, Greeneocharis, Johnstonella, and Oreocarya. New combinations include: Greeneocharis circumscissa var. rosulata, Greeneocharis similis, Oreocarya atwoodii, Oreocarya barnebyi, Oreocarya compacta, Oreocarya crassipes, Oreocarya creutzfeldtii, Oreocarya fulvocanescens var. nitida, Oreocarya grahamii, Oreocarya hypsophila, Oreocarya johnstonii, Oreocarya ochroleuca, Oreocarya roosiorum, Oreocarya schoolcraftii, Oreocarya semiglabra, Oreocarya shackletteana, Oreocarya sobolifera, Oreocarya subcapitata, Oreocarya suffruticosa var. arenicola, Oreocarya suffruticosa var. laxa, Oreocarya suffruticosa var. pustulosa, Oreocarya suffruticosa var. setosa, Oreocarya welshii, Johnstonella angelica, Johnstonella angustifolia, Johnstonella costata, Johnstonella diplotricha, Johnstonella echinosepala, Johnstonella fastigiata, Johnstonella grayi var. cryptochaeta, Johnstonella grayi var. grayi, Johnstonella grayi var. nesiotica, Johnstonella holoptera, Johnstonella micromeres, Johnstonella parviflora, and Johnstonella pusilla.

Phylogenetic Relationships and Evolution in Dudleya (Crassulaceae)

Abstract Dudleya (Crassulaceae) is a genus of succulent perennials endemic to western North America. Interspecific relationships within Dudleya have been difficult to discern due to a lack of synapomorphic characters for the genus or subgenera, highly variable morphologies within species, and extensive polyploidy. Here we present the first molecular phylogeny of diploid members of the genus using sequences from nrDNA and cpDNA. We cloned ITS alleles from six known polyploid individuals to determine their evolutionary origin. We have been able to resolve four clades within Dudleya, but many relationships are still uncertain. Our analyses support the monophyly of the genus and show that Dudleya is more closely related to North American Sedum species of the Sedoideae subfamily than to members of its currently circumscribed subfamily, the Echeverioideae. The current subgeneric distinctions within Dudleya are polyphyletic and should be revised in future taxonomic treatments. We tested the monophyly of several highly variable species and found that D. virens, D. cymosa, and D. abramsii are polyphyletic. The ITS alleles from polyploid taxa were not variable enough to resolve polyploid origins.

Vegetative Anatomy of the Haemodoraceae and Its Phylogenetic Significance

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.

CALYPTRIDIUM PARRYI VAR. MARTIRENSE (MONTIACEAE), A NEW TAXON ENDEMIC TO THE SIERRA DE SAN PEDRO MARTIR, BAJA CALIFORNIA, MEXICO

Abstract Calyptridium parryi var. martirense is described as new. Here we present quantitative measurements and statistical analyses of a number of morphological features that demonstrate the distinctiveness of this new taxon. The new variety differs from the others in having shorter fruits (3.1–4.1 mm) and a correspondingly smaller fruit length to sepal length ratio (1.0–1.4). The capsule is also the widest (1.4–2.2 mm) and the sepals the longest (2.4–3.9 mm) of any other C. parryi variety. Calyptridium parryi var. martirense is currently known only from high elevation locations (1900–2630 m) in the Sierra de San Pedro Mártir, Baja California, Mexico.