Peter C. Hoch

Family-level relationships of Onagraceae based on chloroplast rbcL and ndhF data

Despite intensive morphological and molecular studies of Onagraceae, relationships within the family are not fully understood. One drawback of previous analyses is limited sampling within the large tribe Onagreae. In addition, the monophyly of two species-rich genera in Onagreae, Camissonia and Oenothera, has never been adequately tested. To understand relationships within Onagraceae, test the monophyly of these two genera, and ascertain the affinities of the newly discovered genus Megacorax, we conducted parsimony and maximum likelihood analyses with rbcL and ndhF sequence data for 24 taxa representing all 17 Onagraceae genera and two outgroup Lythraceae. Results strongly support a monophyletic Onagraceae, with Ludwigia as the basal lineage and a sister-taxon relationship between Megacorax and Lopezia. Gongylocarpus is supported as sister to Epilobieae plus the rest of Onagreae, although relationships within the latter clade have limited resolution. Thus, we advocate placement of Gongylocarpus in a monogeneric tribe, Gongylocarpeae. Most relationships within Onagreae are weakly resolved, suggesting a rapid diversification of this group in western North America. Neither Camissonia nor Oenothera appears to be monophyletic; however, increased taxon sampling is needed to clarify those relationships. Morphological characters generally agree with the molecular data, providing further support for relationships.

Outcomes of the 2011 Botanical Nomenclature Section at the XVIII International Botanical Congress

Abstract The Nomenclature Section held just before the 18th International Botanical Congress in Melbourne, Australia in July 2011 saw sweeping changes to the way scientists name new plants, algae, and fungi. The changes begin on the cover: the title was broadened to make explicit that the Code applies not only to plants, but also to algae and fungi. The new title will now be the International Code of Nomenclature of algae, fungi, and plants. For the first time in history the Code will allow for the electronic publication of names of new taxa. In an effort to make the publication of new names more accurate and efficient, the requirement for a Latin validating diagnosis or description was changed to allow either English or Latin for these essential components of the publication of a new name. Both of these latter changes will take effect on 1 January 2012. The nomenclatural rules for fungi will see several important changes, the most important of which is probably the adoption of the principle of “one fungus, one name.” Paleobotanists will also see changes with the elimination of the concept of “morphotaxa” from the Code.

Paraphyly in Tribe Onagreae: Insights into Phylogenetic Relationships of Onagraceae Based on Nuclear and Chloroplast Sequence Data

Abstract Onagraceae are a family of 17 genera in seven tribes, with the majority of species in tribes Onagreae and Epilobieae. Despite the species-richness of these two tribes, to date no phylogenetic study has been done with sufficient taxon sampling to examine relationships between and within these tribes. In this study, we used DNA sequence data from one nuclear region (ITS) and two chloroplast regions (trnL-trnF and rps16) to infer phylogenetic relationships among 93 taxa across the family, with concentrated sampling in the large tribe Onagreae. Results strongly suggest that tribe Gongylocarpeae is sister to tribes Epilobieae + Onagreae, both of which are monophyletic. Within Onagreae, Camissonia seems to be broadly paraphyletic, and Oenothera is also paraphyletic. In Oenothera there appear to be two lineages, one of which has Gaura + Stenosiphon nested within it. At the base of the Onagraceae phylogeny, we have clarified previous confusion regarding conflicting placements of Hauya and Lopezia based on nuclear versus chloroplast data. Results of these analyses are supported by morphology and suggest the need for new taxonomic delimitations, which are forthcoming.

A CLADISTIC ANALYSIS OF CIRCAEA (ONAGRACEAE)

Abstract— Circaea (Onagraceae), a genus of seven species from the northern hemisphere, forms a monophylctic group defined by the following synapomorphies: two stamens (opposite the sepals), fruits indehiscent capsules, hooked hairs on the fruits, and perianth parts reduced to two. A cladistic analysis of the genus was performed using 22 characters from morphology, anatomy and palynology. The seven species and seven additional subspecies were considered the terminal taxa. Polarity of the characters is based on the outgroup comparison method. Eighteen equally parsimonious cladograms were produced, each with 32 steps and a consistency index of 0.75. A successive weighting procedure was applied, resulting in six cladograms with a consistency index of 0.95. All 24 cladograms share the following seven monophylctic groups: (1) all species except C. cordala and C. glabrescens (stipules deciduous); (2) the group of C. mollis, the three subspecies of C. lutetiana and C. erubescens (exsertcd nectary); (3) C. repens and all six subspecies of C. alpina (single‐seeded fruits, stolons terminated by tubers, and viscin threads reduced or absent); (4) the six subspecies of C. alpina (unilocular ovaries with no trace of a second loculc and tardily opening perianth); (5) C. alpina subspecies alpina, micrantha, pacifica, and imaicola (flowers opening on ascending to erect pedicels); (6) C. alpina subspecies alpina, micrantha, and pacifica (translucent leaves); (7) C. alpina subspecies alpina and murantha (glabrous stems). Results of the cladistic analysis support most of the current systematic classification of the genus, except for the relationships among the three subspecies of C. lutetiana.

Flavonoid systematics of ten sections of Ludwigia (Onagraceae)

Abstract Data for the flavonoids of 19 species in 10 sections of Ludwigia are presented. Eight flavonoids, comprising four glycoflavones, of which vitexin and isovitexin are reported for the first time in Ludwigia, and four flavonol glycosides, based on quercetin, are present in these species. Each section treated here has either glycoflavones or flavonols; presence of only onte class is considered to be advanced in the genus as a whole, compared with the presence of both glycoflavones and flavonols in the more generalized sects Myrtocarpus Cinerascentes, and Pterocaulon, which were examined earlier. Only glycoflavones are present in sects Macrocarpon (four species), Seminuda (five species), the ditypic African sect. Africana, the monotypic African sects Brenania, Cryptosperma, and Prieurea, the monotypic east Asian sect. Nipponia, and the monotypic pantropical section Fissendocarpa. Only flavonols are present in the monotypic Old Wodd section Caryophylloidea and sect. Oligospermum, which comprises nine species widespread in the OId and New Worlds.

A Cladistic Analysis of the Genus Gaura (Onagraceae)

Gaura, a genus of 21 species in North America, forms a monophyletic group within tribe Onagreae. Compared to the outgroup (Calylophus), it is clearly defined by three synapomor- phies: indehiscent fruits, four-lobed stigmas, and fruits with fewer than 10 seeds. A cladistic analysis of the genus was performed using 20 characters from floral morphology, fruit morphology, and plant habit and growth characteristics. Polarity of the characters was based on the outgroup com- parison method. Two most parsimonious cladograms, with only a single minor topological differ- ence, were generated, with 29 steps and a consistency index of 0.72. A Nelson consensus tree was constructed, which has the same length as the two cladograms, and an identical topology to one of them. The consensus cladogram defines 12 monophyletic groups. This cladogram supports most of the current infrageneric classification of Gaura, except that sects. Xerogaura and Gaura appear to be paraphyletic groups. The placement of G. lindheimeri within sect. Gaura in keeping with the current classification depends on interpreting two habit characters in this species as being secondarily derived.

Viscin threads on pollen of Circaea ×intermedia Ehrh. (Circaeeae: Onagraceae)

Viscin threads are here described for the exine of Circaea xintermedia Ehrh. (C. alpina L. x C. lutetiana L.). Often, the threads bifurcate, taper distally and have branched terminal ends. The smooth surface has lightly sculptured bands and randomly occurring and positioned sporopollenin globules. At the point of attachment with the exine the threads show either a natural transition with exine surface elements or have bulb-like enlargements. Circaea xintermedia viscin threads present a remarkable contrast to the generally poorly defined viscin threads on Circaea pollen.

Taxonomic changes in Oenothera sections Gaura and Calylophus (Onagraceae)

Abstract The long-recognized genus Gaura was shown recently to be deeply nested within one of two major clades of Oenothera. New molecular data indicate further taxonomic changes are necessary in Oenothera sect. Gaura. We make these changes here, including three new combinations, in advance of the Onagraceae treatment for the Flora of North America. The new phylogenetic studies show that several pairs of taxa treated as subspecies in the most recent revision by Raven and Gregory (1972) had independent origins within sect. Gaura, and are here elevated to species level (Oenothera nealleyi for Gaura suffulta subsp. nealleyi; Oenothera dodgeniana for Gaura neomexicana subsp. neomexicana; and Oenothera podocarpa for Gaura hexandra subsp. gracilis). Also, a nomenclatural problem in Oenothera sect. Calylophus is corrected by adopting the name Oenothera capillifolia Scheele for the species known previously, and nomenclaturally correct, as Calylophus berlandieri Spach. This problem necessitates a new combination Oenothera capillifolia subsp. berlandieri.

Perennation in Epilobium (Onagraceae) and Its Relation to Classification and Ecology

A survey of the morphology and anatomy of vegetative perennating structures in Epilobium reveals a variety of forms, including soboles, sessile and ped- icellate turions, bulbils, rosettes, caespitose shoots, and shoots from roots. The most notable specializations in the perennating buds are the condensed, decussate ar- rangement of leaf primordia and the subsucculent leaves with a lack of mesophyll differentiation. The generalized condition, represented by E. suffruticosum (sect. Cor- dylophorum), is perennation by axillary soboles at the base of parent and derivative stems. The major diversification in perennating structures occurs in sect. Epilobium, in which all classes of structure occur. The most extreme of these is the turion, a strobiloid shoot generally 5-20 mm long, sessile or pedicellate, with arrested inter- nodes and a discrete base, and abundant starch grain storage in the leaves. The distribution of perennating structures in a diverse selection of 17 taxa in sect. Epi- lobium does not correlate well with information on chromosome structural hetero- zygosity, suggesting repeated and independent evolution of similar structures. A major departure from the shoot-from-root morphology is found in sect. Chamae- nerion, especially in the well-studied E. angustifolium, and in E. siskiyouense (sect. Epi- lobium), in which shoots arise from horizontal roots. The structural data correlate well with available information on habit and habitat. Epilobium L., the largest genus of Onagraceae, comprises about 200 species (Raven 1979) and is distributed worldwide at high elevations and latitudes, often in great abundance. This widespread distribution in cool, often mesic habitats derives in large part from a combination of autog- amy, the production of large numbers of small, easily dispersed, tufted seeds, and vigorous vegetative perennation. This report focuses on the last of these features and examines comparatively the anatomy and mor-

Unique tetrads of Epilobium luteum (Onagraceae: Onagreae) pollen from Alaska

Aperture morphology of tetrad pollen of Epilobium luteum (Onagraceae: Epilobieae) from three Alaskan collections is highly variable. The first collection appears to lack apertures altogether and is presumed to consist of immature pollen gains in a genus known to achieve mature size before the apertures become distinctly protruding. A second collection has tetrads with 3- and 4-apertured grains, the apertures in the latter are often irregularly spaced and not in apposition with the apertures of neighboring members. The third collection consists of the more typical 3-apertured members that characterize the majority of Epilobium pollen grains. In all of these collections individual pollen grains (monads) are interspersed among the tetrads. The variations in the number of apertures emphasize the importance of having a comprehensive understanding of the stage of development of the pollen (taxon) examined when describing pollen collections. In the first collection this would mean the recognition that in Onagraceae apertures occur in the later stages of microspore ontogeny. In the latter two collections a thorough background of the literature of the pollen morphology on this largest Onagraceae taxon is useful for the understanding of the significance of a range of aperture numbers on Epilobium pollen grains.