Patrick S. Herendeen

Phylogenetic Relationships in the Caesalpinioideae (Leguminosae) as Inferred from Chloroplast trnL Intron Sequences

Abstract The basal subfamily Caesalpinioideae of the Leguminosae generally is subdivided into four or five tribes, but their monophyly remains questionable. Recent cladistic analyses based on morphological characters and chloroplast rbcL sequences suggest conflicting hypotheses of relationships among tribes and subtribal groupings and of the identification of the basal Caesalpinioideae. Our phylogenetic analysis of the chloroplast trnL intron for 223 Caesalpinioideae, representing 112 genera, plus four Papilionoideae, 12 Mimosoideae and three outgroup taxa, provides some well-supported hypotheses of relationships for the subfamily. Our analysis concurs with the rbcL studies in suggesting that a monophyletic Cercideae is sister to the remainder of the Leguminosae. Among the other tribes of Caesalpinioideae, only the broadly circumscribed Detarieae (including Amherstieae or Macrolobieae) is also supported as monophyletic. The Detarieae s.l. occurs as sister to all Leguminosae, excluding Cercideae. Cassieae subtribes Dialiinae and Labicheinae together are sister to the remaining Leguminosae, which includes a monophyletic Papilionoideae, a paraphyletic Mimosoideae, and several monophyletic groups that correspond to previously defined generic groups or subtribes in the Caesalpinioideae. The trnL intron analysis suggests that basal legumes are extremely diverse in their floral morphology, and that presence of simple, actinomorphic flowers may be a derived feature in a number of lineages in the family. Communicating Editor: Matt Lavin

Angiosperm wood evolution and the potential contribution of paleontological data

Wood anatomy is often viewed as a source of independent data that may be used to assess evolutionary relationships among angiosperms. Comparative anatomical studies document suites of correlated characters that have been interpreted as general evolutionary trends, of which several have been asserted to be irreversible. Paleobotanical data summarized by Wheeler and Baas provide broad chronological corroboration of some wood anatomical trends, such as evolution from scalariform to simple perforation plates and long to short vessel elements. However, the focus on general evolutionary trends rather than on analyzing character distribution patterns in a cladistic phylogenetic context obscures a more detailed understanding of the evolution of wood anatomical features. Patterns of character evolution, including the assertions of irreversibility, need to be tested through cladistic analyses. In this paper selected wood anatomical features from families of Magnoliidae and “lower” Hamamelididae are summarized and mapped onto previously published cladograms as a preliminary means of testing previous hypotheses of wood evolution. The results show that many of the characters are homoplasious and have evolved both in accord with, and counter to, the hypothesized general trends in different groups of flowering plants. In general, changes that confirm generalized trends are more common than changes that are counter to those trends. Future studies should combine wood anatomical characters with other features as part of a cladistic analysis. Fossil woods have not yet contributed significantly to phylogenetic studies, but in the very few cases where they have been linked to fossil reproductive structures, the woods have provided a better understanding of wood anatomy in early members of some families. Data from fossil wood expand the diversity of anatomical structure known in some angiosperm taxa and thus provide additional evidence that might be used in phylogenetic analyses. Fossil woods have the greatest potential to affect phylogenetic analyses where they can be linked to other fossil organs. The best chance for establishing such a linkage is through the study of fossil charcoalified woods that co-occur with other dispersed mesofossils.

A New Fossil Flower and Associated Coprolites: Evidence for Angiosperm‐Insect Interactions in the Santonian (Late Cretaceous) of Georgia, U.S.A.

Plant‐insect interactions are readily identifiable in the fossil record when insect activities cause damage to plant tissues, for example, leaf mining, piercing, galls. However, the inference of insect pollination of extinct plants usually must be based on comparative morphology of plants and insects or based on phylogenetic relationships and pollination habits of extant taxa. The presence of insect coprolites can provide additional evidence supporting the inference of plant‐insect interactions based on the morphology and composition of the fossilized feces. In this article, we describe Noferinia fusicarpa gen. et sp. nov. based on fossil flowers and fruits recovered from the Buffalo Creek Member of the Gaillard Formation (late Santonian, Cretaceous) of central Georgia. The morphology of the flowers—differentiated perianth, basally connate calyx and corolla, inferior ovary, and possible nectiferous pores surrounding the base of the style—is consistent with generalized insect pollination. Associated with Noferinia flowers and fruits in the same sediment samples are five morphotypes of coprolites that are similar in shape and composition to the feces produced by modern beetles that feed on pollen and flowers. On the basis of the morphological features exhibited by Noferinia and by the coprolites containing its pollen, we suggest that Noferinia fusicarpa was insect pollinated.