Crotoneae

Abstract: A short history of the tribal arrangement in the vast family Euphorbiaceae has been given by Henri Baillon in France, Jean Muller of Argau in Switzerland, George Bentham in England, and Ferdinand Pax in Germany. Speculation follows on the ancestors of the group, considered to be polyphyletic and probably derived from more primitive orders with hypogynous flowers, such as Tiliales and Malvales, Celastrales, and Rhamnales, all of which are fundamentally woody, as are most of the Euphorbiaceae. Considered to be ancient characters are the presence of petals, the lack of a disk, the retention of a vestigial ovary in the male flowers, numerous stamens, and the imbrication of the sepals. The sequence of the tribes is based on these assumptions, culminating in the most advanced, such as HUREAE, DALECHAMPIEAE, PEREAE, RIcINEAE, CROTONEAE, JOANNESIEAE, ending with the most advanced of all, the EUPHORBIEAE. A dichotomous key to the tribes and their descriptions is provided, usually listing only the principal genera with the approximate number of species (in parentheses). A more detailed account will be published in the author's third volume of The Genera of Flowering Plants. Twenty of the tribes are illustrated by drawings by the author of representative genera. IN A MASTERLY ESSAY entitled "Notes on Euphorbiaceae" read before the Linnean Society of London in 1878,3 George Bentham made the following statement: "Two men, indeed, both of high standing in the science, and with comparatively ample materials at their command, have recently worked up the order with great care and attention independently of each other, and I would readily have followed the lead of either of them, but that the two have so frequently come to conclusions diametrically opposed to each other, that I have been compelled to steer a course of my own through a labyrinth of tribes, subtribes, genera, sections, or vaguely indicated affinities." The two botanists were Henri Baillon in Paris and Jean MViller of Argau in Switzerland, the latter at the time in charge of de Candolle's herbarium in Geneva. After discussing the different results of these two botanists, Bentham continued: "As for myself, in preparing the arrangement for our Genera Plantarum, I have endeavoured to follow the lead of one or other of my predecessors, or of both when they appeared to be not too much opposed to natural affinities; but I have thought it right to take nothing for granted, and to examine for myself every genus, section, or apparently aberrant species of which specimens were available, reconciling as far as was in my power absolute characters with other evidence of natural consanguinity." As space is limited, I need only quote Bentham's judgment of Baillon's contribution: "This he I Received for publication 5 February 1969. 2 Present address: 4 Cumberland Close, St. Margaret's, Twickenham, England. I J. Linn. Soc. Bot. 17: 185-267 (1878). published in 1858 under the title of 'Etude generale du groupe des Euphorbiacees.' This work showed a great deal of careful research and accurate observation; but its practical utility was much marred by a want of method. It contains no well-defined tribes, nor, indeed, any divisions, except twelve series (of which no characters are given), and no conspectus or short diagnoses of the genera to save the need of successively reading through on every occasion a number of detailed descriptions before you could determine a plant sufficiently to study it .... On the other hand, the plates illustrating some of the most important characters of each genus are most useful, the analysis very accurate and well designed, the execution of the figures all that could be desired." Later Baillon gave a more popular account of the family in the fifth volume of his Histoire des Plantes (1874), with magnificent illustrations by M. Faguet, a few of whose dissections I have used in the drawings accompanying this paper. In this work Baillon recognized only 150 genera, including Daphniphyllum (Daphniphyllaceae), Callitriche (Callitrichaceae), and Dichapetalaceae. In his famous Prodromus4 de Candolle was fortunate to obtain the services of Edmond Boissier for the suborder Euphorbieae. Boissier divided this group into two tribes, I. EUPHORBIEAE, the male flowers without a calyx ("calyculus"), and II. ANTHOSTEMEAE, the male flowers with a distinct calyx. The remainder of the family was contributed by Jean Muiller of Argau, Switzerland (usually abbreviated to Muell.-Arg. to distinguish him from 4 de Candolle, Prodromus 15, 2: 1 (1862).

Abstract: Synopsis of the tribe Crotoneae Dumort. (Euphorbiaceae s.s.) in the State of Sao Paulo, Brazil). Two genera, Astraea Klotzsch, with two species, and Croton L., with 37 species, were recognized for the tribe Crotoneae in the state of Sao Paulo. Keys for genera and species are presented, as well as illustrations of diagnostic characters. The original publication, synonymous, geographic distribution and vegetation of occurrence are refered to each species, along a voucher specimen. A new combination is proposed, Astraea cincta (Mull. Arg.) Caruzo & Cordeiro, for Croton cinctus Mull. Arg., and one neotype and 17 lectotypes are here designated.

Abstract: Croton is the second bigger and more diverse genus in the family Euphorbiaceae, with about 1,200 species distributed in 40 sections, occurring in all tropical areas, most of them in Americas. In South America, Brazil is the country in which a larger number of taxa are found, ca. 356. According to recent classification, the genus belongs to the tribe Crotoneae, and despite the wide and morphological diversity, it would be a monophyletic taxon. However, a phylogenetic analysis using markers of ITS region from nuclear ribosomal DNA, and of trnL-F from plastidial DNA, showed that Croton, like traditionally circumscribed, is not a monophyletic taxon. A taxonomic revision of Croton section Lamprocroton (Mull. Arg.) Pax is presented here. It is a Neotropical group with most of its species occurring from Southeast and South Brazil to southern South America (Uruguay and Argentina). Morphologically, the members of Lamprocroton are characterized as monoecious or dioecious shrubs or subshrubs, with a lepidote indumentum at least in part of foliage, entire leaves with no glands. The staminate flowers have 9 to 16 stamens and the pistillate flowers may have equal or unequal sepals, reduced to absent petals, and styles once or twice bifid. Overall, are recognized 26 species in the group, three of them new to the science. Identification key, morphological descriptions, illustrations, phenological period, as well as data on geographic distribution and general comments of each species are presented. Four taxa were excluded from C. sect. Lamprocroton because they do not show the morphological features that are diagnostics of the section. Four species that are poorly known were not included in the taxonomic treatment.