El género Amaranthus L. (Amaranthaceae) se caracteriza por presentar hierbas monoicas o dioicas, con hojas alternas, flores unisexuales protegidas por brácteas y bractéolas, generalmente tres a cinco sépalos glabros, estambres libres y fruto un utrículo o pixidio. En el presente tratamiento se realiza la revisión taxonómica de las especies monoicas del género Amaranthus, esto es las que conforman Amaranthus subg. Amaranthus (13 especies) y Amaranthus subg. Albersia (Kunth) Gren. & Godr. (52 especies). Cuarenta y seis de estas 65 especies son americanas, mientras que las restantes (19) son de África, Australia o Eurasia. Se establecen las siguientes nuevas sinonimias: A. artineanus Muschl. se considera sinónimo de A. hybridus L. subsp. quitensis (Kunth) Costea & Carretero y A. chihuahuensis S. Watson sinónimo de A. torreyi (A. Gray) S. Watson. Se proponen nombres en nuevos rangos (elevados de variedades a subespecies) para: A. asplundii Thell. subsp. australis (Hunz.) N. Bayón, A. blitum L. subsp. pseudogracilis (Thell.) N. Bayón, A. crassipes Schltdl. subsp. warnockii (I. M. Johnst.) N. Bayón y A. macrocarpus Benth. subsp. pallidus (Benth.) N. Bayón. Se designan lectotipos (15) para Amarantellus argentinus Speg., Amaranthus albomarginatus Uline & W. L. Bray, A. asplundii Thell., A. ataco Thell., A. bigelovii Uline & W. L. Bray, A. blitum L. subsp. emarginatus (Uline & W. L. Bray) Carretero, Muñoz Garmendia & Pedrol, A. bracteosus Uline & W. L. Bray, A. caudatus L. var. alopecurus Moq., A. graecizans L. subsp. aschersonianus (Thell.) Costea, D. M. Brenner & Tardif, A. schinzianus Thell., A. sclerantoides (Andersson) Andersson, A. squamulatus (Andersson) B. L. Rob., A. wrightii S. Watson, Amblogyna squarrulosa A. Gray y Sarratia Moq. Se designa neotipo para A. vulgatissimus Speg. y epitipo para A. ascendens Loisel. Se ilustran por primera vez en forma completa a 14 especies, y a otras ocho de las que sólo existían ilustraciones parciales.

The genus Amaranthus L. (Amaranthaceae) is characterized by its monoecious or dioecious herbs, with alternate leaves, unisexual flowers protected by bracts and bracteoles, usually three to five glabrous sepals, free stamens, and fruit a utricle or pyxidium. A taxonomic revision of the monoecious species of Amaranthus is presented for those species that comprise Amaranthus subg. Amaranthus (13 species) and Amaranthus subg. Albersia (Kunth) Gren. & Godr. (52 species). Forty-six of these 65 species are American, while the rest (19) are from Africa, Australia, and Eurasia. The following taxa are newly synonymized: A. artineanus Muschl. with A. hybridus L. subsp. quitensis (Kunth) Costea & Carretero and A. chihuahuensis S. Watson with A. torreyi (A. Gray) S. Watson. Names at new rank (varieties elevated to subspecies) are proposed for A. asplundii Thell. subsp. australis (Hunz.) N. Bayón, A. blitum L. subsp. pseudogracilis (Thell.) N. Bayón, A. crassipes Schltdl. subsp. warnockii (I. M. Johnst.) N. Bayón, and A. macrocarpus Benth. subsp. pallidus (Benth.) N. Bayón. Fifteen lectotypes are newly designated

A critical review of the Argentinian, Uruguayan, and Paraguayan species of Acalypha L. (Euphorbiaceae) is presented. As a result, 18 species (22 taxa) are accepted, 16 from Argentina, 12 from Paraguay, and five from Uruguay, and 49 names are considered as synonyms. Typifications are provided for A. brasiliensis Müll. Arg., A. cordobensis Müll. Arg., A. friesii Pax & K. Hoffm., A. gracilis Spreng., A. nitschkeana Pax & K. Hoffm., A. multicaulis Müll. Arg. var. glabrescens Pax & K. Hoffm., A. lagoensis Müll. Arg. var. grandifolia Chodat & Hassl., and A. striolata Lingelsh. Identification keys are also provided as are original illustrations of three species and distribution maps of all the accepted taxa.

Monocots, with ca. 65,000 species in 78 families and 12 orders as classified by the Angiosperm Phylogeny Group (Angiosperm Phylogeny Group III, 2009), have traditionally been known as a distinct assemblage from dicots within angiosperms and are now seen as a lineage that diverged from within the more basal of the angiosperm groupings. In this study, the third in a series analyzing pollen characters across the angiosperms, we illustrate the pollen morphological diversity of monocots and analyze 19 palynological and two ecological characters for 120 taxa in 71 families covering the 12 monocot orders and 16 taxa of nine orders in basal angiosperms. Pollen morphological data from previous works and our investigations were optimized onto a new maximum likelihood tree reconstructed from an existing DNA matrix of Chase et al. (2006) using Fitch parsimony, maximum likelihood, and hierarchical Bayesian analysis. From these analyses we infer evolutionary patterns in palynological characters, assess their systematic value, and investigate two aspects (pollination type and habitat moisture) of their ecological adaptation. The highest levels of pollen variation were shown to exist in the Alismatales and Commelinales, with lower levels seen in the Asparagales, Dasypogonales, and Zingiberales; the most variable characters across the phylogeny were found to be pollen outline in polar view, size, and tectum extent. We infer unambiguous plesiomorphic states for monocots and report significant transitions in character states at various levels within the monocot assemblage. Analyses of correlated evolution reconfirmed the hypothesis of an association between exine reduction (or complete loss) and habitat moisture and found significant correlations between various states of exine loss and habitat for hydrophytic–helophytic plants. The presence or absence of the exine itself was found to be more significantly correlated than individual structures, in terms of association with hydrophytic–helophytic plants. The most rapid rate of state changes in pollen characters, in the evolutionary history of monocots, is estimated to have occurred during the Albian-Turonian stage; our work may provide insights into the identification of enigmatic fossil pollen grains from this geological time.