We provide a short history of the development of phylogenetic concepts for the cactus family in the pre-molecular (here meaning pre-DNA) era, beginning from the creation of the first artificial classification systems, over to natural systems, and on to the progress made in the Post-Darwinian era. Although several authors have presented their ideas on the evolution of Cactaceae, it was the botanists Alwin Berger and Franz Buxbaum who made the most essential contributions towards a cactus phylogeny during the 20^th century. In the second half of that century, new techniques and detailed studies (phytochemistry, anatomy, SEM) helped formulate new concepts or revised established concepts about the evolution of cacti.

The succulent life form is a tried and true strategy for plants living in arid environments. It has evolved in many distantly related lineages comprising 12,500 species from 70 flowering plant families and has spawned remarkable radiations. Three major groups are generally recognized: (1) stem succulents (that is, leafless cactus-like growth forms), (2) leaf succulents, and (3) caudiciform and pachycaul succulents. All three lifeform groups are represented in the relatively small suborder Portulacineae. Here we suggest that this diversity provides a unique opportunity to evaluate early cactus evolution within a richer contextual framework. We briefly review what we know about the phylogenetic relationships within the suborder Portulacineae (that is, Basellaceae, Cactaceae, Didiereaceae, and Portulacaceae) and the morphology and ecology of all major Portulacineae lineages. We then outline what we believe to be key areas for future research on these understudied plants and discuss several hypothetical “pre-adaptations” and conditions in ancestral Portulacineae that may have promoted the repeated evolution of unusual succulent life forms.

Recent molecular studies inform relationships among Cactaceae and early cactus evolution. Results of these studies are not uniform. Three topics are considered: (1) the phylogenetic position of Pereskia, (2) characters of the outgroups of Cactaceae, and (3) the character evolution implied thereby. If diminutive habit, succulence, and stem photosynthesis predate the Cactaceae, then character states in Pereskia may represent reversals.

The cacti are renowned desert plants of the New World. The are typically leafless, spine-bearing stem succulents. Species of Pereskia possess broad, regular leaves and have been viewed as being representative of ancestral cacti. A number of previous studies have attempted to resolve phylogenetic relationships within Pereskia and between Pereskia and other cacti. Here, we present the results of a joint analysis along with hypothesis testing using datasets previously published independently by each author. This study clearly shows a basal split in the cacti between a clade of Caribbean-basin-centered Pereskia species and all other cacti. Furthermore, hypothesis testing strongly supports the basal Pereskia hypothesis over an alternative hypothesis in which the Opuntioideae form the basal split in the cacti (although the latter hypothesis was not statistically rejected).

The taxonomic history of the three genera Pereskia, Maihuenia, and Blossfeldia is reviewed and discussed in the context of general historical aspects of cactus taxonomy and in view of ongoing discussion on evolution and phylogenetic position of the three genera. Some updates and additional observations complementing earlier monographic treatments of Pereskia and Maihuenia and other papers on all three genera are provided. The appearance of these cacti since 2004 on websites is briefly analysed with selected data retrieved from Google searches. All recognized species are illustrated.

Opuntia fragilis is the smallest and most cold-hardy species of North American prickly pear, with an unusual distribution. This document is a review of its taxonomy, distribution, and ecology.

Literature on distributions, habitat characteristics, and identification of Opuntia species in the southeastern US is scant. Regional treatments of Opuntia are often ambiguous, limited studies based primarily on herbarium specimens. The present work provides a detailed description of the opuntias found in Mississippi along with their distributions and habitat descriptions. Observations, collections, and measurements were made from natural populations within Mississippi and other parts of the southeastern United States. Plants of all taxa were greenhouse grown for approximately two years to monitor morphological characteristics, which sometimes can be quite plastic. Our two-year study encompassed nearly 150 natural populations among several eastern states. Five species are recognized. Of these, Opuntia cespitosa, O. humifusa, and O. pusilla are the most common in Mississippi. O. aff allairei and O. stricta are found infrequently.

Succulent life forms are a prominent feature of the Sonoran Gulf of California islands (Alcatraz, Cholludo, Dátil, Patos, San Esteban, San Pedro Mártir, San Pedro Nolasco, and Tiburón). Among a total flora of 378 species of vascular plants, there are 62 succulent taxa (16%) in 16 families and 33 genera, which we place in three categories: xerophytic succulents (32), semisucculents (22), and halophytic succulents (8). Succulent plant distribution on each island is unique and reflects the shaping climatic, biotic (including herbivores), soil, and topographical features of each of these microcosms. Cactaceae is the most diverse family (25 taxa), with six endemic species, all small cacti, found on Islas San Esteban, San Pedro Nolasco, Dátil, and Cholludo. The smaller islands in the region have a significantly higher percentage of succulent species. Here we present a discussion of the different succulent categories and a detailed floristic listing for all succulent species, which represents the first specimen-based flora of succulents from Gulf of California islands.

The most recent treatments of the family Cactaceae for Uruguay are that of Arechavaleta (1905), Osten (1941), and Herter (1953–55). While the globular members of the family (Parodia [including Notocactus], Frailea, and Gymnocalycium) are relatively well known through numerous later individual publications, the epiphytic species of Lepismium and Rhipsalis are comparatively poorly-known. Based on herbarium material and recent collections, we present data on the geographical distribution and taxonomy for two species of Lepismium and two species of Rhipsalis. Lepismium cruciforme and Rhipsalis floccosa are new records for the flora of Uruguay. The occurrence of Epiphyllum phyllanthus in Uruguay could not be confirmed.

Kuenzler's hedgehog cactus (Echinocereus fendleri var kuenzleri) is an endangered species thought to be endemic to south central New Mexico on the eastern slopes of the Sacramento, Capitan, and Guadalupe Mountains. We studied macro- and micro-habitat characteristics of Kuenzler's cactus in four study areas in Lincoln and Eddy Counties, New Mexico. Plants were found mostly on southern and eastern aspects at elevations from 1600 to 2100 m and on slopes ranging from 7 to 41°. Herbaceous biomass and foliar cover were similar at three spatial scales (concentric circles with diameters of 30, 56, and 110 cm) surrounding plants. These results suggest that Kuenzler's cacti are randomly distributed with respect to these habitat features, and do not support the hypothesis that Kuenzler's cacti grow in local habitats where associated vegetation provides thermal protection.

Astrophytum coahuilense (Möller) Kayser has had an unsettled taxonomic history since it was originally named as a subspecies of A. myriostigma Lemaire by H Möller in 1927. A review of the systematic and horticultural literature reveals that A. coahuilense has been treated as a variety or synonym of A. myriostigma by botanists in the United States and Mexico but is generally recognized as a distinct species in Germany and other parts of Europe. Recent encyclopedic and regionally significant works treat A. coahuilense as a synonym of A. myriostigma. Previous authors performed hybridization experiments involving the two taxa and reported reproductive isolation between them, but these authors provided little or no quantitative data in support of their observations. The results of my preliminary hybridization experiments are in agreement with these published reports. A. coahuilense and A. myriostigma, when artificially hybridized, failed to set fruit or produced seed that, in most cases, failed to germinate. Furthermore, A. coahuilense and A. myriostigma differ in fruit morphology, mode of fruit dehiscence, and have allopatric geographical distributions of several hundred kilometers. The distinguishing genetic and morphological attributes provide compelling evidence for the recognition of the Coahuila Bishop's Cap as a distinct species.

In several genera of Cactaceae flowers are produced by a specialized, nonphotosynthetic portion of the stem known as the cephalium. The objective of this study is to test if cephalial tissue can be induced to revert to vegetative growth under in vitro conditions. Segments excised from the surface of Melocactus matanzanus cephalium and placed on Murashige and Skoog medium supplemented with 0.1 mg l⁻¹ 1-napthaleneacetic acid (NAA) and 1.0 or 5.0 mg l⁻¹ 6-benzyloaminopurine (BAP) regularly produced vegetative shoots. Shoots were also obtained when kinetin was used instead of BAP, although the frequency of their formation was then lower. One of the reverted shoots was successfully established as a rooted plant ex vitro.

Following a formal request by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), the appropriateness of the listing of Aloe arborescens Mill. (Asphodelaceae: Alooideae) in Appendix II of this Convention was assessed. As part of this assessment, the threatened (Red Data List) status in South Africa, the country within which it is taxonomically most diverse, was also re-assessed, and available information on formal and informal trade taken into account. Following a synthesis of the information available on A. arborescens, it is proposed that the species and its varieties should remain on CITES Appendix II, as their de-listing carries the risk of other Aloe species being traded under this name. It is retained in the Red Data List category for species of least concern (LC).

Adenium multiflorum Klotzsch (Apocynaceae) is lectotypified with the plate accompanying the diagnosis.

Eleven new combinations were published in Cactus and Succulent Journal between January and December 2008. Here we include the Latin diagnosis, holotype information, and original citation for the following taxa and combinations published therein: Aloe altimatsiatrae J.-B. Castillon, Aloe elegantissima McCoy & Lavranos, Dorstenia lavrani McCoy & Massara, Dyckia grandidentata P. J. Braun & Esteves, Dyckia richardii P. J. Braun & Esteves, Melocactus alex-bragai P. J. Braun & Esteves, Pachypodium brevicule ssp leucoxanthum J. Lüthy, Peperomia chutanka Pino, Peperomia dolabriformis Kunth variety lombardii Pino, Peperomia dolabriformis Kunth variety multicaulis Pino et Cieza, and Siccobaccatus insigniflorus (Diers & Esteves) P. J. Braun & Esteves.