Apart from reproducing sexually through the production of seed that follows self- or cross-pollination and fertilisation, representatives of Kalanchoe (Crassulaceae subfam. Kalanchooideae) have evolved a range of different asexual reproductive strategies. Especially several species indigenous to Madagascar show pronounced asexual reproduction that enables them to successfully colonise, and sometimes become weedy in, suitable habitats well beyond their natural geographical ranges. The environmental conditions and ancestral genetic set up which in combination triggered the evolution of asexual reproduction in the genus, particularly in phyllo-bulbiliferous species, are not yet entirely known. The current model suggests that asexual reproduction has evolved as a result of the recruitment of both organogenesis and embryogenesis processes to the leaf margin. We illustrate and present an overview of aspects of sexual reproduction and asexual reproductive strategies in Kalanchoe and discuss to what extent the proposed model explains the diversity of reproductive strategies observed in phyllo-bulbiliferous Kalanchoe species.

The natural hybrid between Aloe arborescens Mill. and A. thraskii Baker (Asphodelaceae subfam. Alooideae) from the eastern coastal parts of the Eastern Cape province of South Africa where the natural geographical distribution ranges of these two species overlap, is described as Aloe ×thammii Gideon F.Sm.

The Chihuahuan Desert Region (CDR) is the largest desert area in North America, and the southeastern portions contain the richest areas in Cactaceae in the continent. This research was advocated to understand the diversity of cacti in northern Zacatecas and southern Coahuila, as well as to explore species rarity, environmental relations and conservation alternatives. A geographical square measuring a quarter degree was intensively surveyed through 50, 3-km long transects, distributed in 25, 6-minute sub-squares. The geographical square was selected because of its altitudinal and environmental heterogeneity. Cacti were identified and local rareness observed, 764 specimens were deposited at the National Herbarium of Mexico (MEXU). Specimen and locality information were captured in the Database for Cacti of Central and North America. A general evaluation of the cactus diversity (species richness), levels of endemism and rarity were performed. A total of 45 species were found, just below El Huizache, Tolimán and Mier y Noriega, with 7 new records for Zacatecas, 2 for Coahuila and 3 for both Mexican states. We found 26 endemic species from the CDR, five endemic to the Main and Meridional subregions and 21 endemic to the Main subregion, sensu Hernández. Two species are endemic to the state of Zacatecas and three species are endemic to both states. A new index for rarity (Average rarity, Ar) is presented, obtained as the mean of five variables: level of endemism, species relative frequencies, local rareness, and climatic and edaphic (soil) specialization. Rabinowitz rarity (1981) was calculated for all species and transformed into numerical values to compare it with the obtained Ar values. There are 26 rare species following Rabinowitz and 16 rare species following Ar (≥0.5). Ar values resulted smooth and with a higher explanation power (r^2). Just five species resulted with a Rabinowitz rarity of 7 (transformed R of 1) and Ar (≥0.82). A general complementarity analysis was used to address conservation in the studied area, which was enhanced with other four complementarity analyses, including our Ar. Nine sub-squares were found relevant for cacti protection. Soil types and a complete climatic analysis from original data were used to search for environmental relations through Principal Component Analyses. The main preferences for climatic variables and anomalies are highlighted. The Ar index is an adequate tool for measuring species rarity and presents it in a balanced and smooth way, not just fixed Rabinowitz categories, allowing the understanding that some species might be rare in different ways in different areas and environmental conditions, something that seems to occur in cacti. Further research is encouraged on Ar for comparisons and even mapping, as well as for Natural Protected Areas (NPA) design.

A new record of Crassulaceae, namely plants that may belong to Umbilicus botryoides Hochst. ex A.Rich., is documented for the Angolan Flora. These plants were observed on the western edge of the Huila plateau near the town of Lubango. They extend the known distribution of Umbilicus in Africa from around 8° S in Tanzania to just about 15° S.

The factors determining cactus species richness and distribution at broad scales are well understood; however, the mechanisms explaining these parameters at local scales are poorly known, particularly in mesic regions. The aim of this study was to analyze if globose cactus species are segregated in terms of the microhabitats they occupy in Córdoba Mountains, central Argentina. In an area of about 40 ha, 19 rocky outcrops including all cactus species (a total of seven species) and covering the main vegetation and topographical conditions were selected. In each of the outcrops, 10 1x1 m randomly selected plots were established. The following variables were measured in each plot: cactus species presence; cover of graminoids, forbs, bare soil, and rock (%); rock size (small, medium and large); slope inclination (°) and aspect; soil depth (cm); and vegetation height (cm). A principal component analysis was performed with environmental variables. Then, segregation of the different cactus species along the three first axes of the PCA, which accounted for most of the environmental heterogeneity, was analyzed. Echinopsis aurea and Gymnocalycium mostii occurred at sites dominated by rock with low vegetation cover. Gymnocalycium bruchii, G. capillense and Parodia submammulosa were present at sites with low rock cover, deep soils and high vegetation cover. Out of the seven cactus species, Parodia submammulossa, Gymnocalycium bruchii and G. capillense did not differ significantly in microhabitat characteristics. Thus, these three species occupied sites with similar microenvironmental conditions, whereas the remaining species occupied sites with particular environmental characteristics. Four of the seven species inhabit unique environments (they do not overlap with the other species in the multivariate space). Moreover, these three species not only are present in similar environments, but also co-occur (they were found together in the same plots). Our results indicate that at the local scale, segregation in space is an important mechanism explaining plant coexistence and local species richness.

Few members of the Cactaceae family occur in cold climates resulting in our limited knowledge about their response to such conditions. We used chlorophyll fluorescence to assess the impact of seasonal changes in the extremes of a continental climate on the photosynthetic performance of Opuntia cespitosa in Canada. Quantum yield (QY, F_V/F_M) was sampled on opposing faces of four cladodes (pads) from April to December, and data for ambient air temperature, morning sky conditions and soil moisture were collected. Soil moisture was negatively related to F_V/F_M, but only on sun-facing pad faces. We found that F_V/F_M was variable at the start and ending periods while the summer months had consistently high values. F_V/F_M decline began more than a month earlier on sun-facing pad faces than shaded faces, with some shaded faces with F_V/F_M > 0.8 even in December. Indeed, when sun- and shade-facing faces were inverted on one pad in late November, F_V/F_M increased on the newly shaded face, suggesting remarkable resilience to recover from photoinhibition. Overall, we suggest photoinhibition of photosystem II (PSII) is related to low temperature and secondarily to light exposure. Although Opuntia only suffers from photoinhibition during the coldest months, photoinhibition appears to be dynamic and reversible. The seasonal response of Opuntia cespitosa appears to mimic that observed for the cold tolerant evergreen conifers.

The genera and species of Asphodelaceae subfam. Alooideae, a predominantly leaf-succulent group, display significant diversity in their phyllotaxis. However, recording, describing, and studying this character for the ca. 1000 species included in the subfamily have not received comprehensive attention to date. An introduction to phyllotaxis is presented, along with a non-destructive method for describing and studying this character in the group. It is concluded that the divergence angle apparent in mature rosettes or stems is most suitable for describing the diverse alooid phyllotaxis systems. This is additionally a less invasive tool than other procedures such as those that record the plastochron ratio or leaf arc. An approach and methodology to studying alooid phyllotaxis is presented, using established phyllotaxis notations with minimal additions. The principal innovation of this approach is that the direction of any curved leaf-ranks is recorded relative to that of the generative spiral, thus rendering their direction of curvature regular and predictable. Furthermore, it is concluded that systematically recording phyllotaxis in the Asphodelaceae subfam. Alooideae has significant diagnostic utility, at both genus and species ranks. In future, including the phyllotaxis formula, in the suggested notation, as part of the descriptions of all alooid taxa will be taxonomically useful. The method is illustrated in the genera Aristaloe, Astroloba, Gasteria, Gonialoe, Haworthiopsis and Tulista.

A previously undescribed, delicate stem-succulent and small-flowered species of Cynanchum (Asclepiadeae subtribe Cynanchinae) from Madagascar is described here. While the exact place of origin of the type material is unknown, the systematic position of the new species is clear. It belongs to a subgroup of always leafless Cynanchum species endemic to Madagascar, the place of highest diversity of leafless representatives of the genus.

Shaw's Agave (Agave shawii subsp. shawii) is a rare plant found in only a handful of occurrences within the extreme southwestern corner of the USA in a highly urbanized region. Seedling recruitment of Shaw's Agave in California is visibly low, and viable seed production appears to have been very low in recent years, and has been identified as a primary threat to the persistence of these populations. We performed pollination trials, seed germination studies, and inventoried floral visitors and potential pollinators (including the collection of invertebrates) to determine if pollination and/or germination failure is limiting reproduction. We placed bat detectors and camera traps near blooming agaves, and observed bird and insect visitation to the flowers. Pollination treatments included hand pollination with cross-individual and selfing trials. Our results found a low amount of seed produced per fruit across the pollination trials. Seedling herbivory was also very high (85% and 100%) in the two treatments. The combination of low seed set and high herbivory may help explain the lack of recruitment observed at multiple sites in recent years. No nectar feeding bats utilized the Shaw's agave in our study area. The only significant insect visiting flowers was the honey bee (Apis mellifera), which gathered nectar without touching the anthers. Hummingbird species were also frequent visitors but generally avoided touching the agave anthers. Only the Hooded Oriole (Icterus cucullatus), a migratory bird, appeared to regularly visit flowers for their nectar, while standing on the flowers and brushing against the anthers, potentially providing some pollination but only for plants blooming during the period the oriole is present in the region. Seedling predation was significant, and poses a considerable threat to this population. Further research into seed set and pollination treatments is recommended.

Variation and deviations in reproductive morphological characters, especially in flower colour and the occurrence of single vs double flowers, in species and hybrids from which cultivars have been selected in Kalanchoe (Crassulaceae subfam. Kalanchooideae) have given rise to the establishment of a multi-million € horticultural enterprise based on, inter alia, K. blossfeldiana and hybrid material of which it is one parent. Kalanchoes are mostly made available for the trade in material grown indoors. More recently, the breeding of kalanchoes as a source of long-lasting cut flowers, as well as incorporating vegetative, not only reproductive, variation into hybrid offspring have received increasing attention. Vegetative characters of horticultural interest are mostly those of the leaves (colour, maculation, shape). Especially given the ease with which kalanchoes, including nothospecies and cultivars, respond to cultivation outdoors in places where water for irrigation is at a premium, material other than K. blossfeldiana-derived cultivars has recently seen an upsurge in popularity. In the family Crassulaceae as a whole, deviations in leaf morphology, such as surface carunculations, is best known among representatives of other crassuloid genera, including Echeveria (Crassulaceae subfam. Sempervivoideae). Such deviations, too, have given rise to the selection and description of numerous horticulturally popular cultivars, for example derived from E. gibbiflora. The development of leaf carunculations is for the first time reported from K. neglecta and K. nyikae, which are endemic to southern and East Africa, respectively. We provide a review of variable and deviating vegetative and reproductive morphologies in Kalanchoe species, nothospecies, and cultivars popular among plant breeders.

Demographic trends can be used to understand population status and the potential for future success. For rare species, studying demographic patterns of extant populations is critical for conservation management and species assessment. Harrisia aboriginum Small ex Britton & Rose, commonly known as the aboriginal prickly-apple cactus, is a columnar cactus restricted to a narrow fringe of coastal habitat in southwestern Florida. Although H. aboriginum has been listed as endangered for nearly a decade, recent surveys of extant populations are lacking, and a number of tropical storms have passed through the geographic range since the last assessment was made. Over two field seasons, we visited ten known extant populations of H. aboriginum to collect demographic and phenological data. Our results indicate that the number of individuals in wild populations, which we estimated at fewer than 200, decreased by more than 50% over the past 15 years. Furthermore, of the 100 plants studied, only 21% were reproductive, with eight observed to have produced fruit while 13 were observed to be in bud. Only 31 seedlings were observed in 4 locations. We suggest that active management and restoration activities, using individuals reared in ex situ conservation management programs, are imperative for the conservation of the species. Future research efforts should focus on understanding patterns of geneflow and outcrossing to help prioritize conservation efforts, as well as the conditions needed for the recovery of the species.