Echinocereus palmeri subsp. mazapil, a new subspecies of Cactaceae from the Chihuahuan Desert Region, Mexico, is described and illustrated. It has only been collected from a highly specialized habitat at two remote localities in the state of Zacatecas and its range is markedly disjunct from that of the typical subspecies. In addition to divergences in geographic range and habitat preferences, E. palmeri subsp. mazapil differs from the typical subspecies by usually having relatively smaller stems with tuberculate ribs and less numerous radial spines, which usually are of unequal length.

The perplexing ancestral phylogenetic placement of Blossfeldia liliputana based on chloroplast DNA can possibly be explained by (1) the hybrid origin and uniparental inheritance of chloroplasts in Blossfeldia and (2) the DNA samples originating from the grafting stock upon which the Blossfeldia was cultivated. The problem with the first of these hypotheses is that nobody knows whether chloroplasts are inherited from one or both parents in Blossfeldia nor how this inheritance pattern may have changed in ancestors of Blossfeldia. Phylogenetic reconstructions of species trees assume that the mode of organelle inheritance is known, and these phylogenies are confounded by reticulate evolution. The problem with the second hypothesis is that most cultivated specimens of Blossfeldia are grafted and nobody is certain whether or not these readily form graft-chimeras. Until both hypotheses are tested, B. liliputana should be considered a highly derived member of the subfamily Cactoideae, as indicated by morphological data.

Agave hurteri Trelease, a Guatemalan species, is reported from cultivation in South Africa. The taxonomy, nomenclature and an amplified description are presented for this comparatively little known species, which is recommended for landscape gardening. Experience in Pretoria has shown that plants will flower from very small bulbils within as little as seven years.

Plants with only a single leaf-pair during most of the year are presented, their morphological features are discussed and the ecological situations in which they grow are investigated. The seven genera with such members, namely Argyroderma (2 species), Conophytum (14 species), Didymaotus (1 species), Dinteranthus (3 species), Lithops (2 species), Pleiospilos (2 species), and Tanquana (1 species) represent different evolutionary lineages; even within a given genus, the unbranched species can belong in different groups. The ecological adaptation cannot be related to any one distinct feature; instead, the success of the extremely reduced growth form in very shallow soils or tiny pockets can be understood as an exploitation of lack of competition from other plants requiring more space for larger root systems in these places. A key to the species included is given, maps for the genera and the relevant species are supplied.

Emilio Chiovenda (1871–1941) is one of the very few Italian botanists devoted to the study of East African succulent plants. A short biography is presented, that emphasizes his contributions to the study of the East African succulent flora and the new taxa he described. It is shown that in his studies on tropical African botany, Chiovenda described 53 new genera and about 1,300 new species and infraspecific taxa. His contribution to the knowledge of the flora of tropical North East Africa remains a lasting memorial. Two previously unpublished photos of Chiovenda, unpublished drawings of Caralluma rivae, and a selected bibliography are included.

Obetia ficifolia, a little-known species of Urticaceae, is endemic to Réunion and Rodriguez Islands. Its status as a species in danger of extinction in the natural state (it is protected by French Ministry decree), amply deserved a more detailed study in the wild. The species has therefore been observed in its natural habitat and today two distinct ecotypes are recognized within the species, one from the north of the island, the second from the south, with different leaf morphologies. The geographical distribution and number of the natural populations on Réunion Island have been mapped. The largest estimate gives a total number of only 150-160 mature individuals, meriting a conservation status based on IUCN criteria of Critically Endangered (CR). O. ficifolia has also been reassessed as a monoecious species, whereas previous descriptions considered it to be dioecious.

The alphabetic index of Opuntia names is continued from Bradleya 21: 63–86. 2003. There are no new names published here, but there are nine typifications (3 LT, 4 NT, 2 ET) and one new cultivar standard.

The species Stenocereus thurberi grows in the Sonoran Desert and produces a fruit known as pitaya by the local people. Recently the economic benefits of exporting fruits of several cactus species have been highlighted, indicating the importance of further studies in the pre- and post-harvest physiology of pitaya fruit. The aim of this study was to develop a model to predict the stage of development in Stenocereus thurberi fruits (pitaya), in terms of days after flowering (DAF). A randomized sampling of fruits with 5, 10, 15, 20, 25, 30, 37 and 40 DAF was done during two consecutive years. A Minolta Chroma Meter CR-300 set in the L*, a* and b* colour space was used to quantify fruit skin colour (Ls, as, bs) and fruit pulp colour (Lp, ap, bp) in every sampled fruit. A basic multiple linear model was proposed. The predictive model was analyzed using the stepwise procedure in forward selection. Several regressors were considered to fit the best model, such as the variables Ls, Lp, as, ap, bs, bp, linear and squared, as well as the chroma and angle hue for both fruit skin and fruit pulp. The F statistic, mean square error, coefficient of determination (r²), Mallows coefficient (Cp) and distribution of residuals around zero were used as indicators of the model's predictive efficiency. The best predictive model included the variables Ls, bs, Lp and bp with r²=0.795 and Cp=4.99. We concluded that it is possible to predict the stage of ripening development in DAF of Stenocereus thurberi fruit by measuring the fruit pulp and fruit skin using the L*, a* and b* space colour.

Based mainly on the plant material and data assembled by Röösli & Hoffmann over many years, the Madagascan pachypodiums are reassessed. A complete iconography is provided. A total of 15 species and 4 subspecies are recognized, with an additional new taxon still awaiting publication. The Madagascan taxa are placed in a separate, newly described subgenus Nesopodium within the genus Pachypodium and arranged in three sections with five series, based mainly on the infrageneric taxa of Schumann (1895) and Pichon (1949). The arborescent, white flowering species of section Leucopodium are rearranged in three series; ser. Pseudoternata is newly described. In contrast to other classifications, P. meridionale is treated here as a synonym of P. rutenbergianum, whereas P. sofiense is, in agreement with Perrier de la Bâthie (1934), treated as a species that is distinct from P. rutenbergianum, because of conspicuous differences in flowers and fruits. The distinct position of the red flowering species and their corresponding section Porphyropodium is confirmed. The shrubby, yellow flowering taxa of section Gymnopus are arranged in two series; ser. Densiflora is newly described. A total number of five geographically separated subspecies are recognized within the polymorphic and widespread P. rosulatum, all with similar flower and fruit characters, among them the recently described P. makayense. A further subspecies from this complex has just been discovered by Röösli & Hoffman and is still undescribed. P. eburneum and P. inopinatum are excluded from P. rosulatum, where Rowley (1998, 1999, 2001, 2002) placed them, and are now associated with P. densiflorum. A survey of seeds yielded some useful results: (a) the shrubby species form a morphologically quite uniform entity; (b) P. rosulatum ssp. bicolor is considerably different from ssp. rosulatum; (c) P. baronii and P. windsorii are quite outstanding within the Madagascan pachypodiums; (d) P. decaryi is strikingly similar to P. rutenbergianum and must be closely related, whereas (e) P. ambongense is quite different from this group and seems to be much closer to P. lamerei; it is placed in the new series Pseudoternata, and finally (f) there is a cryptic species that resembles P. ambongense in some respects and P. lamerei in others; it is identified as P. menabeum, which was commonly treated as a synonym of P. lamerei, and it can be placed in the new ser. Pseudoternata. The present treatment of the genus leaves the African species, including the type (P. tuberosum Lindl.), implicitly in subgenus Pachypodium (ICBN Art. 22.1 and 22.3), which is not further considered here.

The anatomy of non-cactus stem-succulent dicots was examined in the families Apocynaceae (Plumeria, Pachypodium), Asclepiadaceae (Caralluma, Hoodia, Huernia, Pseudolithos, Stapelia, Larryleachia), Asteraceae (Senecio), Crassulaceae (Tylecodon), Euphorbiaceae (Monadenium, Euphorbia) and Vitaceae (Cissus). Some specimens have large, persistent photosynthetic leaves, others are stem-photosynthetic and “leafless”; all had succulence based on pith and cortex, not wood. These specimens had remarkably few of the adaptations that commonly occur in cacti: none had cortical bundles, none had a multilayered hypodermis of extremely thick-walled cells, none had deeply sunken stomata. Few had a thick cuticle or thick-walled epidermis. Many did have some form of collapsible cortex (either cells with plicate walls or extremely thin walls) and members of Apocynaceae and Asclepiadaceae had internal phloem or medullary bundles. Despite being desert-adapted succulents, none of the species had really wide, massively succulent bodies as is common in the Cactaceae: only one (Euphorbia obesa) had a cortex thicker than 12mm, and almost all others had cortexes less than 5mm thick.