Thirty-one collections, representing perhaps ten species and seven unidentified collections, of Echeveria Series Racemosae from the Andes of Ecuador to Argentina are all polyploids, with gametic chromosome numbers from 44 to ~260. Their basic numbers are not apparent, but some probably have 16 or more alleles for each gene, and they can store a great deal of genetic heterozygosity. At metaphase I of meiosis nearly all cells of most collections have a few unpaired chromosomes and/or multivalents. One or a few chromosomes lag behind at anaphase I and are probably lost. Despite these irregularities, they are buffered by their many alleles for each gene; plants with one or a few extra chromosomes, or a few too few chromosomes, evidently survive and reproduce. Their populations must include plants that do not all have exactly the same chromosome numbers or the same dosages of every kind of gene. In cultivation they hybridize readily with each other and with Mexican Crassulaceae, and collectively they are part of a comparium of North and South American Crassulaceae that includes more than 200 species. At meiosis in their hybrids the corresponding chromosomes of the multiple sets from each polyploid parent form pairs preferentially with other chromosomes that came from the same parent. This shows that they are autopolyploids and, unlike allopolyploids, any different alleles of their multiple genes can be shuffled freely at meiosis and reapportioned in any combination. This allows them to undergo rapid rates of genetic recombination, thereby greatly increasing chances of adapting to rapid changes in geology and climate of the Andes during the Pliocene and Pleistocene. This should offer an evolutionary advantage to small plant populations.

We describe an Aloe species collected by Werner Rauh in 1961 and another found in 1976 in Madagascar.

Two new species of Aloe from the Horn of Africa are described and their affinities discussed. Aloe rubrodonta, a member of the so-called Saponarieae group, occurs in the west of Somaliland. It is a rather small, acaulescent species, with rosettes that are solitary or occasionally 2–3 together. It has small red teeth on the leaf margins and a sub-capitate raceme to 30 cm tall. Aloe kahinii, from the eastern reaches of Somaliland, is part of a small group of plants with entire leaves, allied to A. inermis. It forms low clumps of up to 15 rosettes with smooth, dull olive-green leaves and lax, paniculate inflorescences to 45 cm tall.

A new species of Aloe has been discovered at El Kerre, Ethiopia, the type locality of A. jacksonii. This new species, Aloe elkerriana, clearly differs from A. jacksonii in its size, inflorescence, leaves and habit of growth. It closely resembles A. hildebrandtii of Somalia, from which it differs in its pendant habit of growth, much longer and thinner stem, more sparsely branched inflorescence, and shorter brown–coral-red perianth.

Namaqualand stretches along the west coast of South Africa, from the Orange River in the north to the Olifants River in the south. It forms part of the Succulent Karoo, one of only two arid regions to qualify as a hotspot of global significance, and harbors an impressive array of succulents, geophytes and dwarf shrubs. Probably its most famous feature, however, is the mass display of flowering annuals and bulbs which appear after average or above-average winter rains. Aloes form a prominent part of the landscape throughout the distribution range of the genus, and Namaqualand is no exception. A total of 20 aloes occur in Namaqualand of which four (20%) are endemic to the area, with a further seven (35%) being near-endemic. A key to the aloes of Namaqualand is provided, as well as a short description, distribution map and information on habitat, flowering time, and conservation status for each of the species.

A number of large-growing species of Agave L. (Agavaceae) have become firmly established as part of the introduced flora of parts of the Algarve, southern Portugal, particularly close to human settlements. Two species, which include at least four taxa, Agave americana L. ssp americana, A. americana var marginata Trel., A. salmiana Otto ex Salm-Dyck var salmiana and A. salmiana var ferox (K. Koch) Gentry, recorded in southeastern Portugal are briefly discussed here, their residence status is determined, and a key to aid in their identification and that of other cultivated forms of Agave americana is provided. In addition, a putative hybrid between A. americana ssp americana and A. salmiana var salmiana is recorded here for the first time. The nomenclature of the naturalized species of Agave is updated to reflect current usage. The four naturalized Agave taxa are compared to A. franzosinii Baker, which is widely cultivated along the Mediterranean coast of Europe.

A new species of Echidnopsis from northern Eritrea is described. This distinct new species, E. uraiqatiana, is compared with two other nearby highland species, E. nubica and E. cereiformis.

Due to the regular occurrence of drought in southern Africa, there is need for more research on drought tolerant fodder plants such as Opuntia species. The influence of different water applications was evaluated in terms of root and cladode mass, root length, and water-use efficiency for one-year-old cactus pear plants of the species Opuntia ficus-indica (L.) Miller (Morado cultivar) and O. robusta Wendl. (Monterey cultivar). One-year-old cladodes were planted in pots (210 mm diameter × 550 mm deep soil) and grown in the greenhouse at day/night temperatures of 25–30/15–18°C. The water treatments applied were 0–25%, 25–50%, 50–75% and 75–100% depletion of total plant available water. Water-use efficiency (WUE) was defined as the cladode or root dry-mass production per unit of water used. Root mass decreased and root length increased significantly (p < 0.01) for both species with water stress. Due to the finer root system of O. robusta, the root mass was smaller than that of O. ficus-indica. In contrast, the root length/root mass ratio was higher for O. robusta than for O. ficus-indica. The influence of water stress on root die-back was clearly observed in O. ficus-indica but was less noticeable in O. robusta. The lateral roots per taproot increased significantly (p < 0.01) with water stress, with as many as 35 and 70 side roots per taproot for O. ficus-indica and O. robusta, respectively. On average, for all water treatments, the roots of O. ficus-indica and O. robusta composed only 12% and 10%, respectively, of the total plant biomass. In terms of root production, both species used water less efficiently with water stress, but if expressed in terms of cladode production, the WUE decreased for O. ficus-indica and increased for O. robusta with water stress. A water application of only 11 mm was enough to completely hydrate the cladodes of both species at the lowest water treatment. It is clear that O. ficus-indica is more sensitive to water stress than O. robusta. The unique root systems of these species make them adaptable under especially dry conditions.

We present a best-practice method for preparing high-quality Opuntia herbarium specimens, from collection methods to storage. A botanical press having wide, thick, wooden boards is used for cladode drying. A layer consisting of corrugated cardboard, absorbent paper, newspaper, and a thin wood laminate is placed between each cladode. The botanical press is placed in a forced-air furnace at 50–90°C. In the case of nopalitos (young, developing cladodes), podaria are first removed from one side, followed by drying at 45–70°C. Flowers are pressed immediately after collection at 45–60°C. Fruits are preserved in 70% ethanol. Seeds and pulp are removed, and empty fruits are immersed in alcohol for one month; afterwards they are removed from the solution and washed. Fruits are then drained, stuffed with fine sand, and placed in a forced-air furnace at 40–45°C. Finally, the sand is removed and the cavity is filled with resin.

The discovery of a previously unknown isotype of Opuntia vilis Rose, collected by FE Lloyd in 1907 in the state of Zacatecas, Mexico, is reported in the collection of the herbarium of the New York Botanical Garden (NY). This isotype was probably donated to NY by the United States National Herbarium (US) judging by an annotation label included on the voucher. The isotype is composed of seven flower sections, one detached pistil, and one black and white close-up photograph of a plant in habitat. The existence of this isotype has been unnoticed in the literature, probably because the voucher was deposited in the general collection of NY together with other plant material, instead of in a separate type collection. The only annotation mark in the voucher was the blue ink stamp of Britton and Rose for their examination of The Cactaceae (Britton and Rose 1919).

Tunilla D. Hunt & Iliff has been re-evaluated as a synonym of Airampoa Frič, and it has been determined that Airampoa picardoi (J. Marnier-Lapostolle) Doweld should now be accepted as the correct combination for Opuntia picardoi. My earlier evaluation of this species as Tunilla picardoi J. Marnier-Lapostolle ex A. Guiggi & G. Delanoy, with a new type, has been rendered illegitimate by the publication of the 2006 International Code of Botanical Nomenclature.

Eight new combinations were published in the Cactus and Succulent Journal between January and December 2007. Here, we include the Latin diagnosis, holotype information, and original citation for the following combinations published therein: Aloe djiboutiensis McCoy, Aloe ericahenriettae McCoy, Aloe pachydactylous McCoy & Lavranos, Aloe tulearensis McCoy & Lavranos, Arrojadoa hofackeriana (P. J. Braun & Esteves) P. J. Braun & Esteves, Arrojadoa albicoronata (Buining & Brederoo) P. J. Braun, Esteves & van Heek, Arrojadoa rosenbergeriana (van Heek & Strecker) P. J. Braun, Esteves & van Heek, and Echeveria lyonsii Kimnach.