Parasitic plants must be adapted to their hosts, and hosts must have ineffective defenses. Two xeric adaptations in cacti—a broad nutrient-poor cortex and a tough hypodermis—probably are effective defenses. However, Ligaria cuneifolia overcomes these defenses with unusual methods of attack and endophytic growth, although the host (Corryocactus brevistylus) responds strongly. Ligaria cuneifolia induces conversion of thick-walled host hypodermis cells to cork cambium, creating a vulnerable area of parenchyma; it induces formation of new vascular bundles and production of wood in host leaf/bud traces and cortical bundles. The endophyte remains compact, confined near the host surface, it never reaches the host stele. Its interface with the host consists of cytoplasmic parenchyma cells and rare vessels; the endophyte appears to lack sieve tube members. Responses by C. brevistylus include: cortex cells near haustoria (but not near endophytes) produce bark, other cortex cells collapse, and although L. cuneifolia induces formation of secondary xylem in host vascular bundles leading to itself, C. brevistylus produces mostly sclerified xylem parenchyma rather than vessels. These responses are atypical of normal cactus development: L. cuneifolia induces C. brevistylus to develop in novel ways.

The Harrisia cactus mealybug (HCM), Hypogeococcus pungens (Hemiptera: Pseucococcidae), is known to be an effective biological control agent for invasive columnar cacti in Australia and South Africa. In the Caribbean, Central and North America, HCM is an alien invasive species that is threatening native cactus. Despite their negative impacts on ecosystems where cacti are native, no publications have described the symptomatology associated with HCM infestation. This article describes the morphology of the galls produced by HCM on seven host cactus species occurring in Puerto Rico.

Observations of plant-pollinator interactions are an important component of the study of the overall ecological setting of a plant species. Here, we report two species of sphingids as pollinators of Cereus aethiops, a wide-spread shrubby columnar cactus species from the Argentinian Monte vegetation. Cereus aethiops is remarkable for its desiccation tolerance during the dry winter season and rapid rehydration after the first rainfall during the summer season. Rehydration starts within 24 hours after the start of the first significant rain, and is complete within 7 to 10 days. Flower bud initiation is triggered by the first rainfall event, and the time from the first rain to the start of the flowering season shows little year-to-year variation. The flowers conform to the sphingophilous pollination syndrome, and the expected sphingid pollinators could be confirmed by direct observation. Diurnal plant-insect interactions in C. aethiops are insignificant and most likely do not contribute significantly to reproductive output.

The relationship between succulents and herbivores at Gonarezhou are discussed. The savannah of Africa is known for its dense herbivore population. Herbivores and succulents co-evolved—the latter having juicy stems and leaves-but how do succulent plants cope in a hostile semi-arid environment ruled by mega herbivores? The deterioration of baobabs due to elephant utilization is a good thermometer of savannah health.

In 1980, Cutler and his colleagues carried out an investigation of the tetraploid shrubby species of Aloe in Kenya, which include A. nyeriensis Christian and A. kedongensis Reynolds. They concluded that they had evolved from a form very close to the diploid Aloe morijensis S. Carter & Brandham in which chromosome doubling had occurred, followed by spreading northwards of Morijo in Narok County. However, A. morijensis has fibres in the leaves in place of the aloitic cells that produce distinctive exudates in most aloes, including the tetraploid shrubby species. A return to aloitic cells from fibres would be a reverse of an evolutionary trend, and is unlikely. Hence, this conjectured origin of the shrubby species and their relationship with A. morijensis was investigated using anatomical characters not employed in the previous investigations by Cutler et al. The presence of lignified cells was seen in the base, middle and apex of the lamina of A. morijensis while in the case of the tetraploid shrubby species only aloitic cells were found. These results suggest that it is very unlikely that A. morijensis is the ancestor of the tetraploid shrubby aloes.

Ruschia dichroa (Rolfe) L.Bolus is endemic to a semi-arid, mountainous region within the Western Cape, South Africa. This species has often been confused with Ruschia marianae (L.Bolus) Schwantes and Astridia longifolia (L.Bolus) L.Bolus, since all three species have a similar chunky leaf morphology, are fairly large-flowered and may have reddish petaloid staminodes. Astridia longifolia only occurs in northern Namaqualand and is thus geographically well separated from the others, which are both found in the Wuppertal district of the Western Cape. The flowers of Ruschia dichroa differ from those of R. marianae by the presence of filamentous staminodes, which are collected into a cone around the stamens. In addition, the two species flower at different times, with R. marianae flowering from July to September and R. dichroa earlier in winter, from May to July. If not in flower, the two species can be separated by their different habit, R. marianae forming an erect shrub, whereas R. dichroa has a lower, more compact habit with decumbent, spreading branches. Ruschia dichroa differs from both A. longifolia and R. marianae by the finely serrated keels on its leaves, which are smooth in the other two species.

An new locality for Aloe scorpioides Leach from the Serra das Neves is reported. An amplified description is given, noting differences between the plants at the two localities

Some confusion exists regarding the application of the name Aloe ×nobilis Haw. to what is arguably the most widely cultivated, named Aloe L. hybrid in Mediterranean Europe. We show that the name is to be applied to a low-growing, multi-rosette hybrid that likely originated in Europe and does not occur naturally in South Africa. The name Aloe ×nobilis Haw. is neotypified with a Salm-Reifferscheid-Dyck plate published in 1863.

A new subspecies of the widespread C. woodii is named, originating from sheer cliff faces of the lower Kei River in the Eastern Cape, Republic of South Africa.

Four new taxa of the genus Echeveria from the Mixteca Alta region, Oaxaca, are described and illustrated: Echeveria longissima subsp. brachyantha, E. nuyooensis, E. triquiana, and Echeveria uhlii subsp. coelestis. The first is a variant of Echeveria longissima var. longissima and E. longissima var. aztatlensis from which it differs mainly in the shorter corolla, short pedicels, longer stems and its habitat above 2500 m to the south of the localities of the two other known taxa in the series Longistylae E. Walther. The second taxon belongs to series Spicatae (Baker) A. Berger and is related to E. australis (Nudae), E. pittieri and E. tencho. Its distinguishing factors are size of the floral stem, inflorescence in form of a thyrse, and white nectaries. The third taxon is compared to E. fulgens and E. gibbiflora from which it differs mainly in shorter stems, short floral stem, pink-colored corolla, thick leaves, and white nectaries with reddish margins. The fourth taxon is a subspecies of E. uhlii of series Racemosae (Baker) Berger, differing in its bigger size.

A new Cotyledon is described from the Goukou River near Stilbaai in the Western Cape. Cotyledon lutea is a distinct, semi-scandent plant from the thicket vegetation of the Goukou Rivier. It differs from other Cotyledon species by its yellow flowers on long pedicels bearing transversely oblong emarginate squamae. At 3 mm in diameter, these are the largest recorded for the genus Cotyledon.

A new combination, Sedum ×estrelae (Gideon F.Sm. & R.Stephenson) Gideon F.Sm. (Crassulaceae), for a nothospecies in Sedum series Rupestria A.Berger (= Petrosedum Grulich) from central Portugal is published here. It is a natural hybrid between Sedum forsterianum Sm. and Sedum sediforme (Jacq.) Pau.

Crassula montana subsp. borealis, a new, dwarf, cliff-hugging succulent, is described from the quartzitic sandstone cliffs along the Skaaprivierspoort (N.W. of Springbok). It has also been found on the upper slopes of the saw-edged peaks of the Rosyntjieberg (Richtersveld) in the Northern Cape and is known from only these two populations. The cup-shaped rosettes of broadly ovate leaves, which are pitted, immediately distinguish it from C. montana subsp. montana and C. pseudohemisphaerica.

The Colorado hookless cactus (Sclerocactus glaucus) has been protected under the Endangered Species Act since October 11, 1979, as part of the Uintah hookless cactus complex. On September 15, 2009, the U.S Fish and Wildlife Service officially recognized the taxonomic split of this species complex into three distinct species: S. brevispinus (Pariette cactus), S. glaucus (Colorado hookless cactus), and S. wetlandicus (Uinta Basin hookless cactus). Since the date of this taxonomic split, there have been few scientific publications specific to the Colorado hookless cactus. I prepared an annotated bibliography for S. glaucus because limited specific scientific information is available. Citations include information on the legal status, description, distribution, habitat, adaptation, management and monitoring, pests and problems, and seeds and plant production of S. glaucus and other closely-related cactus species.

The bibliography is organized by families. The format of these entries places the title first, with titles alphabetized, for quick scanning of topics. Author and publication information follows, as well as, in most cases, a sentence or two intended as a very brief summary.