Ernst J. Van Jaarsveld

Nectar sugar composition in the subfamily Alloideaec (Aphodelaceae)

Abstract HPLC analyses of nectar samples from 82 species of the genera Aloe, Astroloba, Chortolirion, Gasteria, Haworthia, Kniphofia, Lomatophyllum and Poelnitzia have shown that the sugar compoisition of nectar is remarkably invariable within each of the genera. In the Alloideae, distinct suprageneric groups can be distinguished, based only on the relative proportions of sucrose, glucose and fructose. Three nectar types are present in the subfamily: (1) an alooid type (in Aloe, Kniphofia, Lomatophyllum and Poellinitzia) with less than 5% sucrose and equal proportions of glucose and fructose; (2) a gasterioid type (in Gasteria only) with sucrose dominant and equal proportions of glucose and fructose; (3) a haworthioid type (in Astroloba, Chortolirion and Haworthia) with sucrose dominant but with much more glucose than fructose.

Phylogenetics and diversification of Cotyledon (Crassulaceae) inferred from nuclear and chloroplast DNA sequence data.

Crassulaceae includes approximately 35 genera and 1500 species of leaf and stem succulent flowering plants. The family is nearly cosmopolitan in distribution, but is particularly diverse in southern Africa, where five genera comprising approximately 325 species are found. One of these genera, Cotyledon, includes 10 species that are largely confined to South Africa, where they are commonly found on rocky hillsides, coastal flats, and cliff faces. Species of Cotyledon are characterized by five-parted, pendulous, sympetalous flowers, but the genus is highly diverse in growth form, flower color and size, and leaf morphology. One particularly variable species, C. orbiculata, has been divided into five varieties based on leaf morphology and biogeography; however, the monophyly of this species as well as the relationships among the varieties have not previously been investigated. Parsimony analyses of a combined data set of DNA sequences from chloroplast and nuclear genome provided the first estimate of phylogeny for Cotyledon, and resulted in two minimum-length trees and a fully resolved phylogeny for the genus. Results indicate that C. orbiculata is not monophyletic and suggest the need for additional studies and a revised classification within the genus.

Cotyledon lutea, a New Species from the Western Cape, Republic of South Africa

Abstract: 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.

Analyses of cpDNA matK sequence data place Tillaea (Crassulaceae) within Crassula

Analysis of cpDNA matK sequences for a total of 43 members of the succulent plant family Crassulaceae, including 24 taxa of Crassula, recovered a well-supported clade comprising Crassula species that is sister to the remainder of the family. The resulting topologies do not support the monophyly of the currently recognized subgenera of Crassula, as one member of subgenus Disporocarpa (C. crenulata) is placed as sister to an otherwise monophyletic subgenus Crassula. The major synapomorphy that has been used to recognize the latter subgenus is a base chromosome number of xxa0=xa07 versus a base of xxa0=xa08 in the other subgenus. We cannot assess the utility of this feature for defining subgenus Crassula because a chromosome count of C. crenulata has yet to be published. The five accessions of the recently resurrected segregate genus Tillaea (of 24 total Crassula species) included here were placed in four separate, well-supported lineages, one of which is greatly removed from the other four accessions. This suggests that this genus is not valid and should not be recognized. An initial examination of the evolution of habit indicates that a perennial habit is ancestral and that the annual habit is a feature that has been derived at least twice in the genus.

Bulbine dewetii, a New Cliff-Dwelling Bulbine Species (Asphodelaceae) from the Western Cape

Abstract: n Bulbine dewetii (Asphodelaceae) is named; it is an obligatory geophytic cremnophyte from the sheer rock faces of the lower southern slopes of the Heks River Mountains (Western Cape, South Africa). Bulbine dewetii usually grows solitary (rarely proliferating and forming small groups) with soft pendent leaves, flowering during the month of November (late spring, S. Hemisphere), the flowers open during the afternoon and remain open during the night. The description of this taxon forms part of an extensive survey of cliff-dwelling succulent and bulbous-succulent taxa in South Africa and Namibia.

Extending the Natural Distribution Range of Astroloba herrei Uitewaal (Asphodelaceae: Alooideae): Implications for Its Conservation Status

Abstract: n Astroloba herrei Uitewaal (Asphodelaceae: Alooideae) is currently regarded as one of the rarest and most threatened species in the genus. The species is mostly recorded as having a small, restricted geographical distribution range, as well as a habitat that is vulnerable due, in part at least, to its proximity to human activity. Its distribution range is interpreted as disjunct, as the species is considered to be restricted to two widely separated areas: 1.) the immediate surrounds of Prince Albert in the Great Karoo, Western Cape Province, South Africa, and 2.) a contested spot north of Uniondale in the Little Karoo. We hypothesised that these two areas, separated by 100 km [60 miles], were contiguous, but not through the most frequented routes connecting these two spots. Map overlays for vegetation type, soil type, and geology were used to predict likely habitats in the more inaccessible region through which the areas could be connected, specifically along the northern (Great Karoo) slopes of the Swartberg. Based on the results, the most likely potential localities were identified and visited, and the species was found where predicted. Ground-truthing of the predicted range therefore confirmed that A. herrei is in fact far more widespread than previously believed. Its distribution stretches from west of Prince Albert, along the eastern Swartberg, and across the provincial border into the Eastern Cape Province, where it occurs along the R407 road that connects Prince Albert to Willowmore. At the eastern edge of its range it crosses the Swartberg to the south, and occurs north of Uniondale. Significantly, A. herrei has a natural range which in size by far outstrips that of a number of other Astroloba species. Based on the results of our work we propose that the conservation status of Astroloba herrei be changed from “Vulnerable D2” to “Least Concern”.

Gasteria koenii, a New Gasteria Species from the Swartberg, Western-Cape, South Africa

Abstract: n A new species of Gasteria from the Klein Karoo near Calitzdorp is named, differing from G. brachyphylla by its leaves which are spirally arranged and larger keeled, as well as its flowering which is during summer and autumn.

Astroloba tenax var. moltenoi Gideon F.Sm. & Van Jaarsv. (Asphodelaceae: Alooideae), a new variety in Astroloba tenax Molteno, Van Jaarsv. & Gideon F.Sm. from the south-central Groot Karoo, South Africa

Summary: n A new variety, Astroloba tenax Molteno, Van Jaarsv. & Gideon F.Sm. var. moltenoi Gideon F.Sm. & Van Jaarsv., is described in A. tenax (Asphodelaceae: Alooideae). While in most characters very similar to A. tenax var. tenax, it differs consistently by being a stable, gigantic, nature-based form of the species. This variety, which geographically does not overlap with A. tenax var. tenax, the typical variety, can be easily separated on its size alone. A. tenax var. moltenoi occurs naturally in the south-central Groot Karoo, near Prince Albert in the Western Cape Province, South Africa. The species is illustrated and a map is provided of its geographical distribution range.

Kalanchoe waterbergensis, A new Kalanchoe species from the Waterberg, Limpopo Province, South Africa

Summary: Kalanchoe waterbergensis is described from the western Waterberg margin, just east of Thabazimbi and south of the Kransberg and Marakele National Park (Limpopo Province). Kalanchoe waterbergensis is a distinct succulent from the quartzitic sandstone soils growing on gravelly slopes and rocky terrain in savanna. It differs from Kalanchoe rotundifolia by its glaucous leaves which are auriculate at the base and leaf orientation as well as floral features.

Astroloba robusta P.Reinecke ex Molteno, Van Jaarsv. & Gideon F.Sm. (Asphodelaceae: Alooideae), a new species from the Great Karoo, South Africa

Summary: Astroloba robusta P.Reinecke ex Molteno, Van. Jaarsv. & Gideon F.Sm. (Asphodelaceae: Alooideae) is described as a new species. This species occurs across an extensive geographical distribution range that spans the southern Great Karoo, where it occurs on shale flats and rocky undulating slopes. It is related to, but distinct from, A. foliolosa (Haw.) Uitewaal, which occurs further to the east. Astroloba robusta is immediately distinguished by its unique inflorescence with a robust peduncle, as well as its glossysurfaced leaves with whitish margins and keels, among other characters. It also flowers in winter (May–October, mainly in July and August), while A. foliolosa flowers over summer (August–March, mainly October–January).