Elizabeth M. Marais

Cytological variation and evolution withinPelargonium sectionHoarea (Geraniaceae)

Chromosome numbers of 65 species of sect.Hoarea have been determined. These show three basic chromosome numbers, x = 11, 10 and 9. Only a few species are tetraploid. In five species both diploid and tetraploid cytotypes are reported. Several cases of deviations in chromosome numbers and cytological abnormalities were found, most of these being related to the presence of B chromosomes that occur in eight species. Evidence is presented to suggest that the basic chromosome numbers of x = 10 and x = 9 are derived from x = 11 by centric fusion. Although variation in basic chromosome number withinPelargonium has been the subject of detailed study, this is the first time that evidence has been found for a mechanism of change in basic number, that of centric fusion by Robertsonian translocation. For the species of sect.Hoarea with x = 9, where the evidence for Robertsonian translocation is greatest, this process has probably taken place quite recently. In contrast to results from other sections of the genusPelargonium, the three different basic numbers of sect.Hoarea do not contradict its delimitation as a natural taxon.

Phylogenetic influences on leaf trait integration in Pelargonium (Geraniaceae): Convergence, divergence, and historical adaptation to a rapidly changing climate

PREMISE OF THE STUDY Trait integration may improve prediction of species and lineage responses to future climate change more than individual traits alone, particularly when analyses incorporate effects of phylogenetic relationships. The South African genus Pelargonium contains divergent major clades that have radiated along the same seasonal aridity gradient, presenting the opportunity to ask whether patterns of evolution in mean leaf trait values are achieved through the same set of coordinated changes among traits in each clade. METHODS Seven leaf traits were measured on field-collected leaves from one-third of the species (98) of the genus. Trait relationships were examined using phylogenetic regression within major clades. Disparity analysis determined whether the course of trait evolution paralleled historical climate change events. KEY RESULTS Divergence in mean trait values between sister clades A1 and A2 was consistent with expectations for leaves differing in longevity, despite strong similarity between clades in trait interactions. No traits in either clade exhibited significant relationships with multivariate climate axes, with one exception. Species in clades C and A2 included in this study occupied similar environments. These clades had similar values of individual trait means, except for δ(13)C, but they exhibited distinctive patterns of trait integration. CONCLUSIONS Differing present-day patterns of trait integration are consistent with interpretations of adaptive responses to the prevailing climate at the time of each clades origin. These differing patterns of integration are likely to exert strong effects on clade-level responses to future climate change in the winter rainfall region of South Africa.

Anatomical adaptations in the leaves of selected fynbos species

Fynbos plants experience very harsh conditions during the hot and dry summer months and their leaves are adapted to reduce the loss of water due to transpiration. The leaves of 46 selected fynbos species of 24 families were examined to determine which anatomical adaptations contribute to the reduced rate of transpiration and subsequent reduced water loss. Without exception, all species examined show leaf adaptations typical of xerophytic species. Four typical leaf types are recognized and proposed as models of leaf adaptation: 1. Myrsine type — dorsiventral or isobilateral leaves; more palisade parenchyma present than spongy parenchyma; tissues contain large amounts of phenolic substances. 2. Metalasia type — small dorsiventral leaves with involute margins and a single groove in the adaxial surface; mesophyll is usually inverted. 3. Retzia type — dorsiventral or isobilateral leaves with revolute margins and one or two grooves in the abaxial surface; spongy parenchyma is the main component of the mesophyll. 4. Spatalla type — small centric or near-centric leaves; little or no spongy parenchyma tissue.

Four new species of Pelargonium (Geraniaceae) from the western Cape Province

Pelargonium aciculatum E.M. Marais, P. confertum E.M. Marais, P. fasciculaceum E.M. Marais and P. connivens E.M. Marais are described as new species. All four are tuberous species, belonging to the section Hoarea (Sweet) DC. They correspond on account of their leaf structure and the structure of the androecium. The pollen morphology and the leaf anatomy support this close relationship of the four species. An illustration of each species and a distribution map are provided.

Pelargonium torulosum (Geraniaceae): a new species from the south-western Cape Province, southern Africa

Pelargonium torulosum E.M. Marais, is described as a new species. It resembles P. histrix Harv. and P. stipulaceum (L.f.) Willd. on account of its floral structure, succulent stem and closely spaced leaves. The pollen morphology of the three species as well as the stem and leaf anatomy are compared. An illustration and a distribution map are provided, as well as illustrations of anatomy and pollen.

Section Reniformia, a new section in the genus Pelargonium (Geraniaceae).

A new section of Pelargonium L’Heerit. (Geraniaceae), section Reniformia (Knuth) Dreyer is described in which 8 species and 2 subspecies are included. Pelargonium reniforme Curt, is designated as the type species for the section. All included species are endemic to southern Africa, with the majority of taxa centred in the Eastern Cape Province Section Reniformia is characterised by its floral structure, a basic chromosome number of x = 8 and pollen grains with a striate-reticulale tectum.

A taxonomic revision of the Pelargonium pinnatum species complex (Geraniaceae)

The Pelargonium pinnatum species complex of section Hoarea (Sweet) DC. consists of geophytes with similar pinnate leaves. Macromorphological, anatomical and palynological studies were done to delimit the species and determine their relationship. Three species, P. pinnatum (L.) L’Herit., P. viciifolium DC. and P. trifoliolatum (Eckl. & Zeyh.) E.M. Marais comb. nov., are recognized. Although the species have similar pinnate leaves, their floral structures differ to such an extent that they cannot be regarded as closely related species within section Hoarea.

A taxonomic reassessment of the varieties of Oxalis minuta (Oxalidaceae) and the change of O. minuta var. callosa to specific rank as O. hygrophila

O . minuta Thunb. var. callosa Salter was included in section Sagittatae of the genus Oxalis L., based on superficial morphological resemblance to O . minuta var. minuta . We questioned this placement due to the reticulate pollen grains displayed by this taxon, whereas members of section Sagittatae have rugulate-reticulate pollen grains. A lack of good herbarium and living specimens prohibited a better taxonomic placement of this taxon. Living plants were recently found in the Pakhuis Pass (Western Cape, South Africa), which enabled this re-assessment of its taxonomic affinities. A suite of morphological and palynological characters were identified that differ significantly from both the typical variety and all other members presently included in section Sagittatae . These include the ovate to elliptic anthers, the orientation of long and mid-level reproductive organs, the absence of an indumentum on the leaves, the presence of calli on the leaflets, sepals and petals, reticulately deposited epicuticular wax on the leaves, the broadly funnel-shaped corolla tube and the basally fused anthers. We therefore raise Oxalis minuta var. callosa to specific rank as O . hygrophila Dreyer, and transfer it from section Sagittatae to section Latifoliolatae .

Biosystematic study of Pelargonium section Ligularia: 4. The section Ligularia sensu stricto

The macromorphology, palynology, karyology, cpDNA trnL-F sequences and phenolic components of P appendiculatum (L f) Willd., P crassipes Harv., P fulgidum (L) L’ Herit, P. hirtum (Burm f) Jacq, P. hystrix Harv., P oreophilum Schltr., P pulchellum Sims, P sericifolium J.J.A v.d. Walt, P.stipulaceum (L f.) Willd and P. torulosum E M Marais were studied It is concluded that these 10 species are related and that they should be grouped in a single section

Four species of Pelargonium, section Hoarea (Geraniaceae) and their possible relationships

A description and an illustration of each of the four species are given, Pelargonium aestivale E.M. Marais is described as a new species, the synonyms for P. fissifolium (Andr.) Pers. are given, the illegitimate name P. pilosum Pers, is replaced by P. petroselinifolium G. Don, and P. aristatum (Sweet) G, Don is reinstated as a species. All of them are tuberous species, belonging to section Hoarea (Sweet) DC, The four species have a similar chromosome number, and macromorphological, anatomical and palynological studies were done to delimit the species and determine their relationships. Although the chromosome numbers of the four species distinguish them from the rest of the species in section Hoarea , and although they have several characters in common, these characters are not unique within the section.