Figure 5 - uploaded by Alan R Wood
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Transverse section through one of the longitudinal ridges on the cypsela of Osteospermum potbergense showing epidermis (ep), fleshy layer of thin walled cells (fl), and cypsela wall of sclerified cells (cw). Scale bar = 30µm
Source publication
The new species Osteospermum potbergense A.R. Wood & B. Nord. (Asteraceae–Calenduleae) is described from the Potberg, Western Cape Province, South Africa. This procumbent shrublet is distinguished from all closely related species in Osteospermum and Chrysanthemoides by its coriaceous spathulate or oblanceolate to elliptic-obovate leaves which have...
Contexts in source publication
Context 1
... the distinct leaf margins are cartilaginous and somewhat revolute, and the cypsela is not a fleshy 'drupe', but only has a very thin fleshy outer layer (like other species of sect. Homocarpa) without striking colours ( Figure 5). This subtle character is only observable on fresh material. ...
Context 2
... this layer is the seed coat, which is ornamented, having usually three equidistant main ridges along the whole seed and with smaller parallel twin ridges in between, and finally single small and incomplete ridges between the main and second- ary (twin) ridges. The ridges have vascular bundles which can be seen in cross section ( Figure 5). As the mature fruit dries, the seed coat becomes black or brownish with the ridges becoming visible and prominent, and the epidermis is shed. ...
Citations
... Norlindh recognized the genus on the basis of the presence of drupes in Chrysanthemoides. However, semidrupacious fruit have been reported in other species of Osteospermum, Wood and Nordenstam, 2003). The evolution of drupes is extremely rare in the Compositae, and as far as is known is restricted to this group. ...
... This move left Gibbaria as a monotypic genus until a second species was recently added by a transfer from Osteospermum (Nordenstam and Källersjö, 2009). Norlindh (1943)Wood and Nordenstam, 2003). The evolution of drupes or fruits with a fleshy exocarp is extremely rare Available online at www.sciencedirect.comTable 1 Comparison of the species and infraspecific taxon names recognized by Norlindh (1943) and the unpublished entities recognized by Griffioen (1995), with key characteristics of each entity provided. ...
... and Coriacea T. Norl.) were selected in order to test generic monophyly. Only species from these sections were considered, as other studies have indicated a close relationship between Chrysanthemoides and these sections of Osteospermum (Wood and Nordenstam, 2003; Nordenstam and Källersjö, 2009). It should be noted that O. subulatum DC. (of sect. ...
... Trialata in Norlindh, 1943) and O. triquetrum (unassigned to section in Norlindh, 1943) were transferred to sect. Homocarpa by Wood and Nordenstam (2003). The more distantly related Tripteris microcarpa Harv. ...
The small genus Chrysanthemoides comprises two species within which a number of infraspecific taxa have been recognized, some of which are invasive aliens in Australia and New Zealand. Here we investigate the relationships of the species and infraspecific taxa using both chloroplast and nuclear non-coding DNA sequence data. Results of the analyses of the plastid and nuclear data sets are incongruent, and neither Chrysanthemoides nor Osteospermum is resolved as monophyletic, although there is some support for the recognition of infraspecific taxa. Analyses of the separate and combined data sets resolve two clades within Chrysanthemoides (which include some species of Osteospermum), and these appear to have a geographic basis, one being restricted to the mainly winter rainfall region, the other the eastern bi-seasonal rainfall area. Our results suggest that there is evidence of past or ongoing hybridization within and possibly between these two lineages.
Comprising an area of ±90 000 km2, less than 5% of the land surface of the southern African subcontinent, the Cape Floristic Region (CFR) is one of the world's richest areas for plant species diversity. A recent synoptic flora for the Region has established a new base line for an accurate assessment of the flora. Here we document corrections and additions to the flora at family, genus and species ranks. As treated in Cape plants, which was completed in 1999, the flora comprised 173 families (five endemic), 988 genera (160 endemic: 16.2%), and 9 004 species (6 192 endemic: 68.8%). Just four years later, a revised count resulting from changes in the circumscriptions of families and genera, and the discovery of new species or range extensions of species, yields an estimate of 172 families (four endemic), 992 genera (162 endemic: 16.3%) and 9 086 species (6 226: 68.5% endemic). Of these, 948 genera and 8 971 species are seed plants. The number of species packed into so small an area is remarkable for the temperate zone and compares favourably with species richness for areas of comparable size in the wet tropics. The degree of endemism is also remarkable for a continental area. An unusual family composition includes, in descending order of size, based on species number, Asteraceae, Fabaceae, Iridaceae, Ericaceae, Aizoaceae, Scrophulariaceae, Proteaceae, Restionaceae, Rutaceae, and Orchidaceae. Disproportionate radiation has resulted in 59.1% of the species falling in the 10 largest families and 74.6% in the largest 20 families. Thirteen genera have more than 100 species and the 20 largest genera contribute some 31.5% of the total species number.
The tribe Calenduleae of the Compositae (Asteraceae) has a pronounced centre of diversity in South Africa, particularly in Cape Province. The largest genus, Osteospermum L., contains c.50 species in Africa and southwestern Arabia, including about 40 in Cape Province. Two new species are described here, both narrowly endemic in southwestern Cape Province. Osteospermum
australe is confined to lowland coastal limestone areas in Bredasdorp district, whereas Osteospermum
burttianum has a restricted distribution in the Langebergen mountains in Heidelberg district.
Endophyllum osteospermi is an autoecious, endocyclic rust fungus, which has only been recorded on Chrysanthemoides monilifera ssp. monilifera (Asteraceae, Calendulae), a perennial woody shrub. Both organisms are indigenous to South Africa. Because E. osteospermi is being considered for release in Australia as a biocontrol agent against C. monilifera ssp. monilifera, it was necessary to determine its host range and natural distribution in South Africa. To address this, natural stands of Chrysanthemoides species, as well as other South African asteraceous plants, were monitored for E. osteospermi between 1992 and 2003. A morphological and molecular comparison of specimens referable to Endophyllum was undertaken. Based on these results, E. osteospermi was recorded on C. monilifera sspp. monilifera, pisifera, rotundata, canescens, and subcanescens, C. incana, and an undescribed taxon. E. osteospermi was also recorded on Osteospermum ciliatum, O. pollgaloides, and O. potbergense. Furthermore, a closely related but previously undescribed species, E. dimorphothecae sp. nov. is described on Dimorphotheca cuneata. Aecidium elytropappi is transferred to Endophyllum as E. elytropappi comb. nov., being recorded on Elytropappus rhinocerostis and Stoebe plumosa. This study shows that in South Africa E. osteospermi is restricted to a small group of related plant species in the Calenduleae. This rust is therefore considered suitable as a candidate agent for the biocontrol of C. monilifera ssp. monilifera, and pending the results of host specificity testing, would most likely be safe to introduce into Australia.
