A Taxonomic Revision of the Southern African Native and Naturalized Species of Silene L

Bothalia 42,2: 147–186 (2012) A taxonomic revision of the southern African native and naturalized species of Silene L. (Caryophyllaceae) J.C. MAnnIng* and P. gOLDBLATT** Keywords: Caryophyllaceae, new species, seed morphology, Silene L., southern Africa, taxonomy ABSTRACT The native and naturalized species of Silene L. in southern Africa are reviewed, with full synonomy and the description of two new species from the West Coast of Western Cape. Eight native species and three naturalized species are recognized, including the first identification in southern Africa of the Mediterranean S. nocturna L. The identity of S. aethiopica Burm., which has remained unknown since its description, is established and is found to be the oldest name for S. clandestina Jacq. Patterns of morphological variation within each species are discussed and subspecies are recognized for geographically seg- regated groups of populations that are ± morphologically diagnosable. The following new names or combinations are made among the southern African taxa: S. aethiopica subsp. longiflora; S. burchellii subsp. modesta, subsp. multiflora, and subsp. pilosellifolia; S. crassifolia subsp. primuliflora; S. saldanhensis; S. rigens; and S. undulata subsp. polyantha. Each taxon is described, with information on ecology and distribution, and most species are illustrated, including SEM micrographs of the seeds. InTRODuCTIOn trich (1993) using a combination of trivial characters, and his recognition of the two appears to have been pro- Silene L. (tribe Sileneae), with 600–700 species visional until Silene could be conserved against Lychnis, (greuter 1995b), is distributed mainly through the tem- under which name it had earlier been included by Sco- perate regions of the northern Hemisphere, with its prin- poli (1771). The generic name Lychnis therefore took cipal centre of diversity in the Mediterranean and Mid- priority until it was formally rejected in favour of Silene dle East (Oxelman & Lidén 1995). Over 90 species are (Brummit 1994). recorded in Africa, the vast majority in north Africa, with very few extending southwards into sub-Saharan There are currently two opposing views on generic Africa. Just three native and one introduced species of delimitation in Sileneae. The first, advocated by greuter Silene are known from south tropical Africa (Turrill (1995b), is an inclusive one that recognizes just the two 1956a; Wild 1961), with several additional species cur- genera Agrostemma and Silene. In this sense, Silene is rently accepted in southern Africa. broadly distinguished within subfamily Caryophylloi- deae (Bittrich 1993) by its actinomorphic flowers with Consensus has still to be reached on the delimita- 3 or 5 styles. The alternative view, recently developed tion of Silene. The circumscription of the genus had by Oxelman et al. (2000), proposes the partitioning been gradually expanded over the last few decades of of Silene among seven genera, of which only Lychnis the twentieth century until it coincided essentially with (30 spp.) includes more than a handful of species. The the delimitation of tribe Sileneae (greuter 1995b). This clade that constitutes Silene in this narrow sense is only consolidation was supported by a preliminary molecu- weakly supported in the molecular analysis and is also lar sequence analysis of the tribe (Oxelman & Lidén not easily diagnosed morpholgically from its segregates. 1995), which nested all previously recognized genera Although we favour a more inclusive circumscription of of Sileneae in Silene, with the possible exception of the genus, the native and introduced southern African Agrostemma L., but had been presaged by the break- species are all included in Silene either way. down of morphological differences between recognized segregates when these were examined on a global scale. We follow the infrageneric classification of Silene Cucubalus L., which is deeply nested in Silene, is dis- s. lat. proposed by greuter (1995b), based largely on tinguished primarily by its berry-like fruits, which evi- Chowdhuri (1957) with some rationalization and sev- dently represent a specialized dispersal strategy. Lychnis eral nomenclatural corrections. Although there is mount- L., which forms a discrete clade within Sileneae, was ing evidence (Petri & Oxelman 2011) that at least some traditionally diagnosed by having capsules with as many of these sections are not monophyletic, no satisfactory teeth as styles (vs. twice as many in Silene) (e.g. Chow- alternative has yet been offered. Significant characters dhuri (1957) and Chater & Walters (1964)) but the two at sectional level are the type of inflorescence, presence genera were diagnosed only with great difficulty by Bit- or absence of septa in the ovary, number of styles, shape and venation of the calyx, number of teeth in the dehisc- * Compton Herbarium, South African national Biodiversity Institute, ing capsule, and the shape of the seeds. Private Bag X7, Claremont 7735, South Africa / Research Centre for Plant growth and Development, School of life Sciences, university of Four global treatments have laid the foundations KwaZulu-natal, Pietermaritzburg, Private Bag X01, Scottsville 3209, for our present understanding of the genus (Otth 1824; South Africa. E-mail: [email protected]. ** B.A. Krukoff Curator of African Botany, Missouri Botanical garden, Rohrbach 1869, 1869–1870; Williams 1896; Chow- P.O. Box 299, St. Louis, Missouri 63166, uSA. E-mail: peter.gold- dhuri 1957), and several modern regional treatments of [email protected]. the European species have also been published (greuter MS. received: 2011-12-19. 1995b and references therein). Regional floristic studies 148 Bothalia 42,2 (2012) exist for parts of north Africa (Wickens 1976; gilbert ranks may be useful in some instances, such as in S. 2000) and much of sub-Saharan Africa (Turrill 1956a; aethiopica, where subsp. longiflora may be better treated Wild 1961) but the taxonomy of Silene in southern at the level of forma. The genetics of the maritime forms Africa still rests largely on Sonder’s (1860) treatment in of S. aethiopica and S. undulata also require investiga- Flora capensis, and only minor advances in our under- tion. Our intention, therefore, is to present a preliminary standing of the southern African species have been made classification that can form the basis for future experi- since then (Rohrbach 1869, 1869–70; Bocquet 1977; mental studies in the genus. Masson 1989; goldblatt & Manning 2000). The South African species of Silene are unique among the flora Another intriguing aspect of the genus is its history of the subregion in having been fundamentally misun- and diversification in southern Africa. The indigenous derstood by Thunberg (1794), who misidentified the species are currently distributed among three sections, majority of his collections as European species (Table all of which are best represented in the northern hemi- 1), leaving it to later authors to recognize that they were sphere and presumably originated there. Silene burchel- indigenous to the country and undescribed. Burman lii (sect. Fruticulosae) is widely distributed through the (1768) had earlier made the same mistake, identifying as eastern half of the continent, from Ethiopia (and Arabia) European all but two (S. crassifolia L. and S. aethiopica to the Cape Peninsula in the extreme south, and the most Burm.) of the eight species that he listed from the Cape. parsimonious interpretation is that the species migrated Two previous attempts at revising the southern African from north Africa southwards along the East African species, by g. Bocquet in the 1970s and D. Masson in Afromontane corridor. Silene undulata (sect. Elisan- the 1980s, were never completed but many of the south- the), in contrast, is largely southern African, extending ern African herbarium collections bear annotation labels only as far north as the highlands of eastern Zimbabwe, reflecting Masson’s unpublished species concepts and and its origin in southern Africa remains unclear but names, adding further to the confusion. This revision of long-distance dispersal appears to be more likely. Both Silene in southern Africa aims to redress the situation sections have subsequently undergone minor adaptive and provide a base for future studies of the genus in the radiation in the coastal regions of the subcontinent. The subcontinent. This is especially important as the South third lineage is represented by S. aethiopica (sect. Dip- African winter rainfall region is a minor centre of diver- terospermae), the only native southern African annual sification for Silene in Africa. species. Essentially endemic to the winter-rainfall region in the extreme south and southwest, with no track in Species delimitation in the genus is notoriously dif- tropical Africa, S. aethiopica most likely arrived in the ficult and most African species, especially those with subcontinent through long-distance dispersal. a wider distribution, display a complex and often con- fusing pattern of local variation that defies formal classification (gilbert 2000). The primary reason for this is MATERIALS AnD METHODS almost certainly that the species are often facultatively autogamous, which facilitates the differentiation of local All relevant types were examined, as well as all her- phenotypes, probably independently and repeatedly. barium material from BOL, MO, nBg, PRE, and SAM Population genetic studies are likely to shed significant (acronyms after Holmgren et al. 1990), the primary col- light

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