Global InformationList of Saxifragales of South Africa information
Saxifragales (saxifrages) is an order of flowering plants (Angiosperms). They are an extremely diverse group of plants which include trees, shrubs, perennial herbs, succulent and aquatic plants. The degree of diversity in terms of vegetative and floral features makes it difficult to define common features that unify the order.
In the Angiosperm Phylogeny Group classification system, the Saxifragales are placed within the major division of flowering plants referred to as eudicots, specifically the core eudicots. This subgroup consists of the Dilleniaceae, superasterids and superrosids. The superrosids in turn have two components, rosids and Saxifragales. The Saxifragales order has undergone considerable revision since its original classification based purely on plant morphology, to a classification based on molecular phylogenetics. There is an extensive fossil record from the Turonian-Campanian (late Cretaceous) time, about 90 million years ago (Myr), but molecular studies suggest an earlier origin in the early Cretaceous (102–108 Myr) with rapid early diversification to more modern forms.
The order Saxifragales consists of 15 families, about 100 genera and 2,470 species. Of the 15 families, many are small, with 8 having only a single genus, the largest family being the Crassulaceae (stonecrops) with about 35 genera. Saxifragales are found worldwide, though rarely in the tropics, and in a wide variety of habitats from desert to aquatic. They also have a wide variety of uses, from timber to foodstuffs and ornamental plants.
The anthophytes are a grouping of plant taxa bearing flower-like reproductive structures. They were formerly thought to be a clade comprising plants bearing flower-like structures. The group contained the angiosperms - the extant flowering plants, such as roses and grasses - as well as the Gnetales and the extinct Bennettitales.[1]
23,420 species of vascular plant have been recorded in South Africa, making it the sixth most species-rich country in the world and the most species-rich country on the African continent. Of these, 153 species are considered to be threatened.[2] Nine biomes have been described in South Africa: Fynbos, Succulent Karoo, desert, Nama Karoo, grassland, savanna, Albany thickets, the Indian Ocean coastal belt, and forests.[3]
The 2018 South African National Biodiversity Institute's National Biodiversity Assessment plant checklist lists 35,130 taxa in the phyla Anthocerotophyta (hornworts (6)), Anthophyta (flowering plants (33534)), Bryophyta (mosses (685)), Cycadophyta (cycads (42)), Lycopodiophyta (Lycophytes(45)), Marchantiophyta (liverworts (376)), Pinophyta (conifers (33)), and Pteridophyta (cryptogams (408)).[4]
Four families are represented in the literature. Listed taxa include species, subspecies, varieties, and forms as recorded, some of which have subsequently been allocated to other taxa as synonyms, in which cases the accepted taxon is appended to the listing. Multiple entries under alternative names reflect taxonomic revision over time.
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