Tasmannia R.Br. ex DC.

Tasmannia is a genus of trees and shrubs in the Winteraceae family, one of the few lineages of angiosperms that said ‘no’ to xylem, evolving instead to rely on tracheids to transport water in a way more commonly associated with gymnosperms, and also present in the genera Tetracentron and Trochodendron..Though sometimes considered a basal or primitive feature of the flowering plants, it is now thought that the lack of vessels is a derived characteristic. Feild, Brodribb & Holbrook (2002) hypothesized that vessels were lost in Winteraceae as an adaptation to freezing-prone environments. They suggested that as ancestors of modern Winteraceae passed through temperate conditions present in Southern Gondwana during the Early Cretaceous, they were exposed to selective pressure against xylem and returned to a vascular system relying on tracheids.

The species of Tasmannia were formerly classified as a section in genus Drimys, a related group of Winteraceae native to the Neotropics. Recent studies (see below) have led to a consensus to split the genus into two, elevating section Tasmannia to genus status, comprising the Old World species, with the American species remaining in genus Drimys.

Some references suggest the genus Tasmannia includes some 40 to 50 species, but 36 are currently accepted by Plants of the World Online (POWO 2025). Tasmannia differs from other genera in the family because it is the only genus where flowers are male or female and found on separate plants, i.e. unisexual and dioecious (Vink 1970). Only Tasmannia lanceolata (Mountain Pepper) is widely cultivated in temperate gardens, both for its ornamental and culinary value. It is described under its own entry. In Australia, T. stipitata is also well known as a spice, referred to as Dorrigo Pepper, but it is harvested mostly from the wild (Herbalistics 2024). Tasmannia insipida is grown to a limited extent. According to Simon Grant (pers. comm. 2025) this is regrettable as T. insipida is a much nicer plant than T. lanceloata, with bigger leaves, attractively coloured in spring in shades of red and purple, and bigger flowers. Aside from T. lanceolata and T. insipida, Tasmannia species do not have great horticultural merit (Australia Native Plant Society (Australia) 2025). Some six other species can be found in botanical gardens (BGCI 2024) of which four could be candidates for cultivation in temperate gardens, especially in a warming climate scenario: T. glaucifolia, T. vickeriana, T. purpurascens, and T. xerophila.

Robert Brown is best known in science classrooms as the discoverer of Brownian motion and the cell nucleus, but he was also a prodigious plant collector. While on the HMS Investigator expedition to Australia (1801–1805), he collected two species in Tasmania in 1804 that he found to be similar to Drimys but which differed in having dioecious flowers (Moore 2000, De Candolle 1817). He placed them in a new genus named in honour of Dutch explorer Abel Janszoon Tasman (1603–1659), the first European to reach Tasmania, which in Brown’s time was called Van Diemen’s Land (Coombes 2012). Mercifully for future users of the search function of internet browsers, Brown chose to spell the genus with a double n, presumably based on the Latinization of Tasman as Tasmannus, thereby distinguishing the genus from ‘Tasmania’, which in 1856 became the name for Van Diemen’s Land.

Brown would have published the genus name in the second volume of his Prodromus Florae Novae Hollandiae et Insulae Van Diemen, but as the first volume was a financial disaster the subsequent volumes never saw the light of day (Farmer 1913). It was A.P. de Candolle who published Tasmannia in his Regni Vegetabilis Systema Naturale in 1817, comprising two species named in counterpoint to each other as T. aromatica and T. insipida (De Candolle 1817).

This group of plants has proved to be challenging for taxonomists. In 1862, Ferdinand von Mueller sank the genus into Drimys (Mueller 1862). He retained Tasmannia as a section, which subsequently included members of Drimys found in the Old World. The united large genus was unchallenged until cytological studies (Ehrendorfer et al. 1968) showed that chromosome numbers in Tasmannia are n = 13, but n = 43 in Drimys sensu stricto. This led A.C. Smith, who had originally (1943) supported section status for Tasmannia, to change his mind and elevate it to generic status (Smith 1969). In fact, Smith expressed regret at not having restored Tasmannia to its own genus in his earlier revision. There he had demonstrated Tasmannia’s sharply defined character, but opted for caution and retained Mueller’s position and rank against his inclination and better judgment, a decision that he later felt had hindered taxonomic progress: he concluded that ‘conservatism in nomenclature is more likely to hinder than to advance taxonomic documentation.’ The issue remained a matter of controversy for ensuing decades, with Vink (1970, 1993) leading the “lumpers” who resisted Smith’s elevation of Tasmannia. Doust (2000) found important differences in the initiation of floral organs, as well as indications that the calpytra may have evolved separately in the two genera. The “splitters” finally overcame when Doust and Drinnan (2004) were able to confirm through molecular phylogenetic analysis that Tasmannia and Drimys do not form a monophyletic group. Doweld had previously (2000) taken the split even further, separating out two monotypic genera within Tasmannia (Austrodrimys and Pseudodrimys), but this proposal has received scant attention and was not even mentioned by Doust and Drinnan.