New Bitter Cress Recognised From Auckland Islands
The New Zealand indigenous bitter cresses (Cardamine) are long over due for a full taxonomic revision. Currently the New Zealand Plant Conservation Network accepts seven taxa, though one C. debilis, which is highly variable is treated on the website as an aggregate (agg.) meaning that there is at least more than one entity lurking under that name. Some informal listings suggest that our indigenous Cardamine could comprise over 60 “species”. However, the genus is tricky and is best studied using fresh plant material and a combination of traditional and modern biosystematic tools.In a recent paper, Dr Peter Heenan has started to publish the results of his ongoing revision of the genus. His first paper (Heenan 2008) revisits the status of the endemic subantarctic bitter cress Cardamine subcarnosa. In this revision Heenan (2008) confines C. subcarnosa to Campbell Island, and refers the Auckland Islands plants previously included in C. subcarnosa to a new species C. latior. Both bitter cresses are regarded by Heenan (2008) as “Naturally Uncommon” qualified “RR” (Range Restricted).
Cardamine latior is distinguished from C. subcarnosa by a range of vegetative and fruit characters, including having shorter leaves with more leaflets, leaflets that usually overlap, more prominent leaf margin hydathodes, short and compact inflorescences, distinctly erect and broader siliques with a wider replum, and the septum with a distinct central vein.
Reference
Heenan, P.B. 2008: Cardamine latior (Brassicaceae), a new species endemic to the subantarctic Auckland Islands, New Zealand. New Zealand Journal of Botany 46: 559-566.
Posted: 15/01/2009