A Study of Variation in Haloragis Erecta with Notes on Allied Species

Abstract

Haloragis erecta is a member of the Haloragaceae, a somewhat isolated natural family of moisture-loving herbs usually considered to be allied to the Onagraceae. The three main genera, Haloragis. Gunnera and Myriophyllum. all of which have representatives in New Zealand, are very distinct. Myriophyllum is an aquatic genus of worldwide distribution with five species in New Zealand. Gunnera is almost entirely southern--two closely related subgenera in N.Z./Tasmania and Chile/Fuegia/Falkland Is. contain small, creeping, rather fleshy perennial herbs of wet places, while other South American species (often cultivated) are similar but reach enormous proportions. Haloragis is a large genus of over 60 species centred in Australia and extending to Southeast Asia, New Zealand and the Juan Fernandez Is. (The spelling Haloragis as used by J.R. and G.Forster in their Characteres Generum Plantarum 1776, p.61, when describing the genus, must be conserved against the classically more correct Halorrhagis adopted by many later authors. The name derives from the Greek hals, halos—-"the sea" and rhax, rhagos—-"a grape berry" (misquoted by the Forsters as ragis), and was suggested by the appearance of the fruit in the type species H. prostrata of New Caledonia.) The genus was divided into sections and subsections by Schindler in his monograph of the family in Das Pflanzenreich Heft 32, 1905. New Zealand has four species in section Monanthus (H. micrantha, H. depressa, H. incana, H. procumbens) and two or three including H. erecta in section Pleianthus subsection Cercodia. Subsection Cercodia extends to Australia and Juan Fernandez Is. and, like Gunnera and Myriophyllum elatinoides, presents a problem in discontinuous subantarctic distribution. The plants are short-lived perennial herbs growing up to three feet in height with annual stems springing from a woody base. They are sometimes classed as subshrubs.