Art. XLV.—Notice of the Discovery of the genus Rhagodia in New Zealand.
[Read before the Auckland Institute, 4th June, 1883.]
The genus Rhagodia was founded by the late Robert Brown, many years ago, on some half-dozen Australian plants agreeing in most characters with Chenopodium, but easily distinguished by the fleshy fruit. Several species have since been added, thirteen being described in the “Flora Australiensis;” but up to the present time all of these were supposed to be strictly confined to the Australian continent. Some little interest is therefore attached to the discovery of one of the species in New Zealand, both from its adding a new genus to our Flora, and from affording additional proof of the intimate connection existing between the plants of the two countries. My specimens, which are clearly referable to Brown's Rhagodia nutans, the most widely distributed of the species, were obtained during a recent expedition of the Auckland Naturalists' Field Club to the island of Otatau, which, with Rakino and some smaller islets, guards the entrance to the eastern passage to Auckland Harbour. The plant is abundant all round the shores of the island, and on some of the smaller adjacent ones, usually trailing over the rocks a little distance above high-water mark. The following short description may be useful to those who have not access to the “Flora Australiensis” or other systematic works:—
Rhagodia nutans, R. Br. Prodr. 408; Benth. Fl. Austral. 5, p. 156. A much branched, prostrate or procumbent, herbaceous plant. Branches 6–18 inches long, sometimes hard and almost woody at the base. Leaves
rather thin, green or occasionally mealy-white, opposite or alternate, very variable in size and shape, ¼–1 inch long, lanceolate to broadly hastate, lobed notched or cordate at the base, acute at the apex, quite entire. Flowers diœcious in the specimens examined, but probably often polygamous, small and green, arranged in short and loose-flowered spikes or panicles at the ends of the branches. Perianth deeply 5-lobed. Male flowers usually with 3 stamens, pistil rudimentary. Female flowers with one or two abortive stamens; ovary depressed globose; styles 2. Fruit globose, fleshy, bright red, ⅛ inch in diameter.
There can be little doubt that R. nutans will be found in many localities on our coast line. In habit and general appearance it so closely resembles Chenopodium triandrum as to give rise to the suspicion that, in some cases, it has been mistaken for that plant. In proof of this, I would remark that in the second part of the “Handbook” (p. 739) Sir J. D. Hooker quotes an observation of Dr. Hector's to the effect that the utricle of C. triandrum “is often fleshy.” But this evidently applies to a Rhagodia, as all true species of Chenopodium have dry fruit. I am inclined to believe that a plant observed by myself several years ago at Whangarei, and more recently on the Taranga Islands, and which was on both occasions noted as C. triandrum, should have been referred to Rhagodia.
Since writing the above, my attention has been directed to a paper by Baron Müeller, printed in the Trans. N.Z. Inst., vol. v., and in which (see p. 310) Rhagodia is included in a list of genera, species of which were collected by Mr. H. H. Travers, in the Chatham Islands, in 1871. Unfortunately, it seems that the specimens have been mislaid, and Baron Müeller has thus been unable to inform me as to the exact species obtained. I have also learned from Mr. Kirk that quite recently specimens of R. nutans have been collected by his son, Mr. H. B. Kirk, in a locality in the Wellington Provincial District.