Pua-o-te-reinga

Forest and Bird, Volume 19, Issue 3, 1 August 1988, Page 38

Pua-o-te-reinga

by Forest and Bird member

Cynthia Aston

The Flower of Hades

hismia rodwayi is an extraordinary little plant, remarkable not only for its structure and behaviour, but also for the erratic and discontinuous nature of its observations by botanists and amateurs. It was first scientifically described in "gloomy glens’’ at Opepe near Taupo by Mr H Hill of Napier in 1903, usually appearing in mounds of humus round the bases of kahikatea trees. It was already known to the local Maoris, who called it and the unrelated Dactylanthus Pua-o-te-reinga (Flower of Hades). After being observed at Opepe several times up to 1966. it appears to have disappeared from this original site. R H Steele however found it at Taurewa in 1966, and before this it had been found at Ketetahi on Tongariro, and on Mt Pirongia and at Trounson Park kauri forest in North Auckland. It occurs also in Tasmania and in Victoria, though there have been arguments among botanists as to whether the Australia and New Zealand plants are identical. Originally called Bagnisia (or Geomitra) hilli it is, for the moment at least Thismia rodwayi. The original finding at Ketetahi in 1942 must have been on an old track, a rough logging access abandoned since about 1950 because of its tendency to scour into deep and hazardous runnels. Thirty years later in 1972, Mary and the late Jack Bedford found a number of plants in flower near the new track, and also by a rough hunters’ access nearby. Thismia appears to prefer slightly

disturbed ground. Where the track has since been modified, plants have been in several places distinct from or close to the original findings. The Bedfords also found a single plant in bush near Te Porere. The Pirongia plants were also from a disturbed area where trees have been felled leaving woodchip litter and where there was no undergrowth. Nothing has been recorded about Thismia from either Pirongia or Trounson Park since 1963. The latest finding was at Ohinetonga Track near the Whakapapa river at Owhango, where a number of plants in flower were found recently by Mary Bedford, Anne Symonds and myself. These were on relatively bare, damp, but not obviously disturbed soil. Thismia grows in association with various trees such as tawa, taraire, Kauri, kamahi and five-finger, but it is not directly parasitic on them. Having no green colouring there is no photosynthesis as in normal green plants, and there is a symbiotic relationship not yet completely understood with a fungus. The fleshy roots of Thismia grow horizontally underground. They are whitish to pale brown with roughened patches indicating sites of old fungal infections. Erect shoots arise from the roots, bearing scale leaves and a terminal flower, and simultaneously with the development of the shoot a new root appears and grows rapidly. There are no root hairs (feeding roots) but

fungal filaments (hyphae) enter the root from the soil. These hyphae are also present in the tissues of surrounding tree roots. The structure of the flower, which is deep salmon-pink and can appear from November to January, is quite complex. The inner lobes of the perianth are partially joined to form a lantern or mitre-shaped structure almost hiding the stamens, which are inverted to face down the tube, rather in the manner of a lobster-pot. This may assist pollination by small insects attracted by the nectaries in the base of the tube. If pollination takes place a small capsule forms, the stem lengthening as it develops. There is no definite splitting point. The top part of the capsule becomes transparent and rots away, exposing the brown seeds. Capsules must form only erratically, as Cheeseman remarks ‘‘fruit unknown"’. Thismia thus belongs to the small select band of flowering plants without green matter (others are the orchids Gastrodia, Corybas cryptanthus, and Yoania australis and of course Dactylanthus). Those who do find it are always fascinated by the attractive colour and intricate shape of the flowers, but it is not always easy to find. In unfavourable seasons many of the flowers fail to reach the surface. They appear to develop most freely when a fine spell follows heavy rain. It is extremely easy however when looking for Thismia to be deceived by a red fungus or a miro berry! a&