A warm autumn in Wellington with Barbara Mitcalfe and Chris Horne
On a recent BBB tramp, walk or run you may have noticed that our extraordinarily-warm Autumn weather has encouraged profuse flowering of one of our rarest indigenous lianes, tecomanthe. Cascading over the hand-rail at the Otari Visitor Centre, climbing the Tree House lift tower in the Botanic Garden, clambering up the NZ School of Music at Victoria University, adorning the fence at Kelburn Medical Centre, and thriving on the roof of DOC's Conservation House, Manners St, this robust, Three Kings endemic liane has no Māori or common name, being known simply as tecomanthe.
In 1945 a party of botanists discovered a single plant of what we now call tecomanthe, on Manawa Tawhi, the largest of the Three Kings Islands off the north coast of Northland. Completely unknown to the world of science, it was being browsed almost to death by goats. Fortunately, six cuttings were taken and successfully propagated by horticulturists on the mainland, because the original plant produced no flowers from 1946 to the 1990s, and since then, it has not produced seed. Goat eradication on the island in 1946 rescued this handsome species from extinction, and luckily too, the cuttings produced viable plants, from which all subsequent tecomanthe plants have been grown.
A member of the largely tropical Bignoniaceae family, Tecomanthe speciosa has the DOC Conservation Threat Status of Nationally Critical. Its large, broadly-ovate, glossy, dark-green leaves comprise either one or two pairs of opposite leaflets, and a single terminal leaflet. The plump, green flower buds start off looking like shiny little cucumbers, in cluster of up to 50, growing straight out of the trunks. Then they turn bright white, resembling crowded bunches of small, fat, white bananas. The elegantly-beautiful, pendulous, tubular flowers, greenish-white to creamy-yellow, are each cupped in a green calyx, their petals up to c. 50 mm long. After fertilisation, the numerous seeds develop in woody pods which can often reach 200 mm long x c. 40 mm wide.
Like all small populations of plants and animals in what is called a genetic “bottle-neck”, (for instance, the Chatham Island black robin), Tecomanthe speciosa, a clone, lacks the genetic variability to deal effectively with environmental change. This means that it could more easily be wiped out by e.g. a pathogen, or a climatic change which does not suit its requirements. So if Wellington’s climate continues to warm, maybe we should all encourage lots of plantings of tecomanthe, in order to increase its chances of survival.