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Forest Vines to Snow Tussocks: The Story of New Zealand Plants

Root Climbers

page 52

Root Climbers

The most prominent root climbers are the climbing ratas,37 currently included in the genus Metrosideros. They are able to grow up quite large trunks and are perhaps most abundant on the emergent conifers and the northern rata. Their climbing stems are usually quite slender and the leaves, which form a close mosaic on the tree trunk (Fig. 30), are generally smaller, thinner and more rounded than those of the adult stage. When the stems reach full light high in the tree crown, or adequate light in the lower levels, they form a bushy growth of branches which extend away from the support and eventually bear flowers. At this stage the stems extending up from the ground enlarge considerably and swing away from the host trunk as woody cables (Fig. 31). Metrosideros fulgens and M. perforata form the largest stems, sometimes up to 15 cm or more in diameter, but the others may attain 7-8 cm. Often no leaves are visible near the ground, but the stems can be identified to some extent from the bark — M. perforata has red-brown stringy bark, M. fulgens also red-brown bark separating in thickish strips and the other species have pale whitish bark separating in thin flakes.

Metrosideros albiflora and M. carminea are restricted to the northern North Island. M. albiflora is most common in kauri forests. It has the largest leaves of the group and small, white flowers. M. carminea is much rnore colourful, with masses of large, crimson flowers, and it is now popular as a garden plant. M. perforata, M. fulgens and M. diffusa frequently occur together as far as the northern South Island and M. diffusa continues alone to Stewart Island. M. diffusa often forms slender stems near the ground which spread widely in the humus of the forest floor and climb any trunks they encounter. M. colensoi also reaches the northern South Island, but is more localised in its occurrence, favouring forests on fertile soils such as those of river terraces. The strongly weeping habit of its foliage is a distinctive feature. M. fulgens has large flowers ranging in colour from orange to dark red, while the other species have small white to pinkish flowers. Most of the climbing ratas flower from early to mid-summer, but M. carminea flowers in early spring and M. fulgens is remarkable both for the timing and length of its flowering season — the first flowers may appear in late summer and flowering continues through the winter into early spring.

New Zealand is not the only place where climbing species of Metro- page 53
Figure 31 (left) The cable-like stems of a mature Metrosideros perforata on a rimu (Dacrydium cupressinum). Kaitoke, near Wellington, southern North Island. Photo: M. D. King.

Figure 31 (left) The cable-like stems of a mature Metrosideros perforata on a rimu (Dacrydium cupressinum). Kaitoke, near Wellington, southern North Island. Photo: M. D. King.

Figure 30 (above) Young stage of white climbing rata (Metrosideros perforata) forming a leaf mosaic on a tree trunk.Photo: B. V. Sneddon.

Figure 30 (above) Young stage of white climbing rata (Metrosideros perforata) forming a leaf mosaic on a tree trunk.
Photo: B. V. Sneddon.

page 54
Figure 32 The drooping stems and foliage of kiekie(Freycinetia baueriana var. banksii) completely obscuring a kahikatea trunk. Kaitoke, near Wellington, southern North Island.Photo: J. W. Dawson.

Figure 32 The drooping stems and foliage of kiekie
(Freycinetia baueriana var. banksii) completely obscuring a kahikatea trunk. Kaitoke, near Wellington, southern North Island.
Photo: J. W. Dawson.

sideros
occur. There are climbers related to ours in New Guinea and the Philippines.

The only other root climbing liane in New Zealand is the kiekie (Freycinetia baueriana var. banksii). It belongs to a distinctly tropical family, the Pandanaceae, which is represented by many species of Freycinetia and Pandanus in tropical rain forests. One might expect that the outlying New Zealand species would be of reduced form and perhaps rare. In fact it compares with the largest and most robust tropical species and page 55is abundant in lowland, especially swampy forests as far as the south west of the South Island. Tree trunks are often completely obscured by the foliage of kiekie (Fig. 32), which can extend into the highest crowns 30 m or more above the ground. The leaves are dark green, narrow and a metre or more long with finely toothed cutting edges. The male and female inflorescences found on separate plants are cone-like and surrounded by leaf-like white or purplish bracts, which are sweet and edible. The stems are a few centimetres in diameter and distinctively ringed with leaf scars. They give rise to slender, attaching roots, which branch freely towards their ends and attach themselves firmly to the trunk. Other roots are stouter and grow down the trunk to the ground, often building up into quite thick and rather untidy masses.