Forest Vines to Snow Tussocks: The Story of New Zealand Plants
One shrub and one tree frequently, and several other species less commonly, play this role on tree ferns.
Five-finger (Pseudopanax arboreus) is common as a terrestrial plant in shrubby forest regrowth, but in more mature forest it can be surprisingly frequent as a tree fern epiphyte, mostly on the ponga (Fig. 55), but also on wheki. The seedlings establish at the top of the trunk and, being fairly light-demanding, their leaves soon push between and above the fern fronds. The primary root begins to grow down to the ground, but soon gives off a branch root which grows horizontally around the trunk, sometimes returning to and fusing with the vertical root. It is thus comparable with the girdling roots of the puka and northern rata. The vertical root eventually reaches the ground and sometimes branches to enclose the tree fern trunk in a network of roots near the ground. In the meantime, the crown of the five-finger has continued to branch and grow upward with the tree fern crown following behind it. Raukawa (Pseudopanax edgerleyi) and Coprosma grandifolia may adopt a similar life style but less frequently.
Figure 55 (opposite) Five-finger (Pseudopanax arboreus) epiphytic on a tree fern (Cyathea dealbata). The root/stem junction of the five-finger is indicated with an arrow. Te Marua.
Photo: M. D. King.