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

Mat Epiphytes

Mat Epiphytes

These epiphytes form mats or patches mostly on inclined or horizontal branches, and they comprise three orchids and one fern which range throughout the country. Mat epiphytes may establish directly on bare bark, particularly if it is rough and fissured, but may also avail themselves of moss cushions. The fern is Pyrrosia serpens (Fig. 38), which belongs to a genus of epiphytes centred in tropical Asia. Our species is also found in Australia and the islands of Polynesia. Pyrrosia often establishes directly on bare bark and has slender, freely branching rhizomes which form a complete network over sunny branches. The leaves are simple and smooth-margined, varying from almost round to long and narrow. They have a fleshy texture and a dense felt of buff coloured hairs page 70
Figure 39 Tall kahikatea (Dacrycarpus dacrydioides) with many asteliad nests. South of Kaitaia, northern North Island.Photo: B. V. Sneddon.

Figure 39 Tall kahikatea (Dacrycarpus dacrydioides) with many asteliad nests. South of Kaitaia, northern North Island.
Photo: B. V. Sneddon.

page 71
Figure 40 (opposite) Asteliad nests with the pendent epiphytic fern Asplenium polyodon below them.Photo: M. D. King.

Figure 40 (opposite) Asteliad nests with the pendent epiphytic fern Asplenium polyodon below them.
Photo: M. D. King.

page 72beneath, which presumably restrict loss of water. Pyrrosia also grows on the trunks of trees in the open and on rocks. It can be quite abundant on introduced trees, particularly Cupressus macrocarpa.

The epiphytic orchids42 which form mats or patches belong, or are closely related, to large tropical genera and can be regarded as outliers, reduced in both leaf and flower size. They all have specialised roots which, as well as serving for attachment, also efficiently absorb and store water in a special outer layer of dead cells known as the velamen.

Drymoanthus adversus, often attached to quite smooth bark, is unlike the other species in that it has a short stem, which does not grow along the bark surface. The roots arising at the base of the tuft of leaves are particularly conspicuous as they spread out 'like the rays of a spider's web' for a considerable distance, often encountering the roots of other plants of the same species. Drymoanthus includes our species, another in east Australia and a third in New Caledonia, but there is some doubt as to whether it should be separated from the Asian and Australian genus Sarcochilus. Our two species of Bulbophyllum, although small, form quite dense patches with their branching rhizomes. In common with their many tropical relatives, each of their rhizome segments swells at the end into a water-storing 'pseudobulb' with a single leaf arising from the top. The stalk bearing the small flower or flowers arises from below the pseudobulb. Bulbophyllum pygmaeum is the smaller species with leaves about a centimetre long but it forms larger patches than those of B. tuberculatum. The leaves of B. tuberculatum are several times longer, but this species is less frequently seen and is not known further south than the north coast of the South Island.