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Forest Lore of the Maori

The Rata Tree

page 108

The Rata Tree

An important chief was often alluded to as a rata whakatau or rata whakamarumaru, i.e., the shade-giving, or rather sheltering rata, for he was the protector of the people. A saying among the Whanganui natives is: Ko te rata te rakau i takahia e te moa, the rata is the tree that was trampled on by the moa —presumably in its young State, for even the weight of that great bird would scarcely bend or crush a full grown tree. Anyhow we now know why it is that so many trees of this species are not upright, but have a bend or are in a leaning position. The great majority of the trees seen began life as epiphytes, but occasionally one sees the terrestrial form, usually on the summits of spurs or ridges, and these have solid trunks, not infrequently straight, and these provide fair saw logs for the miller. Of the other form many are so divided as to be useless, except for fuel, for these so-called trunks are, of course, nought but aerial roots that have descended and clasped the host ere developing and coalescing. Long years ago I saw a stump that was 20ft. in diameter at the groundline; the tree itself had been destroyed. In those days some big specimens stood on the range between the Hutt and Porirua, and godless youths were wont, during Sunday expeditions, to set fire to these giants; it was no uncommon thing for a rata to burn for six months, burning slowly away. We have seen many rata from lOft. to 14ft. in diameter, though not solid trunks.

Speaking from personal observation I will say that the rata grows principally on the 1, Rimu; 2, Kahikatea; 3, Pukatea; 4, Hinau; to a lesser extent on 5, Matai; 6, Miro; and occasionally on 7, Tawa; 8, Totara; 9, Maire; 10, Rewarewa; 11, Puriri; and in isolated cases on other species. It has been seen growing on a parapara (Notho-panax arboreum). It seems to carefully avoid the kauri, on which it is seldom seen, and it has been said that the cause of this lies in the fact that the kauri sheds its bark, and so the aerial roots of the rata cannot get a permanent grip on the trunk, but the rata does grow on some other trees which have scaling bark. In all cases the rata seed seems to lodge, germinate, and grow, in or on epiphytic plants, notably on Astelia; these provide a good seed-bed, and the infant rata commences life by thrusting rootlets into the mass of fibrous matter and decayed leaves of the Astelia. Having thus got a grip on the fast-clinging epiphytic host the rata then assails the major host that is to be its sole support in later years. Ere accompanying the rata in its further adventures let it here be said that no such accommodating seed-bed of Astelia is found on the kauri tree, and this fact may account for the peculiarity noted above.

page 109

Having gripped the firmly-seated fibrous mass at the base of an Astelia the infant rata commences its work of leaning on the strong. It sends a questing aerial root down the trunk of the foster-parent, and this downward-trending root sends out subsidiary, lateral grappling rootlets to clasp the trunk of the host; these grip tightly in a manner superficial, not in the truly parasitic manner of the tapia or mistletoe. They grip the trunk closely but are not directly attached to it; if cut through they come away freely. Occasionally one sees two such laterals that have started out in life from the same level, but have grown in opposite directions until they have met on the opposite side of the trunk, where, in some cases, they have coalesced and slowly increased in size until they formed an iron-bound strangle-hold that would claim its toll in future years. The extreme end of the earth-seeking aerial root is rounded, smooth, soft, and looks as if it had been varnished; from this point the root increases in size upward. On reaching the ground the rata has gained its quest, it proceeds to establish a firm grip in the earth, and to develop its aerial roots and lateral arms, in preparation for the time when the decaying host will no longer support it but leave it to support its own weight. Aerial roots will then stand as what we usually view as trunks, while the actual trees are the far-flung branches possibly seventy feet above our heads.

In these epiphytic growths development consists largely in the growth of the main aerial root that will in the future have to act as a trunk, and the true tree, i.e., the branch System, is often not so well developed as it is in terrestrial forms where the tree trunk exists; the biggest heads I have seen pertained to these terrestrial specimens of the species; only very old epiphytic rata have farspread branch-systems.

Two roots, or even branches occasionally, of rata may coalesce, but however tightly they may be confined between those of other species each carries its own bark, they do not grow together. Rata, like pohutukawa, sometimes takes root on cliff-heads and sends long questing roots down the rock face, as we used to see in the Nga Uranga gorge, near Wellington. In the matter of trees with a Spiral twist, in about 90 per cent. of cases the ascending twist is from left to right.

Now the lateral roots thrown out by the earth-seeking aerial roots of our Metrosideros robusta creep round the trunk they are destined to encircle, they do not waste time by wandering out into space to seek support. Yet one occasionally sees very puzzling forms of growth that are not explainable by lowly laymen. I recall one case in which such a subsidiary rootlet, some twenty feet from the ground, had page 110pushed out into space and encircled a stalwart tawa that stood two feet away. Will some kindly, if scornful, expert teil me how the root knew that the tawa was there waiting for it.

The freaks of the rata might well inspire a goodly paper, had one jotted down particulars, and Sketches, during decades that are lost down corridors of time. In the case of rata trees with a pro-nounced leaning tendency, one sometimes sees aerial roots thrown out that form most effective struts to help support the great weight Rarely one sees such a root that has been thrown out up hill, and which acts as a kind of bobstay. A small specimen growing on a pukatea stump had sent its main root downward into and through the decayed wood of the stump. Near Camp Heipipi at Ruatahuna a rata had begun its career far up among the branches of a big matai that was hollow in the middle. The earth-seeking aerial root trailed down the trunk for some distance, and then, seeking an inside passage, entered a knot-hole and continued its journey down the hollow in the centre of the trunk. Having reached the earth it proceeded to develop in size, until its slowly increasing bulk has burst the great matai trunk asunder, and so killed it; the break or split as I saw it was about eight inches in width. A big rata at Tarapounamu still gripped in its deadly embrace a decayed section of the vanished hosttree some fifty feet from the ground. The hollow rata often seen are generally the result of the decay of a closely-embraced host. A rata seen growing on a kauri on Little Barrier island had developed an aerial root three feet in diameter, but in this case the lateral rootlets had not succeeded in clasping the kauri, but had, as it were, wrapped themselves round the parental aerial root.

A rata tree at Ohaua in the Tuhoe district is known by name as the Tohu a Te Ropu, and it is said to be the first of that species to bloom in the district, and in former generations the bird-spear and mutu or snaring-perch were busy on that tree while it retained its blossoms.

The durability of timber in some cases forms an interesting study, as when we find large forest trees growing on sound logs. An illustration of such a phenomenon is given in vol. 9 of the Transactions of the N.Z. Institute. In that case the log matai, a timber that is not durable for a long period when felled by man and left exposed. A considerable number of such tree-ridden logs have been seen, and in the Waikato district was found the stump of a kauri 7ft. in diameter that had grown on and over a silver pine log, the latter being quite sound on that account was converted into posts. In this case, however, the log was buried deep Underground, but the matai referred to was lying on the surface, as also were others I have seen that were page 111supporting trees of considerable size. Why should some trees that fall under natural conditions be so remarkably durable.

Moss was utilized to some extent by the Maori, occasionally for stuffing a rude form of galligaskin worn on rare occasions when crossing snow-covered ranges, for covering newly-born infants, etc.