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Volume 47, 1914
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Art. VI.—Investigations on Phormium.

[Read before the Philosophical Institute of Canterbury, 2nd December, 1914.]

[Abstract.]

It is a remarkable fact that no one has ever attempted to make a thorough botanical study of Phormium, the so-called New Zealand flax, although from time to time botanists have pointed out the necessity of such an investigation on a plant of so great economic importance. The present paper is a brief abstract of a much larger thesis which records the result of my researches in 1910–11. The complete MS. has been lodged in the Dominion Museum, Wellington, where it may be consulted by any one who wishes to carry on further research on Phormium. The whole paper is itself only introductory, as a complete knowledge of Phormium can be obtained only by means of careful observations extending over several years. It must also be pointed out that my work on Phormium has been almost entirely from the botanical standpoint.

The following, then, is a brief outline of the paper:—

Historical.

The first part is mainly historical, and deals with previously published books and pamphlets relating to the subject. Some few of these are short accounts of points of botanic interest, but for the most part they are concerned only with the qualities of New Zealand flax as a fibre-bearing plant. Although Captain Cook and Sir Joseph Banks both mention and shortly describe the New Zealand flax, the first really scientific account of Phormium was given by Labillardière, one of the naturalists of the expedition (1791–92) of the “Recherche” and the “Esperance” in search of the ill-fated La Perouse. Labillardière also grew the plant successfully in France, and accords it the highest praise. He says, “The flax of New Zealand holds the first place among the vegetable fibres known suitable for making rope.”

Later papers deal mainly with Phormium from the economic standpoint. The most important of these is the work of Hector (1872), who under took the compilation of the reports of the Commissioners who were appointed by the Government in 1869 and 1870 “to investigate and report on all matters relating to the manufacture and cultivation of New Zealand flax.” This is the largest and most comprehensive work on this subject that has yet been published. It contains a good account of the cultivation of the plant and of its chemical properties, but the sections in which it is considered from a botanical standpoint must be considered very unsatis-factory.

To this historical sketch I have added a short account of the history of the flax industry and a brief outline of the chief processes concerned in the preparation of Phormium fibre, with the state of the industry at the present time.

The next section deals with the Phormium swamps and with the cultivation of the plant. It is enough to state here that Phormium has never been extensively cultivated in New Zealand, although it is well known

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that much more fibre, and fibre of better quality, is produced from cultivated plants. This is due to the fact that millers will not make plantations while the large natural Phormium swamps exist.

Discussion of Specific Characters.

There has always been a certain amount of discussion with regard to the number of species in the genus Phormium. Hooker (1853) comes to the conclúsion that there is but one species, but almost all later botanists recognize two—P. tenax and P. Cookianum. In my study of various varieties I have found that the two species cannot be absolutely separated After carefully noting the characteristics of each variety, I attempted to put these varieties in some order, and was at once struck by the remarkable continuity of the variation. There is, indeed, a perfect chain of forms more or less closely connected, and the chain is unbroken in passing from “tenax” to “Cookianum” varieties, for “passage forms” link the two species. That this chain is real will be seen in my classification of varieties, though, no doubt, there are yet many links to be added. However, I decided to group my varieties under the two species now recognized, for the following reasons:—

In the first place, it will be seen that forms at one end of the chain are vastly different from those at the other end, and this would perhaps warrant the retention of the two specific names, though, of course, this method is wholly artificial. For this I have the authority of Hooker, who, in dividing the genus into two species, says at the same time that he considers them to be but “races of one plant.” Then, again, I have made many attempts to cross-pollinate extreme forms, and have failed to obtain any results. This is certainly an additional reason for retaining the two specific names. The chief differences between two forms, one from each end of my series of varieties, may be taken as the differences between P. tenax and P. Cookianum. These are,—

(A.) Differences in Vegetative Characters.

I. Habit.—P. tenax, on the whole, may be said to have an erect habit, though in many varieties the leaves are more or less drooping at the tip. The fans are generally set fairly widely apart, and the leaves clasp one another very closely at the base, this being one of the reasons for the more upright habit. P. Cookianum, on the other hand, has a very drooping habit, the fans are more closely set, and the leaves do not clasp each other closely at the base, but fall apart at a very short distance from the base.

II. The leaves of P. tenax are stiff and rigid, this being the principal reason for the erect habit. They are 4–14 ft. long and 2–5 ½ in. broad.

(a.) The “butt,” or clasping sheath-like lower portion of the leaf, is very heavy and long, sometimes being as long as the blade. Its inner surface is more or less brightly coloured, the colour varying from a faint orange-pink to a deep orange. There is generally a fairly large quantity of gum between the two halves of the butt. Very often there is a purple tinge on the outer surfaces at the base.

(b.) The blade is dark green, the lower surface being glaucous.

(1.) The apex is obtuse or acute, and in mature leaves the tip is split into two for several inches.

(2.) The keel is very much thickened on the lower surface, and is brightly coloured with a colour corresponding to that of the margins.

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(3.) The margins are thickened, and brightly coloured orange, red, brown, and black, and there is a tendency for the colour to “run in”—that is, to extend for some distance in towards the central part of the leaf. This occurs only on the upper surface. If this is the case, the whole tip of the leaf then has the same coloration.

The leaves of P. Cookianum are much less rigid, and consequently are all drooping. They are shorter, rarely being more than 5 ft. long, and are much narrower (1–2 ½ in.). The edges of the leaf are inclined to curl back-wards.

(a.) The butt is not so heavy, and is shorter. The inner surface is quite white, or, in rare cases, has a slight pinkish tinge, and there is very little gum.

(b.) The blade is pale green, and the lower surface is rarely glaucous.

(1.) The apex is acuminate, and not so inclined to split into two halves.

(2.) The keel is less thickened, and is of a pale-yellow colour.

(3.) The margins are not thickened, but are translucent, and are of a very pale yellow colour. The unthickened margins probably account for the tendency of the edges to curl outwards.

(B.) Differences in Floristic Characters.

III. P. tenax does not flower as a general rule for many years, and then generally sends up comparatively few flower-stalks; while P. Cookianum very often flowers long before the leaves have reached maturity, and its flower-stalks are much more abundant.

IV. The inflorescence (flower-stalk) of P. tenax is erect, stout, and tall, sometimes reaching a height of 18 ft. It is purple in colour, is glabrous, and has abundant bloom. The bracts are very large, especially those on the lower part of the stalk, and their inner surfaces are orange in colour. On cutting the stalk, sap of a deep-orange colour is expressed.

The flower-stalks of P. Cookianum, on the other hand, droop in all directions. They are slender, and much shorter than those of P. tenax, for they are rarely more than 6 ft. in height. The stalks taper much more towards the apex than do those of P. tenax, and there is much less bloom, and, indeed, in some it is quite absent. The bracts are smaller, and are of a yellowish green colour on the outside and quite white within. The sap is a pale-yellow colour, and much less is expressed on cutting. The panicle of flowers is much smaller.

V. The flower of P. tenax is a dull red or an orange-red in colour, and 1–2 in. long. The three outer perianth-leaves are much deeper in colour than the three inner, which are yellow as the flower first opens, but which afterwards become a bright orange-red. They are either quite erect or slightly recurved at the tip.

The flowers of P. Cookianum are much narrower and slightly shorter than those of P. tenax (1–1 ½ in.). The three outer perianth- eaves are of a bright orange colour, and the three inner on opening are of a decided green tint, which afterwards becomes a light greenish-yellow. The inner perianth-leaves are much recurved at the tip, and are much less brittle than those of P. tenax.

VI. The capsules (seed-pods) of P. tenax are erect or slightly inclined, stout, trigonous, 2–4 in. long, and not twisted. In P. Cookianum they are long (4–7 in.), pendulous, and very much twisted.

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The chief variations which have been taken into account in my classification of the varieties of Phormium are,—

Vegetative Characters.

I. Habit.—The plant may be quite erect, slightly drooping, or very drooping. The fans may be closely set together or wide apart, and the leaves of each fan again may be close together or loosely arranged.

II. The leaves may be rigid or quite flaccid. (It must be noted here that even if the leaves are drooping they are not necessarily flaccid. One variety, No. 9 of my list, for instance, has firm leaves, with abundant and strong fibre, and yet the leaves are drooping.) They may be dark, bright, pale, or yellow green.

(a.) The butt varies in length and in stoutness. There may be little or much “gum,” and the inner surface may be white, pink, or deep orange.

(b.) The blade varies in length, width, thickness, and colour, and its inferior surface in amount of bloom.

(1.) Its apex may be entire, split into two along the midrib, or split into several ribbons. It may be obtuse, acute, or acuminate (tapering gradually to a point). It may be of the same colour as the rest of the blade, or coloured similarly to the margins. It may be rigid or quite soft, and may be curved inwards, straight, or curved outwards.

(2.) The keel varies in thickness and in colour.

(3.) The margins vary in thickness and in colour, the usual colours being bright orange, red, maroon, brown, and black. The margins only may be coloured, or the colour may “run in” on the upper surface, sometimes to a depth of some millimetres.

Floristic Characters.

III. Time of Flowering.—There is a great difference in the time of flowering of the varieties, and this appears to be constant for each variety in any one locality.

IV. Inflorescences.—These vary in number, colour, height, stoutness. They may be erect, slightly inclined, or inclined at various wide angles. The bracts vary in size and colour. The secondary and tertiary branches vary in length. The tip of the inflorescence may be straight or bent over.

V. The flowers vary in number, size, colour, and shape.

VI. The capsules vary perhaps more than any other part of the plant. They may be stout or slender, straight, slightly twisted, or very much twisted. It must be noted here that not only the pendulous capsules are twisted, but many which are quite erect have a decided twist.

Classification.

As I have stated above, I have retained the two specific names—P. tenax and P. Cookianum. P. tenax I have divided into five groups, which are again subdivided into a number of varieties which I have simply numbered, since names might cause confusion. There are twenty-five of these varieties included in P. tenax. Then follow five varieties which are considered as forms intermediate between the two species, and finally eight varieties of P. Cookianum which are included in one group.

The larger groups have been classified mainly according to habit, while varieties are distinguished mainly by floristic characters, though vegetative characters have not been neglected.

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The following is a brief outline of the classification:—

Phormium tenax.
Group A (seven varieties).

I.

Habit, erect; fans well separated.

II.

Leaves, light green, rigid; butt only slightly reddish; margin narrow, distinct, and thickened.

IV.

Inflorescences, erect, stout, straight.

V.

Flower, dark red.

VI.

Capsules, erect, stout, straight.

Group B (three varieties).

I.

Habit, inner leaves erect, outer drooping.

II.

Leaves, light green, rigid, very wide, shorter than those of A; butt very red; margin “running in.”

IV.

Inflorescences, more numerous than those of A, stout, straight.

V.

Flowers, darker red than in A.

VI.

Capsules, very numerous, erect, stout, straight.

Group C (four varieties).

I.

Habit, drooping, especially outer leaves; fans more closely set.

II.

Leaves, dark green, not rigid; margins narrow, distinct, and thickened; butt of medium redness.

IV

Inflorescences, numerous, tapering scorpioid, falling in all directions.

V.

Flowers, dark red.

VI.

Capsuples, inclined at various angles, straight and narrow.

Group D (ten varieties).

I.

Habit, erect; fans closely set.

II.

Leaves, very narrow and rigid; butt of medium redness.

IV.

Inflorescences, few, erect, short and straight.

V.

Flowers, dark red.

VI.

Capsules, erect, short, straight, flattened on top

Group E (three varieties).

I.

Habit, drooping; fans closely set.

II.

Leaves, long and wide; margins narrow, distinct, and thickened; butt of medium redness.

IV.

Inflorescences, numerous, spreading in all directions, straight, tapering, and somewhat slender.

V.

Flowers, bright red or yellowish red.

VI.

Capsules, erect, long, narrow, generally slightly twisted.

Gradation Forms.
Group F (five varieties).

I.

Habit, fairly erect; fans closely set.

II.

Leaves, light green, narrow, thin, and flaccid; margins narrow, distinct, unthickened, and inclined to curl backwards; butt of medium redness.

IV.

Inflorescences, numerous, short, erect, and slender.

V.

Flowers, dark red.

VI.

Capsules, stout, short, erect, straight or twisted.

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Phormium Cookianum.
Group G (eight varieties).

I.

Habit, very drooping; fans closely set.

II.

Leaves, pale green, narrow, short, thin, flaccid; margins translucent pale yellow, unthickened; leaves curl backwards; butt white, short, little gum.

IV.

Inflorescences, numerous, short, tapering, drooping in all directions, stalk sometimes green.

V.

Flowers, short, yellow, inner perianth-leaves much recurved at tip.

VI.

Capsules, long (4–7 in.), pendulous, and very twisted.

Development.

After the classification follows a fairly long account of the development of Phormium. This includes descriptions of the anatomy of various parts of the young plant at successive stages in its development. It ends with a full anatomical account of the mature leaf. This chapter is illustrated with drawings of sections of different parts of the leaf.

Pollination.

My experiments in pollination were carried out with as much care as possible, but it is well known that mistakes easily occur in these experiments, and I hope to verify my statements at a later date. In my paper I have stated that as the result of my investigations I have found—(1) That Phormium is not self-fertile; (2) extreme forms of P. tenax and P. Cookianum cannot be crossed; (3) cross-pollination is easily effected between varieties which are closely related.

The Diseases of Phormium.

The main diseases are merely shortly described, as they would form a large subject for research. I have appended a list of varieties which exhibit ability to resist fungus diseases.

The Fibre.

This section includes a description of the fibre-content of the varieties, with a table of the measurements of the diameter of the fibre and the cavity for each variety. It also gives an account of experiments on the expansion and contraction of the fibre of New Zealand flax and manila hemp.

When explaining the principles followed in the classification I have stated that the Maori system was entirely artificial, since it was based on one character only, and that a character of slight botanical importance—namely, the quality of fibre. After I had arranged my varieties in their groups I sent leaves of all the varieties to be milled and graded, and was surprised to find that almost all the varieties of each group fell into the same grade.

The remainder of the paper is concerned with general conclusions and with a full bibliography of works dealing with Phormium. In addition to the MS. there is a fairly large set of plates and photographs illustrating the chief statements made in the text.