Order Balanophoreae; Tribe Synomorieae.
[Read before the Hawke's Bay Philosophical Society, 17th July, 1924; received by 31st December, 1924; issued separately, 6th March, 1926.]
The root-parasite Dactylanthus Taylori, although known in a slight way since the year 1855 (1), has hardly received that attention from botanists which it deserves. The plant is fairly widely distributed over the North Island, to the north of latitude 40°c S., ranging in bush country from near the sea-coast to inland, where it is found at an elevation of over 3,500 ft. The paucity of references connected with the life-history of the Dactylanthus in this country must be set down to difficulties in the way of a systematic study of this plant, as until quite lately the date of flowering was not known, and few botanists have the opportunity of seeing the growths in situ.
The illustrations given in (3), pl. 30, figs. 1 and 2, show attachments of tiny Dactylanthus rhizomes to the host, also the form of the host attachment in the case of well-grown host attachments on separation from a rhizome. So also pl. 31, fig. 1, illustrates pistillate spadices as they appear when growing on a bank in the gloom of the bush, and fig. 2 shows rhizomes with pistillate flowers as found attached to a host; pl. 32 further shows the spadices of a staminate flower surrounded by a perianth made up of sepals and petals in different whorls.
In Cheeseman (5), vol. 2, pl. 178, there is a rhizome with pistillate spadices only, attached to a host: fig. 1 illustrates a single staminate spadix, and fig. 10 gives a spadix showing both male and female flowers. There is no capitulum at the end of a scaly stem terminated by a perianth containing from 18 to 28 spadices, each spadix crowded with anthers, as illustrated in the margin, and as shown in pl. 32 of my paper (3).
As illustrated by Dactylanthus, by Cordyceps, by Bagnisia, and by another undescribed specimen of a parasite in my possession, the study of parasitism presents many attractive features that offer suggestions for inquiry in several directions in relation to animal and vegetable life. These parasites have allured me to Taupo and the inland bush country adjacent to Opepe on many occasions, owing to the fact that the time of their flowering was unknown. In the case of Dactylanthus only isolated specimens of staminate inflorescences have been seen, and much remains to be learnt of the other parasites named.
Since the issue of Cheeseman's Illustrations of New Zealand Flora (1914) up to March of this year it had not been possible for me to go to Taupo
except in early spring, midsummer, and midwinter. Each time Taupo was visited, a visit was also made to Opepe, in the hope of finding something new and rare in connection with parasitism. Pistillate spadices of Dactylanthus with fruit were usually obtainable, but never the staminate spadices, although the evidence was plain enough that the staminate flowers had bloomed.
Having decided to spend three months at Taupo, commencing in late December, 1923, it became possible to visit Opepe and the surrounding bush country where Dactylanthus and other rare plants are to be found. January and February, however, were unusually dry, and there was not a trace of fungoid growth or of active parasitic life. Towards the close of February, however, the weather broke, and soaking rain continued off and on during March until the date of leaving for Napier, on the 23rd. Although the weather was unfavourable, it was decided to visit Opepe on the 21st March with my native companion, Tamati te Kurapae, chief of the Ngatituwharetoa, who knows the bush country well. We arrived at our destination, eleven miles from Taupo, at 8.30 a.m.
Although hundreds of spadices of Dactylanthus have been examined by me from time to time, I have not seen a spadix with staminate and pistillate flowers as shown in pl. 178, fig. 10, of Cheeseman (5). This must have been sent to Cheeseman by Mr. Frank Hutchinson, jun., from the Puketitiri Bush, although rhizomes and inflorescences were sent by me to Mr. Cheeseman on many occasions.
The forenoon was spent in the bush seeking for Bagnisia and Cordyceps, but our quest for the former was fruitless, though Cordyceps were abundant.
Rain drove us from the bush in the early afternoon, and we sought the shelter of a camp of native rabbiters, where we obtained information about Cordyceps and also obtained a number of live specimens, which the Maoris call the makaroa. The rain having ceased, we started for the gully where in former years the late Mr. A. Hamilton, of the Dominion Museum, and I had spent many delightful hours in the collection of botanical specimens, &c., and where also the late Mr. Cheeseman, F.L.S., of the Auckland Museum, had accompanied me in our search for Bagnisia and Dactylanthus. On approaching the glen I confess that my thoughts were not unmixed with sadness, for only a few weeks earlier Dr. Donald Petrie, M.A., F.L.S., an ardent botanical friend had visited me at Taupo but he was not well enough to go to Opepe.
When the Maori in whose whare we had taken shelter from the rain learnt that we were seeking for waewae-te-atua, by which name Dactylanthus is known to them, they asked to accompany us, for, although they had heard of the plant from others, they had not seen it growing. They knew the pua-te-reinga, which Taylor says was the native name of the Dactylanthus, but which the Taupo natives apply to Bagnisia Hillit, family Burmanniaceae: see (5), vol. 2, p. 198.
The country extending from the plateau near Opepe, 2,300 ft. above sea-level, gradually descends in the direction of Lake Taupo in a series of deep canal-like valleys for 1,000 ft. The valleys run lakeward like the spokes of a wheel from the circumference towards the centre, and each valley in its upper part represents a glen, sometimes wider and sometimes deeper than others, but all are waterless. On the banks grow many kinds of shrubs, such as Aralia, Pittosporum, Weinmannia, Aristotelia, Carpo-detus, &c., among ferns and lycopods, and in summer most of them are truly fairy dells. On entering the glen there was a strong perfume noticeable,
which was at first set down to the moistness of the air; but it grew stronger as we moved down the valley towards the banks from which specimens of Dactylanthus had hitherto been collected. Although the place was so familiar to me, I had never had the slightest suspicion that the valley floor was a veritable garden-meadow of Dactylanthus. Opening out, along the dry floor of the valley for a chain or more, appeared hundred of flowers in clumps. Some were in bud, some half-opened, some in full bloom, measuring 5 in. across, the whole forming a picture that was quite new to us all. As shown (Plates 14,15, and16, fig. 1), the flowers are all staminate, and are raised from 1 in. to 3 in. above the surface. They formed a picture never before seen by us, and expressions of pleasure and of wonder were frequent. I was reminded of the bed of Bagnisia plants found less than half a mile away; but the Dactylanthus flowers were far more numerous, and much larger, and covered a considerable area. The perfume was overpowering, and reminded me of my first find of Dactylanthus, more than twenty-five years ago, at Matarau, near East Cape. Near-by small rhizomes attached to small host-roots were found. These had pistillate flower-heads, which are much shorter than those attached to the rhizomes carrying staminate flower-heads, but are not buried in the ground as is the case with the staminate-bearing rhizomes. All the rhizomes with staminate flowers are buried some inches in the earth, and are much larger and different in shape from the rhizomes producing pistillate flowers. A number of clumps of the flowers with rhizomes and host attachments were carefully dug up and packed for removal as specimens, and the following is a description of the various parts:
Roots of Pittosporum and Aralia are the ones most frequently attacked. Those with staminate rhizomes, which are buried some inches below the surface near the place of attachment, are sometimes 1 in. or more in thickness. The rhizome when fresh can easily be separated from the host by means of boiling in water. The expanded surface of the host very closely resembles the petals of a pansy (Plate 16, fig. 1), and suggests a powerful suction as between host and rhizome. There is no trace that the host suffers from the attack of the parasite, but from specimens collected tiny rhizomes attach themselves to a root not at the end but on the side. When fully grown, however, the rhizome always represents the terminal end of the root. Plate 17, fig. 1, shows the appearance of a host attachment after separation from the rhizome.
The rhizomes containing pistillate flower-heads are much smaller and flatter, and possess warty-looking shoots over the whole surface. The flower-stem is much shorter than in the case of staminate flower-heads. The staminate rhizomes are buried in the ground and grow to a much larger size than the disc-like rhizomes bearing pistillate flowers. When dug up most of the specimens of rhizomes containing staminate flowers had shoots growing in bundles not unlike bundles of young asparagus. These do not appear to reach maturity, but die away following the decay of the spadices forming the staminate inflorescences. From the inside of the rhizome there radiates from the centre, where it is attached to the host, a series of smooth ridges corresponding to the depressions in the petal-like surface of the host. These extend to the cortical layer on the outside, where tiny shoots are formed. Under the microscope these shoots are of two kinds
one containing tiny leaves, the other a pollen-like material having the appearance of resin. When fresh, some of the rhizomes can be cut with a knife and are not unlike pith. The colour is purple, and the taste is neutral. The rhizome hardens by exposure, and when soaked in water gives it a deep-golden colour.
A. Staminate.—A flower-shoot from a staminate rhizome varies in length from 4 in. to 8 in. Scales appear sparsely along its whole length, increasing in number and form up to the perianth. As shown in Plate 16, fig. 1, the perianth consists of sepals and petals, the former being wider and shorter, the latter linear-oblong, the upper tip showing enlarged corners like a cat's ears. The petals vary in colour from a light to a dull purple, and the sepals are streaked here and there with a faint purple colour. The number of leaves in the perianth (see Plate 16, fig. 2) varies from 18 to 28, as seen. The perianth encloses 20 or more spadices. Each spadix is not unlike a canoe-paddle or beaver's tail, the upper part of which is crowded with anthers as shown in the illustration. The anthers are very numerous, and are attached to the spadix in a small curve from left to right. The anthers split lengthwise, and are full of pollen, which resembles under the microscope the resin-like material in the warty shoots of a rhizome. At the place of attachment of spadix and petal there is a tiny claw (Plate 16, fig. 1, c). In the centre of the spadices is a small abortive pistil.
B. Pistillate.—A pistillate inflorescence consists of a scaly stem shorter and less robust than the staminate one. It is terminated by a perianth enclosing 30 or more spadices (Plate 16, fig. 3, c). Each spadix consists of a number of pistillate flowers along its whole length. The style and stigma persist up to the time when the seed is ripe, as do also two tiny scale-like attachments to the ovary. The fruit is a small nut, hard and dry. On the removal of the skin-covering the white portion has the appearance of boiled rice, or coconut. Under the microscope no embryo could be found. In all the specimens examined no single spadix was found containing both male and female flowers as shown in Cheeseman's illustration (5). The flowers are dioecious, sometimes monoclinous.
1. R. Taylor. New Zealand and its Inhabitants. London, 1855.
2. T. Kirk. Trans. N.Z. Inst., vol. 28, p. 493.
3. H. Hill. Trans. N.Z. Inst., vol. 41, p. 437.
4. J. Grant. Trans. N.Z. Inst., vol. 43, Proc. 3, p. 98.
5. T. F. Cheeseman. Illustrations of New Zealand Flora. Wellington, 1914.
Fig. 1.—Staminate flower showing perinanth: a, stamens closed: b, stamens open, with mature anthers; c, single spadix with sepal and petal attachments.
Fig. 2.—Staminate flower and spadices with perianth: a, perianth; b, pollinated stamens
Fig. 3.—Pistillate flower: a, flowers; b, seeds; c, spadices.