Art. L.—On the Freezing of New Zealand Alpine Plants: Notes of an Experiment conducted in the Freezing-chamber, Lyttelton. By L. Cockayne. [Read before the Philosophical Institute of Canterbury, 3rd November, 1897.] Towards the close of last year (1896) Dr. Pairman, of Lyttelton, most kindly undertook to procure for me the use of the Lyttelton Harbour Board's freezing-chamber, so that I might make some investigations into the effect of more or less continuous cold upon New Zealand alpine plants, and so, in the first place, add possibly some facts of importance to our scanty knowledge of the physiology of New Zealand alpines, and, in the second place, furnish some information which might be of commercial value. With regard to this latter I may quote one instance: It is customary in Europe generally, and to a very large extent in Great Britain, to cultivate certain bulbous plants in spring for the sake of their flowers, such plants after flowering being usually destroyed. This has led to an enormous industry in Holland, Southern France, and Italy, also to one of very considerable extent in California and Japan. In New Zealand a similar trade could be developed with regard to our splendid flowering-plant Ranunculus lyallii, Hook. f. Rhizomes of this

collected in its native habitat in September would be in perfect condition for yielding large masses of bloom. Such dormant rhizomes landed in England in December should flower as well as in their native land, and as the demand for such a unique spring flower would be very great a new industry would be established in this country. And so with many others of our alpine plants now by ordinary methods most difficult to export in good condition. Both the New Zealand Agricultural Department and the Lyttelton Harbour Board readily granted Dr. Pairman's request, and the Secretary of the first-mentioned department was pleased to write, “The Government Biologist is of opinion that such experiments will be most interesting, and may have results of great economic value.” Unfortunately, I was not in a position to commence operations before the 10th December, since nearly all the alpine plants I had ready for the experiment being in a greenhouse, it was necessary to harden them off. On the 10th December the following plants were put in a cool-chamber adjacent to the one used for freezing dairy produce. (This chamber is kept at a low temperature by that freezing process known as the “Linde process,” and which consists in forcing a stream of brine, cooled by the evaporation of ammonia, through a number of pipes passing along the ceiling of the chambers):— No. Name of Plant. Where collected. Altitude. 1 * Plants with very little young growth.Podocarpus nivalis, Hook. f. Craigieburn Mountains 900 m. 2, 3 † Plants with considerable young growth.Fagus cliffortioides, Hook. f. Castle Hill 720 m. 4 †Raoulia tenuicaulis, Hook. f. Mount Grey Downs 240 m. 5 ‡ Plants with medium young growth.Luzula pumila, Hook. f. Craigieburn Mountains 1,800 m. 6 ‡Cotula atrata, Hook. f. " 1,500 m. 7, 8 *Helichrysum grandiceps, Hook. f. " 1,050 m. 9 *Ranunculus enysii, T. Kirk Big Ben Range 900 m. 10 ‡Celmisia bellidioides, Hook. f. Craigieburn Mountains 900 m. 11 ‡" laricifolia, Hook. f. " 1,200 m. 12 *" spectabilis, Hook. f. " 1,050 m. 13 *Senecio elæagnifolius, Hook. f. Kelly's Hill, Westland 900 m. 14 †Epilobium crassum, Hook. f. Mount Torlesse 1,200 m. 15 †Fagus solandri, Hook. f. Otarama 450 m. 16 ‡Coprosma propinqua, A. Cunn. Otira Valley 336 m. These plants were all in pots, plunged in earth in a shallow box, and, regarding moisture, rather dry than otherwise. They were removed from the cool-chamber (temperature, 4.44°C.) to the freezing-chamber (temperature, — 1.1°C.) on the 12th December. Here they were kept till the 18th De-

cember, when they were transferred to the cool-chamber (temperature, 5°C.), and allowed to thaw gradually. Upon examination I found that all were dead, or nearly so. H. grandiceps and L. pumila alone doubtfully showed signs of life. The following table shows the amount of cold the plants had been exposed to (temperature taken from log-book of the engineer to the Harbour Board):— Morning Temperature. Evening Temperature. December 12 −1.1° C. −5.5° C. " 13 −1.6° C. −6.6° C. " 14 −4.4° C. −5.5° C. " 15 −3.8° C. −5.5° C. " 16 −3.8° C. −4.4° C. " 17 −2.7° C. −5.5° C. " 18 −2.22° C. Owing to the abnormal condition in which these plants were at the time of their exposure to the cold their death in nearly every instance was only what could be expected; so, considering the experiment so far as it had gone of little moment, I proceeded, in company with Mr. R. Brown, to Mount Torlesse, the nearest point at which alpine plants could be easily procured, hoping to collect some at a high altitude in a dormant condition, or, at any rate, in a much more suitable condition for the experiment than those first used, although the season was rather too far advanced. The weather proved adverse, and we only reached an altitude of 1,250 m., in a fog so dense as to make further progress out of the question. The spot reached, however, was eminently suitable for retarding growth, being exposed fully to all cold and cutting winds. The plants were cut out of the ground in blocks about 6 cm. deep and 11 cm. wide, each block containing several plants. This was done so that the plants in each block would not feel their removal. I shall refer to the objection to this mode of treatment at the end of the paper. The following is a list of the plants in each block, with altitudes, &c.:— No. Name of Plant. Situation, &c. Altitude. 1 Oxalis magellanica, Forst. Shady gully, facing south 1,160 m. 2 Gaultheria antipoda, Forst. " " " Ligusticum aromaticum, Banks and Sol. (var. with very coriaceous leaves) " " " 3 Ourisia cæspitosa, Hook. f. " " " Geranium microphyllum, Hook. f. " " " Gaultheria antipoda, Forst. " " " Oxalis magellanica, Forst. " " "

4 Pozoa hydrocotyloides, Hook. f. Shady gully, facing south 1,160 m. 5 Ranunculus monroi, Hook. f., var. sericeus, T. Kirk " " " Pozoa hydrocotyloides, Hook. f. " " " 6 Brachycome sinclairii, Hook. f. Grassy slope, facing southeast 960 m. 7 Pentachondra pumila, Br. Ditto " 8 Raoulia subsericea, Hook. f. " " 9 Pratia macrodon, Hook. f. Shady gully, facing south 1,120 m. Viola cunninghamii, Hook. f. " " Danthonia semiannularis, Br. " " 10 Euphrasia monroi, Hook. f. " " " Danthonia semiannularis, Br. " " " Gaultheria antipoda, Forst. " " " Epilobium confertifolium, Hook. f. " " " Ourisia cæspitosa, Hook. f. " " " Ligusticum aromaticum, Banks and Sol. " " " 11 Dracophyllum prostratum, T. Kirk Drapetes dieffenbachii, Hook. f. Wind-swept plateau, exposed to south-west 1,250 m. Cotula pectinata, Hook. f. Wind-swept plateau, exposed to south-west " Poa, sp. Wind-swept plateau, exposed to south-west " 12 Drapetes dieffenbachii, Hook. f. Ditto " Ligusticum aromaticum, Banks and Sol. " " Gaultheria antipoda, Forst. " " Poa, sp. " " 13 Ligusticum aromaticum, Banks and Sol. " " Gaultheria antipoda, Forst. " " Leucopogon frazeri, A. Cunn. " " 14 Aciphylla monroi, Hook. f. " " 15 Raoulia eximia, Hook. f. Shingle-slip, facing south-west 1,090 m. It will be seen that a great many well-known alpine plants are absent from this list, notably the following genera: Celmisia, Veronica, Senecio, and Olearia. The first named of these I was debarred from using, since the department pledged me to use no plant having a strong odour, and Celmisia is usually very aromatic; and the remaining genera, being mostly more or less tall shrubs, could not well be removed in small blocks of earth without being injured. The blocks of earth, with their contained plants, were plunged in soil in a shallow box and placed in the coolchamber (temperature, 8.9° C.) on the 18th December. On the 21st December, at 2.55 p.m., the box was transferred to the freezing-chamber (temperature at the time, −2.2° C.) and protected with a sheet of newspaper. Here the

plants were kept during the first period until the 24th December. Temperature of Freezing-chamber During First Period. Morning Temperature. Evening Temperature. December 22 0° C. −1.11° C. " 23 0° C. 0° C. " 24 0° C. −1.11° C. Removed plants into cool-chamber (temperature, 4.4° C.) on the 24th December (temperature of freezing-chamber at time of removal, −1.67° C.), and, after thawing, examined, and found all in a perfectly healthy condition. Removed the paper, and placed them in freezing-chamber for the second period. Temperature of Freezing-chamber during Second Period. Morning Temperature. Evening Temperature. December 25 0.55° C. 1.11° C. " 26 1.11° C. 0° C. " 27 1.11° C. −1.11° C. " 28 0.55° C. −3.33° C. " 29 1.11° C. −5.55° C. " 30 1.11° C. −6.67° C. " 31 1.11° C. On the 31st December the box was removed from the freezing-chamber at 2.15 p.m. (the temperature at the time being −5.55° C.) into the cool-chamber: temperature, 6.67° C. This temperature is 3.67° C. higher than that recorded by Sachs, which killed leaves of beet and cabbage frozen at from −4° C. to −6° C., and referred to in Vine's “Lectures on Physiology of Plants,” 1886, pages 273, 274. I examined the plants at 5.45 p.m., at which time the soil was only partially thawed, but the leaves of the plants quite thawed. Delayed the detailed examination till next day, 1st January, at 7.45 p.m., when I found all in perfect health, excepting Aciphrasia monroi, Hook, f. (slightly blackened at tip of leaf); Euphrasia monroi, Hook, f. (similarly blackened); Oxalis magellanica, Forst. (also a little blackened, but in less degree); and Pozoa hydrocotyloides, Hook. f. (one or two leaves slightly blackened). None had received any serious damage. It is worthy of note that the blooms on Euphrasia monroi, Hook. f., had developed partly during their stay in the freezing-chamber, and were quite unblackened; also, Oxalis magellanica, Forst., only in bud at the time of first putting into the freezing-chamber, was now fully expanded and unhurt. Replaced the box in the freezing-chamber for its third and final period.

Temperature of Freezing-chamber during Third Period. Morning Temperature. Evening Temperature. January 2 −1.11° C. −6.67° C. " 3 −1.67° C. −5.55° C. " 4 −1.11° C. −6.67° C. " 5 0° C. −5.55° C. " 6 −1.11° C. −4.44° C. " 7 0° C. −5.55° C. " 8 −1.67° C. −3.33° C. " 9 −3.33° C. −4.44° C. " 10 −2.78° C. −4.44° C. " 11 −3.33° C. −6.67° C. " 12 −2.22° C. −6.11° C. " 13 −3.33° C. −5.55° C. " 14 −2.22° C. −6.67° C. " 15 −2.22° C. −6.67° C. " 16 −3.33° C. −6.67° C. " 17 −4.44° C. −6.67° C. " 18 −4.44° C. −6.67° C. " 19 −4.44° C. −6.67° C. " 20 −2.22° C. −5.55° C. " 21 0° C. −5.55° C. " 22 0° C. −5.55° C. " 23 −0.55° C. −5.55° C. " 24 −1.11° C. −5.55° C. " 25 −1.67° C. −5.55° C. " 26 −1.11° C. −5.55° C. " 27 −1.11° C. −6.67° C. " 28 −1.67° C. −6.67° C. " 29 −1.11° C. On the 29th January I removed the plants into the coolchamber, and, after thawing them gradually, brought them to my garden at New Brighton. Next day I examined each block of soil, with the following result (the numbers of the blocks are as given before):— No. 1. Oxalis magellanica; dead. No. 2. Gaultheria antipoda; alive. Ligusticum aromaticum; alive. No. 3. Ourisia cæspitosa; dead. Geranium microphyllum; dead. Gaultheria antipoda; very little damaged. Oxalis magellanica; dead. No. 4. Pozoa hydrocotyloides; damaged, but alive in places. No. 5. Ranunculus monroi, var. sericeus; dead. Pozoa hydrocotyloides; as above. No. 6. Brachycome sinclairii; just showing trace of life. No. 7. Pentachondra pumila; dead. No. 8. Raoulia subsericea; dead. No. 9. Pratia macrodon; dead. Viola cunninghamii; dead. Danthonia semiannularis; alive. No. 10. Euphrasia monroi; dead. Danthonia semiannularis; alive. Gaultheria antipoda; alive, not much damaged.

Epilobium confertifolium; dead. Ourisia cæspitosa; dead. Ligusticum aromaticum; alive, somewhat damaged. No. 11. Drapetes dieffenbachii; partially damaged, but not quite killed. Dracophyllum prostratum; very much damaged, but with trace of life. Cotula pectinata; dead. Poa, sp.; alive. No. 12. Drapetes dieffenbachii; as before. Ligusticum aromaticum; alive and little damaged. Gaultheria antipoda; alive. Poa, sp.; alive. No. 13. Ligusticum aromaticum; alive. Gaultheria antipoda; alive. Leucopogon frazeri; dead. No. 14. Aciphylla monroi; much damaged, but not quite dead. No. 15. Raoulia eximia; condition doubtful. Of the plants showing faint signs of life, and even some of the others whose leaves and stems were quite vigorous, the roots were usually so much damaged that the plants could not be expected to survive even with the most careful after-treatment. As a matter of fact, I did not attempt to grow any of them, since it was the eve of my departure on a botanical excursion to the Otago lakes. This excessive damaging of the roots would not take place in a state of nature, but was the result of exposure, owing to the small size of the blocks of earth. Those parts of any plant protected by earth, or its own leaves or those of an adjacent plant, invariably suffered least from the cold. In some instances—for example, with Raoulia eximia—it was difficult to tell whether the plant was alive or not. I have not made any summary to show the average temperature the plants endured, since there is no selfregistering thermometer in the chamber, and the mean between evening and morning temperature would not be reliable. It was during the third period that all the second batch of plants perished, and this seems to have been caused more by the greater length of this period than by any considerably lower temperature. Possibly had the plants been in a dormant condition the result of the experiment would have been very different; at any rate, the method of employing small blocks of earth with plants contained is a very bad one, but under the circumstances no other could be practised. The freezingchamber also is completely dark, and so the plants were ex posed to very different conditions to what they experience in nature. A rather interesting fact noticed was that all the plants were damaged by the cold when in the freezing-chamber and not by the subsequent thawing process. This was ascertained by an examination of each plant previously to the thawing taking place, the black leaves and stems of those damaged being very evident.

Such an experiment as that described here is, at best, a very rough one, and could, of course, be much better conducted in a biological laboratory, where the exact conditions could be regulated. Still, a freezing-chamber offers an easy place for such experiments, and granted plants in the dormant condition, and so arranged that the portion of the plant underground would not get excessive freezing, valuable data as to the cold-resisting powers of our plants might be arrived at. My results are for the most part negative, but they may perhaps induce others to work in the same field, and to avoid the errors inseparable from a first experiment. I cannot conclude without expressing how much indebted I am to Dr. Pairman for his invaluable assistance; to Mr. R. Brown, who accompanied me to Mount Torlesse and helped in the hard work; to Professor A. Dendy, for assistance regarding literature relating to freezing plants; to Mr. A. Milne, chief engineer of the Lyttelton Harbour Board, and his assistants, who gave every help in their power; and to the Department of Agriculture and the Lytteiton Harbour Board.