PLANT LIFE

Press, Volume LXX, Issue 21323, 16 November 1934, Page 12

PLANT LIFE

♦ THE CASS RIVER REGION LECTURE BY IK C. E. FOWERAKER Plants of the river bed and shingle slips in the Cass river region were described in a lantern lecture to the Canterbury Horticultural Society last evening by Mr C. E. Foweraker, lecturer in botany at Canterbury College. Mr Foweraker claimed that although these plants were often small and sometimes not beautiful, there was interest in their evolution under harsh environmental conditions. The meeting was presided over by Mr M. J; Barnett. The lecturer described first the shingle covered tops of the mountains in the region under review, formed of grey wacke rock broken down by sun and frost and otheragents of attrition. They appeared to be desert, but had a vegetation of their own, to the extent of some 20 plants which might be listed as found only there. The chief problem confronting these plants in their growth was to procure and conserve moisture, and for this purpose they had a long central root, leaves with water storage tissue, and other equipment enabling them to withstand extremes of temperature. Of this type was the pen-wiper plant, belonging to the cabbage family. The lecturer devoted some .time to a description of the vegetable sheep, found further east on the slopes of Mount Torlesse, and peculiar to New Zealand. Lantern slides showed the variation in size of this plant, its characteristic habitat on rocks with its root penetrating down through a fissure, and in particular one fine specimen sent to the San Francisco exhibition.

The - shingle slip, continued Mr Foweraker, originally entirely shingle, underwent a process of consolidation, eventually becoming grass land. In this process there was give-and-take, plants invading the shingle and being washed away in the erosion caused by water. It was to be noted that it was not only the destruction of forests but also of any vegetation which allowed erosion.

Transition to Grass Land In the succession of plants which marked the transition from the shingle fan to the grass land, one of the first to come was the Epilobium, which provided binding and humus. There was also the green Raoulia, a mat-like plant growing over rocks, which collected dust and formed a sub-stratum for the oncoming tussock. Small daisies, trefoil and chickweed were to be found, and at the base of the shingle fan the "Wild Irishman." A mixture of tussock and scrub then appeared, the latter, such as the Hymenanthera, being found among rocks, the great food supply in its seed allowing the root to penetrate far down to procure water. Some plants, an Epilobium or a Raoulia tenuicaulis, might appear on a river bed only a few weeks after the water had been diverted to another channel said Mr Foweraker. Later would come the Raoulia Haastii, a mat-like plant of similar type, emerald green in the spring, but a chocolate brown at the beginning of winter because of the pink dye then produced in the cells. There were also cushion plants, the surface of which was formed by a series of rosettes close together. Acidity in the soil had some effect on the type of plant, a change being perceptible as it increased. The plants of the river bed, and others such as the Wild Irishman and gorse, tended to spread out along the surface, while on the grass land they would grow vertically. Additional slides showed many other plants, including Cuprosma and Phormium Tenax, the lecturer stressing that the latter preferred moving water for its habitat.

"These plants may not be of very great horticultural interest," concluded Mr Foweraker, "but they grow under particular conditions, and those conditions must be studied in an attempt to transplant them from their natural habitats." The lecturer, who answered many Questions, was accorded a vote of thanks by the meeting. Some lantern slides of gardens in Christchurch were then shown by Mr W. Williams.