EVOLUTION OF PLANTS.

Otago Daily Times, Issue 19803, 31 May 1926, Page 3

EVOLUTION OF PLANTS.

■W.E.A. CLASS IN BIOLOGY, • TUE FERN ALLIES. The sixth of a series of lectures of the Y7.E.A. Class in biology was held on Friday night in the upper Oliver room, University buildings. The lecturer, the Rev. Dr J. ■E. Holloway, P.N.Z.lnst., lecturer in botany of the University of Otago, before entering upon the subject of the evening briefly reviewed the life history of terns, in which it was seen that there is an alternation of a sub serial spore-bearing with a moisture-loving gamete-bearing generation, as in liverworts and mosses. But, whereas in the latter the spore-bearing generation was a more or less simple structure, and always remained attached to and parasitic upon the gamete-bearing plant, in the ferns it early became independent of the gamete-bear.vg “prothallns” and itself became the plant. Dr Holloway then proceeded to deal with some interesting but less well-known plants commonly termed the “fern allies.’’ These were the existing relics of certain very ■ancient groups of land plants, and they showed the same “amphibious alternation ’ in .heir life -.yclo as did the ferns.

In the Lycopediaceie there was a large number of varieties, popularly spoken of as club mosses. Some of them hung down from the branches and forks of forest trees, others grew in swampy places; and others again on open hillsides. The sporangia, with their spores, were borne on special twig-ends which took the form of little >a or catkins. The spore germinated underneath the ground and gave rise to a colourless, subterranean, more or less tuber-like prothallus, on which the male and female gametes were borne. These, as in ferns, liverworts, etc., were swimming sperms and non-raotile eggs. The fertilised egg developed into the embryo and sporeling plant, and finally into the adult spore-bearing plant. A fungus which lived in the soil penetrated into the tissues of the prothallus and supplied it with food, and so enabled it to live underground away from the light. A very simple member of the Lycopod family named Phylloglossun had been considered by some botanists to be a more ancient type of land plant than any others now living. The Tmesinteris was a very peculiar spore ‘bearing plant, which grew on such as the stems of tree ferns. It belonged to New Zealand and the tropical islands of the Pacific Ocean. The prothallus grew below the surface, and there was a fungus present in its cells which provided nourishment as in the case of Lycopodium. The sporebearing generation had no root The nearest relatives of Tmesipteris were certain fossil plants which were considered to be the most, ancient fossils of land plants yet found. The Equisteum were plants occurring m Northern Hemisphere countries, and were called the “horse tails.” The spores and sporangia were borne in cones, and the prothallus was green and occurred at the surface of the ground, and so was able to manufacture food for itself. The Ophioglossum were the “Adder's Tongue" plants. The species of another kind of fern ally named Botrychium were popularly called the "parsley ferns.” In both these kinds of plants the prothallus was subterranean, and its cells were occupied by a fungus. In summing up, Dr Holloway briefly recapitulated the principal items he had dealt with In order to show that the fern allies illustrated the same life cycle as did the ferns, although they possess many different special characters. The spore-bearing stage, he said, was the "plant” itself, and this needed to distribute its spores in the dry air. The gamete-bearing stage or prothallus needed the presence of moisture in order that the swimming sperms might reach the eggs. These fern allies were the modern representatives of certain verv ancient groups, and It was necessary to go bn to consider the fossil remains of these ancient ancestors. At the conclusion of the lecture Mr Crowther. the chairman. In a few felicitous remarks, said that he felt sure that he voiced the sentiments of the class in congratulating Dr Holloway on the honour conferred on him in being asked by the botanists of America to lecture at the forthcoming congress in America, and furthermore, the students of the YV.E.A. and the University classes should feel proud in having him for their tutor. Mr Dunn, the secretary, in seconding the remarks of the chairman, said that the congress of America was also to be congratulated on having shown great wisdom in selecting Dr Holloway to address the conSr Dr Holloway, In a feeling reply, thanked the members of the class for their appreciative remarks, and said he thought It was very good of the students to have noticed the announcement in the papers, and to have expressed their appreciation in such a marked manner.