W.E.A. NATURAL HISTORY CLASS

Evening Star, Issue 19843, 17 April 1928, Page 5

W.E.A. NATURAL HISTORY CLASS

THE ORCHID FAMILY On Friday evening tho final lecture of this course, was given, when the subject was ‘The Orchid Family.’ Dr Holloway stated that this family is distinguished by the presence ol tho column, tho upright body in the interior of tho flower, formed by the fusion of tho style, the stigma, and the stamens. There arc six members of tho perianth in two whorls. The structure of the low'd- lip or lahellum is often most singular. All orchids have some particular adaptation by which pollination is effected. For instance, one of our Mew Zealand orchids (P.lorostyhs) has a front petal which acts on a kind of spring, and when an insect crawls along the labcllnm it is thrown into the centre of tho flower, the petal closes against the column, and the insect Ims to crawl up tho column to get out. In doing so it comes into contact with Die sttama, where it loaves some of tho pollen collected from another flower, and then brushes against the anther, carrying .away tho pollen masses, which in turn are taken to another flower. Orchids are found all over the world except where the climate is the \eiy coldest and driest; hut they arc most abundant in hot, damp, tropical forests (especially in Sou tlx America) j whore they cling to the trunks and branches of trees and to the stems of large, ferns. They have gorgeously-coloured flowers. These perching or epiphytic orchids are not generally found outside the, tropics. In temperate countries the orchids are terrestrial nr ground orchids, which have tuberous roots that store watci and enable the plants to live, from year to year. Epiphytic orchids have, ordinary clasping roots and also aerial roots, with a special reservoir tissue lor holding water; they also have pseudo (ni false) bulbs, which consist of part ol the stem, which has become swollen and is filled with water. These are found mostly in monsoon countries, where there is a long dry season. There arc sonic ground orchids which are leafless saphrophyt.es, which obtain their food from a fungus which lives on them. New Zealand has both epiphytic and terrestrial orchids, altogether sixty-six species belonging to twenty-one genera. The chict ground orchids arc Pteroslylis (thirteen species), Thelymitra (fourteen species). Aficrotis (one specie), Corysanthes (eight species), Cahulonia (tour species), Gastrodia (three species). The epiphytic ones arc Farina mucronata and E. suavcolcns, Dendrobium Cunninghamii, Bnlbophyllum (two species), and Sarchochilus. On Saturday afternoon members of the class visited the Botanical Gardens, : where a most interesting time was spent in observing tho plants which have formed tho subject of the series of studies just completed. Under the guidance of Dr Holloway special attention was given to ho contents of the orchid house and the fern house, and then an hour or two were devoted to tho native plants on the hillside. After tho address on Friday evening several members spoke expressing appreciation of the way in which Dr Holloway had conducted the class and the excursions, and thanked him specially for his unfailing interest and patience at all times.