July 1951 School Magazine

Brisbane Girls ' Grammar School Magazine

Brisbane Girls' Grammar School Magazine

July, 1951

July, 1951

produced in sharply · defined groups which may be rounded or linear and are found on the under · surface of the sporo- phylls. In the sporophyll of an interrupted fern the sporangia are only found on several pairs of leaflets near the middle of the blade when these leaflets are mature they are small and brown and have the sporangia on their margins. The other leaflets are large green and sterile. The Royal fern also has separate fertile a nd sterile leaves, the sporangia ,being borne on the few ends at the upper end of the leaf. The Grape fern has two distinct parts, one sterile and one fertile, and has a fl at several times compound blade which is its chief photo-synthetic organ, as well as a slender upright portion whose only function is the production of spores. In the Sensitive and Ostrich ferns both these functions are completely separated. On the common polybody the spore cases are on the under surface of the leaf and form circular patches of golden orange or brown. If the spores of two varieties become mixed the weaker one will gradually throw back to the stronger. For example if the leaves of a lacy fern are in contact with those of a fishbone the lacy fern will gradually change into a fishbone . There is one type of fern, abundant in tropical f::JTests, ·called epiphythal which do not grow on the ground but fastened on the surface of the trunk or branches of trees . These do not derive nourishment by sucking the sap of the tree and so do not injure or destroy it. They derive nourishment from the humidity of the atmosphere. The most well-known exam- ple of this fern in Queensland is the Staghorn named for the shape of the leaves of which the bottom ones are used to hold water and humus. Of the other families of ferns not previously mentioned, there are a few genera found ln the tropics and sub-tropics which have leaves that continue to grow for more than one season until they assume a vine-like form which in one ~enus have been known to reach a length of one hundred feet. There are also a few types of ferns which live floating on or submerged in ponds or lakes. The above mentioned ferns are only a very few of the many thousands of ferns which are found throughout the world a fact which delights the heart of every fern collector. .But ferns are more than a mere collector's item, they are some of nature's most beautiful and graceful creations . -JUDITH BUBB 26

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VALERIE POTIER, lV. E.