SPARE HALF HOURS.

Otago Witness, Issue 1901, 17 July 1890, Page 38

SPARE HALF HOURS.

By F. A. Joseph.

DESIGN IN NATURE, IV.

The remarkable modification of flowers to meet the requirements of plants in the first place, and to supply food to the insects in the second affords some Of the most striking evidences of design in Nature perhaps to be met with. This evidence is splendidly supplemented by those instances of plant modification speoially designed for fertilisation by birds. The exigencies of the plants are subordinate to the distribution of insect life in any region ; and the modification of flowers adapted to insect fertilisation would be resultless where insects are absent or even scarce. Nature never makes any such blunders as to clothe a region with plants designed^for insect fertilisation where insects do not abound.. We have a splendid exemplification of this fact in our own island colony, far removed as it is from every continental regicn. Nectar-loving insects are very few in New Zealand, and as a result we find all our most sonspiouous flowers specially adapted for bird fertilisation. Taking our native flax to begin with, its trumpet-shaped flowers form a receptacle often filled to the brim with sweet nectar. This nectar is greedily sought after by the bell bird and the tui, which birds, with their brush-like tongues, not only drink the nectar, but also brush up all the minute insects that collect in quantity around the inside of the flover; and while sc employed I have seen these birds absolutely yellow-crested with the pollen, which is ripest when the flowers are fullest of nectar. It is needless to add that as the birds flit from flower to flower the required cross-fertilisation is accomplished. Then again, the lovely glory-pea, the olianthus, or kowhai kaka-beak, as the Maoris, with their characteristic intelligence, have called it, to distinguish it from an allied flower — the yellow kowhai — has .been specially modified so that the ripened pollen might bo brushed off by the head of the sweettongued and sweet-voiced bell bird. The yellow kowhai itself is dependent upon the visits of these birds for cross-fertilisation, as is also the beautiful crimson mistletoe, the Loranthus lyalli, with its slender bugleshaped flowers. Then last oome the noble ratas and their alließ of the Metrosideros family, — those splendid forest trees, whose arching heads at certain seasons of the year are resplendent with a flaming glory.orown of crimson flowers amid a sea of wavy green. The stameniferous flowers of these trees spring from a little cup filled with the sweetest and most delicately flavoured nectar, and the stamens are so closely studded round the central stigma that it is impossible for the birds to sip the nectar without dusting their heads with pollen. All of these brilliant and conspicuous flowers are devoid of scent .with the exception of the kowhai, which has a delicate, faint scent, but their bright, showy colours reveal their presence in no uncertain manner. The occurrence of nectar-loving birdi and flowers 'modified to secure crossfertilisation from the visits of these, in a region particularly barren in nectar-loving insects, is' surely an evidence of design, of the eternal fitness of things, of the adaptation everywhere displayed over the wide field of earth and animated nature. Who but the man of science, with olear vision, and a mind trained to seek after the truth, would have discovered that, as these sweet little choristers, whose soft ohiming voices fill the forest aisles with a half-wild, half-divine melody, flit about from bough to bough, and flower to flower, they are not merely seeking their own pleasure, but carrying out the Divine behest at the same time. The pity is that wanton hands should attempt to thin the ranks bf such invaluable allies, by reason of whose industry the New Zealand forest has been made brilliant with gorgeous flowers.

In other lands the modification of flowers to secure cross-fertilisation by birds is not so general, as the abundant insects supply, for the most part, Nature's needs ; but there are some plants whose flowers show a marvellous degree of modification to suit the requirements of the case. Over the extended area inhabited by the many species of the humming birdj there are numerous flowers specially adapted for cross-fertilising by these pretty little airy creatures. Then n Australia there are flowers specially adapted for the honey-suckers and the brush-tongued lories. But perhaps the most remarkable example of flower modification for the purpose of being fertilised by birds is witnessed in a South American plant. This plant (Marcgravia) has umbrella-shaped clusters of drooping flowers, and beneath the overhanging flower bunch there are, springing from the centre of the flower, several pitcher-like appendages, which secrete nectar. Now. while a humming bird is hovering over the pitchers and sipping the nectar, its back and wings are freely dusted with pollen from the drooping stamens, so placed as just to hang over the bird's back. This is a wonderful example of special development, only equalled by the modification of flower seen in some of the orchids. The bird as well as the insect, then, plays an important part in the cross-fertilisation of plants, and this is nowhere better exemplified than in our own land, where no less than one-fourth of all the flowering plants are incapable of selffertilisation, and are therefore wholly dependent upon the agency of birds or insects — the former chiefly, as the right kinds of insects are peculiarly scarce.