Page:Popular Science Monthly Volume 33.djvu/328

314 here chiefly concerned, are white and perfumed. Now, nothing in nature is without a reason; and this change of color in the gourd kind from the ordinary normal hue of its race at large is not without a sufficient purpose either. I don't know whether most people have ever noticed that hell-shaped or tubular white flowers are almost always heavily scented. Examples familiar to everybody occur in the jasmine, the stephanotis, the gardenia, the tuberose, and the large white tobacco so much cultivated of late in garden borders. It often happens, indeed, that a plant possesses two allied varieties, one of them blue, pink, or yellow, and scentless, while the other is white and deeply perfumed. In these cases, the first kind is a day-flowering plant, while the second opens and spreads abroad its scent in the dusk of evening. One well-known instance exists in England: the red campion or day-flowering lychnis is pink, scentless, and strictly diurnal; while its ally, the white campion, is beautifully perfumed, and opens its flowers at the sunset only. The reason is that the one species is fertilized by day-flying bees or butterflies, and the other by crepuscular or night-flying moths. Now, in the gray dusk no color can so readily be distinguished as pure white; and lest this peculiarity alone should prove insufficient to attract moths to the patch of light among the dark foliage, the added attraction of perfume is thrown in gratis by moth-fertilized plants. Such night-flowering white blossoms never possess the spots or lines or colored marks on the petals, which serve as honey-guides in other plants to lead the bees straight to the laden nectary. In the twilight, variegation or dappling of that sort would be wholly useless.

The blossoms of the gourds, then, are fertilized by moths, attracted to the plant at nightfall by the white corolla and the rich, heavy perfume of the bell-shaped flowers. This perfume is one of a type much affected by aesthetic moths, and not unpleasant to ourselves in the open air, but too cloying for a room, as is the case also with the kindred scent of stephanotis and tuberose. As soon as the flowers have been all fertilized, the male blossoms wither away to nothing; but the small berry underneath the female ones begins to swell out into a big, round fruit with surprising rapidity. Great heat and much sunshine are of course needed in order to produce this startling result with an annual plant; and hence the gourd family consists mostly of luxuriant tropical or subtropical species. Their center of origin would seem to lie in India, where species and individuals are still most numerous. Thence the gourds have spread, with gradual modifications to suit climatic changes, to all the hotter climates of the Old and New Worlds. Some of them have reached as far as Peru and the Cape of Good Hope. But very few of them have spread far northward, because a northern climate is ill-adapted for such large and