Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 1.djvu/383

 Rh assigned in the Economy of nature, to this family of sea-side plants, viz. to take the first possession of new-formed land, just emerging from the water, we see in the disposition of light buoyant fibres within the interior of these fruits, an arrangement peculiarly adapted to the office of vegetable colonization. The sea-side locality of the Pandaneæ, causes many of their fruits to fall into the water, wherein they are drifted by the winds and waves, until they find a resting place upon some distant shore. A single drupe of Pandanus, thus charged with seeds, transports the elements of vegetation to the rising volcanic and coral islands of the modern Pacific. The seed thus stranded upon new formed land, produces a plant which has peculiar provision for its support on a surface destitute of soil by long and large aerial roots protruded above the ground around the lower part of its trunk. (See Pl. 63. Fig. 1.) These roots on reaching the ground are calculated to prop up the plant as buttresses surrounding the basis of the stem, so that it can maintain its erect position, and flourish in barren sand on newly elevated reefs, where little soil has yet accumulated.

from two to fourteen in number, and many of them are abortive, (Fig. 13.) The seeds within each drupe of Pandanus are enclosed in a hard nut, of which sections are given at Figs. 14, 15. These nuts are wanting in the Podocarya, whose seeds are smaller than those of Pandaneæ, and not collected into drupes, but dispersed uniformly in single cells over the entire circumference of the fruit. (See Pl. 63, Figs. 3, 8, 10.) The collection of the seeds into drupes surrounded by a hard nut, in the fruit of Pandanus, forms the essential difference between this genus, and our new genus, Podocarya.

In the fruit of Pandanus, Pl. 63, Figs. 11, 16, 17, the summit of each cell is covered with a hard cap or tubercle, irregularly hexagonal, and crowned at its apex with the remains of a withered stigma. We have a similar covering of hexagonal tubercles over the cells of Podocarya (Pl. 63, Figs. 2, a. 8, a. 10, a.) The remains of a stigma appear also in the centre of these hexagons above the apex of each seed. (Figs. 8, a. 10, a.)