Page:Popular Science Monthly Volume 19.djvu/375

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Another interesting genus, again of the same family, is Myzodendron (Fig. 16), a Fuegian species, described by Sir Joseph Hooker, and parasitic on the beech. Here the seed is not sticky, but is provided with four flattened, flexible appendages. These catch the wind, and thus carry the seed from one tree to another. As soon, however, as they touch any little bough, the arms twist round it and there anchor the seed.

In many epiphytes the seeds are extremely numerous and minute. Their great numbers increase the chance that the wind may waft some of them to the trees on which they grow; and as they are then fully supplied with nourishment they do not require to carry any store with them. Moreover, their minute size is an advantage, as they are carried into any little chink or cranny in the bark, while a larger or heavier seed, even if borne against a suitable tree, would be more

PSM V19 D375 Cardamine chenopodifolia.jpg
Fig. 17.—Cardamine chenopodifolia. a a, ordinary pods; b, subterranean pods.

likely to drop off. In the genus Neumannia, the small seed is produced at each end into a long filament which must materially increase its chances of adhering to a suitable tree

Even among terrestrial species there are not a few cases in which