THE SPLASH-CUP DISPERSAL MECHANISM IN PLANTS

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Abstract
The late Prof. A. H. R. Buller regarded certain cup-shaped reproductive bodies found among cryptogams as "splash-cups'' which make use of the energy of raindrops for the dispersal of spores, sperms, and gemmae. Buller''s concepts are presented and supplemented by investigations carried out since his death. Raindrops cause the peridioles of the Nidulari-aceae or bird''s-nest fungi to be thrown about 4 feet by splash action. In the genus Cyathus, as a peridiole is jerked out of its cup, the funiculus is torn and this makes possible the expansion of a mass of adhesive hyphae (the hapteron) which clings to any object in the line of flight. The momentum of the peridiole causes a long cord to be pulled out of a sheath attached to the peridiole. The peridiole is checked in flight and the jerk causes the funicular cord to become wound around stems or entangled among plant hairs. Thus the peridiole becomes attached to vegetation and may be eaten subsequently by herbivorous animals. Several morphological features of fruit bodies of the Nidulariaceae are regarded as related to the utilization of the energy of raindrops in rain dispersal and the significance of the splash-cup principle is emphasized. Other splash-cups, the operation of which is described, are the gemma cups of Marchantia and Lunularia; the antheridial disk of Marchantia; the leaf rosette of the male Polytrichum plant; the sclerotium cups of Aleurodiscus minnsiae; the cupulate fruits of Sagina decumbens and Oenothera rosea.