Drift seed

"Darwin himself did some simple yet elegant experiments showing that seeds from some plant species could still germinate after prolonged immersion in seawater. Seeds from the West Indies have been found on the distant shores of Scotland, obviously carried by the Gulf Stream, and "drift seeds" from continents or other islands are also found on the shores of the South Pacific islands."

"The origin of plant life upon the Bermudas, is a question not very difficult of solution, after a careful consideration of facts accruing from the continued observations of several years. The islands are greatly influenced by the current of the Gulf Stream, which brings to their shores numberless objects, animate and inanimate, from the Caribbean Sea. Among such we may instances the seeds of trees, shrubs and plants, which are continually being cast ashore; while the occurrence of several forms, even forest trees, just above high water mark, go far to prove their drift origin. The hard seeds of the Leguminosæ seem especially adapted to withstand immersion in salt water for a length of time, and the fact of this order being better represented than any other favours the presumption. But although several leguminous seeds germinate on the Bermudas, there are some commonly cast ashore which do not; such are the seeds of Entada scandens, and Mucuna urens, which have never yet grown on the islands, notwithstanding their seeds are frequently landed near the trailing stems of Canavalia obtusifolia. Probably the sandy soil of the beach is unsuited to these species, which appear to grow on river banks in the West Indian Islands."

"Drift seeds bob down rivers or cross oceans — I have a dark brown Sea Heart on my desk at the Institute. I picked it up on a beach near Durban, far from the tropical Americas where it might have begun. I've rubbed it like a giant worry bead, glossed its brown skin thinking about its adventures on the currents — Gulf Stream, Equatorial, Canary, Brazil, Atlantic, Benguela, somehow making its way around Africa's tip and up to the tropical sands of KwaZulu-Natal."

"According to Guppy the type of Mucuna seed that is most frequently gathered on the beaches of Western Europe is that provisionally referred by him to Mucuna "near urens" and since suggested to be Mucuna altissimo. A drift seed of this was picked up by Guppy on the beach at Salcombe in Devon. In this the seeds are described as slightly flatter or more depressed than in M. urens and rather over and inch in diameter. They possess a narrower but a similarly encircling raphe. In color they are usually of a dark brown and when of a lighter hue they display black mottlings. Another drift seed, found at St. Helens in the Isle of Wight, is in the Kew Museum. Similar seeds have occurred in the Faroe and the Shetland Islands."