DISPERSAL OF PLANTS BY OCEAN CURRENTS. 75 



Fruits with buoyant husks. — In addition to the coconut, which 

 is provided with a fibrous envelope, and is known to float for long 

 periods of time in the sea without losing its vitality, there are found 

 in the drift of Guam the fruits of Barringtonia speciosa, called "put- 

 nig" by the natives, and Ochrosia mariannensis, called " fago." Both 

 of these fruits have fibrous husks, but that of the Barringtonia has a 

 hard glossy surface, somewhat as in the case of the coconut, while the 

 surface of the Ochrosia is soft and easily eroded. The fruits of this 

 Barringtonia (PI. XXXVIII) are four-cornered and miter-shaped; 

 '.he natives crush them and use them as a fish intoxicant. Those of the 

 Ochrosia are oval in shape, and, like the closely allied Cerbera fruits 

 of Samoa and other tropical countries, are soon deprived of their pulpy 

 parenchyma, and display the cushion of fiber inclosing the mesocarp. 

 This owes its buoyancy to intercellular air spaces. It is elastic and 

 serves to protect the seed from erosion and from the attacks of animals. 



Mangrove fruits. — Great numbers of these spindle-shaped young- 

 plants are continually carried by the tide from the estuaries into 

 which they drop after having begun to germinate on the tree. The 

 fruits of Bhisophora mucronata (PI. LXIV) are easily distinguished 

 from those of Bruguiera gymnorhiza (PI. XL) b} T the four-parted 

 persistent calyx, the calyx of Bruguiera consisting of man}^ segments. 

 Associated with them are found the seeds of the "red-flowered 

 mangrove" {Lumnitzera littorea), called "nana" in Guam; those of 

 Excoecaria agallocha, the "milky mangrove," or "blinding-tree," 

 which grow in catkin-like spikes; and the keeled nuts of the "ufa" 

 {Heritiera liitoralis), the hard shell of which includes a very large 

 air space (PI. LI I). 



Littoral trees and shrubs. — Other seeds found in the drift are 

 those of Pariti tiliaceum and Thespesia populnea, the "pago" and 

 "kilulu" of the natives, both of which belong to the Malvaceae, and 

 have cavities filled with air; the round nuts of Calophyllum inophyl- 

 lum, called "daog;" the boat-shaped "almonds" of Terminalia catappa, 

 called "talisai," often much eroded; the angular woody seeds of the 

 "lalanyug" {Xylocarpus granatum), and the ribbed fruit of the nipa 

 palm (Nyjxi fruticans). Among the plants which grow on the edge of 

 the sea, whose fruit drops into the water continually, are the shrubby 

 Lobelia Jcoenigii and Tournefortia argentea (PI. LXV1II), associated 

 with the creeping "goats-foot convolvulus" (Ipomoea pes-caprae), the 

 seeds of which contain air cavities, and the "Polynesian iron wood" 

 {Casuarina equiseti folia), the cones of which (PI. XLI) are corky and 

 buoyant and inclose seeds provided with wings which adapt them for 

 transportation by the wind. The transparent wings of these seeds are 

 stiffened by the persistent style. When a handful of them is thrown 

 into the air they resemble a swarm of flying insects. Hundreds of 

 these seeds, together with the queer-shaped Barringtonia fruits, are 



