418 PLANTS, SEEDS, AND CURRENTS 



of plants of the shores would be distributed directly by currents, 

 as with Critkmum and Ipomcea, or indirectly in the crevices of drifting 

 logs, as with the small-seeded Silene and Spergularia, or by sea- 

 birds through adhering to their feet and legs, as with Plantago and 

 tJuncus, or carried in their stomachs, as with Polygonum. Very 

 few of the truly native plants of the Azores are fitted for attachment 

 by hooks or similar appendages to birds, the Azorean Sanicula 

 standing very much alone in this respect. It is a genus that has 

 found its way in this manner to several oceanic islands besides the 

 Azores, such as Madeira, the Canary Islands, Juan Fernandez, 

 Hawaii, etc. The number of small- seeded flowering plants that 

 must be lumped together under the head of those distributed in 

 mud adhering to birds is large. This " limbo " of the student of 

 dispersal, to which he assigns a multitude of plants, is not altogether 

 satisfactory; but for the oceanic island we are left but little choice, 

 since only the spores of cryptogams, as is shown below, are adapted 

 for transport by winds over broad tracts of ocean, and not even the 

 minute seeds of J uncus or the yet smaller seeds of Orchids could 

 avail themselves of this agency. We come now to deal more in 

 detail with the modes of dispersal of Azorean plants according to 

 their stations, and will begin with those of the woods. 



1. The Modes of Dispersal of the Plants of the Woods. — As already 

 observed, most of them would be dispersed by frugivorous birds, 

 such as pigeons. The specific or varietal differentiation of the 

 majority of them within the Macaronesian region indicates, as we 

 have seen, a breaking of the link with their original European home ; 

 and it is remarkable that this divergence corresponds with sub- 

 specific differentiation in the Macaronesian islands of the European 

 wood-pigeon, Columba palumbus, whilst the rock-pigeon, Columba 

 livia, has developed an Azorean variety (Hartert and Ogil vie- Grant, 

 Godman). The Canarian wood-pigeons, as we learn from Lord 

 Lilford's book on birds (1893, p. 70), and the Azorean pigeons, 

 according to Drouet, feed largely on the fruits of Persea (Laurus) 

 indica. Pigeons are credited with a liking for the fruits of other 

 genera of plants found in the woods of the Azores, such as Ilex and 

 Hedera. Doubtless the pigeons of Macaronesia are also partial 

 to the fruits of Myrica faya, the hard stones of which would be 

 probably ejected unharmed. The other genera of the woods, such 

 *as Daphne, Juniperus, Picconia, Rhamnus, S mil-ax, Taxus, Vaccinium, 

 Viburnum, etc., would be distributed by frugivorous birds. It 

 .may be added that stragglers may have played an important part 

 in this process, and that we are not restricted in this respect to birds 

 .that regularly visit the islands. In this manner the missel-thrush 

 ;may have introduced the first seeds of the Yew (Taxus baccata) into 

 the group, a matter dealt with in the remarks on that plant in a 

 later page of this chapter. 



2. The Modes of Dispersal of the Plants of the Upland Moors. — - 

 Though we have here again to appeal to the bird, the indications 

 are often largely conjectural. The plants concerned have for the 

 most part either dry small seed-like fruits or minute seeds. The 

 following is a series of measurements of some of the seeds stater 



