XXVII 



SICYOS ' 365 



When, however, we come to consider the feasibility of the stones 

 of the genus having been thus originally carried to Hawaii either 

 from Japan or from North America, we meet with the difficulty 

 presented to us by other Hawaiian genera with stone-fruits, such 

 as Elaeocarpus, or with berries containing large seeds, such as 

 Sideroxylon. 



Sicyos (Cucurbitaceae). — This genus comprises about thirty-five 

 known species, of which three-fourths are confined to the New 

 World, being mainly South x^merican, whilst the remainder are 

 restricted to Hawaii, with the exception of two species in the 

 Galapagos Group and Norfolk Island, and a widely-ranging 

 species, S. angulatus. The plant just named, the small fruits 

 of which possess hooked spines, adapting them for dispersal in 

 a bird's plumage, occurs in Africa, Australia, New Zealand, and 

 America, but has only been recorded in the Pacific islands from 

 the Kermadec Group. 



North America was probably the home of the original 

 Hawaiian species. Hillebrand describes eight species, of which 

 five are not found in more than one island, whilst one species is 

 spread over most of the islands. The fruits vary much in size, and 

 only in a couple of species do they now possess any fitness for 

 attaching themselves to plumage, some of them being pubescent or 

 even glabrate, so that deterioration in the capacity for dispersal has 

 here taken place. Their size is usually a quarter to half an inch 

 (6 — 12 mm.) ; but it is noteworthy that the species with the largest 

 fruit (Sicyos cucumerinus, one to two inches, or 25 to 50 mm.) is 

 the species most widely dispersed over the group. This appears to 

 indicate that there is some other means of inter-island dispersal in 

 this archipelago than by attachment to birds' plumage. The 

 isolation of the genus in Hawaii from the rest of the world is, 

 however, complete, since all the species are endemic ; and when, 

 therefore, we come to ask how Sicyos angulatus, that has been 

 dispersed in the recent era over America, Australia, and New 

 Zealand, is not found in these islands, we are brought face to face 

 with the ever-recurring difficulty, the suspension in later times of 

 the agency of dispersal in the tropical North Pacific. 



Jacquemontia (Convolvulaceae). — This genus, which is chiefly 

 i\merican, is represented in Hawaii by a peculiar species, J. sand- 

 wicensis. This species grows occasionally on the sandy beaches 

 associated with Heliotropium anomalum and Tribulus cistoides ; 

 but it is most at home on rocky ground and on old lava-flows near 

 the sea-border, making its abode often in the pockets of black 



