522 ALTERATION IN FLORA SINCE 



New Zealand which could do this in the past except, perhaps, a few 

 ground birds, it was not to be expected that the flora would contain 

 plants which were so distributed. There are only two genera which 

 are well provided in this respect, viz., Accena and Uncinia. 



In the piri-piri {Acana sp.) the lobes of the calyx are produced 

 into spines, and in several species these are barbed, and hook on ta 

 hair, wool and feathers very effectively. The plants grow not only 

 out in the open, but also especially along the edges of scrub and bush„ 

 so that animals living in the shelter are almost certain to catch the 

 dry fruit as they pass out and in. Sheep and dogs have spread these 

 plants far and wide, and they have thus increased greatly. 



The sedges of the genus Uncinia are also provided with a very 

 efficient hook whereby they catch on to passing animals. From the 

 inside of the base of the utricle a long bristle, which is evidently 

 the produced axis of the spikelet, projects to the length of an inch 

 or more, and this is very strongly hooked at the tip. I cannot say 

 whether the species of Uncinia have spread as those of Accena have 

 done, though it is highly probable that they have. The latter are very 

 abundant and appeal to every one, for they not only get into wool 

 to a very serious extent, but they catch on to dogs, and also very 

 freely hook on to clothing. Uncinia is not nearly so abundant in 

 individuals, not being so efficiently provided with grappling appliances > 

 and it has not been observed to any great extent. 



It is very noteworthy that in both genera the species with the 

 best apparatus for distributing the seeds have a very wide range 

 outside of New Zealand, and almost certainly have developed this 

 character in regions where mammalia are to be found. Thus the 

 species (or group of species) known as Accena sanguisorbce, Vahl, is. 

 found in Australia, Tasmania and Tristan d'Acunha, and the plants, 

 are all strongly barbed. On the other hand A. Buchanani, Hook, f., 

 has the barbs frequently reduced to hairs ; in .4. microphylla, Hook, f., 

 the spines themselves are frequently wanting; while in A. glabra^ 

 Buch., the fruiting calyx is quite unarmed. These three species are 

 confined to New Zealand, and probably originated in these islands. 



The evidence is not so clear in the genus Uncinia. U. tenella, 

 R. Br., U. compacta, R. Br., and U. riparia, R. Br., occur in the 

 Australian region; U. Sinclairii, Boott, in Fuegia; and U. australis, 

 Pers., is said to occur in the Sandwich Islands. The other seven 

 species are endemic, but are in most cases very nearly allied to some 

 of the first-named species. In U. filiformis, Bott., which is endemic, 

 and is the same as or closely allied to U. debilior, F. v. Muell., of 

 Lord Howe Island, the bristle is very feeble and the hook has nearly 

 lost its catching power. 



