24 THE VOYAGE OF H.M.S. CHALLENGER. 



mentioned, though it may possibly not be exhibited by the living plant. The pappus falls 

 from the achenes while they are still in or attached to the receptacle, and the bracts of the 

 involucre are apparently hygroscopic, and when dry, bend over the achenes and prevent 

 them from being dispersed. Of course, this and many other points connected with repro- 

 duction can only be verified on the spot. 



The endemic arboreous genus Cuminia of the Labiatse has dimorphic, functionally 

 unisexual flowers, intermixed in the same inflorescence, the males largely predominating. 

 It is very closely allied to Bystropogon, a genus of upwards of a dozen mostly shrubby 

 species, and some of considerable size, inhabiting the Canary Islands and Western South 

 America. Describing the size of the trunks of several of the Juan Fernandez trees, 

 including the species of Cuminia, Philippi states 1 that they are often one to three feet in 

 diameter; but, judging from what Bertero and others say of the size of the species of 

 Cuminia, a foot would be the outside diameter of the trunk of any of them. Arboreous 

 Labiataa are very rare ; probably the largest are some South American species of Hyptis. 

 A Brazilian species, Hyptis membranacea, is stated by Gardner to be a tree thirty to forty 

 feet high ; another species, Hyptis arborea, a native of British Guiana, New Granada, and 

 Ecuador, grows from twenty to thirty feet high. There are also several large shrubby 

 or subarboreous Labiatre in India, as Colebrookia, Elsholtzia, and Meriandra. 



The shrubby Boraginaceous plant, which we have removed from Cynoglossum and 

 raised to the rank of a distinct genus, under the name Selki.rkia, is allied to the Chatham 

 Island monotypic Myosotidium in structure, but very different in habit. 



Of all the endemic plants, however, the genus Lactoris is the most distinct, being so 

 unique in its structure that its place in the natural system is not easily determined. 

 Philippi referred it to the Magnoliaceae ; but Bentham and Hooker have no doubt correctly 

 placed it in the tribe Saururea? of the Piperaceas, though it differs from all the other 

 genera in the flowers having a distinct perianth, and in being solitary or two or three 

 together, instead of being naked and closely packed in racemes or spikes. Associated with 

 these anomalous structural characters, it has the knotted branches and the aromatic taste 

 and smell of a Piper. 



The structure of the flowers and fruit of the endemic palm Juania austrcdis is still 

 very imperfectly known ; male flowers have not been described, nor has the fruit. It is 

 to be hoped that no opportunity of obtaining complete specimens will be lost. 



Among other endemic plants, Eryngium bupleuroides has analogues in the South 

 European Bupleurum fruticosum, and in the African genera Heteromorpha and Stegano- 

 i 'i nia. There are shrubby species of Planlago in South America, but Plantago princeps 

 of the Sandwich Islands comes nearest Plantago femandezia. 



Another feature in the flora of Juan Fernandez is the almost total absence of Legumi- 

 nosao ; this it shares in common with New Zealand as well as many of the oceanic islands 



1 Botanische Zeilung, 1856, p. 634. 



