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



negundo. However, this and some of the forms referred to Vitex trifolia are so much 

 alike, that without a careful examination of all the specimens, the distribution of the two 

 species — if two there be — cannot be accurately given. Vitex bicolor, Willd., is the 

 same as Vitex negundo. 



Vitex, pubescens, Yahl. 



Vitex pubescens, Valil; [Miq., Fl. Ind. Bat., ii. p. 861 ; Dene., Herb. Timor. Descr., p. 73. ' 



Wetter. — Common in Tropical India from Bengal to Ceylon, and through the Malayan 

 Peninsula and Archipelago, but not known from Australia. 



Petraeovitex riedelii, Oliv. 



Petraeovitex riedelii, Oliv. in Hook. Ic. PI., t. 1420. 



Arrou ; Wetter. — Also in Burn. A monotypic genus, as far as at present known, 

 established on specimens recently collected in these islands. 



Avicennia officinalis, Linn. 



Avicennia officinalis, Linn. ; Miq., Fl. Ind. Bat., ii. p. 912 ; Benth., Fl. Austr., v. p. 69 ; Baker, Fl. 

 Maurit., p. 257. 



Although there are no specimens in the Kew Herbarium of this shrub from the 

 Eastern Moluccas eastward of Timor, it deserves to be mentioned here on account of its 

 remarkable geographical distribution. Taking it as limited in the Flora Australiensis 

 (that is, to include Avicennia tomentosa, Jacq.), it is one of the most widely diffused of 

 littoral shrubs, inhabiting, as it does, the shores of Tropical and Subtropical Asia, Africa, 

 America, and Australia, and extending into some temperate regions, as the Bermudas in the 

 north, and New Zealand in the south. It is common apparently on all the coasts of Tropical 

 Asia ; on the eastern coast of Africa it ranges from the Red Sea to the Cape of Good 

 Hope, and is also common on the western coast ; in America, it is common on both the 

 Atlantic and Pacific coasts; and it grows all round Australia, including the western side, 

 where so very few of this class of widely dispersed plants are found. But, except New 

 Caledonia and the Galapagos, we have no evidence that it occurs in any of the Pacific 

 Islands. It is not mentioned by Endlicher, Seemann, Nadeaud, Jouan, Mann, or 

 Guillcmin ; and there is not a single specimen in the comparatively recent and copious 

 collections at Kew, collected by Powell, Whitmee, and others. Therefore, should it exist 

 at all in Polynesia proper, we may assume that it is rare. This unusual distribution is 

 not easily explained, for many of the other salt-marsh and mangrove-swamp plants with 

 which it is associated elsewhere, abound in many of the Pacific Islands. The plant 

 doubtfully named Avicennia tomentosa in Hooker and Arnott's Botany of Beechey's 

 Voyage, p. 93, from the Sandwich Islands, is Vitex trifolia. 



