PLATE 86.—OLEARIA SEMIDENTATA. 
Famity COMPOSIT/.. | [Genus OLEARIA, Mancu 
Olearia semidentata, Dene. ex Hook. f. Fl. Nov. Zel. i, 115; Cheesem. Man. N.Z. FI. 280. 
Olearia semidentata, which is confined to the Chatham Islands, was. first 
observed between the years 1836- 39 during a hasty visit paid to the group by 
the French exploring-vessel “* Venus” ; and in 1841 a beautiful plate of it was 
prepared under the direction of the well-known botanist Decaisne. It was next 
gathered by Dr. Diefenbach, the naturalist to the New Zealand Company, who 
visited the islands in 1841; and it was from his specimens that the descriptions 
given by Hooker in the “ Flora” and the ** Handbook” were prepared. In 1863 
the Chatham Islands were botanically explored by Mr. H. H. Travers, when 
humerous specimens of the plant were obtained. Since then it has been 
gathered by all visitors to the group, and the main facts of its life-history 
have been fairly well ascertained. 
According to Dr. Cockayne, whose memoir on the ‘‘ Plant Covering of 
Chatham Islands” (Trans. N.Z. Inst. xxxiv (1902), 242-325) is a storehouse 
of information respecting the vegetation of the islands, Olearia semidentata is a 
dominant species in the peat bogs that occupy such a considerable proportion 
of the surface of the main island of the group; excepting always the very wet 
swamps, which have a vegetation mainly composed of Sphagnum. In the bogs 
that are firmer and drier the plants most commonly seen are Lepyrodia 
Travers, Olearia semidentata, and Dracophyllum scoparium var. paludosum, 
forming an association to which Dr. Cockayne gives the name of the Lepyrodia- 
Olearia formation. 
Olearia semidentata, when growing under favourable conditions, forms rounded 
bushes 2 ft. to 3 ft. in height and rather more in diameter. When in full bloom it 
is covered with numerous aster-like flower-heads, the ray-florets of which are 
purple and the disc-florets a deeper violet-purple. It is thus a very beautiful 
and striking plant, fully worthy of a place in colonial and European gardens. 
An excellent illustration of the appearance of the species in its natural home 
is given in the “ Kew Bulletin” for 1910 (p. 122), prepared from a photograph 
taken by Captain Dorrien-Smith, who in 1909 paid a visit to the Chatham 
Islands for the special purpose of introducing the plant into cultivation in 
England. 
The nearest ally of O. semdentata is undoubtedly O. chathamica, the subject 
of the following plate, which differs mainly in its more robust habit, broader 
and more coriaceous leaves, and larger flower-heads, the ray-florets of which are 
usually white, whereas they are almost invariably purple in O. semdentata. 
PuarEe 86. Olearia semidentata, drawn from specimens collected in the Chatham Islands by 
Mr. F. A. D. Cox. Fig. 1, bracts from the involucre (x 4); 2, ray-floret (x 4); 3, disc-floret (x 4) ; 
4, pappus-hairs (x 8); 5, anthers (x 8); 6, style-arms (x 8). 
