PiATE 179.— HOMALANTHUS POLYANDRUS. 



Family EUPHORBIACE.E.] [Genus HOMALANTHUS, A. Juss. 



Homalanthus 'polyandrus, Cheesem. Man. N.Z. Fl. 630. 

 Carumbium polyandrum, Hook. f. Handb. N.Z. FL 248. 



This graceful and attractive tree was discovered in Jvdy. 1854. during a visit 

 made by Captain H. M. Denhani, of H.M.S. "Herald," to Hunday, or Raoul Island, 

 the chief island of the Kermadec Group. The " Herald " arrived on the 2nd July, 

 and remained iintil the 24th of the same month. During this brief stay a survey 

 was made of the island ; and Messrs. J. Milne and W. McGillivray, the naturalists 

 attached to the " Herald," made a small collection of plants. This was placed 

 in the hands of Sir J. D. Hooker, and formed the foundation of a paper on 

 "The Botany of Raoul Island" printed in the "Journal of the Linnean Society" 

 (vol. i, p. 125). Forty-two species were recorded as inhabiting the island, and in the 

 list occurs the name of " Omalanthus nutans," GuilL, a species originally discovered 

 in New Caledonia. In the "Handbook" Sir J. D. Hooker recognized that the 

 Kermadec plant differed from the New Caledonian, and described it under the 

 name of Carumbium polyandrum. As the genus Carumbium is now merged with 

 Hom,alanth'Us our plant must take the name of H. folyandrus. 



In a visit paid to the Kermadec Islands in August, 1887, I had an opportunity 

 of examining the flora of the group, and of collecting specimens of most of the 

 species. At that time H. folyandrus was not uncommon in sheltered places on 

 Sunday Island, and I also saw a few plants in the crater-basin of Macaulay 

 Island. But Mr. W. R. B. Oliver, who visited Sunday Island in 1907-8, remaining 

 thereon for eleven months, states (Trans. N.Z. Inst, xlii (1910), 167) that it is 

 now confined to a few localities inaccessible to goats. According to him, "these 

 animals absolutely determine the existence of the species. They eat the bark 

 from the trunk as high as they can reach, and the tree dies in consequence." 

 With the knowledge that we possess respecting the destruction of the indigenous 

 flora on St. Helena through the agency of goats, it is to be feared that Homalanthus 

 folyandrus is in danger of being blotted out of existence in its only known habitat. 

 Fortunately, it has found its way into Auckland gardens. 



Homalanthus folyandrus is a graceful tree 10 ft. to 25 ft. high. Young plants 

 form slender unbranched rod-like stems 6 ft. to 15 ft. high, with large leaves some- 

 times more than a foot in diameter. Older plants branch freely and have much 

 smaller foliage from 2 in. to 4 in. long. The leaves are quite glabrous, very thin and 

 delicate, glaucous beneath, and with reddish margins. In cultivation in Auckland 

 the leaves often turn dark reddish-brown or sometimes nearly scarlet in winter, and 

 then present a very ornamental appearance. The flowers are arranged in slender 

 erect racemes 4 in. to 9 in. long, the females being few in number at the base of the 

 racemes, the males very numerous and occupying by far the greater part of the 

 raceme. All parts of the plant exude a milky latex when broken or bruised. 



The genus Homalanthus is essentially Polynesian and Malayan. In addition 

 to the New Zealand plant, there are from eight to fifteen others, according to the 

 different views of authors, ranging from Tahiti to eastern Australia, and stretching 

 northwards as far as the Philippine Islands. Several of the species are very 

 closely allied, and it is quite possible that their number will be reduced by future 

 systematists. 



Plate 179. Homalanthus folyandrus, drawn from specimens collected on the Kermadec Islands. 

 Fig. 1 , portion of male inflorescence ( x 4) ; 2 and 3, front and back view of anther ( x 5) ; 4, female 

 inflorescence (x 2) ; 5, pistil ( x 5) ; 6, longitudinal section of fruit (x 3) ; 7, seed (x 3) ; 8, longitudinal 

 section of same ( x 3) ; 9, half of embryo ( x 6). 



