210 SECTIONAL ADDRESSES. 



The Tung oil trees, Aleurites Fordii and A. montana, whose seed yields 

 a very valuable drying oil, are now being introduced through Kew and the 

 Imperial Institute to all suitable Dominions and Colonies. In these trees 

 the flowers are borne in clusters, and each flower-cluster usually consists 

 of a large number of male flowers surrounding a single female flower. It 

 was noticed some years ago that certain trees under cultivation in America 

 bore two or three female flowers in each cluster or inflorescence. Selected 

 seed from this ' multiple-cluster ' type appears to transmit this charac- 

 teristic, and trees showing this favourable variation may thus be expected 

 to crop more heavily, and yield more oil, than trees with only one female 

 flower in the cluster. 



Trees of A. Fordii planted in New South Wales are proving very variable 

 in their fruit yield, and Mr. Penfold informs me that the }aeld of fruit per 

 tree varies from 25-362 ; unfortunately we do not yet know whether the 

 higher-yielding trees are of the ' multiple-cluster ' type or whether 

 they are only ' high-yielders ' of the normal form. 



The problem, therefore, which may arise is analogous to that which 

 confronts us with Para rubber in the matter of latex- yield ; with Cacao 

 as regards permanent poor-yielders and permanent heavy-yielders ; or 

 with Cavendish Bananas in the Canary Islands, some forms of which peld 

 bunches of fruit from suckers only 13 months old, while in other cases 30 

 months elapse before the fruits are ripened. Cases such as these, and 

 there are many others of a like nature, afiord an apt illustration that 

 Economic and Systematic Botany can pro^^de romances, possibly of more 

 scientific interest to the botanist than to the commercial planter, but of so 

 great material importance to the latter that the botanist looks to the man 

 of affairs for the financial assistance to help him to discover their solution. 



Comparable with what has been described for Eucalyptus dives is the 

 case of the Indian grass Cymho'pogon Martiyiii Stapf. Two forms of this 

 grass are recognised, which grow on adjoining parts of the hills of the 

 Bombay Presidency and other parts of India. One form, ' Motia,' jrields 

 an oil with an average Geraniol content of 91.3 per cent., and prefers the 

 drier hillsides — the other, ' Sofia,' with an average of 42.7 per cent, of 

 Geraniol in the oil, occurs in the moister localities. In some parts these 

 two physiological varieties grow in contiguous areas and tend to intermix 

 where they grow close together. They can be recognised by the differences 

 in smell, but beyond a slight difference in the pose of the leaves they cannot 

 be separated by any definable botanical characters. From the Economic 

 point of view the essential difference between the two types of oil is that 

 ' Sofia,' or ' ginger-grass ' oil, contains a strong-smelling substance called 

 i-carvon, which is not present in ' Motia ' or ' Palmarosa ' oil ; this latter 

 oil is the one which is considered of superior quality and commands a 

 higher price in the markets. 



The trees which peld Balsam of Peru and Balsam of Tolu afford a 

 somewhat similar problem. These are regarded as varieties of Myroxylon 

 halsainum (L.) Harms, or Toluifera balsamum L., the only recognisable 

 difference so far found between them being the structure of the resin cells 

 of the cotyledons in the two cases. ^^ 



19 See Harms, NotizbUUt des Kgl. Bot. Gard., No. 43 (1908), p. 94. 



