50 



Mueller's last report to the Acclimatization Society. The 

 lemon scented gum, or E. citriodora grows only on the 

 mountains on the tropics. It is without exception the finest 

 of our gum trees, with a smooth bark, and timber almost as 

 close-grained as European box. The leaves emit so powerful 

 an odour of oil of lemon as to be quite pungent. Use has been 

 made of the essential oil by Mr. Bosisto, of Eichmond, Victoria, 

 whose original researches into the properties of the Eucalypti 

 have led to their being largely utilized for the purpose of 

 commerce. Mr. Bentham, who has not seen the trees in 

 growth, supposed that JE. citriodora might be a variety of E. 

 corymbra, but the trees are as different as possible. 



In comparing the list of introduced plants which have 

 become weeds in East Australia and Tasmania, the difference 

 is very striking, but these differences depend no doubt 

 entirely on soil and climate. Thus you have in Tasmania a 

 large muster of European forms in which the British pre- 

 dominate, owing to the intercourse being chiefly with those 

 islands. It is difficult, however, to account on these grounds 

 alone why some species spread so rapidly and not others. 

 Thus Hypochoeris glabra seems to have taken possession of 

 all your meadows about Hobart Town, and you have already 

 to struggle against such intruders as Cardnus lanceolatus, 

 Cardnus Marianus, TJlex europeus, Hosa rubiginosa. In some 

 parts of Victoria it is Medicago denticulate and Rumex acetosella f 

 the latter a most dreadful pest to the farmer. In Adelaide 

 and indeed through all the rich plains of South Australia on 

 red soils, Cryptostemma calendulacea excludes all other vege- 

 tion affording rich green feed in spring only, and then utterly 

 disappearing, except that it leaves a mass of woolly pappus 

 behind it which is a very serious inconvenience to wool 

 growers. In September and October the country is one golden 

 mass with its flowers. It is said to be from the Gape, and 

 was unknown in Australia 25 years ago. But in the more 

 northern part of east Australia, quite a different introduced 

 vegetation presents itself. There it is Sida rhombifera, Lan- 

 tana camera, Verbena bonariensis, Asclepias curasavica, Opun- 

 tia vulgaris, Ageratum Mexicanum, and Alternanthera noaosi- 

 flora. S. rhombifera, which is a malvaceous plant, bids fair 

 to be an alarming pest. It is a short twiggy shrub, as tough 

 as whalebone, covering every inch of good soil with a dense 

 scrub of about two or three feet high. It is almost impossible 

 to^eut it down, owing to the toughness of its fibre, which may 

 be utilised one day. Preparations of it I have seen made 

 into ropes, <fcc. It is whiter and more silky than the finest 

 flax. I have been in no part of the tropics where it has not 

 become a common weed. Asclepias curasavica is another plant 



