BOTANICAL AND CHEMICAL CHARACTERS OF EUCALYPTS. Ill 



of this gi-oup — viz. E. inaryinata, E. TodUana, E. megacarpa, and 

 E. santalijoUa—preiev to grow but it would be interesting to find out. 

 The group commonly known as the ' Peppermints, ' comprising 

 E. piperita and its allies, has a, very characteristic type of cotyledon; 

 it is usually of medium size, more or less quadrilateral, with rounded 

 lobes and the emargination is slight or almost absent. The stem and 

 under-surface of cotyledons and primary leaves are characterised by 

 a deep purplish colouration. It may be that the origin of this group 

 is 'through E. Planchoniana or a near relation thereof. This species 

 has a large cotyledon, emarginate and cuneate at base; it is the one 

 exception in the group in having parallel anthers instead of reniform. 

 As is well known, it occurs along the eastern coast in Northern New 

 South Wales and Queensland. It is interesting to note that, in this 

 group, the cotyledons diminish in size in the species growing at the 

 highest altitudes. 



There remain now the emarginate cotyledon Eucalypts with cotyle- 

 dons of medium or small size and emargination slight or very extreme. 

 Under this heading come about half the species of Eucalypts and the 

 majority of interior or dry country species. Some of them, with larger 

 divergent-lobed cotyledons, such as E. globulus and its allies, prefer a 

 cool moist mountain climate; many, however, have either very small 

 cotyledons with little or no emargination or else Y-shaped cotyledons in 

 which the lobes of the laminse are almost linear and the emargination 

 so extreme as to make the cotyledon of the shape of the letter Y. The 

 species with such cotyledons, or very small cotyledons, are mainly dry 

 country species. Practically all these Eucalypts contain cineol in fair 

 amount; most of them contain pinene, some of them aromadendral, a 

 few phellandrene but none of them contain pipentone in their oils. 

 The Y-shaped cotyledon Eucalypts probably originated in Western 

 Australia, possibly from E. cornuta or its allies; they then spread east 

 along the Great Australian Bight but they do not seem to have crossed 

 the Dividing Eange, except in one instance, E. squamosa being found 

 in the neighbourhood of Sydney on the Hawkesbury Sandstone. As it 

 is also found at Eylstone on the Western slopes of the Divide, it has 

 probably reached the eastern coast from the west. This species 

 appear only just to maintain a precarious existence, as the moist coastal 

 conditions do not suit it well. Concurrently witli the alteration of the 

 size and shape of the cotyledon leaves there has been an alteration in 

 the size and shape of the fruits. In the Corymbosa group the urn- 

 shaped fruit, with its narrower neck and everted rim, is the most 

 characteristic; there is one fertile seed in each cell, with its longest 

 diameter vertical and closely packed round with sterile seeds. In some 

 species a membraneous prolongation of the testa is found to promote 

 wind dissemination but this must have prevented ready exit of the seed 

 from the fruit; this winged membrane is absent from the higher forms. 

 With the introduction of emargination, the vertical diameter of the seed 

 became greatly lessened, the seed broader and enlarged at one end, that 

 in which the expanded lobes of the cotyledon lay ; the folding of the 

 halves of the cotyledons was vertical instead of transverse. This has 

 been followed by a corresponding alteration of the fruits ; the everted 



