40 LEAVES 



EUCALYPTUS LEAVES 



(Folia Eucalypti) 



Source, &c. Eucalyptus leaves are obtained from Eucalyptus 

 Globulus, Labillardier (N.O. Myrtacece), the ordinary 'blue gum' 

 tree of Victoria and Tasmania. This tree, which is one of the largest 

 known, attains a height of over 100 metres ; it is cultivated in 

 Italy, Spain, southern France, Portugal, Algeria, and other warm 

 countries. It grows rapidly, and is largely planted in unhealthy marshy 

 districts, such as the Campagna near Rome, upon which it exercises 

 a beneficial influence. 



The tree is remarkable for the dimorphism of its leaves. On young 

 plants these are opposite, ovate, cordate at the base, and sessile, and 

 they grow with one surface directed upwards and one downwards. 

 On the upper parts of older trees, longer, scimitar-shaped leaves 

 are produced, the short petioles of which are twisted so that the 



FIG. 27. Eucalyptus leaf. Reduced in size. (Maisch.) 



leaves grow with one margin directed upwards and the other down- 

 wards ; these alone are employed in making preparations of eucalyptus 

 leaves. They are collected in southern Europe and dried. Both 

 forms of the leaf are used fresh for the distillation of the volatile oil. 



Description. Eucalyptus leaves are well characterised by their 

 great length (up to 30 cm.) and narrow, ensiform outline. They 

 taper gradually towards the apex, but narrow rather abruptly at 

 the base into a short, twisted petiole. The lamina is thick, coriaceous, 

 and, when quite dry, brittle. The margin is entire and somewhat 

 thickened ; the midrib is not prominent on either surface, and the 

 lateral veins, most of which leave the midrib at an acute angle, anasto- 

 mose near the margin to a continuous line. The leaves are quite 

 glabrous, but distinctly punctate from the presence of numerous 

 oil-glands situated in the mesophyll ; these are best observed by 

 examining the surface with a lens whilst the leaf is held against a 

 strong light. The surfaces are frequently marked with a number of 

 minute warty brown spots (groups of cork cells). 



The odour of fresh eucalyptus leaves is strong, camphoraceous, 

 and characteristic ; in the dry leaves it is less perceptible until they 



