102 Mr. R. B. Hind^ un Gcuyraphic Botany. 



ogenous plants to have their leaves horizontal, thus forming a 

 right angle with the stem, or with their points inclining towards 

 the horizon. Some depart from this, as the Salix babylonica, and 

 the weeping variety of Fraxinus excelsior. In endogenous plants, 

 on the contrary, the leaves generally tend towards a vertical po- 

 sition, which perhaps their weight prevents them from attaining ; 

 so that it is customary to find them forming an angle of 45*^ with 

 the horizon. The mixture of the large herbaceous EndogencE with 

 a vegetation chiefly exogenous, conveys a remarkable character to 

 the physiognomy. 



Besides the peculiar features offered by leaves, there are others 

 which will be occasionally prominent. They may be found in 

 the unusual development, or some idiosyncrasy, of the various 

 organs, and are perhaps only discoverable in particular instances. 

 Sometimes the inflorescence is the source ; at others the flowers, 

 fruit, or floral appendages. A^ery difierent is the appearance of 

 the trees of some species of Cassia laden with theii- long slender 

 black pods and light pale foliage, from a grove of Hibiscus and 

 Psidium in the Pacific, or of Melastoma in the Brazils. 



A general impression is conveyed by the prevalence of certain 

 colours in flowers ; in some situations nothing but yellow flowers 

 are seen, in others only white or blue, till the repetition is almost 

 tiring. The varieties of colours, being dependent on the presence 

 of heat and light, alter with the latitude ; hence a relation between 

 the two can be established. For the same reason there will exist 

 a similar relation with the seasons of the year. Colours have 

 been ari'anged by Schubler and Funk under two series which 

 they have called oxidized and deoxidized ; but DeCandolle pi'O- 

 posed to call them respectively xanthic and cyanic, from the ge- 

 neral prevalence of the colours in each. This arrangement * ap- 

 pears to have been chosen with considerable happiness, since 

 most flowers range themselves under one or the other, and it 

 aff"ords a basis by which colours can be compared and their re- 

 lative importance ascertained. There is one variety of coloration 

 which they take no notice of further than to give their reasons 

 for not assigning it a place in their series, and this is white. The 

 reasons seem good and philosophical in theory, but in practice it 

 will sometimes be impossible to assign every white flower to some 

 particular colour, as is recommended; I shall therefore venture 

 to use it as a colour for the present, according to general opinion. 



White or pale-colovired flowers prevail over all others ; they are 



* These series are developed in their ' Uiitersuchungen iiber die Farben 

 der Bhithen,' 1825. Some details may be met with in DeCandollc's ' Phy- 

 siologic Vegetale/ torn. ii. pp. 901-924, and in the Library of Useful Know- 

 ledge, Bofany, pt. 4. pp. 120-124, by Dr. Lindley. 



