LANDMARKS OF BOTANICAL HISTORY GREENE 133 



of the things he is describing, whereas it is quite certain he is only 

 compiling from travellers and historians. To this picture of 

 Egyptian dendrology he will add yet another member of this same 

 alliance of trees, and this the most remarkable one. Forbiddingly 

 spinescent or thorny like the others, it has a more delicate foliage, 

 like that of a fern. Whenever a branch of this tree is disturbed 

 by a touch, all the leaves upon it seem very suddenly to wither 

 away and collapse; then after a little time they revive and return 

 to their former condition. This quaint description of what has 

 been called sensitive foliage is probably the oldest extant. The 

 species that was described by Theophrastus is doubtless Mimosa 

 polyacantha. These and as many more kinds of tree and shrub 

 he mentions by name and short description as "peculiar to that 

 region." 



In succeeding chapters he dwells at some length upon the ligneous 

 growths of the Arabian deserts, where it rains no oftener than once 

 in four or five years, and trees are scarce and all of them spinescent 1 ; 

 and describes the varied and often luxuriant silva of the more 

 distant Indies. 2 It is to be remembered here that Theophrastus 

 was contemporary with Alexander the Great, whose expedition 

 to the farther Orient was the first of its kind in all history to in- 

 clude among its officials learned men whose duty it was to write 

 up the geography, climatology, and even the zoology and botany 

 of the regions traversed; an enlightened thought of Alexander's, 

 beyond doubt suggested by his boyhood's illustrious tutor, Aristotle , 

 father of all nature study. 3 To the manuscripts brought back 

 by this scientific staff of Alexander, Theophrastus was indebted 

 for all that he knew of the farther Oriental plant ecology and 

 geography; and all that remains of those reports is what the phi- 

 losopher quoted from them. The originals were long since lost. 

 In these chapters of Theophrastus we have the earliest, and very 

 interesting and faithful accounts of the banyan tree (Ficus Ben- 

 galensis, Linn.), citron (Citrus medica, Risso), the cactus-like 

 euphorbia (E. antiquorum, Linn.), the oleander (Nerium Oleander, 

 Linn.), the tamarind (Tamarindus Indica, Linn.), a tree which they 

 reported to possess the singular faculty of folding up closely its 

 pinnated leaflets at nightfall and going to sleep for the night; 



Book iv, ch. 8. 



2 Ibid., ch. 5. 



' See Bretzl, Botanische Forschung des Alexander zuges; also an excellent 

 abstract of the same by Dr. F. Fedde inAbhandl. des Bot. Verein Branden- 

 burg for 1903, pp. 97-109. 



