THE POPULAE EDUCATOR. 





LESSONS IN BOTANY. VI. 



SECTION IX.- 



-OEGANS WHICH LOOK LIKE LEAVES, BUT 

 WHICH ABE NOT LEAVES. 



WE already discovered, at a very early period in our investiga- 

 tions, that Nature plays some strange tricks in the construction 

 of plants, causing one thing to look like another, as though for 

 the express purpose of deceiving us. We discovered that 

 neither pine-apples, nor strawberries, nor figs, were merely 

 fruits. We shall now discover that certain things which 

 appear like leaves are not leaves. 



What would the reader think as regards many of the cactus 

 tribe ? Would he not think these curious plants were all leaves ? 



Botanists denominate an enlarged and flattened organ of this 

 kind by the term phyllodium, a word derived from the Greek 

 cpuAAoj' (pronounced ful'-lon), a leaf, and fiSos (i'-dos),form, and 

 which therefore means having the form or semblance of a leaf. 



One example more of a portion of a plant resembling a leaf, 

 but which is not a leaf, and we have done. It might have been 

 mentioned whilst we were treating of the cactus, to the condition 

 of which the phenomenon about to be mentioned is similar. 

 Perhaps the student has occasionally seen growing in the hedges 

 the shrub called the butcher' s-broom, Ruscus aculeatus. Like 

 the cactus, this plant seems to present the curious appearance 

 of flowers springing from the surface of a leaf. Flowers, how- 

 ever, never grow in that position. The part resembling a leaf 



52. STIPULATE LEAP LEAP OP PANSY. 53. BRANCH OF THE BUTCHER'S-BBOOM. 54. LEAVES OF THE ATJSTBALIAN ACACIA. 55. 1ATHYBUS 



AFHACA. 56. VINE TENDEIL. 57. PITCHEK PLANTS. 



The fact is, they are totally without leaves, the leaf-like portions 

 'being merely flattened stems which fulfil the functions of leaves. 

 What would he think, again, of those two little leaf -like expan- 

 sions recognisable in the pansy, of which we give a drawing 

 (Fig. 52) ? These are not separate leaves, but leaf appendages 

 which botanists denominate stipules. Hence the leaf of the 

 pansy is said to be stipulate ; and the reason why we did not 

 represent the pansy leaf amongst the other leaves a short time 

 back was, because the term stipulate had not been explained. 

 The word stipule is derived from the Latin stipula, the husk 

 round straw, because the stipules stand out from the stem of 

 the real leaf in much the same manner as the leaves of wheat 

 or barley spring from the stalk at intervals. 



Occasionally the petiole, or leaf-stalk, itself becomes expanded 

 into a leaf -like form, and the real leaves are stunted. This 

 peculiarity characterises many of the acacias which grow in 

 Australia. The appended diagram (Fig. 54) will render the 

 peculiar condition more evident. 



is no leaf at all, but only a flattened branch. The accompanying- 

 diagram (Fig. 53) represents a sprig of butcher's-broom, in 

 which this peculiar conformation is very evident. 

 SECTION X. METAMOKPHOSES OK CHANGES TO WHICH 

 LEAVES AEE SUBJECT. 



Just as certain parts of vegetables not leaves may assume the 

 general appearance of leaves, so, on the other hand, leaves occa- 

 sionally lose their own specific appearance, and look like things 

 they are not. 



For example, who at first glance would think that the prickles 

 on common furze were leaves ? Nevertheless, they are ; the 

 ordinary flat leaf -like appearance being lost. 



Again, many of those tendrils which shoot from slender plants, 

 enabling them to lay hold of neighbouring objects and derive 

 support, are nothing mere than modified j.eaves. This is the 

 case with the plant Lathyrus Aphaca, a representation of which 

 we give above (Fig. 55). 



The student is not, however, to imagine that all tendrils are 



