BOTANICAL SUBJECTS. 205 



In seaweeds we do not meet with any. It is only when plants, 

 as I said, began to emerge from a water life into an atmospheric 

 life, that stipules evidently were of service as means of protection. 

 It is true that we find them in plants which are half aquatic and 

 half atmos]3heric, but one can never tell whether these have been 

 directly evolved from seaweeds, or have degenerated from dry 

 land plants into swamp and semi-aquatic plants, and have inherited 

 their stipules. 



Among cryptogams, we first meet with organs that might be 

 taken for stipules in ferns.* Marattia has two expansions at 

 the base of what might be called the petiole of the circinate frond, 

 which probably are the homologues of stipules. In the Marattia 

 these appendages appear to be distinct from the frond. Indeed, 

 if we look upon the frond and the leaf as stems, or, at all 

 events, as branches, which comes to the same thing, we shall see 

 the original function of stipules may have been as bud-scales, 

 that is, protectors of the young undeveloped bud against heat, 

 cold, &c. The reason that so many ferns have them not may 

 well be that they are often well furnished with protecting hairs or 

 scales. 



If we examine Begonias, we very frequently find that the 

 so-called stipules are really well developed bud-scales, which form 

 a complete protection to the terminal bud and are repeated as 

 flower-bracts. The bud-scales of the White Poplar are in- 

 distinguishable from the stipules of the same. The bud-scales of 

 certain oaks are of the same tan colour as the sti^^ules, and 

 indistinguishable from them. 



Asa Gray says that bud-scales can either be stipules, as in 

 Magnolia, Tulip-tree, Beech, &c., or the base of leaves, as in the 

 Horse-chesnut. In this tree, it is not easy to say whether the 

 bud-scales are more of the nature of a pair of connate stipules, 

 with the blade undeveloped, like the glumes of certain grasses, or 

 of the nature of undeveloped leaves proper, the scale formino- the 

 base of the leaf, as Asa Gray su^Dposes, for the order to which 

 the Horse-chesnut belongs is loith or without stipules. 



That stipules are often unimportant appendages, indeed 

 remnants of once important organs, is quite evident ; for they are 

 frequently insignificantly small, and drop off as soon as the leaf is 



* Nicholson says that stipules are found in one or two ferns. — (" Diet, of 

 Card.") 



