i44 



being mere dots covered with a tiny shield, despite their 

 very obvious difference in cutting and appearance generally. 

 The shield of the Male Fern, however, is kidney shaped, 

 and attached to the centre of the dot, at the indentation, 

 while that of the Shield Fern is quite circular, and 

 attached by a central stalk. Another genus, that of Poly- 

 podium, has also its spores in similar dot-like heaps, but 

 the distinguishing character here is that there is no cover 

 at all, as we may see by examining the common Polypody 

 (P. vulgar e) of the hedges, or its very different relatives, 

 the Beech Fern (P. phegopteris), Oak Fern (P. dryopteris), 

 and Limestone Polypody (P. calcareum), all members of a 

 very extensive tribe. We see, therefore, from these few 

 examples out of a large number which might be cited, that 

 fern fronds carry, by means of their spore heaps, the 

 evidence of their family relations, while the foliage of 

 flowering plants performs no such office, since their genera 

 are determined entirely by the construction of the flower, 

 by the study of which alone the botanist can determine the 

 genus in the case of newly-discovered plants. 



Development of Fronds and Leaves. 



Another difference between the fern frond and foliage 

 proper is that every frond springs direct from the root 

 stock ; unless it be upon a bulbil plant, which, however, 

 does not alter the principle, since the first phase of even 

 such plant is the formation of a fresh rootstock on a small 

 scale. If, therefore, we compare a fern with a fern-like 

 flowering plant, say a Grevillea or a Thalictrum adiantifolia, 

 we shall note that the fern-like leaves of the latter spring 

 from an ascending stem, while in even a Tree Fern, every 

 frond springs straight from the central growing point, and, 

 on examination, will be found to be sending its own indi- 

 vidual set of roots down the trunk, which last is merely 

 a perpendicular form of the creeping rootstock which in 



