SUPPLEMENT. 



coloration of these leaves, which are frequently called by the general 



name of perianth, the presence of nectar-glands, ets. , are devices to 



attract insects and insure proper fertilization. 



The Sperniatophyta are divided into the two following classes, the 



characters of each being appended: 



Class 1. Angiospermae. [Greek, signifying covered seeds.] 

 Plants havino^ their ovules enclosed in a sac 

 or ovary formed of one or more carpels. Fertil- 

 ization effected by the growth of a tube from the 

 pollen-grain after it has lodged on the apex of the 

 ovary (stigma); this tube penetrates a small open- 

 ing in the ovule, and through it the contents of 

 the pollen-grain are transferred to the ovule. 



Class II. Gymnospermae. [Greek, sig- 

 nifying naked seeds]; Plants having their ovules 

 borne exposed on the surface of a scale. Fertiliz- 

 ation effected either by the growth of a pollen 

 tube or by the direct contact with the ovule of 

 small moving bodies known as antherozoids, anal- 

 ogous to the spermatozoids in animals; these are 



of^an El)he^dr'a°ffam1iy discharged from the ripe pollen grain after it has 



Gnetace£e)showiDgtheflow- i i i ,1 /• i 1 11 



er clusters. lodged on the female sporophyll. 



CHAPTER II. 



The Class Gymnospermae. {Fig. 1.) 



The Gymnosperms, as they are commonly called, contain all of 

 our familiar evergreen coniferous trees, and therefore constitute a 

 prominent feature of the forests in the colder temperate regions. The 

 class is of great interest, not only by reason of its antiquity, but because 

 it represents a vanishing type. Not more than 450 species of gymnos- 

 permous plants are now known to exist, while in Cretaceous and 

 Tertiary times the group was much greater. Certain genera like 

 Sequoia, containing the redwoods and big trees of California, at present 

 restricted to a small strip of territory on the Pacific coast, were 

 formerly abundant in many different geological horizons of the country. 

 The gymnosperms represent the lowest type of fiovvering plants, making 

 a close approach in the details of their mode of fertilization and devel- 



