REPRODUCTIVE ORGANS OF PLANTS. 299 
ot orders, and Series are groups of classes. In botanical 
classification as now universally employed—classification 
after the Natural System—all plants are separated into 
two series, as follows: 
1. Flowering Plants (Phenogams) which produce 
flowers and seeds with embryos, and 
2. Flowerless Plants (Cryptogams) that have no proper 
flowers, and are reproduced hy spores whieh are in most 
cases single cells. This series includes Ferns, Horse-tails, 
Mosses, Liverworts, Lichens, Sea-weeds, Mushrooms, and 
Molds. 
The use of classification is to give precision to our no- 
tions and distinctions, and to facilitate the using and ac- 
quisition of knowledge. Series, classes, orders, genera, 
species, and varicties, are as valuable to the naturalist as 
pigeon holes are to the accountant, or shelves and draw- 
ers to the merchant. 
Botanical Nomenclature.—So, too, the Latin or Greek 
names which botanists employ are essential for the discrim- 
ination of plants, being equally received in all countries, 
and belonging to all languages where science has a home. 
They are made necessary not only by the confusion of 
tongues, but by confusions in each vernacular. 
Botanical usage requires for each plant two names, one 
to specify the genus, another to indicate the species. 
Thus all oaks are designated by the Latin word Quercus, 
while the red oak is Quercus rubra, the white oak is 
Quercus alba, the live oak is Quercus virens, etc. 
The designation of certain important families of plants 
is derived from a peculiarity in the form or arrangemert 
of the flower. Thus the pulse family, comprising the 
bean, pea, and vetch, as well as lucern and clover, are 
ealled Papilionaceous plants, from the resemblance of 
their flowers to a butterfly, (Latin, papilio). Again, the 
mustard family, including the radish, turnip, cabbage, wa 
