ch other; that is,
they are to genera what genera are to species. As familiar
illustrations, the Oak, Chestnut, and Beech genera, along with the Hazel
genus and the Hornbeams, all belong to one order. The Birches and the
Alders make another; the Poplars and Willows, another; the Walnuts (with
the Butternut) and the Hickories, still another. The Apple genus, the
Quince and the Hawthorns, along with the Plums and Cherries and the
Peach, the Raspberry with the Blackberry, the Strawberry, the Rose,
belong to a large order, which takes its name from the Rose. Most
botanists use the names "Order" and "Family" synonymously; the latter
more popularly, as "the Rose Family," the former more technically, as
"Order _Rosaceae_."

530. But when the two are distinguished, as is common in zoology, Family
is of lower grade than Order.

531. =Classes= are still more comprehensive assemblages, or great
groups. Thus, in modern botany, the Dicotyledonous plants compose one
class, the Monocotyledonous plants another (36-40).

532. These four grades, Class, Order, Genus, Species, are of universal
use. Variety comes in upon occasion. For, although a species may have no
recognized varieties, a genus implies at least one species belonging to
it; every genus is of some order, and every order of some class.

533. But these grades by no means exhaust the resources of
classification, nor suffice for the elucidation of all the distinctions
which botanists recognize. In the first place, a higher grade than that
of class is needful for the most comprehensive of divisions, that of all
plants into the two _Series_ of Phanerogamous and Cryptogamous (6); and
in natural history there are the two _Kingdoms_ or _Realms_, the
Vegetable and the Animal.

534. Moreover, the stages of the scaffolding have been variously
extended, as required, by the recognition of assemblages lower than
class but higher than order, viz. _Subclass_ and _Cohort_; or lower than
order, a _Suborder_; or between this and genus, a _Tribe_; or between
this and tribe, a _Subtribe_; or between genus and species, a
_Subgenus_; and by some a species has been divided into _Subspecies_,
and a variety into _Subvarieties_. Last of all are _Individuals_.
Suffice it to remember that the following are the principal grades in
classification, with the proper sequence; also that only those here
printed in small capitals are fundamental and universal in botany:--

SERIES,
CLASS, Subclass