s, &c.

GRAFTING.--This takes place outdoors from March to May, at the earlier
time for deciduous trees and shrubs, and later on for evergreens. The
actual time depends upon the season.

Where seed is not expressly mentioned below, it must be understood that
this is the natural, and in many cases the best, way to propagate.

The following trees can only be raised from seed to do any good
afterwards, though a few of them will throw up suckers, which can be
taken off and replanted: _Aesculus_ (Chestnut), _Ailantus_, _Alnus_
(Alder), _Arbutus_, _Betula_ (Birch), _Carpinus_ (Hornbeam), _Carya_
(Hickory), _Castanea_ (Sweet Chestnut), _Celtis_ (Nettle tree), _Fagus_
(Beech), _Fraxinus_ (Ash), _Gleditschia_ (Honey Locust), _Juglans_
(Walnut), _Laburnum_, _Liquidambar_, _Morus_ (Mulberry), _Prunus_,
_Pyrus_, _Quercus_ (Oak), _Sophora_, _Ulmus_ (Elm), and _Zelkova_. The
varieties of any species of the above, and, in fact, of nearly all hardy
trees, must be budded or grafted on the species they are forms of, but
an exotic species should never be worked on the native representative of
the genus--_e.g._ _Aesculus flava_ should not be budded on the Common
Horse Chestnut, as the latter is far too strong a stock for the
smaller-growing Aesculus.

_Acer_ (Maple) and _Tilia_ (Lime or Linden) can be raised from seeds or
by layering, the Lime especially being largely propagated from layers,
which soon form strong young trees. The varieties of Maple are best
worked on stocks of the species they belong to.

_Crataegus_ (Thorn), _Catalpa_, and _Robinia_ (Locust tree), can be
raised from suckers or root-cuttings, if seeds cannot be got. Any of
their varieties are usually budded or grafted on stocks of the parent
species.

_Ilex_ (Holly), _Magnolia_, _Populus_ (Poplar), _Platanus_ (Plane), and
_Salix_ (Willow). The Holly is easily raised from cuttings and layers,
the second roots readily when layered, and the latter three are
propagated in large quantities by winter cuttings. The White Poplar
(_Populus alba_) is an exception, as this can only be increased by
root-cuttings.

INCREASING HARDY SHRUBS

The best of our hardy flowering shrubs are grouped under seven natural
orders, and a knowledge of the order to which a plant belongs is in most
cases a guide to its propagation, as the majority of the species
contained in an order are, as a rule, increased by the same methods.

BERBERIDEAE.--This contains _Akebia_ and _Berberis_, which