ylly, meiophylly, and meiotaxy may be employed, according
as the individual leaves are altogether wanting, or with reference to
the diminished number of parts in a whorl, or a decrease in the
verticils.

=Aphylly.=--Entire suppression of the leaves is a rare phenomenon. Under
ordinary circumstances it occurs in most _Cactaceae_, in some of the
succulent Euphorbias, and other similar plants, where the epidermal
layers of the stem fulfil the functions of leaves. But even in these
plants leaf-like organs are present in some stage or another of the
plant's life.

Partial suppression of the leaf occurs sometimes in compound leaves,
some or other of the leaflets of which are occasionally suppressed.
Sometimes, as Moquin remarks, it is the terminal leaflet which is
wanting, when the appearance is that of _Cliffortia_, at other times the
lateral leaflets are deficient, as in _Citrus_ or _Phyllarthron_.
_Ononis monophylla_ and _Fragaria monophylla_ may be cited as instances
of the suppression of the lateral leaflets. If the blade of the leaf
disappears entirely, we have then an analogous condition to that of the
phyllodineous acacias.

With reference to the strawberry just mentioned, Duchesne, 'Hist. Nat.
Frais.,' p. 133, says that this was a seedling raised from the _fraisier
des bois_, and the characters of which were reproduced by seed, and have
now become fixed. The monophyllous condition has been considered to be
the result of fusion of two or more leaflets, but however true this may
be in some cases, it is not the case with this strawberry. M. Paillot
states that he has found the variety in a wild state.[465]

In like manner varieties of the following plants occur with simple
leaves, _Rosa berberifolia_ (_Lowea_), _Rubus Idaeus_, _Robinia
pseudacacia_, _Fraxinus excelsior_, _Sambucus nigra_, _Juglans nigra_,
&c.

In one instance seen by the writer every portion of the leaf of a rose
was deficient, except the stipules and a small portion of the petiole.
(See abortion.)

=Meiophylly.=--A diminished number of leaves in a whorl occasionally
takes place; thus, in some of the _Stellatae_, and frequently in _Paris
quadrifolia_, the number of leaves in the verticil is reduced. Care must
be exercised in such instances that an apparent diminution arising from
a fusion of two or more leaves be not confounded with suppression.

=Meiophylly of the calyx or perianth.=--A lessened number of sepals is
not a very common occurrence