This may be seen on comparing the two columns below, of which the L.H. one refers to Architecture, and the R.H. one to Natural foliage.

  (Architecture) (Natural foliage)
                         RULES: 
  Governed by severe Exhibits apparent playful
  rules of Repetition, Freedom.  There are
  Axiality, Symmetry, etc., underlying Rules, which
  which are apparent to are detected by the scientific
  the passer-by.  Hence Botanist; but these
  Artificial foliage, being are not seen by the casual
  regular in its structure, observer.
  is more appropriate than
  the (apparently) irregular
  growth of Natural
  foliage. 
                       CHARACTERISTICS: 
  Rigidity and Stability.  Elasticity and Tremulousness
                                       in every breeze.

LINES OF COMPOSITION: 
Geometrical lines.                    In determinate curves,
The geometrical lines                which are very subtile,
and spirals of Artificial            and varied, and therefore
foliage demand an unmoving           suitable to a hanging and
surface for proper view.             swaying material.

The curves of Nature
They would generally be  spoiled     are not spoiled when on a
if not on a plane surface.           folded material.

DISTRIBUTION: 
Symmetrical.  The                     Balanced.  The growth
symmetry of artificial               of natural foliage is generally
foliage is appropriate to            symmetrical; but
that of Architecture.                this is not apparent.

                        BEAUTY: 

Depends on form, with More appropriate to objects
color as a secondary adjunct. which depend on color for

          
                                                                their principal charm.

There have been waves of the desire to introduce Natural foliage into Architecture (e.g. in the “Decorated period” of Gothic architecture); but the Artificial elements have always proved too strong, and the two have never mixed.  In Architecture, everything has three dimensions; and the artificial foliage is carved with leaves, etc., of a suitable thickness:  in Natural foliage the tenuity of leaves, etc., is such that it cannot be reproduced.  Even in the architraves round the glorious doors of Florence the natural foliage is not always a success; and where Ghiberti has stopped short in the ductile bronze, it is not probable that the modern carver will succeed in stone.  It may therefore be suggested that the close imitation of Natural foliage should be confined to objects of two dimensions, i.e., to plane surfaces and figured materials.