inary leaves spread horizontally, and
present one face to the sky and the other to the earth, there are some
that present their tip to the sky, and their faces right and left to the
horizon. Among these are the _equitant_ leaves of the Iris or
Flower-de-Luce. Inspection shows that each leaf was formed as if _folded
together lengthwise_, so that what would be the upper surface is
within, and all grown together, except next the bottom, where each leaf
covers the next younger one. It was from their straddling over each
other, like a man on horseback (as is seen in the cross-section, Fig.
165), that Linnaeus, with his lively fancy, called these _Equitant_
leaves.

161. =Leaves with no distinction of Petiole and Blade.= The leaves of
Iris just mentioned show one form of this. The flat but narrow leaves of
Jonquils, Daffodils, and the cylindrical leaf of Onions are other
instances. _Needle-shaped_ leaves, like those of the Pine, Larch, and
Spruce, and the _awl-shaped_ as well as the _scale-shaped_ leaves of
Junipers, Red Cedar, and Arbor-Vitae (Fig. 166), are examples.

[Illustration: Fig. 166. Branch of Arbor-Vitae, with awl-shaped and
scale-shaped leaves.]

162. =Phyllodia.= Sometimes an expanded _petiole_ takes the place of the
blade; as in numerous New Holland Acacias, some of which are now common
in greenhouses. Such counterfeit blades are called _phyllodia_,--meaning
leaf-like bodies. They may be known from true blades by their standing
edgewise, their margins being directed upwards and downwards; while in
true blades the faces look upwards and downwards; excepting in equitant
leaves, as already explained.

163. =Falsely Vertical Leaves.= These are apparent exceptions to the
rule, the blade standing edgewise instead of flatwise to the stem; but
this position comes by a twist of the stalk or the base of the blade.
Such leaves present the two faces about equally to the light. The
Compass-plant (Silphium laciniatum) is an example. So also the leaves of
Boltonia, of Wild Lettuce, and of a vast number of Australian Myrtaceous
shrubs and trees, which much resemble the phyllodia of the Acacias of
the same country. They are familiar in Callistemon, the Bottle-brush
Flower, and in Eucalyptus. But in the latter the leaves of the young
tree have the normal structure and position.

[Illustration: Fig. 167. The ambiguous leaf? (cladophyllum) of
Myrsiphyllum.]

[Illustration: Fig. 168. Same of Ruscus, or Butcher's Broom.]

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