Pharmaceutical botany - Lighthouse Survival Blog

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PHARMACEUTICAL BOTANY
In the Divided leaf the incisions extend to the mid-rib, but the
segments are not stalked. Ex. : Watercress.
If the venation is pinnate, the preceding forms may be described
as pinnately incised, lobed, parted, or divided. If the venation is
radiate, then the terms radiately or palmately lobed, incised, etc.,
are employed.
The transition from Simple to Compound Leaves is a very gradual
one, so that in many instances it is difScult to determine whether a
given form is to be regarded as simple or compound. The number
and arrangement of. the parts of a compound leaf correspond with the
mode of venation, and the same descriptive terms are applied to outline,
margin, etc., as in simple leaves.
Leaves are either pinnately or radiately compounded. They are
said to be abruptly pinnate or paripinnate when the leaf is terminated
by a pair of leaflets; odd pinnate or imparipinnate when it terminates
with a single leaflet. When the leaflets are alternately large and small,
the leaf is interruptedly pinnate, as the Potato leaf. When the term-
inal leaflet is the largest, and the remaining ones diminish in size toward
the base the form is known as lyrate, illustrated in the leaf of the
Turnip.
Radiately or palmately compound leaves have the leaflets attached
to the apex of the petiole. When these are two in number the leaf
is bifoliate, or binate; if three in number, trifoliate, or ternate; when
four in number, quadrifoliate, etc. If each of the leaflets of a palmately
compound leaf divides into three, the leaf is called bi-ternate; if this
form again divides, a tri-ternate leaf results. Beyond this point the
leaf is known as decompound. Example of decompound leaf seen in
Cimicifuga.
Leaf Texture.—Leaves are described as:
Membranous, when thin and pliable, as Coca.
Succulent, when thick and fleshy, as Aloes, and Live Forever.
ScARious, when dry and scaly.
Coriaceous, when thick and leathery, as Eucalyptus, Uva Ursi and
Magnolia.
Leaf Color.— Petaloid, when of some brilliant color different from
the usual green, as the Coleus and Begonia, and other plants which are
prized for the beauty of their foliage rather than their blossoms.
Leaf Surface.—Any plant surface is: