Horticulture Principles and Practices

FIGURE 3–20 Selected common
leaf forms: (a) filiform, (b) linear,
(c) elliptic, (d) lanceolate, (e)
ovate, (f) obvate, (g) hastate, (h)
cordate, (i) peltate, (j) spatulate.
(a) (b) (c) (d) (e) (f)
(g)
(h)
(i)
(j)
Selected com-
FIGURE 3–21
mon leaf shapes.
Rachis
Leaflet
Odd pinnate Even pinnate Bipinnate
Quadripinnate Trifoliate Palmate
80 Chapter 3 Plant Anatomy
3.4.4 FOLIAGE LEAF FORMS
The form of a leaf refers to the shape of the lamina. Leaves range from narrow needles
(as in pines) to circular shapes as in water lily (Victoria amazonia). The most common
leaf forms are shown in Figure 3–20. Each shape is representative of only the particular
class, since there are degrees of expression as well as size in each group. Certain leaf
forms involve incomplete or partial separation of the lamina into parts called lobes. Certain
species have deeply lobed leaves.
3.4.5 COMPOUND LEAF SHAPES
Simple leaves occur individually with one lamina (single leaf). A compound leaf consists
of two to many small leaves (leaflets or pinnae) arranged on either side of the
midrib or rachis in a variety of patterns (Figure 3–21). Compound leaves with this
arrangement are called pinnate leaves. In certain species (e.g., ferns), the pinna is further
subdivided into secondary segments, or pinnules. Leaves with secondary segments
are called bipinnate leaves. Further subdivision produces tri- and quadripinnate
leaves.