Horticulture Principles and Practices

Twiner
Inflorescence
tendril
Holdfast
roots
Banner
Petiole
tendril
Leaf tip
tendril
Wing
Keel
FIGURE 2–27 Twiners. Twining species have a variety of adaptive features for attaching
to nearby physical supports. These are modifications of stems, leaves, or roots.
FIGURE 2–28
flower.
Petals of a typical legume
divides the United States into ten zones. Zone 1 is the coldest, and zone 10 is the
warmest. Plants’ adaptive ranges may be narrow or broad. For example, a shrub such as
cinquefoil (Potentilla fruticosa) is adaptable to zones 2 through 7, and lantana (Lantana
camara ‘Nivea’ L.) is adapted to zones 9 and 10. All plants may be placed into one or
more of these hardiness zones.
2.5 FLOWERS IN CLASSIFICATION
Flowers are described in detail in Chapter 3. They play a major role in the classification
of flowering plants (angiosperms) because flowers have very stable plant parts in different
environments.
Flower characteristics may vary within certain families. However, specific flowers
are characteristic of certain families. For example, the legume family (Fabaceae) is characterized
by an irregular flower with a keel petal, two wing petals, and a banner petal
(Figure 2–28). These flowers develop into a fruit, the legume. The grass family (Poaceae)
is also characterized by a flower with a spike inflorescence (Figure 2–29). In the nightshade
family (Solanaceae), the petals of the flower are fused into a corolla tube with stamens
(male flower parts) fused to the corolla (Figure 2–30).
The sunflower family (Asteraceae) has a compact inflorescence in which numerous
tiny flowers (florets) are arranged in a manner to resemble a single large flower
(Figure 2–31). The spurge family (Euphorbiaceae) has a rather unique inflorescence
(Figure 2–32).
56 Chapter 2 Classifying and Naming Horticultural Plants
2.6 SOME FAMILIES OF HORTICULTURAL IMPORTANCE
The following is a partial listing and brief discussion of important crop families of
horticultural interest.