Horticulture Principles and Practices

FIGURE 2–21 A tuber, represented
by Irish potato
(Solanum tuberosum).
(Source: George Acquaah)
Cool-season Plant
A plant that grows best at
daytime temperatures of
between 15° to 18°C
(60° to 65°F).
Warm-season Plant
A plant that grows best at
daytime temperatures of
between 18° to 27°C
(65° to 81°F).
d. Tubers. Tubers look like modified roots. The difference between them is that
tubers are swollen stems, whereas roots are swollen roots (Figure 2–21).
e. Greens. Greens are vegetable crops whose leaves are usually picked at
tender stages to be used for food. The leaves are generally cooked before
being eaten.
3. Adaptation. Just like fruits, certain vegetable species prefer cool temperatures
during production, and others prefer warm temperatures. Based on seasons in
which they grow best, vegetables may be classified into two groupings.
a. Cool season. Cool-season crops require monthly temperatures of 15 to 18°C
(60 to 65°F). Examples are sugar beet (Beta vulgaris) and cabbage
(Brassica oleracea).
b. Warm season. Warm-season crops prefer monthly temperatures of 18 to
27°C (65 to 81°F). Examples are okra (Hibiscus esculentus), eggplant
(Solanum melongena), corn (Zea mays), and shallot (Allium cepa). It should
be mentioned that plant breeders have developed cultivars with wide
adaptation for many crop species. For example, popular garden crops
including corn, tomato, and pepper are grown over a wide range of climates.
Even though cultivars with cold or heat tolerance may have
been bred for different crops, commercial large-scale production occurs in
regions of best adaptation of these crops, unless production is under a
controlled environment (greenhouse).
4. Botanical features. Vegetables may be classified according to specific botanical
characteristics they share in common.
a. Vines. Vines are plants with stems that need physical support; without it
they creep on the ground or climb onto other nearby plants in cultivation.
Examples are squash, pumpkin, and cucumber.
b. Solanaceous plants. Solanaceous plants belong to the family Solanaceae.
Examples are eggplant, tomato, and pepper.
c. Cole crops. Cole plants belong to the Brassica family. Examples are cabbage,
cauliflower, and broccoli (Brassica oleracea var. botrytis) (Figure 2–22).
52 Chapter 2 Classifying and Naming Horticultural Plants
2.4 CLASSIFICATION OF ORNAMENTAL PLANTS
Ornamental plants may also be classified based on stem type, growth cycle, leaf form,
use, and other characteristics.