Principles of Plant Genetics and Breeding

3 Frequently, the scientist who first named the plant
adds his or her initial to the binary name. The letter
L indicates that Linnaeus first named the plant.
If revised later, the person responsible is identified
after the L, for example, Glycine max (L.) Merr. (for
Merrill).
4 The generic name may be abbreviated and can also
stand alone. However, the specific epithet cannot
stand alone. Valid examples are Zea mays, Zea, Z.
mays, but not mays.
5 The cultivar or variety name may be included in the
binomial name. For example, Lycopersicon esculentum
Mill cv. “Big Red”, or L. esculentum “Big Red”. The
cultivar (cv) name, however, is not written in italics.
Operational classification systems
Crop plants may be classified for specific purposes, for
example, according to seasonal growth, kinds of stem,
growth form, and economic part or agronomic use.
VARIATION 77
Table 5.3 Important field crop families in the division Magnoliophyta (flowering plants).
Monocots
Poaceae ( grass family) In terms of numbers, the grass family is the largest of flowering plants. It is also the most
widely distributed
Examples of species: wheat, barley, oats, rice, corn, fescues, bluegrass
Aracaceae (palm family) The palm family is tropical and subtropical in adaptation
Examples of species: oil palm (Elaeis guineensis), coconut palm (Cocos nucifera)
Amaryllidaceae (amaryllis family) Plants with tunicate bulbs characterize this family
Examples of species: onion, garlic, chives
Dicots
Brassicaceae (mustard family) The mustard family is noted for its pungent herbs
Examples of species: cabbage, radish, cauliflower, turnip, broccoli
Fabaceae (legume family) The legume family is characterized by flowers that may be regular or irregular. The species
in this family are an important source of protein for humans and livestock
Examples of species: dry beans, mung bean, cowpea, pea, peanut, soybean, clover
Solanaceae (nightshade family) This family is noted for the poisonous alkaloids many of them produce (e.g., belladonna,
nicotine, atropine, solanine)
Examples of species: tobacco, potato, tomato, pepper, eggplant
Euphobiaceae (spurge family) Members of the spurge family produce milky latex, and include a number of poisonous
species
Examples of species: cassava (Manihot esculenta), castor bean
Asteraceae (sunflower family) The sunflower family has the second largest number of flowering plant species
Example of species: sunflower, lettuce
Apiaceae (carrot family) Plants in this family usually produce flowers that are arranged in umbels
Examples of species: carrot, parsley, celery
Cucurbitaceae (pumpkin family) The pumpkin or gourd family is characterized by prostrate or climbing herbaceous vines
with tendrils and large, fleshy fruits containing numerous seeds
Examples of species: pumpkin, melon, watermelon, cucumber
Seasonal growth cycle
Plants may be classified according to the duration of
their life cycle (i.e., from seed, to seedling, to flowering,
to fruiting, to death, and back to seed). On this basis,
crop plants may be classified as annual, biennial, perennial,
or monocarp, as previously discussed in Chapter 4.
Stem type
Certain plants have non-woody stems, existing primarily
in vegetative form (e.g., onion, corn, sugar beet) and are
called herbs (or herbaceous plants). Shrubs are plants
with multiple stems that arise from the ground level
(e.g., dogwood, azalea, kalmia), while trees (e.g. apple,
citrus, palms) have one main trunk or central axis.
Common growth form
Certain plants can stand upright without artificial support;
others cannot. Based on this characteristic, plants