Info

Usually parallel

Usually in multiples of three

Scattered

Usually parallel

Usually in multiples of three

Scattered

Usually netlike Usually in fours or fives

In a ring

Usually netlike Usually in fours or fives

In a ring

35.1 Monocots versus Eudicots The possession of a single cotyledon clearly distinguishes the monocots from the other angiosperms. Several other anatomical characteristics also differ between the monocots and the eudicots. Most angiosperms that do not belong to either lineage resemble eudicots in the characteristics shown here.

35.2 Vegetative Organs and Systems The basic plant body plan and the principal vegetative organs are similar in monocots and eudicots.

The root system anchors and provides nutrients for the shoot system.

The root system anchors and provides nutrients for the shoot system.

Monocots Dicots Leaf

Leaf:

Petiole-

Flowers, made up of specialized leaflike structures, are adapted for sexual reproduction.

Flower

Node

Internode

Roots

Flowers, made up of specialized leaflike structures, are adapted for sexual reproduction.

Flower

Node

Internode

Roots

Stem

Flower Stem Internode

Apical bud

Lateral bud

Apical bud

Leaf:

Petiole-

Stem

Lateral bud

There are two principal types of root systems. Many eu-dicots have a taproot system: a single, large, deep-growing primary root accompanied by less prominent lateral roots. The taproot itself often functions as a nutrient storage organ, as in carrots (Figure 35.3a).

By contrast, monocots and some eudicots have a fibrous root system, which is composed of numerous thin roots that are all roughly equal in diameter (Figure 35.3b). Many fibrous root systems have a large surface area for the absorption of water and minerals. A fibrous root system clings to soil very well. Grasses with fibrous root systems, for example, may protect steep hillsides where runoff from rain would otherwise cause erosion.

Some plants have adventitious roots. These roots arise above ground from points along the stem; some even arise from the leaves. In many species, adventitious roots can form when a piece of shoot is cut from the plant and placed in water or soil. Adventitious rooting enables the cutting to establish itself in the soil as a new plant. Such a cutting is a form of vegetative reproduction, which we will discuss in a later chapter. Some plants—corn, banyan trees, and some palms, for example— use adventitious roots as props to help support the shoot.

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