7.2: Introduction

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An essential part of a plant’s survival is obtaining access to water. Early plants did this by having small, creeping forms that grew in areas that would stay moist, never far from any surface. These plants did not have roots or the ability to transport water with xylem tissue. Instead, they absorbed and lost water across their tissues. As you can imagine, this would be a limiting state for plants and, soon after they moved onto land, plants evolved true roots with vascular tissue. Lignified tissues in roots would provide increased strength and stability for burrowing into the substrate (likely not yet a true soil) and access to water stored underground. Vascular tissue throughout the plant would allow water absorbed through the roots to be transported to other areas of the plant, meaning that tissues could elevate out of the water, getting increased access to sunlight.

In this lab, you will learn the general developmental pathway for tissues in the root, as well as the different anatomical organization of two groups of flowering plants: monocots and eudicots. Monocots, like corn and other grasses, germinate from seed with a single first leaf (called a cotyledon). Eudicots germinate with two leaves. Though this seems like a trivial distinction, these groups differ in many areas of growth and development.

Contributors and Attributions

Maria Morrow (College of the Redwoods)