This Flexbook is an eTextbook on High School Biology.  Chapter 9 is devoted to plant biology.

The Flexbook discusses plant characteristics, their importance,  and life cycle.  Following that are lessons on plant evolution and seed plant evolution.

Next, the student answers a series of challenge questions to check for understanding.  They see the results so they know what to review.

The next sections discuss plant classification, nonvascular and vascular plants.  This is followed by lessons on seed plants, angiosperm, the plant cell, plant tissue, and plant growth.

Next, the students delve into roots, stems and leaves.  Then follows lessons  on plant reproduction and life cycle, the life cycles of nonvascular  and vascular plants,  gymnosperms and angiosperms.

The plant chapter ends with lessons on plant adaptations and plant responses

Teachers can assign the Flexbook to their students.  Free registration and login is required

This Flexbook is an eTextbook on Middle School Life Science.  Chapter 7 is devoted to plant biology.

The Flexbook discusses plant characteristics, evolution,  reproduction and life cycle, and classification.  There are also section devoted to vascular and nonvascular plants, and seedless vascular plants

The next sections discuss the importance of plants, and seed dispersal.  This is followed by sections angiosperm, plant hormones and tropisms.  The plant chapter ends with a section on adaptations.

Each section has discussion questions and practice problems to check for understanding.  If a student answers a practice problem incorrectly, the section of the text containing the correct answer appears for reviews.

Teachers can assign the Flexbook to their students.  Free registration and login is required.

Khan Academy offers self-paced lessons in plant biology for middle and high school students.

The Biology Library Unit on Plant Biology discusses phototropism and photoperiodism.

In the Middle School Biology Course, the Unit on Matter and Energy in Organisms provides lessons in photosynthesis.

In the Biology Unit on Photosynthesis, for grades 9-12, students learn about light dependent reactions, the Calvin cycle, and photorespiration.

PBS LearningMedia has hundreds of resources for plant lessons.  They includes videos, interactives, media and lessons for all grade levels.

You can filter by grade, by type of resource and subject area to name just of a few of the resources.

What I find particularly helpful are the Collections of resources on a specific plant theme.  There are dozens of these collections.

Exploratorium offers several “Science Snack” activities students can experiment with on plants.  In one activity, kids try to bring pieces of vegetable back to life.  In another they create a leaf filter to see the range of the light spectrum different plant materials use most.

Each activity provides a list of materials and how to conduct the experiment.  It also provides some scientific background on what’s taking place in the experiment.