A NEW LEAF

The image below is a photo of the exhibit panel. Following it is a transcript of the panel.

Photo of the panel from the exhibit.

Leaves create more surfaces for light reception.

For many plants, the leaf is the chief photosynthetic organ. Before leaves evolved, photosynthesis occurred in other organs, such as the stem.

Leaves can also be modified for other uses. Nettle leaves defend with stinging hairs. Cactus spines are specialized leaves that reflect light, retard water loss, and defend the plant.

leafy plants include ferns, cycads, conifers, and flowering plants

New feature:

leaves increase surface area for receiving the solar energy needed for photosynthesis

When? 370 million years ago to present

PICTURE CAPTIONS:

Horsetails and their relatives have leaf-like structures, each of which has only one vein.
fern leaves , or fronds, have branched veins
Diagram showing common ancestry and evolution of horsetails, ferns, and conifers from organisms with roots. Evolution of ferns and conifers is where leaves branch off.