The Leaf with Little Bumps

At the autumn path edge lay an oak leaf with its underside already facing up. Two little greenish-yellow balls with a touch of red were attached to it. Puschel stopped and crouched to study them without lifting the leaf.

Puschel“The leaf has packed food for a journey. Two tiny apples!”

Flauschi knelt on the other side of the leaf and held the green magnifying glass a little way above one ball. It was firmly attached to the leaf. There was no little fruit basket and no stalk like an apple’s.

Flauschi“Growths like these can be plant galls. A gall is a place where a plant has grown differently from usual. It can look like a ball or a little disc, for example.”

Puschel“Did the leaf make the bump itself?”

Flauschi“The material grows from the plant. But another living thing can cause that growth. Tiny gall wasps are involved in some oak galls. Their young are called larvae and look different from the adult insects.”

Puschel imagined a tiny wasp with a builder’s trowel. Flauschi smiled and shook her head. A gall wasp did not assemble the ball from pieces of wood. The plant formed the tissue: its own material, made of many tiny building blocks.

Puschel“Then it is not a home glued on. It is a grown one.”

Flauschi“In many kinds of gall wasp, a larva lives inside the gall. It finds food and shelter there. We cannot see from outside whether our find has an animal inside just now.”

Flauschi explained that not every leaf bump came from a gall wasp. Other small living things could cause galls too. Colour and a round shape were not enough to identify the exact cause.

Puschel“Then we will not open the front door. Perhaps someone needs some peace.”

They left the leaf and both balls where they lay. Puschel kept his paws to himself. His little travel apples were not fruit to taste. As they walked on, he still smiled: a single leaf could have a surprising amount to tell them.