Lesson 1
A tube made of cells
Plants have two kinds of pipes. Water pipe cells carry water up from the roots. Sugar pipe cells carry food. Scientists call this food pipe phloem (say it: FLOW-em).
The pipe is made of long cells lined up end to end, called sieve tube cells. Where two cells meet, there is a wall full of little holes called a sieve plate. Sugary sap flows through the holes from one cell to the next.
Try thisPress Cut it open on the 3D model to see inside the tube and its sieve plates.
Lesson 2
Companion cells
Sieve tube cells are alive, but they have no nucleus, so they need help. Right next to each one is a smaller companion cell that does have a nucleus. It helps keep the sieve tube cell working and helps load sugar into the tube.
The sugar goes wherever the plant needs food: down to the roots, into fruits, and up to growing tips and new leaves.
Try thisPress Send sugar to watch sugar travel through the sieve plates.
Lesson 3
Who else likes plant sugar?
Tiny bugs called aphids poke a thin, straw-like mouth into the phloem and drink the sweet sap. Some ants even look after aphids to collect the sweet drops the aphids leave behind.
Try thisPress Aphid visit to see an aphid sip from a sugar pipe.
Wow!The sugar in maple syrup was made in maple leaves in summer, then carried away to be stored in the tree. In early spring, people collect the tree's sweet sap and boil it down into syrup!
Quiz
Sugar pipe quiz