Lettuce

Unlocks once you've harvested 60 Radish, 50 Leek and 40 Celery in all; unlocking it is then free.

A seed costs 5 spare parts and grows for 4m 10s (3m 20s on fertilized soil), needing water 4 times on the way: it stops growing until it's watered. It gives 6 harvests, growing back from scratch after each one.

Each harvest is one Lettuce and 5 spare parts: 30 from one seed, 25 more than it cost, over 25m 1s of growing. In a Biofuel Converter each one is worth 4 biofuel.

A Reaper chip can improve its grow time, watering, harvests, biofuel or earnings.