Apium graviolens
Developed in the 1800s at Erfurt, Germany, this extremely rare miniature form of celeriac grows about the size of a large walnut.  It is succulent and sweet when harvested the first year or in overwintering cold frames.  A biennial best grown in sandy soil, this luxury bonsai vegetable is a perfect garnish or an unusual addition to sauces and soups.  Minimum 50 seeds, $4.50. Germination, 95%.