Florentine, or sweet fennel grows right on the surface of the soil.  It develops a bulbous stem from which the fronds develop.  Both the bulb and fronds can be used.  
The bulb has a crunchy texture quite like celery but with an aniseed flavour.  It is delicious raw in salads, or cooked and is a particularly good accompaniment to fish.  The pretty fronds can be snipped into salads and other dishes imparting their sweet aniseed flavour.