Root crops are swollen roots or stem parts in which spare food, mostly starch, is stored (Root crops 4). For that reason they form an important source of food and some species are commercially cultivated, see Sugar and starch producing plants.

The largest variety of root crops is found in the tropics, the most important species being:
- sweet potato, Ipomoea batatas;
- cassava, Manihot esculenta (Root crops 2);
- yams, Dioscorea sp.

Other starch containing root crops are:
- cocoyam, Xanthosoma sagittifolium;
- taro, Colocasia esculenta;
- arrowroot, Maranta arundinacea;
- topee tambu, Calathea allouia (see Maranta arundinacea);
- edible canna, Canna edulis;
- ullucu, Ullucus tuberosus;
- oca, Oxalis tuberosa;
- ysano, Tropaeolum tuberosum;
- tiger nut, Cyperus esculentus (see Cyperus papyrus);
- lotus, Nelumbo nucifera;
- water chestnut, Trapa natans;
- Chinese water chestnut, Trapa bicornis, (see Trapa natans). However, the sedge Eleocharis tuberosus (see Cyperus papyrus) is also called Chinese water chestnut.

In the cooler and higher tropical areas, as well as in the temperate regions, the potato, Solanum tuberosum (Root crops 3) is a very important root crop.

Well known root crops from the temperate regions are:
- sugar beet or mangel, Beta vulgaris;
- beetroot, Beta vulgaris;
- celeriac, Apium graveolens var. rapaceum;
- swedes, Brassica napus var. napobrassica;
- wild carrot, Daucus carota;
- parsnip, Pastinaca sativa;
- radish (Root crops 1), winter radish and rettich, Raphanus sativus;
- salsify or oyster plant, Tragopagon porrifolius (see Scorzonera hispanica);
- Jerusalem artichoke, Helianthus tuberosus (see Helianthus annuus).