Fivehead Arable Fields Nature Reserve, also a Site of Special Scientific Interest (SSSI), is worth visiting not because of the scenery or the views, since the three fields are not visually different to any others, and are part of a generally flat, featureless landscape, but because of the large number of rare plant species found here - mostly arable weeds, traditionally plants of agricultural land that flourished before widespread use of pesticides and fertilisers, but are now greatly reduced. The most scarce species are broad-fruited cornsalad, corn buttercup, narrow-fruited cornsalad, shepherd's-needle, slender tare and corn parsley, and there are several dozen other plants recorded here, most also uncommon, such as small toadflax, sharp-leaved fluellen, round-leaved fluellen and spreading hedge-parsley.
The fields are maintained solely for the benefit of the plants; they are ploughed each autumn, a process that helps the seeds to generate, but otherwise left undisturbed. Visitors may walk anywhere in the fields, which are crossed by ridges and furrows from the ploughing, making progress a little difficult, especially when wet. Some of the plants, like the broad-fruited cornsalad, are very numerous and easy to find, while others take more effort. It would be easy to spend two hours or more looking for the various species.
The three fields are situated on the west side of Cathanger Lane, one mile west of Fivehead village near the southern edge of the Somerset Levels, and are identified by a notice just behind the entrance gate, beside a verge with parking space for several vehicles. Ahead is the southernmost field (6 acres), good for the corn buttercup. A gate a little way along leads to the northwest field (14 acres), treated as two compartments for management purposes, while a third gateway is to the northeast field, 11.5 acres. All the ground is gently sloping, to the south, underlain by fertile, clayish, calcium-rich soils which have developed from the blue lias bedrock, mudstone and limestone.