Dataset dealing with exhaustive vascular plant surveys in field margins of three hedgerow networks of the LTSER Zone Atelier Armorique (DEIMS.ID : https://deims.org/31e67a47-5f15-40ad-9a72-f6f0ee4ecff6).

All vascular understory plants were sampled in 25 m long plot (one plot per field margin) placed in the middle of the field margin to avoid multiple edge effects from connection with other field margins.

To incorporate local heterogeneity in field margin structure, all the width of field margins (N= 341) was sampled. Abundance-dominance of plants was scored using an ordinal scale according to Tansley (Tansley, 1935). The taxonomic standardization was based on Flora europaea (Tutin et al., 1993). Some taxa were identified only to genus as their identification at the seedling stage may show great discrepancy between observers. Field work was carried out from May to July for the two vegetation surveys (1994, 2015).