This data set include 11004 roots from 69 coarse root systems of Pinus pinaster trees. These trees belong from the same local provenance of P. pinaster trees germinated in the field and grown in the same area (forest range of the “Landes de Gascogne” in Southwest France).These trees were aged 3, 4, 6, 13 and 50 years. The description of excavation procedure of coarse root system can be found in Danjon et al. 2005 and the measurement procedure is described in Danjon and Reubens (2008) and Saint Cast et al. (2019). The four root traits selected as classifiers, and computed for each root axis (Id Axis), included three geometrics and one vigour traits, as follows:

• CSAco : Basal cross-sectional area (CSA) measured 2 cm from the base of the axis, divided by the tree cross-sectional area at the collar (co) to consider the axis size.
• Tropism intensity is computed as the ratio of the depth difference between the two ends of each excavated root over the length of the root axis. Roots with tropism close to 0 show a high plagiotropism (trend to bend horizontally), those with tropism close to 1 have a positive gravitropism (trend to bend downwards), and those with tropism close to -1 have a negative gravitropism (trend to bend upwards).
• Parent root tropism intensity is the tropism intensity of the parent root of the axis.
• Branching angle is estimated using a vector method. It was defined for all roots from two 10-cm long vectors to describe both the parent root direction before the branching point and the daughter root direction after the branching point (see Fig. 1 in Saint Cast et al. 2019). The branching order is also given by root axis. Two calculated attributes can be found in this data set: the root type classification obtained by clustering and the final root type classification (Saint Cast et al., submitted) as:

Order1: taproot OverSize: Oversize roots were mainly horizontal roots branching from the stump or secondary sinkers in the oldest root systems. Hh: Horizontal roots branching from horizontal roots Hv: Horizontal roots branching from vertical roots Vh: Vertical roots branching from horizontal roots Vv: Vertical roots branching from vertical roots

Danjon F, Fourcaud T, Bert D (2005) Root architecture and wind-firmness of mature Pinus pinaster. New Phytologist 168:387–400. https://doi.org/10.1111/j.1469-8137.2005.01497.x

Danjon F, Reubens B (2008) Assessing and analyzing 3D architecture of woody root systems, a review of methods and applications in tree and soil stability, resource acquisition and allocation. Plant and Soil 303:1–34. https://doi.org/10.1007/s11104-007-9470-7

Saint Cast C, Meredieu C, Défossez P, et al (2019) Modelling root system development for anchorage of forest trees up to the mature stage, including acclimation to soil constraints: the case of Pinus pinaster. Plant Soil 439:405–430. https://doi.org/10.1007/s11104-019-04039-4