Clonal plants are widely distributed in all types of ecosystems, and dominate in many of them. Vascular connections (e.g. stolons or rhizomes) of clonal plants can transport resources such as carbohydrates, water and nutrient between interconnected ramets. This feature has been long considered to be adaptive in all types of ecosystems, particularly in environments where resources or stressful factors are patchily distributed in both time and space. Many studies have shown that the stressed ramets of clonal fragments can be supported by resource translocation from the connected unstressed ramets, for example, clonal integration can alleviate local stress caused by shading, drought, salinity, serpentine soils, mechanical stimulation and sand burial. Ultraviolet-B (UV-B) radiation (280-315 nm) can result in deleterious effects on many plant growth processes because it is strongly absorbed by many macromolecules and causes their conformational changes, especially proteins and nucleic acids. Environmental UV-B radiation is highly variable in spatial and temporal distributions. It is controlled by a great deal of factors, such as changes in the solar elevation with latitude, time of day, season and clouds. Little is still known about the response of physiological integration in clonal plants to heterogeneous ultraviolet-B radiation. In this study, pairs of connected and severed ramets of the stoloniferous herb Trifolium repens were grown under the homogeneity (both of ramets received only natural background radiation) and heterogeneity of UV-B radiation (one of the ramet received only natural background radiation and the other was exposed to supplemental UV-B radiation). Changes in intensity of nutrient integration were followed with ¹⁵N-isotope labeling of the xylem water transport. Stomata density, length, the thickness of wax, cuticle epidermal cell and palisade tissue were observed to study leaf anatomic characters. The effects of heterogeneous UV-B radiation on chlorophyll fluorescence of a clonal plant T. repens were evaluated. In order to assess the patterns of physiological integration contents of chlorophyll and UV-B absorbing compounds were determined. When ramets were connected and exposed to heterogeneous UV-B radiation, the percentage of ¹⁵N left in labeled ramets that suffered from enhanced UV-B radiation was higher and their transfer to unlabeled ramets lower. The intensity of physiological integration of T. repens for resources decreased under heterogeneous ultraviolet-B radiation in favor of the stressed ramets. Severing groups under UV-B radiation had more closed stomas (according to stomatal length) and the thickness of palisade tissue, results were reversed in connecting groups, indicating physiological integration plays a role in anatomic characters. Additive UV-B radiation resulted in a notable decrease of the minimal fluorescence of dark-adapted state (F_o), the electron transport rate (ETR) and photochemical quenching coefficient (q_P) and an increase of non-photochemical quenching (NPQ) under heterogeneous UV-B radiation, while physiological connection reverse the results. Chlorophyll and UV-B absorbing compounds were shared between connected ramets under heterogeneous UV-B radiation. Ultraviolet-B stressed ramets benefited from unstressed ramets by physiological integration, improving resource efficiency on clonal plants in less favorable sites.