Background <p>Understanding the allocation of nitrogen (N) and phosphorous (P) among various plant organs is crucial for gaining insights into plant nutrient uptake, utilization strategies, and overall growth and life history strategies. However, little is known about the nitrogen and phosphorus allocation strategies among the three major plant organs (e.g., leaves, stems, and roots), particularly in phylogenetically closely related species. To investigate N and P allocation strategies among different plant organs, we collected 912 individuals of 62 <i>Artemisia</i> species, encompassing three subgenera, from 81 sites across a broad environmental expanse in China.</p> Results <p>Average N and P concentration and N: P ratios in major plant organs of <i>Artemisia</i> species have significant variations among the subgenera and ecosystems. Across all 62 species, the numerical values of the scaling exponents of N(α_N), P(α_P), and N: P(α_{N: P}) between leaves and stems, and leaves and root were consistently more than 1, while the corresponding scaling exponents for stems versus roots were either close to or less than 1; however, the numerical values of the scaling exponents among the three plant organs differed at subgenera levels but were relatively consistent across different ecosystems. Climate and soil had little effect on the numerical values of the scaling exponents among plant organs of <i>Artemisia</i> species at different local sites.</p> Conclusion <p>Our results found that the allocation of N and P among plant organs in <i>Artemisia</i> species differs at the subgenera level, suggesting that it is necessary to consider different subgenus levels when exploring plant nutrient concentration and allocation. Conversely, a conservative nutrient allocation strategy prevails at the ecosystem level. Thus, a key insight from these results is that nutrient allocation strategies of closely related species are phylogenetically conserved and are comparatively insensitive to local environmental conditions.</p>