We report the nitrogen (N), phosphorus (P), and carbon (C) stoichiometry for each of the five organ‐types (leaves, aerial stems, reproductive organs, roots, and tubers) of 17 actively growing Eranthis hyemalis plants differing in size (as measured in g C). We also report the N, P, and C stoichiometry of 20 winterized tubers, which are the only perennial organs of this species. Comparisons between whole‐plant and winterized N/C and P/C levels indicate that N was resorbed from aerial organs and stored in tubers by the end of the growing season. Leaves were substantial reservoirs for N and P. With few exceptions, N scaled isometrically with respect to C for each organ‐type, whereas P scaled as the 3/4 power of C. Thus, N is proportional to P3/4, which is proportional to C regardless of organ‐type. Additionally, annual growth rate G of shoots (leaves and aerial stems) scaled as the −3 power of leaf N/P quotients such that G was proportional to the 3/4 power of leaf P. We suggest that these scaling relationships (together with previously reported allometric trends across herbaceous species) show that growth is constrained by organ‐specific N and P allocation patterns (presumably to proteins and ribosomes, respectively).