The current discussion on solution phase classical vs non-classical nucleation and growth (Ostwald ripening) suggests that additive-controlled processes generally follow the non-classical path. However, most of such studies are concerned with completely defined cases, involving fine chemical surfactants as additives. Nevertheless, among the reported biogenic ligands-based approaches, the use of the extract of lignocellulosic waste (PM) presents a novel case of size and morphology control. Due to the plant origin of PM, this may also shed light on the role of humic substances in natural environment-based crystallisation processes. However, during this study, it remained difficult to conclude the exact role of the PM extract in shaping and controlling the crystallisation process. This is primarily due to the complexity of the degraded lignocellulosic substance (PM) based dilute aqueous extract. Thus, this invites more specific inquiries in greater detail. Moreover, to some degree, this study using non-classical crystallisation theory (Fig. ) alludes to the possible role of degraded humic substances affecting mineralisation in geological and soil environments. For instance, the acid and base hydrolysis pathways of iron sulphate salt resulted in two different iron oxides, whereas the change in solution additives, i.e. capping ligands, tweaked its crystallisation process. This led to the same iron oxides but with different shapes (shape anisotropy) and crystalline forms (polymorphism). Based on the previous studies, this could be ascribed to the alteration of prenucleation cluster formation and crystal growth dynamics due to the specific electrostatic interaction of the ligands with the early-stage crystallite faces. As observed, the morphologies of the iron oxide NPs (Fig. ) in the absence of any additives-based external perturbation in solution remain inclined to the random distribution of regular shapes. This is indicated by the axial ratios of the nanoparticle's dimensions (a/b~1) for FeAH and FeBH close to unity. This shows that in the absence of external perturbation, crystal growth remains random due to thermal energy. The diffusion-controlled growth of the nuclei gives rise to the random distribution of fairly regular shape particles. Thus, irrespective of the pathways (acid or base hydrolysis), no significant shape resolution occurs in the case of the processes where there is no external ligand present (FeAH and FeBH) in the system. This is due to the absence of guiding interactions during the crystallisation process, resulting in random growth in all directions. However, on the contrary, in the case of additives present in solution (FeCT, FeMC, FePM), the preferential electrostatic interaction of the additives with given faces of seed crystallites might have affected the crystal growth kinetics (described elsewhere of specific crystallite faces, resulting in directed shapes. This could also have affected the prenucleation cluster formation (PNC) in the metastable region of the binodal curve. However, in both cases, more pronounced shape resolution, as reflected in axial ratios (a/b≠1) diverging significantly from unity, can emerge. Moreover, the overall crystal growth dynamics of nanoparticles coupled with phase separation remain under the tussle of free energy (∆G) and surface energy (E). Considering the role of poorly defined biogenic ligands toward the pathways of crystallisation under different conditions, it appears closer to the so-called non-classical crystallisation process, often led by analytical grade surfactants. A similar case of shape anisotropy in zinc oxide nanoparticles due to the preferential interaction of capping ligands with specific crystallite faces by overcoming the screening effect of precursor anion has also been observed in our previous study (LM Verma et al. 2024). Moreover, the polymorphic variation of hematite (Fe2O3) as α, ε, and γ phases, along with the formation of magnetite (Fe3O4) phase in the process, is often intertwined with their corresponding natural crystal habit and, thus, is not straightforward. In fact, such phase transition of iron oxides and shape anisotropy is governed by other thermodynamic and kinetic factors and may or may not involve the direct role of ligands at all. For instance, even in non-classical crystallisation pathways, many energy pathways could be available to the system, having distinct outcomes in terms of shape and form. Nonetheless, in the present case, the rationalization of variation in shape using the framework of non-classical crystallisation theory appears fairly independent of the phasic variation of hematite (Fe2O3) (α, ε, γ) forms. However, given its relevance to the mineralisation processes in natural environments and the complexity of iron oxide polymorphism, this needs to be further investigated on a case basis and in far greater detail under more suitable conditions. 11,40