Main conclusion <p>Far-red light is stressful to <i>Marchantia polymorpha</i> and reduces the efficiency of photosystem II. In response, Marchantia reorganizes the chloroplast ultrastructure, forming Rubisco condensate regions to physicochemically concentrate CO₂.</p> Abstract <p>The light spectral composition is one of the key photomorphogenesis factors. Far-red light (FRL) resulted in marked changes in the morphology of <i>Marchantia&#xa0;polymorpha</i> chloroplasts. However, most aspects of this photomorphogenesis remain unexplored, and this work is devoted to elucidating their nature. We studied in vitro cultured <i>M. polymorpha</i> under FRL or wide spectral range illumination. Transmission electron microscopy and Au-immunolabeling were used for analysis. Gene expression and protein quantification were performed via RT‒PCR and Western blotting. FRL causes the appearance of non-membrane formation in the chloroplast, which has not been previously described for <i>M. polymorpha</i>. This region is enriched in ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and is surrounded by starch grains. FRL negatively regulates the accumulation of Rubisco in <i>M. polymorpha</i> at the transcriptional level. Our study revealed that<i>,</i> under FRL action, <i>M. polymorpha</i> experiences a marked decrease in the key enzyme involved in CO₂ assimilation, Rubisco. At the same time, Rubisco condensate structures are formed in chloroplasts, which can be considered a compensatory strategy for the realization of the CO₂ concentrating mechanism, which is widely known in phylogenetically close groups.</p> Graphical abstract <p></p>