Purpose <p>Some toxic plants have strong morphological similarities with edible wild plants. Therefore, poisoning often occurs due to accidental ingestion. It is important to identify poisonous plants in edible plant mixtures, even if the samples have been digested. In the present study, we developed a method for genus and species identification in mixed samples using massive parallel sequencing (MPS).</p> Methods <p><i>Veratrum oxysepalum</i> and <i>Colchicum autumnale</i> are the most common causative plants of such accidents and their morphological features are similar to those of the edible <i>Hosta sieboldiana</i>. In this study, we used <i>V. oxysepalum</i> and <i>C. autumnale</i> as the target poisonous plant species. We developed and optimized an MPS analysis method for <i>trnL</i> and <i>rbcL</i> regions that are commonly used in plant species identification. Initially, DNA from poisonous plants (<i>V. oxysepalum</i> and <i>C. autumnale</i>) and edible plants (<i>H. sieboldiana</i>) were mixed in various ratios and analyzed using MPS. Next, we prepared cooked materials and simulated gastric contents from <i>V. oxysepalum</i>, <i>C. autumnale</i>, and <i>H. sieboldiana</i> and analyzed them using MPS.</p> Results <p>We detected both poisonous and edible plant DNA when mixed in equal amounts. Poisonous plants were also detected in cooked or simulated gastric acid content. These results suggest that our method can be used to identify the genera or species of plants present in cooked materials and simulated gastric contents.</p> Conclusions <p>These results indicate that MPS techniques are useful for the forensic analysis of plant materials.</p>