Accurate Medicinal Plant Species Identification from Leaf Images using Convolutional Neural Networks

By Aryaman PattnayakReviewed by Susha Cheriyedath, M.Sc.Nov 21 2023

In an article published in the journal Information, researchers developed a practical ensemble learning approach using convolutional neural networks (CNNs) for accurately identifying medicinal plant species solely from images of their leaves.

Recognizing these beneficial plants is crucial as they are valuable sources of diverse therapeutic compounds for treating numerous ailments. However, manual identification by taxonomic experts can be prone to errors and inefficiencies. Hence, developing automated artificial intelligence (AI) techniques for plant classification can significantly boost the reliability, efficiency, and accessibility of these plant recognition systems.

Sources of Healing Compounds

Medicinal plants contain various bioactive phytochemical ingredients such as alkaloids, tannins, essential oils, and flavonoids that can help treat various diseases and health conditions. According to the World Health Organization, over 21,000 plant species worldwide potentially have medicinal value. About 80% of people worldwide rely on traditional plant-based medicines as their primary health remedies.

However, correctly identifying medicinal plant species through traditional manual means can take time and effort. Plant taxonomy experts require extensive botanical morphology and terminology knowledge for accurate classification. The predominantly manual process is slow, tedious, expensive, and prone to human errors and subjectivity. A shortage of trained taxonomists also leads to a ‘taxonomic impediment’ in reliably cataloging plant biodiversity.

Hence, developing more automated AI techniques for efficiently and objectively recognizing medicinal plant species is crucial. Computer vision and machine learning can help expedite plant classification and reduce dependency on scarce human experts. Leaf images serve as an informative and convenient source for identifying plant species.

Automated Leaf Image Classification

In this work, the researchers employed an ensemble learning strategy combining multiple CNN models to classify medicinal plant species from leaf images alone accurately. Transfer learning and fine-tuning techniques were leveraged to enhance the automated classification performance.

The models were trained and validated on the benchmark Mendeley Medicinal Leaf Dataset containing 1835 images evenly representing 30 different medicinal plant species. After preprocessing, the dataset was split into 70% images for training and 30% for model testing.

State-of-the-art CNN architectures Visual Geometry Group 16 and 19 (VGG16 and VGG19) and DenseNet201 pre-trained on large image datasets were chosen as base models. Their penultimate layers were replaced with customized layers for multi-class prediction. The CNNs were first trained individually via transfer learning to classify the medicinal leaf images.

Extensive hyperparameter tuning using grid search was performed to optimize each model. The standalone CNN models achieved individual solid results, with DenseNet201 attaining the best test accuracy of 98.93%. However, combining models via ensemble techniques improved robustness and balanced predictions further.

Ensemble Learning for Classification

The researchers created ensemble classifiers by averaging and weighted averaging of the individual predictions from VGG16, VGG19, and DenseNet201. This allowed them to systematically harness their complementary feature learning and discrimination capabilities for enhanced results.

The most effective ensemble was VGG19 + DenseNet201 using simple averaging, which attained a remarkable test accuracy of 99.12%. This ensemble leveraged the dual strengths of the VGG and DenseNet architectures. It outperformed the individual models, improving accuracy over VGG19 and DenseNet201 by 7.43% and 5.8%, respectively.

Analysis using metrics like precision, recall, and F1-score also showed that the ensemble strategy significantly boosted overall predictive performance compared to the standalone CNN models on this medicinal plant classification task.

The proposed approach enhanced accuracy in classifying this standardized medicinal leaf image dataset compared to previous benchmarks. The study demonstrates how ensemble learning can firmly integrate the predictive capabilities of different complementary CNN models.

Results and Impact

The proposed medicinal plant recognition framework showcases how advanced deep learning techniques can automate identification by learning from leaf image data alone. The ensemble model only requires scanned images of medicinal leaves without needing extensive manual feature engineering.

By reducing reliance on scarce taxonomists, the AI approach can improve the efficiency, reliability, and accessibility of systems for cataloging and utilizing medicinal plant biodiversity. As computational capabilities continue improving, enlarging model training datasets can further enhance generalization performance across more plant species.

According to the researchers, as machine learning algorithms get exposed to broader plant data, ensemble techniques show promise for automating the identification of a greater diversity of medicinal plant species in the future. Their implementation in tools like mobile apps could aid field workers globally in accurately mapping and monitoring these invaluable botanical resources.

Future Outlook

This research exemplifies integrating state-of-the-art deep learning to automate critical aspects of plant recognition. As techniques advance, AI-driven tools could approach or even exceed human capabilities in specialized domains like species identification. They could provide trusted aides to taxonomists and field botanists while making plant recognition more accessible.

Real-world deployment would require establishing highly accurate models across more extensive plant diversity by expanding datasets and fine-tuning algorithms. Advances in image processing, neural architectures, and training procedures will unlock recognition capabilities at higher resolutions and from multiple viewpoints.

Integrating multi-modal sensor data beyond images can provide a more comprehensive representation of plants and their context. Widening the scope beyond leaves to involve flowers, bark, growth patterns, and more morphological aspects can improve recognition and reduce ambiguity.

Overall, the study demonstrates a significant enhancement in a vital facet of plant identification using AI. It highlights the transformative potential of machine learning in replicating, automating, and surpassing human capabilities in specialized recognition tasks. Such AI systems can help digitize, democratize, and improve the reliability of fields like botany.

Source

Hajam, M. A., Arif, T., Khanday, A. M. U. D., & Neshat, M. (2023). An Effective Ensemble Convolutional Learning Model with Fine-Tuning for Medicinal Plant Leaf Identification. Information, 14(11), 618. https://doi.org/10.3390/info14110618, https://www.mdpi.com/2078-2489/14/11/618