This document reviews various machine learning and deep learning algorithms that have been used for plant leaf recognition and classification. It summarizes 11 academic papers describing methods using support vector machines, convolutional neural networks, random forests, K-nearest neighbors, and other algorithms to classify plant species from leaf images with different levels of accuracy. The document concludes that these papers have suggested techniques to optimize accuracy, including preprocessing, feature extraction, and algorithm optimization, but that deep learning techniques like VGGNet often achieve the highest accuracy rates.