The term 'Highland Plant' can be summarized by the crossword solution 'GORSE, ' which is a five-letter word. GORSE is a type of flowering shrub that is native to Europe and parts of Asia and Africa. It is often found in temperate climates, particularly in mountainous regions such as the Scottish Highlands. GORSE is known for its bright yellow flowers and spiny branches, and it is often used as a hedge or windbreak.