Since Europeans first began cataloguing the plant species of Maryland in the early 18^th century, over 3,000 woody and herbaceous species have been recognized. The most important, by necessity, were those which provided food and shelter. Once their basic needs were addressed, settlers began to explore and describe their finds to their brethren across the Atlantic. Because of its diverse geology, hydrology and land formation, Maryland was home to an abundance of plant species, creating unique natural communities and providing habitat to wildlife.

Early documents by these gentlemen botanists provide current researchers with a picture of the landscape at the time of colonization. Since that time, an estimated 300 plant species have become extinct. Declines in number are due to a variety of factors: loss of habitat through conversion to development or agriculture, changes in hydrology, fragmentation, pollution, even over-collection. The Maryland Natural Heritage Program currently tracks approximately 840 species, monitoring population numbers and restoring viable habitat, where possible.