Arboretum Botanical Glossary

Acute Cut at a sharp angle. This feature helps describe plant form, function, or identification.

Adaxial Facing towards the stem of a plant. The upper surface of a leaf.

Adnate Having a fusion of unlike parts. In mushrooms, the attachment of the fertile tissue (the gills, tubes, spines, etc.) to the stipe (stem) in which the attachment is perpendicular to the stipe (stem)

Adnexed In mushrooms, the attachment of the fertile tissue (the gills, tubes, spines, etc.) to the stipe (stem) in which the fertile tissue typically curves upwards towards the pileus (cap)

Adventitious Occurring in other than the usual place - example roots appearing on an above-ground stem Did you know? Corn produces adventitious “prop roots” above the soil that brace the tall stalk against wind.

Agaric Describing a fungus having a cap (pileus), gills (lamellae), and a stem (stipe), i.e., what most people would call a mushroom Did you know? The mushroom above ground is only the fruiting body. Most of the fungus lives hidden as mycelium in soil, wood, or leaf litter.

Pollution Removal estimates the amount of air pollution removed by trees each year as pollutants deposit on leaf surfaces or are taken up through leaves. The value is reported as ounces per year. Learn More Poor air quality is a common problem in many urban areas. It can lead to adverse effects on human health, damage to landscape materials and ecosystem processes, and reduced visibility.…

Alternate Arranged on different sides of a stem - usually refers to leaves that appear alternately, first on one side of the stem, then on the other - not in opposing pairs Did you know? Leaf arrangement is one of the fastest winter identification clues. Maples usually have opposite leaves, while oaks and elms have alternate leaves.

Amphibious Growing both on land and in water. This term helps record, compare, or interpret plant and site information. Did you know? Some amphibious plants grow different leaf shapes underwater than they do above water, allowing the same plant to function in both environments.

Amplexicaul Clasping the stem, as in the case of the base or stipules of some leaves Did you know? Some clasping leaves form small cups around the stem that can collect rainwater and organic debris.