The Michaelmas daisy, or Aster amellus, is a European species of aster that is usually white, bluish, or lavender in appearance. These flowers can reach heights of 15 to 30 inches (40 to 70 centimeters), and typically produce daisy-like blooms that are 1 to 3 inches (2.5 to 7.5 centimeters) wide. The Michaelmas daisy usually flowers in late summer and early fall. It's considered pretty easy to grow and resistant to most extremes in temperature. It generally thrives best in full sunlight, in well-drained, alkaline soil.
Botanists currently recognize about 200 species of aster, most of them native to Europe. There are several hundred Central and North American species that resemble members of the Aster genus, but scientists have decided to classify these species differently. Most of them are nevertheless still commonly referred to as asters.
The various species of European asters grow to varying sizes and can produce blooms of varying colors. The Michaelmas daisy is considered the Aster genus's type species, meaning that scientists believe this plant possesses all the major defining characteristics that should be found in all species of the genus. The Michaelmas daisy is a perennial plant, meaning that it will typically grow back from the roots year after year without being replanted.
These plants are typically capable of thriving without care, and have been observed to spread both through the roots and through seeds. They seem to prefer average soil, but can also grow well in soil that contains large amounts of clay or sand. Many gardeners prefer to plant the Michaelmas daisy along the edges of flower beds and along garden paths, since these flowers don't usually get as tall as some varieties of aster. Cutting off the stems a few weeks before blooming begins can help to keep the flowers short, and separating any clumps every few years can help them to thrive.
The genus name Aster is derived from the ancient Greek term for "star," probably because the aster's blooms resemble the rays of a star. Some people may refer to these plants as "starflowers." Several butterfly and moth species feed on members of the Aster genus. These insects include the flame shoulder moth and the hummingbird hawk moth.