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Aster is a plant that has nearly 180 different types. Most types of aster are well-behaved and a visually pleasing and appropriate ground cover in gardens and landscapes. However, there are several types of aster that are considered weeds and can quickly take over just about any landscape. Among them are slender aster, white wood aster, and hoary aster. All types of aster are in the same family as the sunflower. However, these three types of weedy aster can be rambunctious pests that spread quickly and gain traction to overrun other native plants and herbs.

Because there are so many types of aster, there are a number of scientific names for undesired clumps of aster. Hoary aster is known by the scientific name Dieteria canescens. White wood aster’s scientific name is Eurybia divaricate. And slender aster goes by the scientific name Symphyotrichum divaricatum.

Weedy aster is either a short-lived broadleaf perennial plant that can grow up to 4 feet tall, or they may be a tall, spindly annual weed. In most cases, weedy forms of aster grow in clumps. Stems can be woody near the base as they mature. Leaves are small and hug close to the plant’s stem. In some types of aster, leaves and stems may be hairy, while in others they may be bare. Most weedy varieties of aster produce flowers that have a bright yellow central disc that are actually considered tiny flowers. They are surrounded by a ray of petals that can range in color but generally are white, purple, or pale pink in color.

These stubborn weeds are spread throughout most of North America, Central America, and parts of South America. They are native to parts of Australia and are taking over areas strangling out some endangered species of plants. The aster can grow in almost any soil conditions and climates, as indicated by its extensive habitat. However, it prefers moist soil with poor drainage. It can be seen commonly in pastures, old fields, orchards, roadsides, waste spaces, and no-tillage agronomic fields.

Because there are so many species of aster, there are a number of unique characteristics to this weed. Some reproduce by seed only, while others reproduce by both seed and rhizome. The root systems are generally fibrous and shallow, though the more mature the plant is, the more difficult it is to control. Flowers can bloom during any time of the year, though many of the weedy asters bloom in late summer until early fall. They may produce fruit, which is light to dark brown in color. They are cone-shaped and have a tuft of silky hairs attached to the top of the fruit. Each fruit contains a single seed inside. Although they can spread quickly and weed control with these plants can be difficult, there is no known toxicity, unlike many other types of pasture weeds.