When it comes to distinguishing between the Frost Aster (Symphyotrichum pilosum) and the Calico Aster (Symphyotrichum lateriflorum), there are a few key differences to consider. While both are species of asters, they have distinct characteristics that set them apart.
1. Flowerhead Size: One noticeable difference between the two asters is the size of their flowerheads. The Frost Aster typically has larger flowerheads compared to the Calico Aster. The Frost Aster’s flowerheads are more substantial, with a diameter ranging from 1 to 1.5 inches (2.5-3.8 cm). On the other hand, the Calico Aster has smaller flowerheads, measuring around 0.5 to 0.75 inches (1.3-1.9 cm) in diameter.
2. Petaloid Rays: Another distinguishing feature lies in the number of petaloid rays on the flowerheads. Petaloid rays refer to the thin, elongated petals surrounding the central disk flowers. In the case of the Frost Aster, it typically exhibits a greater number of petaloid rays compared to the Calico Aster. The Frost Aster can have up to 40 or more petaloid rays, giving it a fuller and more vibrant appearance. Conversely, the Calico Aster usually has fewer petaloid rays, ranging from 10 to 25, resulting in a more modest and delicate look.
3. Leaf Shape and Arrangement: The leaves of these two asters also differ in their shape and arrangement. The Frost Aster has lance-shaped leaves that are densely hairy, giving them a grayish-green appearance. These leaves are arranged alternately along the stems. In contrast, the Calico Aster has narrower leaves that are smooth or sparsely hairy. The leaves of the Calico Aster are also arranged alternately.
4. Habitat and Growing Conditions: Understanding the natural habitat and growing conditions of these asters can also help differentiate them. The Frost Aster is commonly found in dry, open areas, such as prairies, fields, and roadsides. It thrives in full sun and well-drained soil. On the other hand, the Calico Aster prefers moist to slightly dry soil and is often found in woodland edges, meadows, and along stream banks. It can tolerate a range of light conditions, from full sun to partial shade.
It’s worth noting that while these differences can generally help identify the Frost Aster and the Calico Aster, there may be variations within each species due to factors like regional variations or hybridization. Therefore, it’s always beneficial to consult a field guide or seek expert advice for precise identification.
In my personal experience, I have come across both the Frost Aster and the Calico Aster in various garden settings. The larger, showier flowerheads of the Frost Aster make it an excellent choice for adding a pop of color and attracting pollinators like bees and butterflies. Its abundance of petaloid rays creates a stunning display in late summer or early fall.
On the other hand, the Calico Aster’s delicate appearance and smaller flowerheads make it an ideal option for adding a touch of elegance to a garden. I have found that its ability to tolerate different light conditions and its preference for slightly moister soil make it versatile in terms of planting locations.
Understanding the differences between these two asters can help gardeners make informed decisions when choosing plants for their landscape. Whether you opt for the larger, showier Frost Aster or the more delicate Calico Aster, both species offer beauty and diversity to any garden setting.
