Common Michaelmas Daisy
- Latin synonym: Aster x salignus
- Family: Daisy Family – Compositae, subfamily Asteroideae
(formerly Aster Family – Asteraceae)
- Growing form: Perennial herb.
- Height: 60–130 cm (25–50 in.). Stem many-branched at top, bristly, bristles short-haired at least at top. With subterraneous runners, forms stands.
- Flower: Flowers 2–3 cm (0.8–1.2 in.) wide, single flower-like capitula surrounded by involucral bracts. Capitulum’s ray-florets white–lightish purple, tongue-like; disk florets yellow, tubular, small. Stamens 5. Gynoecium composed of 2 fused carpels. Involucral bracts overlapping in 2–3 rows, often spreading, same length, tapered, usually with membranous margins at base. Capitula a corymbose group.
- Leaves: Alternate, stalkless, not amplexicaul. Blade ovately lanceolate, long-tapered, sparsely sharp-toothed, short-haired, rough.
- Fruit: Does not develop.
- Habitat: Shores, beside ditches, roadsides, waste ground, gardens, parks. Ornamental, left over and escape from old gardens.
- Flowering time: August–October.
- Harmfulness: Harmful invasive species.
Common michaelmas daisy is a cross between New York aster (Symphyotrichum novi-belgii) and panicled aster (Symphyotrichum lanceolatum), but it behaves as an independent species. The hybrid has been created by gardeners who were looking for new perennials. As an ornamental common michaelmas daisy is flamboyant and content with little. It thrives in old gardens and has often also spread far from the place it was originally planted. Probably due to this tendency, common michaelmas daisy has been replaced in modern gardens by better-behaved and more impressive aster species or varieties. Common michaelmas daisy also demonstrates its vigour when it ventures into the wild, where nowadays it forms broad, dense stands. It has grown here and there in the wild in Finland since the 19th century, but it only became more common much later. It probably escaped from gardens, especially in the form of unwanted root cuttings which have travelled by water and ended up on the banks of flooding rivers. From the river banks it has spread gradually downstream, all the way to the mouth of the river, and has taken over territory from large Finnish herbs. There are still separate stands in many places around inhabited areas, beside allotments and on waste ground. Especially small stands are often only noticed when they begin to flower, which happens quite late, not until summer turns to autumn.
New York Aster (Traditional Michaelmas Daisy, Confused Michaelmas Daisy)
Symphyotrichum novi-belgii (Aster novi-belgii)
New York aster, which is a parent species of common michaelmas daisy, is grown quite commonly in Finnish gardens. The most common variety in perennial flower beds seems to be the low-growing, only slightly developed native variety, whose exact origins are difficult to pinpoint. It has adapted to Finnish conditions remarkably well. Central European New York asters begin to flower in the Finnish climate only when autumn comes, but the Finnish variety flowers already in the middle of summer. It doesn’t demand any care or attention, so it can survive for a long time on its own. Common michaelmas daisy is highly reminiscent of New York aster, from which it differs – if it differs at all – in its extra height, smaller flowers and the narrow base of its upper leaves. New York aster’s leaves are on the other hand always slightly amplexicaul. As cultivated ornamentals, asters have on the other hand crossed back and forth with each other so many times that definitively classifying one species from another is impossible.