Flat-topped White Aster (Doellingeria umbellata)

Detailed information for an alpine or subalpine species recorded along Howker Ridge Trail. Use the back link to return to the catalog.

Short Description

Flat-topped White Aster, sometimes called Parasol Whitetop, is a robust wildflower found in wetter pockets of the mountains. It commonly grows 3–5 feet tall, unbranched except near the top where it bears a **broad, flat-topped cluster of white blossoms**. You might encounter it in soggy clearings or along streams below Howker Ridge, where its bright white flower clusters stand out against the grasses and goldenrods in August. The plant’s leaves are long (3–6 inches), narrow and lance-shaped, with a rough texture, arranged alternately up the stem. Near the top, the stems branch into a wide panicle (almost like a candelabra) of dozens of small daisy-like flower heads. Each head has 10–15 white rays around a yellow center. In full bloom, a single plant looks like it’s carrying a **bouquet of mini-daisies all in one plane**, hence “flat-topped.” The effect can be quite showy, especially when masses of these plants bloom together in a damp meadow. Flat-topped Aster often forms colonies via rhizomes, spreading in favorable wet soil. It’s an important species in high-elevation swamps and upland marshes in the White Mountains, often growing alongside joe-pye weed, swamp goldenrod, and sedges.

TYPE

Wildflower

ELEVATION

500–3,000 ft

HABITAT

Moist meadows, streambanks, and open woods; often in swampy thickets or near seeps

BLOOM / SEASON

July–September (clusters of small white daisy-like flowers)

LEAF & STEM

A tall, erect perennial 3–6 ft in height, often with a reddish or green smooth stem. The stems are usually unbranched until the inflorescence. Leaves are numerous, up to 6 inches long but only ~1 inch wide, lanceolate with a tapering tip and sometimes a slight toothed edge; lower leaves may have short petioles, upper leaves are sessile (clasping the stem). The inflorescence is a **flat-topped compound umbel or panicle** – many branchlets of roughly equal height bearing flower heads, giving a level-topped appearance from above. Each flower head is about 1/2 inch across, with 8–15 white ray florets and a central cluster of yellow disk florets (which age to a dull cream). The rays are somewhat irregular in length, giving the daisies a slightly ragged look. After bloom, it produces small wind-dispersed achenes with a tuft of bristles. The plant’s roots are fibrous and it also has creeping underground rhizomes, allowing a clump to expand outward over years.

SIMILAR SPECIES

Flat-topped Aster is distinctive in having a large, flat-topped inflorescence of many small white flowers. Other white asters in the region either have more rounded clusters or bloom later. **White Wood Aster (Eurybia divaricata)** grows in shade, is shorter (1–2 ft) and has only a few blossoms per cluster. **Fall (Frost) Aster (Symphyotrichum pilosum)** sometimes has a broad array of white flowers, but it’s a shorter, bushier plant of dry fields with fuzzy stems. **Boltonia (Boltonia asteroides)** has a similar large spray of white daisies but is more common in cultivation or low wetlands further south. Non-aster lookalikes include **Thoroughwort (Eupatorium perfoliatum)**, which has flat-topped white flower clusters but they are fuzzy and lacking ray petals. If the plant is tall, in a moist meadow and topped with a platter of small white daisy flowers in mid-late summer, it’s likely Flat-topped Aster.

ECOLOGY

This species thrives in mountain wetlands and provides valuable services there. It attracts a variety of pollinators: bees, wasps, small butterflies, skippers, and especially many types of flies frequent the nectar-rich flowers. Its bloom time (midsummer to early fall) overlaps with late-season pollinator activity, and it serves as a **larval host for the Harris’ Checkerspot butterfly and Pearly Crescentspot**, which lay eggs on aster leaves. Insects feeding on its nectar become prey for spiders and birds, thus integrating the plant into the food web. The seeds (small achenes) have tufts that aid dispersal by wind and may also be eaten in small amounts by seed-eating birds or rodents. Because Flat-topped Aster often grows in colonies, its thick stands can help bind soil in wet meadows and stream margins, reducing erosion during floods. It also offers some cover to frogs, toads, and insects in marshy areas – standing tall above grasses and sedges. In winter, the dried seed heads persist and can catch drifting snow, contributing to a microhabitat that insulates overwintering insects at ground level. Ecologically, it is a resilient plant tolerant of both water-logged soils and periodic drying, helping it persist in the fluctuating water conditions of mountain wetlands.

STATUS

Flat-topped White Aster is generally common across its range (eastern North America) and is not considered threatened. In New Hampshire and the broader White Mountain region, it’s a typical component of wet meadows and riparian zones. It is listed as secure globally (NatureServe G5). Locally, occurrences can be abundant where habitat is suitable – for instance, in beaver meadows or along brook edges – and it often benefits from habitat disturbances like beaver activity that maintain open wetland conditions. One potential local threat is succession: if a meadow grows up into forest, this sun-loving aster will decline. It is also sensitive to prolonged drought since it prefers moist soil, so extended dry spells (which may increase with climate change) could reduce its vigor in some sites. However, it has a broad distribution from Canada to the southern Appalachians, indicating high adaptability. No conservation measures are targeted specifically at this aster, but wetland protection efforts indirectly conserve it. In summary, Flat-topped Aster is currently doing well and remains a widespread, thriving wildflower in its habitats.

Field Notes

A tall, erect perennial 3–6 ft in height, often with a reddish or green smooth stem. The stems are usually unbranched until the inflorescence. Leaves are numerous, up to 6 inches long but only ~1 inch wide, lanceolate with a tapering tip and sometimes a slight toothed edge; lower leaves may have short petioles, upper leaves are sessile (clasping the stem). The inflorescence is a **flat-topped compound umbel or panicle** – many branchlets of roughly equal height bearing flower heads, giving a level-topped appearance from above. Each flower head is about 1/2 inch across, with 8–15 white ray florets and a central cluster of yellow disk florets (which age to a dull cream). The rays are somewhat irregular in length, giving the daisies a slightly ragged look. After bloom, it produces small wind-dispersed achenes with a tuft of bristles. The plant’s roots are fibrous and it also has creeping underground rhizomes, allowing a clump to expand outward over years.
This species thrives in mountain wetlands and provides valuable services there. It attracts a variety of pollinators: bees, wasps, small butterflies, skippers, and especially many types of flies frequent the nectar-rich flowers. Its bloom time (midsummer to early fall) overlaps with late-season pollinator activity, and it serves as a **larval host for the Harris’ Checkerspot butterfly and Pearly Crescentspot**, which lay eggs on aster leaves. Insects feeding on its nectar become prey for spiders and birds, thus integrating the plant into the food web. The seeds (small achenes) have tufts that aid dispersal by wind and may also be eaten in small amounts by seed-eating birds or rodents. Because Flat-topped Aster often grows in colonies, its thick stands can help bind soil in wet meadows and stream margins, reducing erosion during floods. It also offers some cover to frogs, toads, and insects in marshy areas – standing tall above grasses and sedges. In winter, the dried seed heads persist and can catch drifting snow, contributing to a microhabitat that insulates overwintering insects at ground level. Ecologically, it is a resilient plant tolerant of both water-logged soils and periodic drying, helping it persist in the fluctuating water conditions of mountain wetlands.
Flat-topped White Aster is generally common across its range (eastern North America) and is not considered threatened. In New Hampshire and the broader White Mountain region, it’s a typical component of wet meadows and riparian zones. It is listed as secure globally (NatureServe G5). Locally, occurrences can be abundant where habitat is suitable – for instance, in beaver meadows or along brook edges – and it often benefits from habitat disturbances like beaver activity that maintain open wetland conditions. One potential local threat is succession: if a meadow grows up into forest, this sun-loving aster will decline. It is also sensitive to prolonged drought since it prefers moist soil, so extended dry spells (which may increase with climate change) could reduce its vigor in some sites. However, it has a broad distribution from Canada to the southern Appalachians, indicating high adaptability. No conservation measures are targeted specifically at this aster, but wetland protection efforts indirectly conserve it. In summary, Flat-topped Aster is currently doing well and remains a widespread, thriving wildflower in its habitats.

Howker Ridge • Plant