Eriophorum vaginatum L. var. spissum (Fernald) B. Boivin

Cotton sedge, hare’s-tail cottongrass, tussock cottongrass, sheathed cottonsedge

Hare’s-tail cottongrass is a tussock-forming sedge native to North America.

Plants: Stems (culms) are round, oval, or triangular in cross section. The stems are very thin, about 11.8 mils (0.3 mm), and densely packed into tussocks.

Leaves: There are a few basal, alternate leaves, and a few higher up, but they are easy to miss amongst the many stems. Each leaf is up to 1/32″ (1 mm) wide, resembling a grass blade, and may be nearly as long as the stem.

Flowers: Flowers appear in a compact cluster at the tip of the stem, appearing elliptic at first, then more hemispheric as the plant matures. If you look closely, the numerous flowerheads are arranged in a spiral pattern. The cottony flowerheads are ¾–2″ (1.9–5 cm) in size.

Fruits: 1/16–⅛″ (1.9–3.5 mm) long. They are triangular to rounded in cross-section. White bristles around the base of each flower extend in length, becoming ¼–¾″ (8.3–19 mm) long, producing the “cotton.” Seeds (achenes) are 1/16–⅛″ (1.9–3.5 mm) long, and shaped like teardrops. They are three-sided when viewed in cross section. The tussocks of narrow stems, white bristles (vs. brownish), and erect (vs. nodding) orientation are identifying features.

Habitats: Peaty bogs and acidic wetlands.

Similar species.

Online References:

References:

Older scientific or horticultural names

Eriophorum vaginatum var. spissum description by Thomas H. Kent, not updated.

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