This moss is very common in habitats that receive adequate moisture. It prefers bogs,
forest stream edges, and similar moist, somewhat shaded habitats. If it remains wet, it tolerates full
sun.
Most mosses are very low-growing,
but haircap moss is from 1¾-12″ (5-30 cm) tall, sometimes even reaching 2′ (70 cm).
There’s a reason mosses are small: they are
non-vascular plants—lacking a mechanism for transporting water and nutrients throughout the plant.
By contrast, other plants use a trick called transpiration. Water evaporates out of pores in the leaves,
drawing water up from the roots and throughout the plant. Without transpiration, mosses have to stay small in order to
survive. Haircap mosses, though, have evolved a modest vascular system, so they can grow larger.
Plants: These mosses form extensive dense, verdant soft carpets.
Individual plants are often 1¾-4″ (5-10 cm) in height, and can exceed 12″ (30 cm).
Stems are usually unbranched.
Leaves: Leaves are ⅛-¼″ (6-8 mm), rarely up to ⅜″ (1.2 cm)
in length. They are long and narrow, erect when dry and curved when wet, dark green to brown in old age. They are crescent-shaped in
cross-section, resembling miniature
Aloe vera leaves. Viewed from above, the sharp leaves look starlike, and
they are arranged in a spiral around the stem.
Fruits: Thin green or red stems called seta are
1¾-3½″ (5-9 cm) long. They
support a green to golden brown fibrous bundle, the calyptra. The
calyptra is about ⅛-⅜″ (5-10 mm) tall and ⅛″ (4 mm) around,
with a sharp tip. The calyptra encloses the capsule, a structure 1/16-3/16″ (3-6 mm) long, somewhat
cubical, that is brown to dark red-brown.
The two darker-colored plants have male "splash cups" on top, where sperm is produced. · 9/29/2010 · Nashua River Rail Trail, Ayer, Massachusetts · ≈ 4½ × 3″ (11 × 7.9 cm) ID is uncertain
About 3" x 3". · 7/29/2023 · Townsend State Forest, Townsend, Massachusetts
About 2" x 1.75". · 7/29/2023 · Townsend State Forest, Townsend, Massachusetts