fan clubmoss

not listed

N5 - Secure

SNR - Unranked

not listed

There are seventeen species of Diphasiastrum worldwide, five in North America, two in Minnesota. Fan clubmoss (Diphasiastrum digitatum) occurs in North America east of the Great Plains. It is the most abundant Diphasiastrum species in North America. It is common in eastern and north-central Minnesota. It grows in well-drained, moist to dry soil, in dappled sunlight to light shade, in open, upland, coniferous and deciduous woodlands, thickets, and sandy fields.

Fan clubmoss is an erect, evergreen, perennial club moss. It produces long-creeping, sparingly-branched, horizontal stems (rhizomes) that lie on the surface of the soil. The rhizomes are light green, hairless, round in cross section, and 1 ⁄32″ to ⅛″ (1.3 to 2.7 mm) in diameter. They are sparsely to moderately covered with tiny, scale-like leaves that often drop off. These leaves are, dry, thin, somewhat transparent, and appressed to spreading. They are narrowly pointed at the tip, linear to narrowly lance-shaped, 1 ⁄16″to 3 ⁄16″ (1.8 to 4.5 mm) long, and 1 ⁄32″ (0.6 to 1.2 mm) wide. Fibrous roots emerge from the underside of the rhizomes.

Upright shoots appear at intervals on the upper side of the rhizomes. The shoots can be 6″ to 20″ (15 to 50 cm) tall but fertile shoots, those with cone-like spore-bearing structures (strobili), are usually less than 12″ in height, and vegetative shoots, those without strobili, are usually less than 8″ in height. The stem is round, hairless, and moderately covered with appressed to slightly spreading, scale-like leaves. These leaves are awl-shaped, 1 ⁄16″ to ⅛″ (1.8 to 3.5 mm) long, and 1 ⁄32″ (0.6 to 1.0 mm) wide. They are narrowly pointed at the tip and continue down the stem at the base.

Each stem has two or more branches near the base. The branches ascend from the stem then spread horizontally, more or less parallel to the ground and on the same plane, sometimes beneath the forest litter (duff layer). The stem and branches almost never have narrow areas marking the start and end of annual growth (annual constrictions).

Each branch forks up to three times. The ultimate branchlets are ⅛″ (2.8 to 3.9 mm) wide. They are flat, green, and shiny above, flat, pale, and dull below. There are four ranks of leaves, one on the flat upper side, one on the flat underside, and one on each narrow side. The lateral leaves are the largest. They are appressed to spreading, ⅛″ to 3 ⁄16″ (3.1 to 5.5 mm) long, and 1 ⁄32″ to 1 ⁄16″ (1 to 2 mm) wide. The leaves on the upper side are liner lance-shaped and appressed. The free tip of the blade is no more than 1 ⁄32″ (1.5 mm) long. The leaves on the underside are the smallest and are poorly developed. They are spreading, narrowly triangular, and no more than 1 ⁄32″ (1 mm) long.

At the end of each fertile shoot two upright stalks (peduncles) emerge with a cluster of 2 to 4, rarely more, strobili at the tip. The peduncles are 1¾″ to 6″ long, hairless, round in cross section, and conspicuously leafy. These leaves are somewhat whorled, linear lance shaped to nearly thread-like, and no more than ⅛″ (3.3 mm) long. The strobili are on short branches that appear whorled but are actually at the end of minute forks at the tip of the peduncle. They are often arranged as two pairs. Each strobilus is light green, narrowly cylinder-shaped, 9 ⁄16″ to 19 ⁄16″ (14 to 40 mm) long, and 1 ⁄16″ to ⅛″ (2 to 3 mm) wide. About half of the strobili have a short, up to 7 ⁄16″ (11 mm) long sterile tip. The strobili are densely covered with small, scale-like bracts (sporophylls). Each sporophyll is triangular and 1 ⁄16″ to ⅛″ (1.7 to 2.8 mm) long and wide. A single kidney-shaped spore-bearing structure (sporangia) is hidden beneath each sporophyll. The sporangia split open and the spores are released in late summer to fall. The spores are dispersed by wind.

6″ to 20″

Well-drained moist to dry. Open, upland, coniferous and deciduous woodlands; thickets; and sandy fields. Dappled sunlight to light shade.

Late summer to fall

Sources

2, 3, 4, 5, 7, 24, 28, 29, 30.

Native

Common in eastern North America and in eastern Minnesota

Club mosses in the genus Diphasiastrum readily crossbreed with other species in the same genus. The hybrids that are produced are fertile. Fertile hybrids are common in the animal kingdom but rare in the plant kingdom.

Location: Superior Hiking Trail, Cook County