Whip Broom Moss

Plant / dispersed
slime of Pulmonata spreads or disperses deciduous branch of Dicranum flagellare

Dicranum flagellare has been reported from Northwest Territories by W. L. Peterson (1979) and Arizona by I. M. Haring (1961). It is easily recognized because of the presence of unique axillary, flagelliform branchlets, in clusters of 2-6, which some plants in each colony almost always possess. The branchlets are deciduous and represent another type of asexual reproduction present in species of Dicranum, e.g. deciduous branchlets with linear, crisped leaves in D. montanum, and deciduous leaf tips in D. fragilifolium, D. tauricum and D. viride. C. E. Correns (1899) discussed the flagelliform branchlet type of asexual reproductive in D. flagellare as well as the other types of asexual reproduction occurring in the genus. The only species likely to be confused with D. flagellare if the flagelliform branchlets are overlooked or cannot be found is 25. D. montanum. For distinctions see the discussion under that species.

Plants in dense tufts, usually bearing 2-6 dark green, stout, terete branchlets, 1-4 mm, in the axils of the distal leaves, each flagelliform branchlet with short, ovate to lingulate, broadly acute to obtuse, ecostate or shortly and indistinctly costate leaves closely appressed to the axis, yellowish green to dark green, glossy. Stems 0.5-6 cm, densely tomentose with light brown to reddish brown rhizoids. Leaves falcate-secund to nearly straight, crisped to weakly crisped when dry, smooth, (1-)2-4(-5) × 0.3-0.6 mm, concave below, tubulose above, from a lanceolate or ovate-lanceolate base to an acuminate subula, apex acute; margins smooth to serrulate above; laminae 1-stratose; costa percurrent or sometimes ending just before apex, ¹/6-¹/4 the width of the leaves at base, smooth to ± rough with papillae or small teeth on abaxial surface near apex of leaf, abaxial ridges absent, with a row of guide cells, two stereid bands above and below not extending above the leaf middle, adaxial epidermal layer of cells not differentiated, the abaxial layer with some cells differentiated; cell walls between lamina cells not bulging; leaf cells smooth or weakly abaxially prorate above; alar cells 1-stratose, distinctly differentiated, not extending to costa; proximal laminal cells elongate-rectangular, not pitted or with few pits, (12-)24-38(-70) × (4-)10-15(-18) µm; distal laminal cells short-rectangular to quadrate, not pitted, (5-)12-14(-23) × (5-)7-12(-14) µm. Sexual condition dioicous; male plants as large as females; interior perichaetial leaves abruptly long-acuminate, convolute-sheathing. Seta 1-2.5 cm, solitary, yellowish to brown. Capsule 1.5-3 mm, straight and erect or nearly so, striate when dry, yellowish brown to brown; operculum 0.5-l.6 mm. Spores 12-19 µm.

Dicranum flagellare var. minutissimum Grout

Dicranum flagellare Hedw. Descr. 3: 1. 1791
Dicranum miquelonense Ren. & Card. Bot. Gaz. 14: 93. 1889. Dicranum miquelonense crispatulum Roll, Hedwigia 36: 42. 1897. Dicranum crispatulum Kindb. Eur. & N. Am. Bryin. 189. 1897.
Dioicous: fertile plants in compact, dark-green to pale yellowish-green tufts, with more or less abundant, deciduous, flagellate branches from the axils of the upper leaves, bearing minute, appressed, scale-like leaves: stem-leaves variable, 3-4 mm. long, usually curved and somewhat spreading all round or sometimes crispate or falca te-secund, l anceolate, subtubulose above, slightly serrulate on the margin and more or less rough on the back in the upper part, with a broadly acute of slightly obtuse apex; costa not quite percurrent, just above the broadened base about one fourth the width of the leaf -blade, in cross-section below showing 6-8 guide-cells with about 2 rows of smaller cells above and below scarcely or not forming stereid-
r-
bands; alar cells usually brownish, scarcely extending to the costa, the cells above all with uniformly slightly thickened, not pitted walls; lower leaf-cells rectangular, 2-8 times as long as wide, the upper ones shorter, from square to 2-3 times as long as wide; inner perichaetial leaves about the length of the stem-leaves, costate, from a convolute base abruptly, often truncately or retusely, narrowed to a smooth point about one third the broader part in length, the margin just below the base of the point crenulate or denticulate: seta finally reddish, about 1.5 cm. long: capsule cylindric, erect, straight or nearly so, up to 3 mm. long, slightly ribbed when dry; annulus of two rows of cells; lid with its beak nearly two thirds as long as the capsule; peristome-teeth divided more than three fourths down, red and vertically striate one half up, the very slender forks pale and papillose above: spores slightly rough, about 16 fi in diameter.
Type locality: Germany.
Distribution: Newfoundland to British Columbia, Montana, and South Carolina; also in