[*][*][*] Thallus wider (2´´ or more), simple or irregularly lobed.
4. A. séssilis, Spreng. Thallus decumbent, irregularly lobed, 1–2´ long, 3–5´´ wide; involucre none; pedicel ¾–1´ long, sometimes folded upon itself and remaining within the calyptra, the capsule thus appearing sessile; antheridia on elongated receptacles.—Wooded swamps. Elongated floating forms, 5–6´ long, have been found in the White Mts. (Farlow, Faxon).
5. A. pínguis, Dumort. Thallus 1–2´ long, decumbent or ascending, fleshy, linear-oblong, simple or slightly lobed, the margin sinuate; diœcious; involucre short, lacerate; calyptra cylindric, smooth; capsule brownish, furrowed; antheridia in 2-lobed receptacles.—Wet banks, N. J. to Ohio, and southward. (Eu.)
Order 138. ANTHOCEROTÀCEÆ. (Horned Liverworts.)
Plant-body a thallus, irregularly branching, flaccid, without epidermis or pores, and more or less vesiculose. Involucre single, tubular. Calyptra rupturing early near the base, and borne on the apex of the capsule. Capsule dorsal, pod-like, erect or curved outward, more or less perfectly 2-valved, usually stomatose, tapering into a pedicel or often sessile with a bulbous base. Columella filiform. Elaters with or without spiral fibres. Spores flattish, more or less convex-prismatic, papillose or smooth.
1. Anthoceros. Capsule narrowly linear, exsertly pedicelled, 2-valved. Elaters present.
2. Notothylas. Capsule very short, sessile, not valved below the middle. Elaters not obvious.
1. ANTHÓCEROS, Micheli. ([Pl. 22.])
Thallus dark green or blackish, usually depressed, variously lobed, with large chlorophyll-grains, frequently glandular-thickened at the apex or in lines along the middle so as to appear nerved. Monœcious or diœcious. Capsule linear, 2-valved, exsertly pedicelled. Elaters simple or branched, often geniculate, more or less heteromorphous, the fibres wanting or indistinct. (Name from ἄνθος, flower, and κέρας, horn, from the shape of the capsule.)
1. A. læ̀vis, L. ([Pl. 22.]) Thallus smooth, nearly flat above; diœcious; involucre 1–2´´ long, trumpet-shaped when dry, repand-toothed; capsule pale brown or yellowish, 1–1½´ long; elaters rather short, yellowish; spores yellow, nearly smooth, angular.—Wet clay banks, from Canada south and westward. (Eu.)