Ephemerum crassinervium
Ephemeraceae
earth moss, ephemerum moss
virtually absent or to 1 mm (to 3.7 mm in Micromitrium synoicum), rhizoids absent or few.
lanceolate, broadly linear or ligulate, acuminate, sometimes narrowed distally from shoulders, 0.8–2.5 × 0.15–0.4 mm;
margins serrulate or serrate, with teeth sometimes recurved up to 45°;
apex acuminate and papillose;
costa at the base thin or not always apparent, stronger distally, often filling the acumen, percurrent or excurrent, papillose;
areolation firm proximally and distally compact to dense;
median laminal cells in ± vertical rows, smooth or slightly papillose;
distal laminal cells papillose.
rarely more than 12, the proximal small, broadly triangular to ovate, ecostate, apex acuminate, the distal becoming larger, linear, lanceolate, or ligulate, with or without shoulders, margins distal to the middle entire, serrulate, serrate, or spinose, apex acuminate; costate or ecostate;
laminal cells lax and transparent, long-rhomboidal to rectangular, in some species becoming denser distally, smooth, papillose by projecting distal ends, or spinose.
virtually absent or very short.
autoicous, dioicous, or synoicous.
with columella resorbed before meiosis;
stomates in proximal half or scattered throughout.
globose or ovoid, without or with an apiculus, cleistocarpous or opening along an indistinct or distinct ring of cells near the equator;
exothecium of 1–2 layers of lax and thin-walled cells;
stomates absent or superficial with two guard cells.
persistent, mitrate, and minute, or fugacious, mitrate or cucullate, and irregularly lobed or torn at the base, covering up to 2/3 of the capsule.
various, 43–120 × 35–80 µm.
appearing reniform, globose, or variously angled, 20–120 µm, ranging from barely papillose to coarsely warty, the elaboration often correlating with degree of maturity, usually bearing small remnants of a hyaline membrane, orange, red, brown, or black.
asexual reproduction by fragments and rarely by thick-walled elongate, swollen protonematal segments, commonly brown, and persisting on or in the soil.
arising from the protonemata, from rhizoids, or just proximal to the perichaetium; small, bud-like with ecostate leaves of lax areolation, broadly triangular to broadly ovate.
consisting of the 1–3 most distal leaves on the stem, typically the largest and best developed.
conspicuous.
1–3 per perichaetium with immersed to emerging capsules.
Ephemerum crassinervium
Ephemeraceae
Varieties 2 (2 in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Genera 2, species ca. 35 (2 genera, 8 species in the flora).
The Ephemeraceae are usually found in sunny or partly shaded areas, on moist or drying disturbed soil, where there is little competition from more persistent mosses and larger plants. They are visible for the most part as patches of greenish, alga-like protonemata with minute leafy plants and are best seen in the field when the protonemal mass is most abundant and green, with leafy plants that are green and approaching maturity.
The distinguishing characters of the leaves are derived from the largest, usually the most distal, leaves. The middle and proximal leaves vary in shape, marginal cells, and costal development. For example, the distal leaves bear the well-developed costa, but the proximal leaves are usually ecostate, and the middle leaves vary from ecostate to weakly or markedly costate. In the nominally ecostate species the proximal and middle leaves are ecostate, but the largest leaves, while in a strict sense ecostate, may have in the costal position thicker walled cells or a few undifferentiated cells in a double layer. As seen in cross-section, the double-layered cells are not organized as a costa and do not differ from other laminal cells, except that they may have very slightly thicker walls. In surface view the double layer is barely distinguishable.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Distal leaves lanceolate to broadly linear and acuminate, with compact to rather dense areolation in the distal two-thirds | var. crassinervium |
1. Distal leaves broadly lanceolate to oblong-lanceolate or ligulate and subulate, often narrowed from a slight to prominent shoulder, densely papillose in the distal half | var. texanum |
1. Calyptra minute, tightly adherent at or near the apex of the capsule, persistent; capsule cleistocarpous or with a ring of differentiated cells at or just distal to the equator, ± globose, without a well-developed, multicellular apiculus; costa commonly absent, but occasionally suggested by a few median cells with thick walls or in a short and indistinct double layer distal to the leaf middle; laminal cells lax, hyaline, smooth. | Micromitrium |
1. Calyptra covering most of the distal half of the capsule, fugacious; capsule cleistocarpous, ovoid, and distinctly apiculate; costa well-developed, except mostly absent in Ephemerum serratum; laminal cells of the leaves lax in the proximal half and in the distal half firmer, smaller, and usually papillose. | Ephemerum |
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