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BFNA Title: Reboulia |
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Aytoniaceae - Reboulia XX. REBOULIA Raddi Opusc. Sci. Bologna 2: 357. 1818,
orthography conserved "Rebouillia" * [For de Reboul, Italian botanist] Marie L. Hicks Plants in depressed mats, dichotomously branched with
occasional apical or lateral adventitious branches of ventral origin; green
to dull green with purplish margins, underside purple; dorsal surface firm,
not areolate; with slightly elevated air pores. Thalli 10‑‑18 cells
thick medially, gradually tapering to the margins, the interior tissue with
few oil cells; air chambers simple, without photosynthetic filaments; dorsal
epidermis without oil cells, epidermal cells with thin walls and distinct
trigones, air pores surrounded by 3‑‑6 concentric rings of cells with
thickened walls and trigones; ventral scales in 2 rows, purple, lunate, with
scattered oil cells and few slime papillae along the margins; appendages
purplish with decolorate apices, linear, hair‑like; rhizoids dense along
ventral midline, smooth or with internal pegs. Specialized asexual reproduction
absent. Sexual condition
monoicous; androecia dorsal, sessile, distinct, discoid to reniform or
lunate, thickened, purplish, ringed by small subulate purple scales; gynoecia
terminal, in apical notch, gynoecial stalk with one rhizoid furrow and white
hair‑like scales at base and apex; carpocephalum hemispheric, the proximal
half lobed, each lobe with a 2-labiate slit, and containing one sporophyte; pseudoperianth
absent. Sporophyte seta not elongating. Capsule spherical, irregularly circumscissile, the distal portion
disintegrating; capsule wall without thickenings. Spores areolate, the areolae bordered by winglike ridges; elaters
2‑‑4 spiral. Species 2 (1 in the flora): worldwide except
Antarctica, on soil. SELECTED REFERENCES
Evans, A. M. 1923.
Rebouliaceae. In C. C. Haynes,
M. A. Howe and A. W. Evans. 1923. Sphaerocarpaceae--Marchantiales,
Sphaerocarpaceae, Riellaceae, Ricciaceae, Corsiniaceae, Targioniaceae,
Sauteriaceae, Rebouliaceae, Marchantiaceae. North American Flora Ser. I, Vol.
14(1). New York Botanical Garden, New York.
Frye, T. C. and L. Clark. 1937.
Hepaticae of North America. University of Washington Publ. in Biology,
University of Washington, Seattle.
Schuster, R. M. 1992. The Hepaticae and Anthocerotae of North America.
Vol. 6. Field Museum of Natural
History, Chicago. The genus can be recognized by the conspicuous cluster
of white hair‑like scales at both the base and apex of the gynoecial stalk
and by the very narrow, hair‑like scale appendages. 1. Reboulia hemisphaerica
(Linnaeus) Raddi Opusc. Sci. Bologna
2: 357 Marchantia hemisphaerica Linnaeus, Sp. Plant. 1138.
1753 Plants with somewhat crenulate, undulate margins. Thalli
2--4 × 0.5--0.9 cm, elongate, slightly widened distally; epidermis
persistent, smooth; air pores and areolation indistinct; epidermal cells
45--50 × 30‑‑35 µm with small bulging trigones; air pores
surrounded by 3‑‑5 concentric rings of 6‑‑8 cells each; ventral scales with
decolorate margins and scattered oil cells; appendages 2‑‑3 per scale, linear
and hair‑like, 2‑‑3 cells wide, ending in 1‑‑3 single cells. Sexual
condition paroicous (rarely
polyoicous, but usually with some paroicous thalli in the mat); androecia reniform to lunate or
reduced and chevron-like, positioned 1‑‑10 mm posterior to the base of the
gynoecial stalk; gynoecium in apical notch, stalk 1.5‑‑3 cm, purplish;
carpocephalum green, with air pores in the upper portion, 4‑‑5 lobed below,
each lobe directed downward, the slit widening to form a circular opening as
the sporophyte expands. Sporophyte
capsule pale greenish; Spores
yellow, 65‑‑80 µm; elaters 250‑‑350 × 10‑‑12 µm, 2‑‑3 spiraled. Capsules mature March--August. Soil over rock that is
commonly but not exclusively calcareous, habitats that are at least
periodically moist, temperate areas; subcosmopolitan: Alta, BC, Man., Ont,
Que.; Ala., Ariz., Ark., Calif., Colo., Conn., D.C., Fla., Ga., Ill., Ind.,
Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont.,
Nebr., N.H., N.J., N.Mex., N.Y., N.C., Ohio, Okla., Oreg., Pa., R.I., S.C.,
Tenn., Tex., Utah, Va., Vt., W.Va., Wis.;
South America; Europe; Asia;
Africa; Australia; Pacific Islands. Reboulia hemisphaerica, with its wide distributional range, exhibits
considerable variation. From time to
time these plants have been variously described as autoicous or dioicous as
well as paroicous. The North American populations appear to be rather
consistently paroicous, rarely failing to produce either androecia or
gynoecia. When this failure occurs,
some populations may appear to be autoicous or dioicous but paroicous
individuals can usually be found within the mat of plants. Also, in Reboulia collections, the size of androecia decreases with age
and, before elongation of the gynoecial stalk, androecia are quite turgid and
bear marginal scales. As the
gynoecial stalk elongates and sporophytes mature, the androecia shrink and
marginal scales often fall away. Additional synonyms for the species are
given by T. C. Frye and L. Clark (1937). DOUBTFUL TAXA Reboulia hemisphaerica subsp. australis R. M. Schuster has
been reported from Quebec, Massachusetts and Virginia. This name, based on
New Zealand plants, is a synonym of R. queenslandica (Stephani) M. L. Hicks. The Australia and
New Zealand populations are rather consistently autoicous, and no
undoubted North American material has been located. For following two taxa, Reboulia
hemisphaerica subsp. acrogyna (R.
M. Schuster) R. M. Schuster (reported from Texas), R. hemisphaerica subsp. dioica
R. M. Schuster (reported from North Carolina), material is not
available, and the assigned characters do not justify taxonomic recognition. |