BFNA Title: Sphaerocarpaceae
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Date: Sept. 16, 2017
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Bryophyte Flora of North America, Provisional Publication
Missouri Botanical Garden
BFNA Web site: http://www.mobot.org/plantscience/BFNA/bfnamenu.htm

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4. SPHAEROCARPACEAE  Heeg

Anonymous

Habitat terrestrial. Thallus prostrate, compressed dorsiventrally, consisting of a flat multistratose central thallus bearing regular, succubous leaf-like lobes that are 1-stratose; thallus mostly concealed beneath crowded involucres, without scales. Specialized asexual reproduction none. Sexual condition dioicious, male plants smaller than female, gametangia dorsal on main thallus segments; antheridia each in a bottle-shaped involucre. Spores unicellular or in persistent tetrads when shed, with thick sculptured walls.

Genera 2 (2 in the flora): on soil in subtropical to temperate areas; North America, South America, Europe, Africa, Australia.

The Sphaerocarpaceae branch symmetrically, pseudodichotomous or simple. Rhizoids are present, unbranched, smooth-walled, colorless, arising at the base or near the base of the ventral surface or along the costal region. Ventral scales are absent. Cells are thin-walled and lacking noticeable oil bodies. Gametangia develop acropetally, one per involucre. Sporangia have a very short or essentially lacking seta. The capsule wall is 1-stratose, nurse cells (sterile cells) are present, elaters absent.

1. Tubers lacking; capsule ovoid, spores yellowish brown to dark or blackish brown..........             ..................................................................................................................  1. Sphaerocarpos

1. Tubers present, oval, flattened, not photosynthetic; capsule spheric, spores black...........             .........................................................................................................................  2. Geothallus

SELECTED REFERENCE  Shuster, R. M.  1992.  The Hepaticae and Anthocerotae of North America, East of the Hundredth Meridian. Chicago.

1. SPHAEROCARPOS Boehmer, Def. Gen. Pl., ed. 3, 501. 1760 * [Greek, sphaero, globose, and carpos, fruit, alluding to shape of capsule]

Stephen L. Timme†

Plants short-lived annuals, hyaline green, light green to bright green, sometimes becoming reddish or purplish, 2- to multistratose in the median region, grading to 1-stratose and entire leaf-like lobes . Specialized asexual reproduction occasional as tubers. Sexual condition dioicous. Antheridial plants generally 0.1--0.3 times smaller than the archegonial. Archgonial plants 2--15 mm in diameter; lobes 1-stratose, not divided or lobed, generally succubous. Cells lacking trigones, quadrate to hexagonal. Capsule ovoid. Seta very short, not elongating, of 4 cell rows. Spores large, spore wall reticulate or not, faces aerolate; aerole with or without tubercles, cristatae, lamellae, crenulae or spines. 

Species 8--10 (6 in flora): terrestrial specialists almost always occupying disturbed or temporary habitats; nearly worldwide, but disjunct, sporadic and localized throughout range; North America, South America, Europe, s Africa, s Australia.

Species of Sphaerocarpos have capsules maturing February through May.

SELECTED REFERENCES   Crandall-Stotler, B. and R. E. Stotler.  2000.  Morphology and classification of the Marchantiophyta.  In: Bryophyte Biology, A. Jonathan Shaw and B. Goffinet, eds.  Cambridge Univ. Press, New York.  Pp. 21--70.  Frye, T. C. and L. Clark.  1937.  Hepaticae of North America.  Univ. Wash. Publ. Biol. 6: 1--162.  Haynes, C. C.  1910.  Sphaerocarpos hians sp. nov., with a revision of the genus and illustrations of the species.  Bull. Torrey Bot. Club 37: 215--230.  Schuster, R. M.  1992.  The Hepaticae and  Anthocerotae of North America, East of the Hundredth Meridian.  Chicago.  Schuster, R. M.  1984.  Evolution, Phylogeny and Classification of the Hepaticae.  In: R. M. Schuster, ed. New Manual of Bryology, Vol. 2, pp. 892--1070.  Nichinan, Miyazaki, Japan.

1. Spores separating at maturity.

2. Spores less than 85 \um in diameter, pale yellow to yellowish-brown; archegonial involucres less than 1.4 mm . . . 1. Sphaerocarpos cristatus

2. Spores 85 \um or greater, blackish-brown to yellowish-brown; archegonial involucres 1.5 mm or longer; southeastern U.S.A. . . .2. Sphaerocarpos donnellii

1. Spores remaining in tetrads at maturity.

3. Spore surface with thickenings in parallel or nearly parallel lines, occasionally with reticulations . . .3. Sphaerocarpos drewei

3. Spore surface with thickenings definitely reticulate, not in parallel lines.

4. Apex of the archegonial involucre with a large orifice greater than 50 \um, generally as wide as the medial portion of the involucre; involucres tubular to ovoid; spore tetrads less than 90 \um at maturity . . . 4. Sphaerocarpos hians

4. Apex of the archegonial involucre with a small orifice less than 140 \um, mouth contracted; involucres flask-shaped, obpyriform, clavate, obovoid to subglobose; spore tetrads generally more than 90 \um at maturity.

5. Tetrads spinose in profile, less than 135 \um at maturity . . . .5. Sphaerocarpos michelii

5. Tetrads crenulate in profile, greater than 135 \um at maturity . . . 6. Spaherocarpos texanus

1. Sphaerocarpos cristatus M. Howe, Mem. Torrey Bot. Club 7: 66.  1899  E

Archegonial plants 2.5--8.5 mm in diameter; lobes nearly orbicular. Involucres 0.8--1.3 mm, densely aggregated, nearly obscuring the thallus, cylindric to obovoid, rounded to the apex.  Antheridial plants to 2 mm long, cuneate, often bifurcate, lobes ovate to oblong, involucres 500--585 \um high, bottle-shaped, expanded at the base and abruptly narrowed and becoming tubular toward the apex.  Sporangia 500 \um or more.  Spores of tetrads separating before maturity, light yellow to yellowish brown, 48--83 \um, somewhat aerolate, mostly cristate, appearing to radiate from near the middle, lacking medial tubercle, ridges sinuous to slightly crenulate, 3.8--7 \um high, appearing to radiate from the central part of the face, slightly anastomosing, with 1--6 aerolae across the face.

On soil; low elevations; Calif.

Sphbarocarpos cristatus is rare, known only from California in Alameda, Tulare, San Joaquin, and Santa Clara counties.

2. Sphaerocarpos donnellii Austin, Bull. Torrey Bot. Club 6: 157. 1877  E

Sphaerocarpos terrestris Underwood & Cook

Archegonial plants 8--10 x 4--7 mm, solitary or forming mats, lobes divided to the costa, oblong to obcuneate, sinuous, marginal cells ca. 30 × 68 \um; involucres 1.5--2.4 mm high, tubular, ovoid, ellipsoid to pyrifrom, truncate at the apex, orifice rounded.  Antheridial plants 2.5--4 mm in diameter, lobes divided to the costa or nearly so, cuneiform to obdeltoid, sinuous; involucres flask-shaped, 0.5--1.1 mm high.  Sporangia 700--855 \um.  Spores of tetrad separating at maturity, 85--135 \um, nearly tetrahedral, yellowish, dark brown to blackish brown, basal margin lobed and dentate, aerolae 3--4 across the face, surface granulate, 13--27 \um in diameter, ridges generally appearing wrinkled, blunt to spinose at the intersections and thus appearing spinose or nearly so in profile, central tubercle generally present in each aerola, to 24 \um high.

Damp sandy soil, muddy shores, organic muck over coral limestone; low elevations; Fl., Ga., Miss., S.C, Va.

Sphaerocarpos donnellii is very localized and restricted to the Southeastern Coastal Plain. 

3. Sphaerocarpos drewii Wigglesworth, Univ. Calif. Publ. Bot. 16: 129. 1929  E

Archegonial plants 1--1.5 mm long, bifurcate, sometimes with an elongated branch, becoming reddish or purplish at the margins, lobes wedge-shaped, ca. 550 \um wide with quadrate marginal cells; involucres cylindric to obovate, 0.5--1.1 mm high, crowded over the thallus and nearly obscuring it.  Antheridal plants ca. 1--1.5 mm long, lobes somewhat wedge-shaped; marginal cells isodiametric, involucres flask-shaped, to 365 \um high.  Sporangium 335--595 \um.  Spores remaining in tetrads at maturity, 65--155 \um, brown to dark-brown; lamellae granulate and occasionally lobed, running parallel to one another or nearly so, occasionally branching, lacking tubercles; not reticulate.   

Soil; low elevations; known only from Calif. (San Diego Co.).

Sphaerocarpos drewii and the following species are the rarest of the North American Sphaerocarpos.

4. Sphaerocarpos hians Haynes, Bull. Torrey Bot. Club 37: 225.  1910  E

Archegonial plants 3.5--7 mm in diameter, growing in isolated tufts, lobes crispate and somewhat ascending, involucres 1--2.5 mm high, tubular, ovoid, to obovate, generally flaring at the apex; orifice large, wider than or as wide as the involucral apex or nearly so.  Antheridial plants 1.8--2.1 mm in diameter, cuneate, oblong to orbicular, involucres 235--415 \um high, greenish, becoming purplish with age, vase-shaped, narrowing toward the apex or obovate.  Sporangia 570--590 \um. Spores in permanent tetrads at maturity, 62--85 \um, yellowish brown, cristate, ridges to 5 \um high, forming reticulae or in parallel lines, crenulate to tuberculate in profile, areolae present, 4--6 across the face, sometimes with 1--2 tubercules. 

Damp clay or alluvial soils; low elevations; Idaho, Oreg., Wash. 

5. Sphaerocarpos michelii Bellardi, App. Fl. Pedem,, 52. 1792

Sphaerocarpos sphaerocarpus Howe 

Archegonial plants 8--13 mm in diameter, lobes ovate, involucres generally obscuring the thallus, 1.3--2.6 mm high, nearly obovoid, clavate, tubular, pyriform to nearly globose, orifice small.  Antheridial plants ca. 1 mm in diameter, lobes generally arching over the involucres, involucres 250--330 \um high.  Sporangia 735--760 \um.  Spores remaining in tetrads, 80--125 \um, brownish to nearly black at maturity, aerolae 6--9 across the face, each ca. 12--20 \um in diameter, occasionally with a central tubercle, ridges at the junctions spinose, 7--12 \um high. 

Damp soil of fallow fields, sandy soil of tall-grass prairies, and soils of seasonal flooding; Kan., Tex., Mo. (Franklin and Howell cos.), S.C. (Chester Co.), Va. (York Co.); South America (Argentina); Europe; Atlantic Islands (Canary Islands).

Sphaerocarpos michelii is found in in eastern Kansas and a few counties in Texas as scattered and isolated populations, while being rare elsewhere.  It is very similar to S. texanus.

6. Sphaerocarpos texanus Austin, Bull. Torrey Bot. Club 6: 158. 1877

Sphaerocarpos berterii Austin; S. californicus Austin; S. michelii var. californicus Underwood

Archegonial plants 6--15 mm in diameter, nearly orbicular to cuneate; bright green to hyaline green, central axis 2- to multistratose, lobes 1-stratose, crispate, obovate to slightly obdeltoid, apex rounded, involucres sessile, generally 2--2.6 mm high, obpyriform, fusiform, ellipsoid to slightly clavate, contracted to the orifice, mouth very small.  Antheridial plants 2--6 mm in diameter, green to nearly hyaline green, lobes cuneiform to obdeltoid, involucres 260--360 \um high, crowded over the dorsal surface, orbicular, oblong to flask-shaped.  Sporangia ca. 620--700 \um.  Spores permanently united in tetrads, yellowish brown to dark brown, 115--175 \um, granulate to areolate, areolae 5--7 across the face, lacking a median tubercle, reticulations 15--30 \um in diameter, crenulate or not.

Soils of disturbed areas and areas of seasonal flooding; Ala., Ark., Calif., Fla., Ga., Ill., Kans., Ky., La., Miss., Mo., N.C., Okla., Oreg., S.C., Tenn., Tex., Va., Wash.; South America (Uruguay); s and c Europe, n Africa; Atlantic Islands (Canary Islands); Australia.  

Sphaerocarpos texanus is the most widespread and commonest species of the genus.  It is considered weedy because of its apparent habitat preference.  Sphaerocarpos texanus has not been reported from the Intermontane region of North America, which includes Arizona, Colorado, Utah, Idaho, Wyoming, Nevada, New Mexico, Idaho, and Montana, or from the very northcentral and northeastern regions of the flora area. 

2. GEOTHALLUS Campbell, Bot. Gaz. 21: 13. 1896. * [Greek, geo, earth, and thallós, green or young shoot, twig; alluding to primary thallus partially buried]  E

Terry T. McIntosh

Plants annual, green to bright green, central thallus multistratose, wedge-shaped or nearly orbicular, usually unbranched, sometimes dichotomous, 5--7 x 3--4 mm, laterally producing large, 1-stratose leaf-like lobes that are somewhat palmately arranged, smaller lobes found dorsally, thalli attached to ground by colourless rhizoids. Cells lacking trigones, quadrate or hexagonal. Specialized asexual reproduction present as tubers, non-photosynthetic, oval and more or less flattened, multistratose, 1--2 x 1 mm. Capsule nearly spheric, about 1 mm. Seta very short, with bulbous foot sunk in the thallus.  

Species 1: endemic to North America (California).

The capsules mature February through May.

Further details of this extraordinary, rare liverwort including germination and subsequent growth of the tubers can be found in the highly detailed work of D. H. Campbell (1896b). Morphologically, this genus is more similar to Fossombronia rather than Sphaerocarpos. The tubers germinate in winter.

SELECTED REFERENCES   Campbell, D. H. 1896a. A new Californian liverwort. Bot. Gaz. 21: 9--13. Campbell, D. H. 1896b. The development of Geothallus tuberosus. Ann. Bot. 10 (40): 489--510. Doyle, W. T. 2012. Geothallus tuberosus.

 The IUCN Red List of Threatened Species. Version 2015. Schofield, W. B. 2004. Endemic genera of bryophytes of North America (north of Mexico), Preslia 76: 255–-277. Wolery, M. G. and W.T. Doyle. 1969. The distribution of Geothallus tuberosus. Bryologist 72:  413--417.

1. Geothallus tuberosus Campbell, Bot. Gaz. 21: 13. 1896  E

Antheridial plants and archegonial plants generally the same size, sometimes the archegonial plant slightly larger. Antheridial involucres bottle-shaped with narrow necks, unistratose.  Archegonial involucres cylindric, with wider mouth than antheridial involucres, unistratose. Nurse cells present, 48--108 /um; Spores large, black, nearly spheric, 120--140 /um, smooth with reticulated ridges.

On fine-textured mineral soil, especially in somewhat shaded sites around vernal pools and other wet depressions; low elevations; Calif. (Alameda, Riverside, San Joaquin, San Diego, Santa Clara and Tulare counties).

Mainly due to urbanization, Geothallus tuberosus has been extirpated from many known sites. There may be undiscovered populations in similar habitats in adjacent Mexico. It is considered globally rare (ICUN).