Journ. Hattori Bot. Lab. No. 62: 299-329 (June 1987)

STUDIES ON METZGERIALES: 1. NORTH AMERICAN ANEURACEAE

RUDOLF M. SCHUSTER1

INTRODUCTION During the course of forty years of study of North American Aneuraceae (Ric­ cardiaceae) it has become evident to me that both Aneura and Riccardia present pro­ blems not addressed by the extant literature. In this paper I attempt to deal with these problems; for some, only tentative solutions present themselves. Indeed, my purpose is to call attention to some intractable problems whose resolutions may necessitate careful cytological work, growth experiments, and even genetic analysis, if and when we reach such a point in Hepaticology. In any event, the current "pigeon holing" of plants hardly reflects the actual, vastly more complex situation. Several papers directly or indirectly impinge on this study - that of Evans (1938) on capsule-wall anatomy, done with the usual care and precision typical of all of his work, and the study on oil-bodies of British Riccardia species by Little (1968). Prior to publication of this last, very helpful paper, I had drawn and described the oil-bodies of all American taxa and realized that both R. latifrons s. lat. and R. multifida s. lat. were actually species-complexes. That much was readily evident ; what was not evident at all, and what still remains ill-founded today, is how to treat these taxa in a taxonomic sense. Among biologists - but not necessarily among taxonomists, who are bound by a code that insists on a precision the material fails to reflect - it is common knowledge that taxa exist in all shades and manifestations. The current code states that if the ambiguity with regard to the status of a taxon is reflected in the way this is treated, that taxon is invalidly described. Therefore, in this paper, I adhere to this dictum - but, in the discussions, I try to make clear that such a treatment ill serves the complexities of the group. That complexity was already evident from the work of ShowaIter (1926, 1928), who showed that the supposedly "simple" Aneura pinguis consisted of a series of "races" that were, in part, intersterile. Showalter dealt only with material from a limited area of temperate eastern North America and western Europe. What if he had has ac­ cess to material from, i.a., the Rio Negro of Brazil. the north coast of Ellesmere I. , Campbell I. (situated midway between New Zealand and the Antarctic), and Taiwan? I have studied material from all these areas (and collected it from all but the last) ! Morphologically it all seems virtually inseparable. Of necessity, I cannot deal here with problems of fertility barriers as they impinge

I Cryptogamic Laboratory, HadJey, Massachusetts, 01035. Emeritus Professor of Botany, University of Massachusetts, Amherst. 300 Journ. Hattori Bot. Lab. No. 62 1 987 on taxonomy. But these concepts must, marginally at least, impinge on our taxonomic evaluations. Mitigating against these limitations are several facts: (a) I have repeatedly collected each of the taxa treated and am familiar with their ecology and "behavior"; (b) fortunately, starting about 35 years ago, I began to make, and slowly accumulate, detailed notes on the gametophytic anatomy of populations sampled, the capsule-wall anatomy, the spatial relationships of the gametangia, and the presence vs. absence of oil-bodies (and, if present, their numbers and sizes) in both epidermal and hypodermal cells. For all the taxa, detailed drawings were prepared - especially when two species occurred admixed. The bulk of illustrations, formal diagnoses, and details as to dis­ tribution are all appearing in Vol. V. of my Hepaticae and Anthocerotae of North America (Columbia Univ. Press, 1988). In this paper critical analyses of the more difficult out­ standing problems and attempts at solutions are presented. The two treatments are intended to complement each other. At the outset, let me emphasize that no future progress is likely to be made with "traditional" methods of study. Herbarium specimens of Riccardia species, even if well prepared, are of limited use as are specimens without sporophytes. And, indeed, dead material - thus without oil-bodies - is often almost worthless. Hopefully the "Nomenklaturfanatiker" (to use the derisory term of Reimers) will keep this in mind and avoid useless name changes based on old (and often poor) herbarium specimens.

K EYS TO NORTH AMERICAN TAXA OF RlCCA RDIA For orientation two keys are presented, one with emphasis on cytological features, the other using sexuality as the prime criterion. Key to Living Plants of Riccardia 1. Oil-bodies in epidermal cells 2-4 or even 5- 10 or more, often in central clusters. Bisexual. Often with gemmae...... 2 2. Thallus margins bordered with a unistratose hyaline border 3- 6 cells wide; auto- ecious; sexual branches from leading axes ...... R. sfricfa 2. Thallus margins tumid, not bordered; synoecious; sexual branches from leading axes or primary branches ...... R. jugata 1. Oil-bodies 0 or 1(2) in epidermal cells...... 3 3. Some epidermal and all (or almost all) hypodermal cells with oil-bodies ...... 4 4 . Oil-bodies absent from at least 5 % of epidermal cells. Ultimate thallus segments with a translucent unistratose wing mostly (2)3-4(5) cells wide ...... R. mU/fi/ida. .. 5 5. Autoecious (but ~ and c3 branches sometimes sympodial). Primarily northern in range ...... R. multi/ida subsp. mU/fi/ida 5. Largely or entirely synoecious (occasional su pplementary c3 or ~ branches present). Primarily southern ...... R. mufti/ida subsp. synoica 4 . All (R. pa/mafa, some) epidermal cells with 1 or 2-several oil-bodies. Thallus segments never conspicuously winged [in R. chamedryfolia a 1- 2(3)-cell wide wing occasionally distinct]. Auto- or dioecious ...... 6 6 . Autoecious. Epidermal cells thin-walled, over 80 % of cells with oil-bodies. Thalli thin, main segments not tumid or rounded on R. M. SCHUSTER: Studies on Metzgeriales, I 301

margins; regularly or irregularly 2-3-pinnate usually, creeping in growth; almost never on decaying wood. Gemmae rare ...... R. chamedryfolia 6. Dioecious. Epidermal cells thick-walled, under 20 % of cells with oil­ bodies. Thalli firm, to 8-9 cells high on main axes, opaque, main seg­ ments tumid or rounded on margins; irregularly pinnate to, distally, su b­ palmate, mostly with ascending branches; on wood. Gemmae common ...... R. pa/mala 3. Neither epidermal nor hypodermal cells with oil-bodies. Autoecious ...... R. lalifrons .. 7 7. Main thalli usually under 1 mm wide, soon losing apical dominance, the branching becoming irregular; cross sections never lunate, dorsal surface flat to convex. Xylicolous ...... R. latifrons subsp. lalifrons 7. Main thalli to ] .5-].8 mm wide, retaining apical dominance, branching 1- 2- pinnate (if 2-pinnate, the secondary pinnae sl ight, very few) but distally merely pinnatifid (pinnae lobelike, reduced, short). Cross sections of main segments often lunate. On peat ...... R. lalifrons subsp. arclica Key to Plants with Sex Orga ns 1 . Dioecious; thallus margins opaque, never unistratose for more than 1 cell row; branching irregularly I-pinnate to subpalmate...... 2 2 . Thallus concave above, channeled; plants slightly, irregularly pinnate; thallus 5, rarely 6 cells thick at middle of main segments, the segments crescentic in cross section, 500- 1000 ft wide; epidermal cells usuall y with 1 oil-body each ...... [R. incurvataF 2. Thallus usually biconvex, slightly convex above; plants freely, irregularly palmately branched, dark green, segments only 200--300 ft wide; thallus 7-9 cells thick on main segments; epidermal cells usually without oil-bodies (present in less than 20 % of cells) ...... R. pa/mala ] . Monoecious; thallus usually flat or convex above; plants regularly to irregularly 1- 3- pinnately branched...... 3 3. Ultimate (and usually penultimate) segments of thalli pellucid and unistratose for a width of 2--4 or more cells, on main axes for a width of usually 0)2 cells; plants usually freely 2- 3-pinnately branched; oil-bodies typically 1- 3(4) or more per hypodermal cell, bluish to brownish gray. Capsules with inner cell layer without thickenings (or with them thin and exceedingly vague, not sharply defined); outer layer with nodular thickenings, hardly tangentially extended; often with gemmae...... 4 4 . Sexual branches widely spreading, often in sympodial clusters of 2-3 branches, not partially hidden under thallus margins, when solitary usually nearly at right angles to the axis they arise from; sexual branches variable in position, often largely on primary or secondary branches; epidermal cells 25- 35(40) x 50--75(100) ft, each with 1 or rarely 2 large oil-bodies in some cells, others lacking them; ultimate thallus segments not dilated

2 R. incurvata Lindb. has been reported a single time from North America (Tennessee; Sharp 1939). Frye and Cl ark (1937- 47) properly refused to accept the report, the sole collection having been destroy­ ed. I have seen no material of the species from North America. 302 Journ. Hattori Bot. Lab. No. 62 1 987

at apices ...... 5 5. Uniformly autoecious; androecial branches elongate, lingulate, with 2 rows of antheridia; thallus cross sections distinctly biconvex, the ul­ timate segments (3)4-5 cell layers thick medially, with unistratose margins usually 2-3 cells broad. Capsule valves with cells 20-40 (average 30) fl wide; spores 12- 15 fl, elaters 12- 15 fl wide. [Northern] ...... R. multi/ida subsp. multi/ida 5. Largely or entirely synoecious;

5-6/1- to 4-6 X 7-9/1-, somewhat smaller (25-36 x 60-72 /1-), ± thick-walled. Appalachian Escarpment ...... R. jugata 6. Thalli regularly to irregularly (l)2-3-pinnate. Capsule with inner cell layer with very faint semiannular thickenings (usually barely visible, even under oil­ immersion); thalli thin, delicate, but opaque; epidermal cells typically with 1 large oil-body each. Mostly on wet rocks or wet clayey banks, rarely invading dead wood nearby ...... R. chamedryfolia

1. R. latifrons Lindb. (and its subsp. arctica). Although most often easily recognized, arctic phenotypes (subsp. arctica)3 are in many respects more easily confused with similar arctic phenotypes of R. chamedryfolia (Schuster & Damsholt 1974) than with any other plant. At the same time, a plant with much the aspect of R.latifrons, R.jugata, occurs in the Appalachian Mts.; cf. infra. In theory, however, living plants of R. latifrons can be separated from all other regional Riccardia taxa by the uniform lack of oil-bodies. Even this criterion, however, may break down in the Arctic (cf. p. 305). Such arctic fen ecotypes of R. latifrons may be essentially inseparable ecologically and morphologically from similar ecotypes of R. chamedryfolia (R. sinuata). Both may occur as ecocopies that are light green, broad, closely once-pinnate or pinnatifid (the "pinnae" may be so short they appear to be mere broad, dilated lobes of a seemingly unbranched thallus), with the pinnae variably abbreviated and often lying contiguous. Main axes of such plants may be unusually broad, to 1400- 1800 p, wide or more, con­ cave antically, the lateral margins varingly elevated. Such "broad phenotypes" (e.g., plants from West Greenland, RMS & KD 70-2877) "may be so very variable as to defy description." The main thallus is band-shaped, broad, often quite fiat on both surfaces, with blunt, never unistratose margins; the juxtaposed lateral branches, many or most of which may remain very short, give the irregularly pinnatifid aspect already alluded to and may sometimes grow out, then becoming broad, and themselves become pinnatifid. Some lateral branches may grow out into narrow, colorless, rhizoid-bearing geotropic axes, elliptical in cross section, forming stolons that rarely, if ever, branch; others form abbreviated sexual branches. The latter are usually normal (subsessile ~ branches, rarely stipitate; more rarely elongated archegonial branches occur with 6-8 archegonia dorsal on the branch in two rows). Androecial branches may arise from the stolons or may occur in sympodial groups of 2 or 3 from the main axes; they may also be sessile or ± stipitate. Rarely, a short gynoecial branch is flanked on each side by an androecial branch, forming a sympodial bisexual complex. A number of such moorland populations from Greenland, Newfoundland, and Nova Scotia have now been studied; all lack oil-bodies in all epidermal and, normally,

3 R. latiJrons subsp. arctica Schut. & Damsholt, subsp. n. Subspecies subsp. lati/rons congruens omni cellula (epidermali hypodermalesve) sine guttis olei, differens axe principali latissimo, 1.4-1.7 (I .8) mm la!., et crescentia apicali dominante, et marginibus thalli saepe ascendentibus (segmentes a sectione transversa visis lunatis), Type: Tasiussaq Fjord, South Greenland (RMS & KD 82-1701; hb. RMS). Found growing in acid fens and moors, always amidst Sphagnum. 304 Journ. Hattori Bot. Lab. No. 62 I 987

TABLE l.

subsp. {atifrons subsp. arctica Main segments 800-1000, rarely to 1200- Main segments to (1400) 1500-1800 fl wide. 1500 fl wide. Cross sections lenticular and weakly convex on Cross sections often shallowly lunate, (5)6-8(9) both sides, 5-6(7) cells high on main segments. cells thick on leading segments. Plants± deliquescent-branched, main axis soon Plants 1(2)-pinnate, the broad main axis with unrecognizable; branches elongating, soon persistent dominance, the branches ± ab­ indistinguishable from main axis. breviated, often very short. Stoloniform axes absent or very rare. Stoloniform axes frequent or common. Gemmae occasional. Gemmae always absent. Elaters with spiral 7-11 fl wide. Elaters with spiral 5 fl wide. all hypodermal cells. Occasional phases of R. palmata that can be confused with R. latifrons are noted under the former. Two major problems remain with regard to R. latifrons: (a) the status of the arctic-subarctic, peat-inhabiting phenotype, or subsp. arctica; (b) inter­ relationships of R. latifrons and R. jugata. R. latifrons and subsp. arctica: In Schuster and Damsholt (1974) a series of peat­ inhabiting, monoecious, arctic populations from West Greenland were discussed. It was noted that some had oil-bodies in epidermal+ hypodermal cells, others in perhaps under 5 % of hypodermal cells; still others lacked oil-bodies. Because of this puzzling variation in oil-body presence, the plants were all referred to R. sinuata (= R. chame­ dryfoUa), the "broad form" of which they closely resembled. However, in 1982 K. Damsholt and I intensively collected Hepaticae in South Greenland ; in moors, amidst Sphagnum, we again and again found populations which seemed identical to the West Greenland plants. All of them, however, uniformly lacked oil-bodies in all cells. Reluctantly we concluded that two taxa, with an identical ecology and aspect, occurred in West to South Greenland, surely separable only on the basis of oil-bodies - the most tenuous of distinctions. Yet, in temperate areas, R. chamedryfolia and R. latifrons differ in growth form, in aspect, and in presence vs. absence of oil­ bodies! Also, they are usually very distinct regarding their ecology. The oil-body-free arctic plants are referred (Schuster 1988) to R. latifrons subsp. arctica. It was furthermore demonstrated that this taxon occurs southward, in blanket moors, at least as far as Newfoundland and southern Labrador, where it was frequent in Empetrum-dominated moors. This plant differs from subsp. iat{frons as in Table 1. The comparison (Table 1) fails to adequately describe subsp. arctica. The plants, closely creeping over or amidst Sphagnum, show an indeterminate leading axis, con­ trasted to the free lateral pinnae which are (with rare and sporadic exceptions) de­ terminate in length and (longer pinnae) may bear a few, usually 1-3, narrow, very short pinnules. Distally the plants are often almost sympodially branched, main axis and pinnae (and pinnules, often mere slight lobes of the pinnae) being crowded. R. latifrons subsp. latifrons, although usually found over decaying xylem, occasion- R. M. SCHUSTER: Studies on Metzgeriales, I 305

ally occurs in peat bogs, in New England and Minnesota. Such plants, insofar as I have seen them, fail to attain the large dimensions quoted here for subsp. arctica. It is not impossible, however, that eventually a cline will be found to occur, connecting the two extremes. The ecology of subsp. arctica is distinctive: the plant always occurs in moors, usually moory slopes or blanket bogs, associated with Cephalozia loitlesbergeri, C. lunulifolia (South Greenland), C. connivens, Calypogeia sphagnicola, Mylia anomala, and (Newfoundland) also Kurzia setacea, Odontoschisma sphagni, Lophozia marchica (L. laxa). In most areas Empetrum is consociated and (Newfoundland) at times Sar­ racenia purpurea, Utricularia cornuta, and Schizaea pusilla. All populations here referred to subsp. arctica are uniformly devoid of oil-bodies except for one doubtful collection from West Greenland, in which under 5 % of cells had solitary oil-bodies (Schuster & Damsholt l.c., p. 339).

2. R. jugata Schust., sp. n. Species synoecia; rami sex uales 0' ad basis,

TABLE 2. R. [ati/rons R.;ugata Consistently autoecious. Consistently synoecious. Epidermal cells lack oil-bodies. Epidermal cells (younger shoots) with (1)2- 4(6-8) oil-bodies, in older sectors to 12-15 oil-bodies. Hypodermal cells lack oil-bodies, or, rarely, Hypodermal cells with 2- 3(4- 7) oil-bodies in all have 1 or 2(3) in under 5-10% of cells. cells. Dorsal epidermal cells (32)36-54(56) x 65- Dorsal epidermal cells (25)30-36 x (40-50)60- 90(100-125) ft on mature axes, thin-walled 72 ft on mature axes, thick-walled at maturity. when mature. Spores (14)15- 17(1 8.2) ft · Spores 10-12(13-14) ft . Elaters 10-12(13-15) ft in diam. Elaters 8-10(12) /' in diam .

On the strongly gemmiparous, yet fertile plants, the oil-bodies appear to be exceedingly variable and deviant. In some instances there is a single, small oil-body per epidermal cell, or occasionally none; in other cases there are 2- 3, or even 4-5. Isolated cells, in both the epidermal layer and in hypodermal cells have extremely unusual oil-bodies, linear to vermi­ form in shape and only 7- 8.5 11 wide x 35-50, occasionally even 60 11 long. These plants grew under abnormal conditions: on a wet log, carried down by the stream, lodged amidst rocks. Adding to the complexity, a peculiar gynoecial phase of R. palmata grew associated (but only locally admixed). The R. jugata differed at a glance in the lack of erect, linear branches (gemmae occurring at the tips of relatively unmodified, prostrate branches), which were developed in abundance in the R. palmata. The unisexual plants of the latter also contrasted strongly with the bisexual branches of the former. As a consequence, in spite of the similarity in the small-celled and often thick-walled epidermal cells, R. jugata and R. palmata obviously bear no immediate affinity to each other. The type material (RMS 40684), collected in 1958, shows free development of postmature capsules. Valves are ca. 22011 wide x 650-750 11 long. Epidermal cells agree almost perfectly with those of R . chamedry/olia and R. latifrons; they bear conspicuous, sharply defined radial bands that extend nearly or quite across the inner tangential walls - thus visible as bands in surface examination; on the free, or outer, tangential walls they appear nodular or nearly so, since they are not extended on to the free tangential walls, or only as short spurs, thus essen­ tially L-shaped. Epidermal cells average (12-13)15-2011 broad x 55- 70 11 long; they lie in approximately 16 rows, as do the inner cells. The inner cell layer consists of cells about equal in their dimensions [Le., ca. (12- 13)15-2011 wide x 50-60, occasionally 7011 long] that at first glance appear to lack distinct thickenings; on careful examination, however, it is evident that the radial walls of the adaxial cell faces bear somewhat irregular, faintly nodulose, sheet­ like thickenings. These faint nodular thickenings are extended on to the free (hence inner) tangential faces as ill-defined, faint, brownish tangential strips that are hardly sharply enough defined to warrant the use of the term "bands." In the relatively delicate and very ill-defined development of semiannular "bands" of the inner capsule layer, R . jugata more closely ap­ proaches R. sinuata than R. lati/rons. Spores are only 10-12, rarely 13- 14 11 in diam., hence smaller than in R. lati/rons; they are yellowish brown and faintly verruculose. Elasters are 8- 10(12) 11 in diam. and bear a spiral 5- 7 11 wide. R. M. SCHUSTER: Studies on Metzgeriales, I 307

Branching in R. jugata is so variable as to initially cause some confusion in un­ derstanding this taxon. When the plants are well developed they may be regularly 2- and locally 3-pinnately branched; this usually is associated with development of few sexual branches (which to some extent destroy the branching symmetry since they are determinate in length and fail to innovate apically). The plants are closely prostrate and adnate when first invading wood; they are so freely ramified that they literally completely hide the substrate, in extreme cases the ultimate branches becoming ap­ proximated if not overlapping. With age and crowding, penultimate and ultimate branches in some cases become more linear and ascending; this is particularly so when the plants grow admixed with other bryophytes. With development of sexual branches, the 2-3-pinnate character of the plant may undergo change: the sexual bran­ ches occur either on both sides of the leading axes, in which case the leading axis (or the part thereof bearing sexual branches) often becomes rather closely and regularly pinnulate with the subcapitate sexual branches, or else the sexual branches arise from one or both sides of branches of the first, less often second, order. In any case, the symmetry of branching is to some extent obliterated. The sexual branches, almost all very similar in width and length, apparently never deviate in their bisexuality. An­ theridia vary, admittedly, from 3-8 per branch; they are situated in well-defined pock­ ets, of which the anterior I or 2 may be somewhat oblique, pointing toward the branch apex, rather than opening strictly dorsally. In all instances, the antheridial chamber is well defined, and the opening completely circumscribed, often rather circular in form. Despite the initially misleading variability in branching, R. jugata is an easily recognized plant in the field, even with the naked eye. The yellow-green to deep green color, the constant restriction to moist, decaying wood, and in particular the abundant development of short, but conspicuous, sexual branches - usually along both sides of the leading axes, together with the generally R. latifrons-like appearance, give the plant an unmistakable facies. It should be emphasized that once the species was understood, on the basis of microscopic study, it was possible to find it at will, often several times per collecting day, and - without fail- recognize it in the field . Such are surely criteria of an excellently circumscribed species.

3. R. palmata (Hedw.) Carruth. Perhaps the least complex of any of the holarctic species, this taxon occurs through­ out much of Europe, and in North America from the High Arctic of Greenland (77° 30' N.) south possibly to central Florida, west to Alaska and California. It has also been reported from Bermuda (early reports from Madagascar, by Pearson, and South America, by Montagne, can almost surely be dismissed as based on errors in iden­ tification). Muller (1951-58, p. 505) emphasized that R. palmata is lacking in southern Europe and has a generally northern range. In North America it appears to have both (a) an amplified range and (b) a wider ecological amplitude, associated with differences in morphology. As noted, it occurs into the High Arctic (Kanak, Inglefield Bredning, 308 Journ. Hattori Bot. Lab. No. 62 1 987

RMS 45606a; CS plants, with chromosome no. n= 9 or 10; also some 12 other collec­ tions from the general area) and evidently to central Florida, in an area often dominat­ ed by Sabal palmetto, the common tree palm in Florida. The Florida reports require verification (I have not collected the species there). The species is usually readily identified by the (a) dioecious inflorescences ; (b) linear ultimate segments; with maturity usually ascending to suberect; (c) almost sym­ podial nature of the ultimate segments, the thallus usually losing apical dominance; (d) small, usually thick-walled epidermal cells; (e) lack of oil-bodies in at least 75-80 % of epidermal cells, but with most or almost all hypodermal cells with 1 rather small (rarely isolated cells with 2) oil-body; (f) frequent presence of gemmae on the ascending ultimate segments. These frequently form under conditions when nearby populations of R. latifrons, R . ehamedryfolia, R. multifida uniformly lack them. Problems, however, occur even with R. palmata, i.a. the following: 1) In 1960 I made some 12 collections - mostly fragmentary - of what appeared to be R. palmata in Northwest Greenland (Kanak, Kangerdlugssuak, Kekertat, and Kangerdluarssuk). Most were sterile but some (e.g., RMS 45606a, from Kanak) bore androecia; a chromosome count of n= 9 or 10 was made of this collection (by Dr. J. Wilce), which is in accord with temperate-zone R. palmata (n = lO). Cross sections of the main thallus show the typical bi­ convex, elliptical form with the thallus to 9 cells high, normally seen in R. palmata. In three subsequent seasons in Greenland (1966, 1970, in West Greenland; 1982, in South Greenland) no other collections of the species came to hand. I thus remain reluctant to place these high arctic populations into R. palmata - but, unless an undescribed taxon is at hand, they can only be referred here. As is often the case with " normal" R. palmata, gemmae occur in at least one of the Greenland collections (RMS 45618a, Kanak). Associated taxa are an improbable sounding lot: Antheliajuratzkana, Cephalozia plenieeps, Nardia geoseyphus, Odontosehisma maeounii, Anastrophyllum minutum, Lophozia excisa, Marsupe!fa aretiea, Gymnomitrion eorallioides, G. eoncinnatum, even Prasanthus suecieus! Most populations were found over Sphagnum. Obviously none were from the "usual" habitat: decaying wood. Even in less high latitudes, R. palmata may occur, if rarely, on peaty soil over basalt ledges, associated with Lophozia grandiretis, L. heteroeolpos, L. incisa, Blepharostoma, and Odontosehisma maeounii - all Ca-tolerant taxa (Schuster 1953). 2) Oil-bodies in R.palmata show much more variation than Little (1968) found in British material. The following are only a few of the deviations noted. (a) In RMS 74-2850d the ~ plants almost all lack oil-bodies in epidermal and marginal cells, as well as in the majority of hypodermal cells in ultimate branches (these are so chlorophyllose it is impossible to be precise). On older segments, however, often 15-25 %, or even more, of the epidermal cells bear oil-bodies (each cell with J, usually subspherical and 7-9 ft). (b) In RMS 74-2026 (Vermont) intramarginal, more rarely also marginal, epidermal cells frequently had solitary, small (under 7 x 9 ft) oil-bodies, but other epidermal cells usually lacked them. Hypodermal cells, aside from isolated, oil-body-free cells, had solitary oil-bodies. (c) In Appalachian populations other slight variations occur: thus in RMS 41001 (North Carolina) all epidermal + marginal cells appear to lack oil-bodies, the hypodermal have 1- 2 oil-bodies; in RMS 29480 (North Carolina) oil-bodies occur in only a few isolated epidermal cells, hypodermal R. M. SCHUSTER: Studies on Metzgeriales, r 309 cells have 1 each; in Scho/ield 9544 (North Carolina) all epidermal cells lack oil-bodies, hy­ podermal ones appear to all have 1 oil-body each; in RMS 45082 (North Carolina) rare epi­ dermal cells have 1 oil-body, hypodermal cells have 1, rarely 2, oil-bodies; in RMS 45393 epidermal cells lack oil-bodies, hypodermal cells have 1- 2 each. (d) In northern populations there seem to be no differences in oil-body form: thus in RMS 84-37675c (Newfoundland) no marginal cells ever have oil-bodies but under 20% of other epidermal cells each bear 1 oil­ body; hypodermal cells always have 1. In general, epidermal cell oil-bodies are small and ovoid (6- 8 x 9- 12, rarely 14/1); hy­ podermal ones are a little larger [7- 10 x 11 - 14(15) ft]. MUlier (1939) correctly noted the [general] lack of epidermal cell oil-bodies but stated that other cells had 1, occasionally 2- 3, oil-bodies each. In none of the many American popula­ tions studied were 3 oil-bodies ever seen in hypodermal cells. The Greenland plants were much like other American populations: epidermal cells with 0- 1 oil-body (7- 8 x 9- 11 ft); hypodermal cells with 1(2) oil-bodies (7- 8 x 9-15 ft). 3) Although usually separated from R. lati/rons by the narrower ultimate segments and the smaller thick-walled, mature epidermal cells, R. pa/mala produces some deviations, especially in the southeastern United States, which may cause problems. Thus in coastal Mississippi (RMS 19222) thallus segments may be over 550 I~ wide - wider than the norm in R. pa/mala. Yet mature thalli were (5- 6)7- 8 cells high and had small [24- 27 x 40- 55(58) ft] epidermal cells. Sometimes such plants, on decaying xylem, bear few or no ascending ultimate segments and then, in aspect, approach R. /ati/rons. Almost all populations seen had thick­ walled epidermal cells but one population (RMS 45177, South Carolina) had virtually le pto­ dermous epidermal cells - yet they were only 22- 28 ft wide (and hypodermal cells bore I, infrequently 2, oil-bodies each). Thus, in extreme cases, especially southward, R. palmala may mimic R . lali/rons. When sterile, such plants may remain a source of difficulty and appear consistently separable on only two bases: smaller epidermal cells and presence of 1 or J- 2 oil-bodies in hypodermal cells. In my experience, R. pa/mata produces gemmae rather frequently throughout its range. They thus occur in some high arctic populations (see above), as well as in austral populations (coastal Alabama, Mobile; RMS A-J23a). I have not studied the other regional taxa in detail with regard to gemma formation but, in general, American phenotypes of these taxa are uni­ formly devoid of gemmae except for R. lati/rons.

4. R. chamedryfolia (With.) Grolle4 This malleable and difficult taxon is likely to be confused principally with two other species: R. latifrons, when arctic phases are at hand (cf. above, under R. latifrons subsp. arctica) and R. multifida, especially when phases with thinner thalli are at hand. The following pages deal almost exclusively with the problem of how to separate R. multifida from R. chamedryfolia. The relatively scattered distribution and rare occurrence of R. chamedryfolia in the • It is unfortunate that the long-used name, R. sinuata (Oicks.) Trev. (1877), based on Jungerrr.annia sinuata Dicks. (1790), which has been used consistently for this species for virtually two centuries, has been replaced by an ill-suited and ugly epithet, which had been forgotten for over two centuries! This is an ideal illustration of what Jones (1958, pp. 354-55) had in mind when he argued that search for such earlier names "is a mischievous game which is better left unplayed." 310 Journ. Hattori Bot. Lab. No. 62 198 7

Appalachian upland region is somewhat mystifying. Most often it is replaced there by R . multifida, which occupies much the same habitats. Northward R. chamedryfolia may occur around the peaty-stony periphery of shal­ low; acidic tarns, as on Cape Breton, N .S. (RM S 43038a), at levels where kept constantly moist and periodically submerged, associated with R. multifida, Calypogeia muelleriana, Marsupella emarginata, Pa/lavicinia, Pellia epiphy//a, Cephalozia bicuspidata, Scapania irrigua (and/or paludicola). Weak forms in such sites may be only laxly I-pinnate, with short, rounded pinnae, and leading thalli 4 or 5 cells thick. The species extends into the Arctic (as in West Greenland; Schuster & Damsholt 1974) where it may occur over and amidst Sphagnum, in moory sites and fens, around shallow tarns. Differentiation Likely to be confused only with R. latifrons (see p. 303) and R. multifida. T. chame­ dryfolia and R . multifida share the same freely pinnately compound frond - usually freely 2-pinnate or even 3-pinnate - are similar in size (up to 2-3, rarely 4, cm long when well developed), are both monoecious, and typically have the thallus (on the main axes) 6-7 cells thick medially (in R. chamedryfolia up to 8-9 cells thick). The similar ecology may lead to potential confusion. Furthermore, both taxa show a bewildering amount of variation, presumed to be the result of reaction to differences in moisture conditions and light intensity, as well as nutritive conditions. When R. multifida and R. chamedryfolia occur admixed they are usually distinct at a glance, the latter usually having wider and clearly nonmargined segments. Occasion­ al plants (if only herbarium material is at hand) may be almost impossible to place (cf. p.317). Confusion between the two species has persisted; for instance, Schiffner (Krit. Bemerk. XXVI: 20, 21, 1941) states that R. chamedryfolia [= sinuata] var. stenoclada Schiffn. in K. MUller [Aneura s. var. stenoclada Schiffn. ex K. Mull., Rabenh. Krypt.-Fl. ed, 2, 6( I) : 339, 1908] is synonymous with R. multifida var. uliginosa. This phenotype (?environmental modification), admitted by Schiffner to closely approximate R . mUltifida in branching (3-4 X pinnate), and in presence of a unistratose border of the ultimate segments 2, locally 3, cells wide, has been studied from material from the type locality (Schiffner, Hep. Eur. Exsic. 1292). I would agree with Schiffner that a variant of R. multifida is at hand. The same is true for No. 1294, issued in the same series ~ . Confusion between R. multifida and the form of R. chamedryfolia called var. major also appears to have been widespread. Material from Sussex, England (W. E. Nicholson), issued as no. 1263 in Schiffner's Hep. Eur. Exsic. is close to delicate forms of R. multifida in the thallus cross sections, which are 4-5 cells high on upper portions of the main axes and on penultimate branches but possess unistratose margins 2 cells broad on the thal­ lus borders. Capsule-wall anatomy also clearly shows an approach to R. multifida since

• Stenoclada-like phases of R. chamedryfolia may occur on ledges in rocky brooks, where covered by shallow, flowing waters (e.g., RMS 19760, Tishomingo Co., Miss.). Such plants have narrow seg­ ments, flat dorsally, convex below, that are relatively rigid and 6-8(9) cells high medially. R. M. SCHUSTER: Studies on Metzgeriales, I 311 radial walls of the inner cell layer are irregularly thick-waIled (evident as sinuous brown­ ish thickening layers, scarcely distinct as individual vertical bands), with the thickening either not extending over the tangential walls at all, or merely as an obscure, pale brown sheet over their adaxial halves. More rarely, diffuse and ill-defined radial bands extend out across the inner tangential faces as obscure, pale brown, incomplete bands. In such cases there is an approach to typical R. chamedryfolia. However, in no case could bands even approaching in development those figured in Evans (1938, fig. 4E) be demonstrated. In fact, careful study of the capsules in many collections of the difficult R. chame­ dryfolia-multijida-synoica complex demonstrates that there occurs so much intraspecific variation virtually no differences that can be regarded as valid remain. The following paragraphs are relevant. Variation Capsule-wall Anatomy. (I) Epidermal layer: The external cell layer in R. chame­ dryfolia has been described in detail by Evans (1938) as with basically semiannular bands, the adaxial walls of each cell being provided with a series of radial bands (visible, in end­ view, as brown nodular thickenings) which extend across the inner tangential walls, but fide Evans (I938, p. 28) "rarely stretch more than half way across, and for the most part, taper gradually or abruptly to blunt points." The degree of development of the tangential extensions is described and figured by Evans as essentially the same in R. chamedryfolia and R. multifida (compare his figs. I A and 4A). In material of R. multijida from the southeast (and in R. m. synoica), however, the following condition prevails: the adaxial radial walls have strong, well-defined brown thickenings, and these either end when they attain the outer tangential walls or extend very slightly on to it, soon becoming evanescent; on the inner tangential walls they rarely extend across more than 0.25 the cell width and are thin, ill-defined, and soon thin out and become imperceptible, when at all distinct. In many cases, indeed, the inner tangenti­ al extensions are nearly, the outer ones quite, obsolete. According to Schiffner, who studied European material, the epidermal layer has nodular thickenings - i.e., radial thickenings ending at the outer tangential walls, not forming spurlike extensions on the tangential walls. His observations agree closely with those I made in studying a large number of collections of R. m. synoica even though some capsules could be found with short and vague tangential extensions. I would describe the thickenings of the epidermal layer in R. multijida (incl. subsp. synoica) as follows: epidermal cells with strong radial thickening bands (evident as nodular, brown bulges), and thus with nodular thickenings which hardly to slightly extend on to the inner tangential faces, and rarely barely on to external tangential faces (the thickenings then becoming vaguely semiannular). In R. major Lindb. (nearly universally regarded as either a variety or synonym of

6 As is stressed under the discussion of the thallus section, both of these specimens agree with R. multifida in that the unistratose thallus border is usually 2 cells broad. It should be emphasized that this is no absolute criterion, isolated ultimate thallus segments in R. chamedryfolia occasionally being unistratose for a width of 2 or even 3 cells (see, i.a., fig. VII: 1 in Mizutani & Hattori, 1957). 312 Journ. Hattori Bot. Lab. No. 62 I 987

R. chamedryfolia) the epidermal layer of the capsule wall is quite dltterent !fom that of R. multifida (I base my observations on 2 European specimens - Schiffner, Hep. Eur. Exsic. nos. 1263 and 1264, both from England)." Capsule wall anatomy is identical in both specimens and may be regarded as typical of "R. major." Epidermal cells have relatively broad, strongly defined semiannular thickenings; in other words, adaxial radial bands extend out in a continuous arc on to both inner and outer tangential walls. Typically, internal tangential extensions are sharply defined for 0.5-0.65 the cell width, then gradually thin out and disappear. However, tangential extensions of the outer tangential faces are usually abbreviated, but never are both tangential extensions vestigi­ al. Often the sharply defined and heavily pigmented inner tangential bands extend vir­ tually across the cell before becoming vague and indistinct. The difference in this regard between "R. major" and R. multifida is very marked. In this respect "R. major" closely agrees with typical R. chamedryfolia, of which it is probably a mere environmental phase. For instance, North Carolina plants of R. chamedryfolia clearly show that epi­ dermal cells have short tangential extensions of the outer tangential walls, but long and prominent extensions of the inner tangential walls. This essentially agrees with Evans' observations for R . chamedryfolia, except that he presumed the tangential bands to "rarely" extend more than midway across the cell. In plants from South Calolina (RMS 40936) either outer or inner tangential extensions are often obsolete, but never both at once. Evans stated that epidermal cells varied from 12- 35 ft in width, with the average ca. 20 ft; in North Carolina plants epidermal cells averaged somewhat broader than the inner cells, 22-25 ft wide, and usually occurred in l6, rarely 17, rows. In other cases (RMS 40936) the cells averaged 16- 20 ft broad. The number of cell rows appears to be more constant in the epidermal than in the inner layer, where longitudinal subdivision is more frequent, often resulting in 24-27 cell rows, with the cells considerably nar­ rower (ca. 13-16 ft wide). This supplementary division is not always present, and then the inner cells lie in only ca. 18 cell rows. 2) Inner Cell Layer: Evans (l.c., p. 27) discusses the conflicting statements with regard to the form of thickenings of the inner capsule wall layer in R. chamedryfolia. Schiffner (1900) described both R. chamedryfolia and R . multifida as with the same pat­ tern of thickenings of tbe capsule walls. The inner layer, in botb cases, was described as lacking rodlike or bandlike tbickenings, although the adaxial radial walls were admit­ tedly somewhat browned, "was von einer etwas sHirkeren, aber gleichmassigen Verdick­ ung herriihrt." However, Scbiffner (l.c., p. 18) emphasizes that in "R. major" the inner capsule cell layer shows "blass braunlicbgelbe, undeutlich begrenzte, aber vollstandige Halbringfasern." Evans (l.c., p. 27) also emphasizes that Schiffner later found (I 906) that R. chamedryfolia (typical) may have "vaguely defined but definite bands ... present on the inner tangential walls of the inner layer." Macvicar (1926, p. 55) also em­ phasizes this for R. chamedryfolia, stating that the outer capsule wall cells have broad semiannular thickenings, but the inner are provided "with paler coloured, narrow semi annular thickenings." Evans (l.c.) illustrates the epidermal and inner layers of the R. M. SCHUSTER: Studies on Metzgeriales, I 313 capsule wall for R. chamedryfolia, and shows distinct semiannular thickenings present on both cell-layers. Although his illustrations show them nearly equally developed in both layers, he notes (p. 29) that the bands of the inner layer "are less well developed and less deeply pigmented than those in the cells of the outer layer; in many cases, indeed, they are indistinct ... These bands, in the majority of cases, form extensions on the inner [freel tangential walls, representing the tangential bands described by Schiffner, but no similar extensions are developed on the outer tangential walls." Such tangential bands are developed in the majority of cells in well-developed plants I have studied (e.g .. RMS 40936), but these are thin and vague. By contrast, R. multifida is described as having an inner cell layer essentially devoid of distinct bands of thickening. However, as has been observed by both Schiffner and Evans, the radial adaxial walls bear a more or less even layer of brownish thickening material. Evans (I.e., p. 23) further indicates that these nearly even radial layers of sheets of thickenings may extend for variable distances on to both tangential walls, even though the tangential sheets are difficult to see, in surface view, except as gradually thinning colored layers, with the layer of deposit appearing "as a faintly pigmented band along the adaxial side of the cell, leaving a colorless band along the abaxial side." Evans further states that occasional cells show vague indications of more or less evident bands (as in his fig. 1B), extending 0.5 or more across the tangential faces of the cells. In this, R. multifida clearly approaches R. chamedryfolia. Typical material of R. multifida (auto­ ecious form; RMS 28827, McDowell Co., N.C.) demonstrates the presence, again only in occasional cells, of very vague, barely perceptible, incomplete and gradually at­ tenuated bands on the free tangential faces of the inner cell layer. Development of such bands is of significance in determining the status and position of "R. major." In "R. major" (as exemplified by Schiffner's Hep. Exsic. nos. 1263, 1264), the inner cell layer shows the adaxial radial walls thickened by a brown sheath of secondary deposit, with this sheath (as seen in profile, in surface view of capsule valve) ± sinuous, because of its unequal thickness. The radial walls, however, do not or only exception­ ally bear definite bands (and thus cannot be said to bear nodular thickenings). This layer of thickening, which is usually more strongly developed and less even than in R. multifida, extends ± over the tangential walls, sometimes as an even sheath, sometimes as ill-defined, usually short and thin, bands. In no case were cells found in which the bands wece nearly as strongly developed as illustrated in Evans (I.e., p. 28, fig. 4E). In fact, careful comparison of these specimens shows almost perfect agreement with R. multifida and R. m. subsp. synoica as regards the nature of the inner cell layer thick­ enings. Phases of R. chamedryfolia distinguished at times as var. major thus at first glance would appear separable from R. chamedryfolia s. sfr. on the basis of lack of semian­ nular bands of the inner cell layer. At first glance, this contradicts Schiffner's earlier observation (R. major with supposedly weak semiannular thickenings ; R. chamedryfolia with a thin sheet of thickening). However, study of typical plants of R. chamedryfolia from North Carolina shows clearly that typical R. chamedryfolia may also lack distinct 314 Journ. Hattori Bot. Lab. No. 62 198 7 semiannular bands of the inner cell layer. In the latter plants, the free (inner) tangential faces showed a thin, often barely perceptible band of brownish deposit, thinning out and disappearing usually at or near the cell midline. This deposit is more evident from a cross section of the valve, where it is seen to extend for fully half the cell width in some cases. Almost always the tangential band of thickening was almost uniform (therefore easily overlooked) and only exceptionally could differences in thickness (and intensity of pigmentation) be found, with vague indications of ill-defined bands in a very few cases. R. major and R. chamedryfolia (s. str.) thus agree in that the epidermal cell layer shows ± semiannular thickenings, adaxial in position with respect to the midline of the capsule valves; these thickenings are ill-defined and thin on the tangential walls in R. multifida, or may be quite absent on the outer tangential walls. R. "major" may show stiff, thick, strongly developed, and more heavily pigmented semiannular thick­ enings, often extending virtually across the inner tangential face (and sometimes across the outer tangential face) of the cell. In spite of the narrowly unistratose ultimate thallus segments, this plant belongs to R. chamedryfolia rather than to R. multifida. R. multifida and R. m. synoica consistently have the inner cell layer with a sheet of brownish thickening over adaxial radial walls; this sheet extends more or less on to the adaxial halves of the tangential walls (and is rarely sporadically localized as very vague bands). In the essential lack of perceptible, defined semiannular bands, R. multifida thus virtually agrees with the specimens I have seen of R. "major" (Schiffner, Hep. Eur. Exsic. nos. 1263, 1264).7 By contrast, typical R. chamedryfolia bears, on the inner cell layer, more or less distinct, if poorly demarcated, semiannular bands which are less strongly developed and less pigmented than those of the epidermallayer.8 Present studies, as well as consideration of the careful and painstaking work pre­ viously done on this problem by both Schiffner and Evans, suggest that capsule-wall characters in the entire R. multijida-synoica-chamedryfolia-major complex are subject to such an amplitude of variation that no rigid and definitive, specific distinctions can be made. At best, it may be said that in R. multijida (incl. subsp. synoica) thickenings of both outer and inner layers are reduced to a minimum, often with the tangential thickenings in both layers vestigial. In R. "major" the outer layer may have the semian­ nular bands strongly developed (Schiffner suggests that this is not invariably the case), but the inner layer may have the semiannular bands weak (fide Evans 1938, Schiffner 1906) or essentially lacking (fide my observations and those of Schiffner 1900). In typical R. chamedryfolia the degree of development of the inner layer bands may reach a maxi­ mum (as in the material described by Evans) even though studies of Schiffner (1900) and

7 This disagrees with Schiffner's statement (1900, p. 18) that R. "major" agrees with R. chamedryfolia in the form of the thickenings of the epidermal layer but bears, on the inner tangential walls of the inner layer, yellowish brown, indistinctly defined but complete semiannular bands, although the radial walls are devoid of thickening. B Although Schiffner (1900, p. 9) indicates that R . chamedryfolia may lack semi-annular bands of the inner cell layer. R. M. SCHUSTER: Studies on Metzgeriales, I 315

mine indicate such bands may be nearly lacking, while the epidermal layer also shows semiannular bands that are at all times developed more strongly (and more sharply defined) than those of the inner layer. From the preceding, it is clear that the attempt by Evans (I.c., p. 35) to separate­ on the basis of capsule-wall anatomy - the Riccardia species into two groups (R. multifida and R. incurvata on one hand, R. chamedryfolia, R. latifrons, and R. palmata on the other) cannot be maintained. The first group supposedly has bands of the inner tangential walls of the inner layer either "lacking or scanty and vaguely defined"; the second group supposedly shows these bands, in well-developed sporophytes, "abundant and much more clearly defined." These distinctions are subject to intergradation and are of slight value for the separation of groups of species. Variation in thallus form: "Typical" R. chamedryfolia is the hygrophytic phase of the species, characterized by a thicker thallus, 6-9(10) cells thick, always opaque to the margin (and unistratose for at most 1 cell width) and by often strongly dilated apices of the main axis and branches (which may even attain a width of 2.2- 2.5 mm!). Such plants are usually irregularly 1- 2- 3-pinnate and typically remain sterile or are sparingly fertile. In my experi­ ence, if the plant is emersed it becomes more copiously (often 3-4-pinnate), often more regular­ ly, pinnate; at other times (fide Macvicar 1926) it may be only slightly pinnate. Such plants are more copiously fertile; the main axis is only 5- 6 cells thick, the branches often only 4, or even only 3, cells thick medially; branches are usually not dilated distally. These plants oc­ casionally have thallus margins unistratose for a width of 2- 3 cells and consequently are barely and narrowly bordered; at one time they were distinguished as R. major or R. sinuata [chamedryfolia] var. major. This distinction appears to have no valid taxonomic basis. Variation in oil-body number and cell size: According to MUller (1954 in 1951- 58, p. 501) almost all cells, including the apical ones, bear 1-2 oil-bodies varyi ng from 9 ft to oval and 7 x 10 ft. In the North Carolina material the epidermal cells often, but not always, have a single, small (ca. 6-9 x 9-11 ft) oil-body, while the hypodermal cells have 1, less often 2, larger oil-bodies ranging from 9 x 18-20 ft to 12 x 20 ft, thus much larger than described by MUller. In South Carolina plants (RMS 37667) epidermal cells also bear, with isolated exceptions, a single oil-body, but this is narrowly elliptical to fusiform and up to 10 x 20 It. By contrast, hypodermal cells commonly have 2-3 oil-bodies and these are up to 9- 12 x 30 ft or even 9 x 36 ft! Isolated hypodermal cells possess 4--6 oil-bodies per cell. Similarly, other South Carolina plants (RMS 40918,40936) have marginal cells with small oil-bodies (5 x 7 to 7 x 10 ft), the epidermal cells with I oil-body ca. 5-8 x 10-12 ft (only sporadic epidermal cells without an oil-body); the hypodermal cells with 1- 2, in isolated cells 3-4, very large oil-bodies ranging up to 7- 8 x 25- 34 ft. As in other examined collections, the larger hypodermal oil-bodies are often crescentic and slenderly fusiform, with one or both ends pointed. It is possible that these plants from the Blue Ridge Escarpment gorges represent a different genotype, but the typical thallus structure and the clearly autoecious inflorescences suggest that disposition of the material under R. chamedryfolia can hardly be avoided. Other South Carolina plants (RMS 40893) have 1-2 epidermal oil-bodies, 2-3, occasionally 4- 6, hypodermal oil-bodies. The former are smaller, more or less oval, to 9 x 13 ft; the latter are often ± crescentic or fusi­ form, to 6-9 x 25-28 ft. It is evident from the foregoing that the number and size of the oil-bodies are subject to considerable variation. The almost constant presence of oil-bodies in the marginal and epi- 316 Journ. Hattori Bot. Lab. No. 62 198 7

TABLE 3. Oil-bodies in R. chamedryfolia

Nova Scotia New York SOllth Carolina [43038 , 43037] [44502b] [44621] [37667] [40918,40936] [40893] No. per 0-1(2) (1-2)3-10(12) 1(2) (0)1 or 1 1-2 epidermal cell No. per hypo- 1- 2 3- 6- 9 1-2 2-3(4-6) 1-2(3-4) 2- 3(4- 6) dermal cell ------dermal cells, however, serves as a major differentiating feature from the often sim ilar R. multifida. As is emphasized in the diagnosis, "normal" R. chamedryfolia has oil-bodies in nearly all hypodermal cells and these range from 1- 2 per cell up to, rather often, 3- 5 per cell. The epidermal cells may, in part, lack oil-bodies or have them present only singly (as in the North Carolina plant). However, in some cases the plant referable to "var. major", with thallus seg­ ments only (3)4-5 cells thick, may have more numerous oil-bodies, thus approaching R. jugata and R. stricta. In plants from Sixmile Cr., Ithaca, N.Y. (RMS 44502b), unfortunately sparse and sterile but typical in thallus characters, epidermal cells, which are thin-walled and (39)40-45(52) fl wide x 60- 100 fl long, bear (1 - 2)3- 10(12) oil-bodies per cell, in both the smaller cells near branch apices and in mature cells. Cells with only 1 or 2 oil-bodies, which occur only sporadically, have the oil-bodies up to 5- 6 x 15- 18 fl; the more frequent cells with numerous oil-bodies have them elliptical to subspherical and 5- 7.5 x 4-6 fl. Hypodermal cells are little larger in diam. (50-55 fl) than epidermal cells, but somewhat longer (130-160 fl); they usually also bear many oil-bodies, ranging from 3- 6--9 per cell. Oil-bodies average slightly larger than those of the epidermal cells. According to Mizutani & Hattori (1957, p. 48), Japanese plants bear 1-5 oil-bodies of both epidermal and hypodermal cells. As Table 3 indicates variation appears to be much more extensive and non-correlated. The number of oil-bodies, as well as their absence from some cells, apparently undergoes some geographic variation. Thus in West Greenland, at the northern edge of its range, in some populations only 1- 5 % of epidermal cells bear oil-bodies (and these are relatively small, 7- 7.5 x 8- 10 fl), while hypodermal cells all appear to have single oil-bodies, of somewhat larger size (9 x 10-12 to 10 x 14 11); cf. Schuster & Damsholt (1974). Other phenotypes have oil-bodies in a majority or almost all epidermal cells and apparently in all hypodermal cells. [Such pop­ ulations may occur at the same locality as oil-body-free plants, here referred to R. {atifrons subsp. arctica; cf. p. 303. Separation of dead material of arctic phases of the latter and of R. chamedryfolia may be virtually impossible.] Little (1968, p. 537) states that in British R. chamedryfolia oil-bodies occur "in nearly all the cells," 1- 2(3) per cell, and are 8- 15 x 9- 20(35) fl in size; on p. 539 he states they occur in "at least 70 % of the epidermal and marginal cells". Clearly, studied over a wide range, R. chamedryfolia is a formidably variable and difficult taxon.

5. R. multifida (L.) S. F. Gray and Allies This species - or species complex - is even more difficult to circumscribe than is R. chamedryfolia. Problems resolve themselves around 3-4 "areas": (1) distinction from R . chamedryfolia: (2) the status of synoecious plants, usually xylicolous, found in the southeastern United States; (3) the status of autoecious plants, also from the southeast, R. M. SCHUSTER: Studies on Metzgeriales, I 317 almost never found on decaying wood, in which there is a marked increase in number of oil-bodies. The third problem is discussed (p, 326) under R, stricta. These problems will be discussed in the cited order.9 1) R. multifida vs. R. chamedryfolia: I have repeatedly collected these species growing admixed or adjacent, from Newfoundland (Long Peninsula: between York Harbour and Frenchman's Cove; RMS 84-3501; S. of Bellburn's; RMS 84- 3652,84- 3653c, 84-3671) to Nova Scotia (French Mt., Cape Breton J. ; RMS 43038a) south to South Carolina (Whitewater R. near Jocassee ; RMS 40893a). Where these taxa occur admixed, clear distinctions are found in their cytology. Anatomical differences between R. mUltifida and R. chamedryfolia, however, often seem to disappear. Thus, in plants of R. chamedryfolia from South Carolina (RMS 40893, Whitewater R. Gorge) cited in Table 3, which were quite clearly distinct cyto­ logically from the admixed R . multifida, ultimate branches may be unistratose for a width of 2- 3 or even 4 cell rows - a R. multifidaB~,:) racter. Such plants also retain the other "chamedryfolia chacellracters"IO- sucdistinct development of semiannulannular bnds" of epidermal cells accompanied by faintbut discernible, partly semiannular bands (or at lest tangential spurs) of the inner cell layer. Plants of R. chamedryfolia cited above differ from many other collections of that species in frequently having 3 or more oil-bodies of hypodermal cells while in other collections there are regularly, or almost so, 1-2 oil-bodies per cell. Such deviations appear to be within the genetic potential of a single species and suggest at best dif­ fering populations. Although such mixed collections prove beyond doubt that two distinct species are at hand, R. multifida may produce seasonal forms, or forms under cultivation, that are inseparable in many respects from R. chamedryfolia. Plants with the typical crenulate ultimate branches of "normal" R. multifida (Hawley Bog, Mass., RMS 43960a) are illuminating in this respect. Although the older growth showed the gibbous, subquadrate marginal cells of R. multifida, even on leading segments in some cases, and had widely unistratose ultimate branches, younger growth, under cultivation, differed as follows: ultimate branches unistratose for 0.5-\.5 cell width; marginal cells elongated, not projecting or gibbous - the thallus margins thus smooth; epidermal cells mostly with an oil-body present (rare in older portions of the thallus); margina cells often to usually with a single small oil-body. Furthermore, the younger growth was

9 A fourth major problem which I cannot resolve here is the status of R . nana Mizutani & Hattori (1957, p. 32). This is supposed to differ from "normal" R . multifida in the smaller spores, ca. 10-12 J10 in diam., and in the less regular branching. In R . multifida subsp. synoica spores are (9}10- 15 I' vs. the 13- 16 J10 usually given for subsp. multifida. R. nana, like subsp. multifida, usually lacks epidermal oil­ bodies but has 1-2 hypodermal oil-bodies. It is possible that the smaller spore size reflects less optimal growth conditions. 10 Although usually the wide unistratose border of ultimate segments of R. multifida easily separates it from R . chamedryfolia, the distinction is not absolute. Thus Mizutani and Hattori (1957, p. 32) separate R. chamedryfolia on the basis of a unistratose border "I cell broad (or obsolete)" but their fig. VI: 11 - 12 shows unistratose margins 2 or even 3 cells wide! Little (1968) notes that the latter taxon may have a wing 2- 4 cells wide "in some ... forms." 318 Journ. Hattori Bot. Lab. No. 62 1 987 much less regularly pinnate and had relatively infrequent, more distant branching - a feature common in R. chamedryfolia, rare in R. multifida. Indeed, the entire facies of the more recent growth was that of R . chamedryfolia, although the width of epidermal and hypodermal cells remained within the dimensions cited above for R. multifida. Thus it is evident that under certain conditions, R. multifida may produce growth forms superficially inseparable from R. chamedryfolia. Inversely, it has been shown above that in R. chamedryfolia a unistratose margin more than 1 cell wide may occur - hence if "blindly" keyed, material of R. chamedryfolia may be sought under R. multifida. The discrimination of the two species thus remains a matter of the utmost difficulty in certain cases; fortunately, these are of exceptional occurrence. It is probably safest, in view of the exceptional variability of the members of the R. chamedryfolia-R. multifida complex not to name such annectant forms - even though they remain a challenge to the worker. 2) Sexual Branch Variation: R. multifida shows much variability with regard to orientation and form of sexual branches. In a series of populations from the southeast, particularly the Coastal Plain and Piedmont of the southeast, and occasionallyelsewhere, the plants bear bisexual branches that are usually simple, i.e., do not arise in clusters. These plants are distinguished on a following page (p. 320) as subsp. synoica. Eliminat­ ing populations with bisexual branches from consideration, we find that there still re­ mains a high level of variability in the nature of the sexual branches. Typically, R. multifida has short, somewhat capitate gynoecial branches that may arise either from the margins of the leading axes or from branches of the first, or more rarely, second order; these branches are surrounded distally by a cluster of laciniae formed of several large "hairs," - or more properly, capillary lobes. The gynoecial branch usually pro­ duces only 2- 4 archegonia. The androecial branches vary in length but mostly are linear and bear anywhere from 2- 8 pairs of antheridia, sunken into dorsal "pockets" - or, inversely hidden by antical proliferation of the surface of the antheridial branch. In both cases the sexual branches are simple and, although often occurring closely juxtaposed, almost never arise from a common base. This is the typical condition illustrated (and/ or described) by Macvicar (1926), Milller (1954, in 1951-58), Frye & Clark (1937, in 1937- 47), Schuster (1949, 1953), and others. From this condition there is variation as follows: (a) Gynoecial branches often in sympodial clusters, usually with 3 branches arising from a common base, usually from the margins of the leading axes; each gynoecial branch elongates, simulating a 0 branch, with up to 8- 12 pairs of archegonia, lying in 2 well-defined lines. Antheridial branches very rare - the plant superficially appearing dioecious and ~ in many cases - linear, simple, typical. [Ex­ ample: High Falls of Big Creek, Rabun Co., Ga., RMS, s. n.] .'!

11 American plants almost always have d and ¥ branches arising in rather close proximity and pseu­ dodioecious populations are rarely seen. Mizutani and Hattori (1957, pp. 29, 51 - 53), while admitting the species is bisexual, state that of 54 fertile collections attributed to R. multi/ida, 31 bore only ¥ bran­ ches, 2 only d branches, 3 d and ¥ branches on [supposedly] separate plants in mixed stands, and only 18 collections were clearly bisexual. They noted that in Japanese populations attributed by them to R. multi/ida "the male branch seems to be relatively rare." East Asiatic populations clearly seem rather different and require further comparative studies. R. M. SCHUSTER: Studies on Metzgeriales, I 319

b) Gynoecial branches solitary, never with antheridia at base. Androecial branches as frequent, or more so, as gynoecial ones, usually oblong to linear, usually solitary, but oc­ casionally in sympodial clusters of 3. Gynoecial branches never with more than 2 rows each of 3-4 archegonia. [Example: Whitewater Gorge, S.c., RMS 40898]. This represents a freely 3(4)-pinnate phase with optimal development of the linear 0 branches which are always some distance from the gynoecial ones. e) ¥ Branches almost all arising from leading axes, short, typically developed, apparently never with antheridial chambers at base; 0 branches exceedingly rare, linear. [Example: Whitewater Gorge, S.c., RMS 40891a]. This represents an extreme shade phase which is only 1- 2-pinnate, with slender branches, and almost total suppression of 0 branches. d) Sexual branches sometimes solitary, but usually in sympodial clusters of 2-3, bisexual, with 1- 2 pairs of antheridia at the base, 2- 3 pairs of archegonia at the apex, or occasional ones unisexual and with 3-4 pairs of archegonia in 2 rows; no separate antheridial branches (or these at least very rare). Very large, 3-pinnate, prostrate form, superficially identical with typical R. multi/ida. [Example: Chattooga R., below El\icotts Rock, Rabun Co., Georgia, RMS 39840; = subsp. sYfloiea]. This represents the intermediate type between typical R. multi/ida and the smal\, less regularly pinnate, typically xylicolous subsp. sYfloiea. The preceding discussion illustrates the fact that in R. multijida there is often a tendency toward suppression of the linear androecial branches supposedly characteristic of the species. In one case (subsp. synoica) antheridia develop at the bases of the ~ branch, in the other, there appears to be simply a reduction in number of d' branches developed to the point where these are often demonstrable only with prolonged dissec­ tion of large masses of material. Mizutani and Hattori (1957, pp. 29- 30) also note that in Japanese plants it is often difficult to demonstrate d' branches, while the ~ ones may be abundantly developed. Their table (l.c., p. 29) suggests that R. multijida is at times dioecious, since they report more collections (31) with "female branches only" than those (I 8) with "both [d' and ~ branches] on the same thallus." I am convinced, how­ ever, that with prolonged examination it is always possible to demonstrate a monoecious inflorescence in true R. multijida. It is also possible that Mizutani and Hattori had before them some material of the subsp. synoica and overlooked the few antheridia found at the bases of the ~ branches. This is very easily possible when material with immature or mature calyptrae is studied, since by the time these develop the antheridia are generally disintegrated.

6. R. multijida subsp. synoica Schust., subsp. n. Subspecies subsp. nlultifidae similis, differens ramis synoeciis sexualibus, e 2 ordinibus antheridi­ orum in basi atque 2-aliquot archegoniis distaliter consistentibus ; nonulli rami unisexua les raro quoque adsunt; differens necnon thallis tenuioribus, segmentis ultimis media in parte solum 3-stratosis, alis unistratosis 4- 5 cellularum latitudine. Type: Vancleave, Mississippi (RMS 192/8; hb. RMS) . A formal diagnosis and figures are in Schuster (1988). Here phenotypic variation shall be discussed. In the preceding section on R. multijida s. sir. (subsp. multijida) the considerable variability in that taxon in form, orientation and sexuality of gametangial branches was discussed. The last collection cited in detail (RMS 39840) marked a transition point between "normal" subsp. multijida, which only rarely invades decayed wood, and the 320 Journ. Hattori Bot. Lab. No. 62 1 987

southeastern subsp. synoica, which is most often xylicolous. Especially in the Southern Appalachians, anum ber of such vigorous, 2(3)- or 3-pinnate, copiously branched pheno­ types occur on moist or wet rocks; these taxa show the vigor and aspect of subsp. multifida - but have a high proportion of bisexual gametangial branches. The existence of such seeming intermediates suggests that the synoecious phases be considered a sub­ species of R. multifida, rather than an autonomous species. J initially was convinced that subsp. synoica was a fully autonomous species; this conviction derived from the fact that outer Coastal Plain populations of this entity always occurred on acidic, organic substrates (usually decayed wood) and often showed a much less regularly pluripinnate branching mode than characteristic of autoecious R. multifida. Study of over 500 individual plants of the entire complex, however, eventually showed that - as in R. diversifolia Evans - the orientation of gametangia was highly plastic. Some of this malleability is systematically analyzed (pp. 322-326), using eight phenotypes, each slightly different in the "mix" of synoecious and unisexual gametangi­ al branches. These examples span several "typical" xylicolous phenotypes, but end with four from damp or moist rocks - thus inorganic substrates. These last phenotypes are in a small minority and are especially cited to prove that there are transitional ele­ ments between the two subspecies. Typical subsp. synoica is constantly fertile and fertile plants are usually easily separated on the basis of the synoecious inflorescence. Although, as in other known synoecious species of the genus, there is much variation in this regard, typical subsp. synoica has sexual branches that are mostly short (ca. 250 fl wide and long), essentially hood-shaped, with the ventral lamellate portion of the hood extended outward some­ what further than the dorsal lamellate portion. Each inflorescence usually bears only (2)3-5 globose antheridia, each ca. 70-75 fl in diam., and at least 2, usually 3-4, arche­ gonia (of which only 1- 2 may mature). The "hood" consists of a unistratose plate of cells, the apices of which are lobed or crenulate by projecting cells. In material from near Manns Harbor, N .C. (RMS 28386) a single, highly elab­ orated sexual branch was found: the fertile branch, though short (ca. 800 fllong x 500 fl wide), more nearly resembled a short sterile branch, with somewhat upcurved lateral wings. Several antheridia were situated near its base ; these were partially obscured by finger-like cellular outgrowths from the dorsal thallus surface. [These outgrowths did not fuse to form walls surrounding discrete antheridial chambers, but presumably re­ present a less extreme development along these lines.] In addition to the several an­ theridia on the branch dorsum, several more antheridia, without finger-like papillae between them, occurred near the apex; situated below them (and thus somewhat ob­ scured) were 3-4 mature archegonia. This sexual branch, except for its somewhat greater length and presence of several more antheridia near the base, corresponds closely with the "normal" type of sexual branch for subsp. synoica. Thus, even in those cases where the sexual branch becomes slightly more elongate (and could potentially be confused with the antheridial branches of R. m. multifida) it still may be synoecious. Several plants seen had sexual branches of the previous type but still more elabo- R . M. SCHUSTER: Studies on Metzgeriales, I 321

rated. In these, 2-4, rarely 5, pairs of antheridia occurred in two lines and were situated dorsally on the branch, whose thin margins were somewhat dorsally curved. Each an­ theridium was sunken into a pocket, formed by dorsal, finger-like and ridgelike out­ growths a single cell-layer thick, forming a spongy, irregular network. Such elongated antheridial branches were 400- 550 fl long X 320-360 fl wide and closedly simulated the antheridial branches of R. m. multifida - with one important difference. In each case the branch apex clearly bore archegonia. Younger inflorescences may simulate antheridial spikes - the archegonia being evident only on careful dissection of the apex. However, in older inflorescences with the antheridia decayed (leaving 2 rows of pits on the basal portion of the fertile branch), we find that the closely papillose, green, globular calyptra issues out of the branch apex. Of many such plants studied, with either the hood­ shaped, reduced fertile branch with 2-4 antheridia or an elongate branch with 4-5 pairs of antheridia in more or less discrete chambers, every case revealed the presence of archegonia (or young calyptrae) at the branch apices. By the time immature calyptrae are evident, antherida usually have disintegrated. Several times, however, I have seen undehisced antheridia, in the cavities at the bases of immature calyptrae. The antheridia invariably occur above and basad of the archegonia, hence the latter may be overlooked unless the inflorescences are somewhat compressed arti ficially. Although much material of subsp. synoica shows rather regular 2-3-pinnate branch­ ing, prostrate portions of plants (which may be quite broad, up to 1 mm wide) may be loosely monopodially branched. Some of the monopodial, attached branches may in turn (with crowding) become ascending and free of the substrate; these ascending branches are then often somewhat palmately pinnate, with the branches so closely crowded as to destroy all illusion of pinnate branching. The erect, often somewhat crowded branches are also narrow (400- 500 fl wide), while the main, adnate axes may be 750-900 fl, exceptionally 1000 fl, wide. Capsules show only a limited amount of variation. The epidermal layer usually consists of 16 cells rows, 8 on each side of the midline (valve axis). Adaxial faces of longitudinal walls show strongly developed vertical bands, in surface view usually ap­ pearing in the form of brown, semicircular nodules. Typically the radial bands show virtually no tangential extensions on free tangential walls (or only very short, vague, spurlike extensions) but on inner tangential walls the radial bands may be scarcely ex­ tended (as on the outer tangential walls). More rarely, however, the inner tangential extensions are well developed, extending half way or more across the tangential faces (as in RMS 20341 a). Cells of the inner layer may be in 16 rows (and then are equal to the epidermal ones in width), but occasional cells may be longitudinally divided, thus increasing the number of cell rows. Inner cells appear to lack secondary thickenings, but careful study reveals that the adaxial radial walls bear a thin, brown layer of secon­ dary deposit, occasionally slightly uneven (rendering the wall slightly sinuous in pro­ file). Very careful focusing shows that this adaxial layer extends slightly over adjacent portions of the free tangential walls, forming an obscure brown layer. More rarely the 322 Journ. Hattori Bot. Lab. No. 62 1 987

tangential sheath is unevenly developed, with a faint, barely perceptible tendency for the formation of ill-defined bands. Under no conditions, however, can the tangential walls ever be said to have semiannular bands. Capsule-wall anatomy of this plant is essentially identical (as regards thickenings of both epidermal cells and virtual absence of such thickenings in the inner cell layer) to that of the widespread R. m. multifida (as described by Evans 1938, p. 22). However, subsp. synoica has smaller sporophytes, with valves only 200-240 (250) P, wide x 550-700 ft long (described by Evans as 450 p, in R. m. mUltifida). R. m. synoica also has the cells only 12- 17 p, wide (in RMS 28386; in R. m. multifida described as 20-40 p, wide, with an average of 30 p,). These differences mayor may not prove signifi­ cant.12 The width of the valves (and of their cells) appears to be nearly constant in syn­ oecious plants. In RMS 2034Ja (Miss.) the epidermal cells average 15 p, wide, those of the inner cell layer also 15 p, wide. In RMS 20261 (Miss.) cells of each layer average 13- 15 p, wide. In RMS 19218 (Miss.) epidermal cells average 14-15 p, wide, the some­ what more subdivided inner cells average only 10- 15 p, wide (mostly 10-12 p,). Char­ acters of the capsule valves and their dimensions have been studied on dozens of cap­ sules, from over six locations; they appear to be constant within narrow limits. Variation in Gametangial Branches : The limited collections of subsp. synoica demonstrate great polymorphism, espec­ ially as regards the spatial relationships between antheridia and archegonia. Variation in sexuality and in gametophyte form is best illustrated by a discussion of the following phenotypes. 1) RMS & Blomquist 28540 (on moist soil over rocks, The Caves, New Hope Creek, Orange Co., N.C.) shows regularly 3-pinnate thalli, with older chief branches, as well as main axes, bearing short sexual branches. "Archegonial" branches, in all cases, are clearly synoecious and show, behind the archegonial chamber (formed by finger-like cellular papillae and plates of cells) 2-4, occasionally 6, antheridial cavities. Plants of this collection, in their narrow branching, as well as copious degree of branching are very close to typical R . m. multifida. The main branches (700-900 fl wide; 5- 6 cells thick medially), however, are still clearly planoconvex, as are the 3-4(5) cells thick branches; the latter are translucent on the lateral fourths, only the median 0.5 of the segment being muitistratose. Occasionally, on these plants, one can also find a small lateral branch that is totally androecial - with usually ca. 6 antheridial pits, although in one case a branch was seen bearing a single antheridial pit. Unisexual, mostly 0, branches are very rare. 2) RMS 28674 (Hemlock Bluff, Wake Co., N. C.) is a form with unusually broad branches - so wide that parallel-directed branches of the same plant often overlap. Ultimate branches are only 3 cells thick, ca. 90 fl thick - but 1000- 1200 fl wide - thus 12 x or more as

12 The differences become more difficult to demonstrate in a specimen from North Carolina (RMS 28812) in which the sexual branches are usually sympodial, but not synoecious. This stands, in many respects, intermediate to R. multi/ida s. str.; it has the valves 250-320 /1 wide and cells average 17-21 f' broad. R. M. SCHUSTER: Studies on Metzgeriales, I 323

wide as thick; main thallus branches are 5 cells thick (ca. 130- 140 It), about the same width (very occasionally to 1600-1800 fI. wide). In its very close and broad branches the plant looks much like R. sinuata and shows a cross section that is flat (or slightly concave) above, convex - though often only slightly - below, thus differing from "typical" multi/ida. The main thallus, only 5 cells thick, also differentiates it from subsp. multifida (where it is usually 6-7 cells thick). In all cases the archegonia (4- 8 in a group, in the plants studied) occur closely associated with antheridia. Either archegonia occur at the apices of antheridial branches (as described above), or in the sinus between 2 short and approximated antheridial branches. Several plants bore only antheridial branches (linear, with 6-8 antheridia in 2 rows). The clear consociation of archegonia and antheridia, and the thin and planoconvex thalli place these plants with subsp. synoica - even though the facies approaches that of R. chamedryfolia. The chief, as well as ultimate, branches bear a unistratose border 2, rarely 3, cells wide. Epidermal thallus cells often contain a single oil-body; hypodermal cells, by contrast, usually have 2 large, fusiform, grayish and opaque oil-bodies. 3) RMS & Blomquist 29220 (xylicolous, on decaying Nyssa aquatica logs; swamp 1.5 mi E. of Whiteville, Columbus Co., N.C.). The sexuality of several hundred individual plants was studied. Almost always the very short sex ual branch (of the same type as typical of pre­ vious collections) was somewhat hood-shaped, with 2- 3, occasionally 4, antheridia, and an­ terior to (and below) them 2- 3 archegonia. The form of the somewhat hooded, very short sexual branch (consistently without antheridial pits) is identical with RMS 28386 (Dare Co., N.C.). Exceptionally, however, relatively elongated branches whose crenulate, unistratose lateral margins and apices were upcurved (resulting in a sulcate branch), were noted; the dorsal sulcus had 2 more or less irregular lines of archegonia, at times totalling 12- 18 in number. Such archegonial branches lack all trace of antheridia - and are comparable rather to the linear antheridial branches of R. m. multi/ida than to the archegonial branches of "typical" Riccardia. This collection is also of interest in that it shows every possible stage from immature archegonia and antheridia to fertilized archegonia, to fully mature sporophytes. In my experience, it is extremely unusual to find all phases of the reproductive process going on simultaneously. The plants are not only extremely fertile (probably correlated with the synoecious sexuality) but also freely gemmiparous. The gemmiparous branches are often directly adjacent to sexual branches, and formation of the latter does not appear to inhibit formation of the former, and vice versa. Gemmiparous branches are usually readily evident since development of gemmae appears to eventually inhibit branch elongation. As a con­ sequence, such branches gradually become narrowed and attenuate. With development and release of the endogenous gemmae, the epidermal cells become empty; consequently the apices of gemmiparous shoots are often somewhat whitish in appearance. 13 4) RMS 19218, 20341a (from decaying logs, near Yancleave, Miss.). These plants vary

13 All phases of sexual reproduction and sporophyte formation in subsp. synoica continue all year long, interrupted intermittently only by cold weather. A crop of spores appears to be released from early spring until late in the fall. Furthermore, sexual branches are initiated at all times of the year when growth can proceed. In this, subsp. synoica contrasts strongly with subsp. multi/ida, in which sexual branches are produced during the late spring or early summer, with the calyptra undergoing maturation in late summer and early fall, the enclosed sporophyte nearly mature by the onset of winter. In early spring the sporophytes are matured and about this time the next crop of organs is laid down. I have collected material of subsp. synoica with developing and mature archegonia and antheridia, as well as open capsules, from June to October. 324 Journ. Hattori Bot. Lab. No. 62 1 987 greatly in the type of branching, from simply pinnate to irregularly bipinnate, locally with clustered, subpalmate branching (RMS 19218) to freely 2- 3-pinnate (RMS 2034Ja). They are unusually pellucid in appearance, since the ultimate (as well as penultimate) branches are unistratose for 3- 5 cell rows. The hyaline thallus "wings" are therefore very strongly marked and are formed of obliquely oriented cells; median thallus sectors are 3-stratose for a width of 4-5(6-8) cell rows, with the cortical cells more longitudinally oriented. The narrower, most pellucid ultimate branches may be only 400--450 J1, wide but mature branches range from 675- 800 J1, wide. They show a dorsal epidermis with distinct differentiation into 3 types of cells : small marginal cells, mostly subquadrate, averaging 30- 36 J1,; larger cells of the unistratose wing, obliquely oriented, averaging 34-40 x 60-70 J1,; longitudinally oriented cells in 3- 6 median rows or more, averaging 32- 36 It wide x 64- 80 J1, long. The characteristic form of the thallus is also evident from cross sections. The middle of ultimate segments is only 70/1 thick, 3-stratose, ca. 650 J1, wide; the unistratose wing is usually 4--5 cells broad. Medullary cells, in one layer, average 38 x 38 J1, to 38 x 65 It in diam. The extreme thinness of such ultimate segments (6- 9 x as wide as thick) is characteristic. Older segments (e.g., those bearing sexual branches) are 6- 8 x as wide as thick (675 J1, wide x 82 J1, high), have unistratose margins 2- 3(4) cells broad, and are normally 4 cells thick medially. Tn the extremely delicate and thin thalli, these plants are distinctive; they form the most delicate extreme of the species. Disposition of sex organs in these populations varies only slightly; no long andro­ ecial branches could be found. Branches bearing antheridia, in most cases, were nearly flat and thin, like ordinary branches, with entire margins, occasionally produced as scattered turgid papillae. Such branches bear only 2- 3 antheridia and the branch is extremely short (ca. 325- 400 fl wide X 300- 350 fl long). Antheridia are not sunken in (or surrounded by) tissue proliferated by the dorsal surface of the branch but are simply ses~ile dorsally, with localized papillae or short, papilliform teeth shielding them in part (especially posteriorly) ; only occasionally do these teeth partially circumscribe antheridial chambers. The smallest of these (immature?) branches appear to contain only 2 antheridia, without any archegonia. All the larger gametangial branches bear 3-4 antheridia and 2- 4 archegonia anterior to them (and slightly ventrally displaced). In many cases, young calyptrae could be found at the apices of such sexual branches, with the remnants of 2, occasionally 2-3, antheridia (or antheridial cavities) at their bases. With calyptra maturation, the evident synoecious condition becomes impos­ sible to determine. The mature calyptra bears a dense "corona" of short, crowded, turgid, hyaline papillae at its summit; it averages ca. 350- 420 fl in diam. X 1200 fl long. 5) RMS 39840 (soil-covered damp rocks, subject to submersion, W. bank of Chattooga R . below Ellicotts Rock, Rabun Co., Ga.). Superficially identical with typical R. mu/tijida in the regularly 2- 3-pinnate branching and prostrate growth. The ultimate segments bear a hyaline, unistratose wing (2)3(4) cells wide, with the median 0.5- 0.65 of the thallus pluristratose. Sexual branches occasionally are isolated, but often occur in sympodial clusters of 2- 3; in almost all cases they are synoecious, with 1- 2(3) pairs of antheridia at the base and 2- 3(4) pairs of archegonia distalIy. In a few cases apparently exclusively ¥ branches are found. None of the sexual branches seen are prominently elongated or bear numerous sex organs in 2 R. M . SCHUSTER: Studies on Metzgeriales, I 325 rows; no purely antheridial branches were seen. The plants are inseparable from typical R. multifida except for the high incidence of bisexual reproductive branches, all of which appear restricted to the margins of leading axes. 6) H.S. Conard, Aug. 1958 (from a stone along a brook, 4- 5 mi N. of Route 64, High­ lands-Cashier Rd., ca. 3 mi E. of Highlands, Macon Co., N.C.) is optimally developed, like the preceding collection; regularly 3-pinnate, with arching and procumbent, almost yellow­ green thalli. The hyaline margins of the narrow, ultimate segments are also optimally developed. Sexual branches, at first glance, appear to be all gynoecial and the plant appears dioecious. However, on isolated gynoecial branches single antheridia occurred in a basal cavity and on one plant a separate androecial branch was found. Sexual branches are almost all short, almost all confined to the margins ofleading axes, never occurring in pairs or sympodial clusters. These plants, inseparable from typical R . multifida except for the predominant occurrence of antheridia at gynoecial bases, are clearly transitional between "normal" R. multifida and snbsp. synoica. 7) RMS 11487 (bog at Grand Portage, Cook Co., Minn.). Freely 2- 3-pinnately branched, these plants represent a rather narrow phase (chief axes rarely over 800 ft wide ; penultimate segments 600 ft wide; ultimate segments often only 450 ft wide). Ultimate segments are very pellucid and thin, 3-stratose medially, with margins unistratose for a width of 3 cells; penul­ timate segments are 4 cells thick, and still unistratose for a width of 3 cells. The thickest seg­ ments found were only 6 cells high. Sexual branches are of particular interest; a few lingulate 6' branches, without archegonia at the apex are discernible. Other, perhaps more numerous, elongate 6' branches show 1 or 2 archegonia at the apex. More frequent are short and relatively broad branches, with laciniate and fringed margins, superficially appearing purely archegonial, with groups of 4-6 or more archegonia at the apices but 2-3, occasionally 4, antheridial cavities near the base. Rather rarely 1 or 2 6' branches occur at the base of a purely ~ branch, forming a sympodium. 8) RMS 28812 (on wet stones, along a cascading stream, lohns Creek, 6 mi N . of Marion, McDowell Co., N.C.) is critical in that it forms a transition between the rather small and delicate synoecious "typical" material (and concept) of subsp. synoica, and the more robust, autoecious "typical" R. m. subsp. multifida. Plants are 3-pinnate, rather regularly so, and quite robust. Ultimate segments are 600--750 (780- 850) ft wide x 90- 100 ft high, 3--4 cells high medially, thinning out to unistratose margins 2-3 cells broad; chief segments are biconvex, 7 or even 8 cells thick medially, the margins unistratose merely for a width of 1- 2 cells; such segments are 1000-1200 ft wide. The sexuality of these plants differs considerably from that of all the preceding collections. Isolated, elongate d branches of the "multifida" type are frequent; how­ ever, more frequent is a sympodium consisting of a short, laciniate-margined ~ branch, bearing at its base, on one or both sides, a linear d branch. I saw no ~ branches which were not subtended by 1 or 2 d branches, although isolated d branches were not infrequent. As already noted, these plants possessed sporophytes with broader valves than in preceding collections, averaging 250- 320 fl broad, with their cells slightly wider than in "typical" synoica, ca. 17-21 fl broad (cells in \5-17 rows). Spores also averaged barely larger (12-14.5 fl) and elaters were wider (9-1 1, but occasionally only 7-8 fl). 326 Journ. Hattori Bot. Lab. No. 62 1 9 8 7

Relationships with Extraterritorial Taxa In the extreme polymorphism of the sexual branches, R. m. synoica approaches the Chilean R. diversiflora Evans. Evans (1921, pp. 167- 172) found that the sexual branches were either d' or ~ , or d' at the base, ~ at the apex. Sympodial systems ap­ parently do not occur. The slight deVelopment of antheridial "chambers" (e.g., pro­ tective elaborations of the sexual branch surrounding the antheridia) closely matches the condition often found in subsp. synoica. R. diversiflora differs from R. m. synoica in branching type, with secondary branches often remaining short and rudimentary, e.g., in the form of latent rudiments, and in the less distinctly winged thallus, the uni­ stratose margin merely J or 2 cells broad. The Indonesian R. androgyna Schiffn. (Schiffner, 1900a, p. 44) also has sexual branches that are antheridial at base, archegonial at the apex, as well as purely male. This species also falls in the R. multifida complex (as does, evidently, R. diversiflora). Similarly, R. insular is Schiffn. (Schiffner, 1907, p. 66, pI. 6, figs. 1-7) is also hetero­ ecious, with some sexual branches ~ at the base, d' above, and with purely d' and ~ branches present in addition. This species, in the inversed position of the antheridia and archegonia on the bisexual branches, is clearly distinct from other taxa here considered. Its thallus characters, however, are extraordinarily close to those of R. m. synoica and R. m. multifida, particularly in the form of the thallus sections. S. Amell (1953) has indicated that two South African species [R. saccatiflora (Steph.) S. Am. and R. stephanii (8esch.) Jones] may possess bisexual branches, al­ though both of these species appear to more frequently have unisexual branches and, on the basis of the thallus sections, differ considerably from subsp. synoica.

7. R. stricta Schust., sp. n. Species autoecia; rami sexuales solum e marginibus lateralibus axim principalium orientes, erecti suberective (saepe, necnon, sursum flexi ut aut paralleli aut infra thallum sterilem iacant); omnes cel­ lulae epidermales atque cellulae a lae unistratosae guttis olei praeditae, (4)5-7(8) in pluribus cellulis marginalibus, (4-6)7-10(11-18) in alii cellulis epidermalibus. Species aliter R. multifidae similis. Type : Florida, Clay Co.: Gold Head Branch State Park (RMS 37212; hb. RMS). In over a 25- 30 year period I made six collections of R. multifida-like plants, in an area from central to western Florida. Oil-body data and detailed notes were made from each of these collections. Although (as Table 4 shows) some variability occurs, these populations seem to belong to a single species that differs from R. multifida in several critical features: (a) all epidermal cells have oil-bodies and these range, with isolated exceptions, from 2-6, even 8 (rarely) per cell, often forming a central cluster; (b) hy­ podermal cells usually also bear 3 or more - mostly 3- 9, rarely to 10-18 - oil-bodies in a central cluster; (c) plants are uniformly autoecious; sexual branches tend to form only along the older main axis, in 2- 3 pairs that may be juxtaposed (less often primary branches may intervene between succeeding sexual branches); (d) spores are rather small, 10-12 f1 in diam. In the type material, furthermore, sexual branches are erect and may be even slightly displaced under the thallus margins; d' branches may be twisted, so that an- TABLE 4. Riccardia multifida and R. stricta: Population criteria. ;.i [R. multifidal [R. strictal Criteria RMS40957 ?= RMS 37212 RMS42213 RMS44081 RMS44096 RMS44093 en ("l :t Ultimate segment margin unistratose, 2(3) (4)5-6(7) 2-4(5) ..,c: cell rows '" ;.>'" Wholly autoecious ( +) or partly + ,If + + If + + en synoecious ( _.), or geminate a Cl. branches (If) (ij. '"0 Epidermal cells, oil-body number 0 4-6 2-5(8) 2-5 (1)2-4(5) 1-3(4) to 3-5 :::l ~ per cell (mature cells) <> N (JQ Hypodermal cells, oil-body number 1(2) (4-6)7- 10(11 - 18) (3)5- 9 or more 2-3 3-5(9) 3-5(6) <> per cell ; size 8 x 10-14 to 9 x 20 I' large s;'"' . Sexual branches erect, or widely s e s-i .",....'" spreading, or intermediate

IV '"-..l 328 Journ. Hattori Bot. Lab. No. 62 1 987 theridial chambers open laterally or even ventrally. These criteria, subject to some variation, as is normal in Riccardia, appear to be quite adequate to separate a distinct species, R. stricta. In the type, gemmae are ab­ undantly formed - as is often the case in R. m . synoica, but very rare in subsp. multifida. If only the type plants were at hand, the status of R. stricta would be unassailable. In this plant epidermal cells usually have 4-6 or 5-7(8) oil-bodies, hypodermal, (4-6)7- 10(11- 18) oil-bodies and, erect sexual branches, usually segregated to limited portions of the main thallus, are the norm. However, three collections from Liberty Co., Florida (RMS 44081 , 44096, 44093), collected within a small area, cause some concern: on an average they show a lower number of oil-bodies in epidermal cells (usually 2-5, extremes of I and 8 in isolated cells) as well as in hypodermal cells (usually 3- 5, extremes of 2 and 6- 9). Presence of oil-bodies in all mature epidermal cells, including marginal ones, seems to conclusively separate even these plants from all phases of R. multifida. Unfor­ tunately, they all possess sexual branches which tend to be suberect or inclined, with reference to the main axis, and are never arched basally so as to lie parallel to the axis. One of these collections (RMS 44081) also deviates from the remainder in having some sexual branches sympodial or geminate (Table 4). Discovery of R . stricta visibly complicates identification of dead plants of the multifida complex. When there are no oil-bodies present, then only the tendency for sexual branches to occur in 2- 3 juxtaposed pairs, limited in origin to the main axis, seems definitive - and, with study of more material, even this may not prove a fully stable criterion. Variation within R. stricta is shown in Table 4, contrasted to a "normal" Floridian plant of R. multifida subsp. multifida. The preceding treatment of the three multifida-like entities (multifida s. str. , syn­ oica, stricta) largely serves to expose for further investigation a wide range of problems, some of which can be resolved only with mass collections (and immediate study of living plants), perhaps supplemented by cultivation experiments. This study, if it does nothing else, should demolish the former, "comfortable" idea of a single taxon in the multifida complex, showing limited variation. Instead, one sees a partial cline within the species proper in oil-body criteria and, in the Southeast, one sees entities split off (synoica, stricta) which remain extremely difficult to interpret. The data presented are to be regarded as only a mere beginning in the process of resolving species structure and limits.

REFERENCES Arnell, S. 1953. Hepaticae collected in South Africa 1951. T. Sv. Bot. Tidskr. 47(1): 107-18,7 figs . Dickson, J. 1790. Fasciculus Secundus Plantarum Cryptogamicarum Britanniae. Pp. 1-31. Evans, A. W. 1921. The genus Riccardia in Chile. Trans. Conn. Acad. Arts Sci. 25 : 93- 209, figs. 1-13. - - . 1938. The structure of the capsule wall in certain species of Riccardia. Ann. Bryol. 10 : 20- 35, 6 figs . Frye, T. C. & L. Clark. 1937-47. Hepaticae of North America. Univ. Wash. Publ. BioI. 6(1 - 5): 1- 1018. Jones, E. W. 1958. An annotated list of British hepatics. Trans. Brit. Bryol. Soc. 3(3): 353- 74. R. M. SCHUSTER: Studies on Metzgeriales, I 329

Little, E. R. B. 1968. The oil-bodies of the genus Riccardia Gray. Trans. Brit. Bryol. Soc. 5 : 536-40, 1 fig. Macvicar, S. M. 1926. The Student's Handbook of British Hepatics. 2nd ed., pp. i-xxix, 1-464. Eastbourne. Mizutani, M. & S. Hattori. 1957. An etude on the systematics of Japanese Riccardias. J. Hattori Bot. Lab. 18: 27-64, figs. 1-12. Muller, K . 1939. Untersuchungen uber die Olkorper der Lebermoose. Ber. Deutsch. Bot. Gesell. 57(8): 325-70, pIs. 14-15. --. 1951-58. Die Lebermoose Europas, in Rabenhorst's Kryptogamen-Flora, 3rd ed., 6 : 1-1365, figs. 1-514. Schiffner, V. 1900. Kritische Studien Gber Jungermannia sinuata Dicks. und Aneura pinnati/ida N. ab E., sowie Gber Riccardia major S. O. Lindb., etc. Lotos 1900(8): 1-26 [of reprint]. --. 1900a. Die Hepaticae der Flora von Buitenzorg. I. Pp. 1-220. Leiden. - - . 1906. Bemerkungen Gber Riccardia major S. O. Lindb. Osterr. Bot. Zeit. 56(5-6): 169-74. --. 1907. Die Lebermoose der deutschen SGdpolar-Expedition 1901-1903. Deutsche SGdpolar- Exped. 8(Bot.): 59-80. Schuster, R. M. 1949. The ecology and distribution of Hepaticae in central and western New York. Amer. MidI. Nat. 42(3): 513-712, pIs. 1-18, figs. 1-13. --.1953. Boreal Hepaticae, a manual of the liverworts of Minnesota and adjacent regions. Amer. MidI. Nat. 49(2) : i-v, 257-684, figs. 1-16, pIs. 1-110. - - .1980. The Hepaticae and Anthocerotae of North America. Vol. IV. Pp. 1-1334, Columbia Univ. Press, New York. --. 1988. Ibid. Vol. V. [In press] -- & K. Damsholt. 1974. The Hepaticae of West Greenland from ca. 66° N. to 72° N. Meddel. om Gronland 199(1) : 1-373, figs. 1-33, 80 maps. Sharp, A. J. 1939. Taxonomic and ecological studies of eastern Tennessee Bryophytes. Amer. MidI. Nat. 21: 267-354. Showalter, A. M. 1926. Studies in the cytology of the Anacrogynae. H. Fertilization in Riccardia pinguis. Ann. Bot. 40 : 713-26, figs. 1-4, pIs. 25-27. --. 1928. Ibid. V. Hybrid fertilization in Riccardia pinguis. La Cellule 38: 295-348, figs . 1-29, pis. 1- 5. Trevisan, V. 1877. Schema di una nova classificazione delle Epatiche. Mem. Reale 1st. Lomb., Ser. 3,4: 383-451.