Studies in the Marchantiales ( Hepaticae ) from southern Africa . 9 , The genus Marchantia and its five local species

In this, the ninth and final article in the series on southern African Marchantiales. a taxonomic account is given ol the genus Marchantia which is locally represented by five species. Two of the three subgenera that are recognized, namely subgenus Marchantia (with two species, M. polymorpha subsp. ruderalis and M. berteroana). as well as subgenus Chlamidium (Corda) Bischl. which is divided into three sections, namely Paleaceae (with M. paleacea subsp. paleacea). Chlamidium (with M. pappeana subsp. pappeana) and Papillatae (with M. debilis) are treated. The third subgenus. Protomarchantia Schust.. is absent from the region. Corrections need to be made to the Marchantia species given in Magill & Schelpe's (1979) checklist and in Arnold & De Wet (1993). Descriptions and illustrations of the taxa together with distribution maps, their ecology and a key to the subgenera and species are provided. Only traditional taxonomic methods were employed and this treatment closely follows that of Bischler-Causse ( 1993a). the recognized world authority on the group. All southern African specimens held at BOL and PRE. as well as a few from other herbaria have been studied and some new collections have been added. It is shown that M. polymorpha subsp. ruderalis has been introduced, as it is only known from local nurseries. The presence here of M. paleacea subsp. paleacea is confirmed, although it is rare. Otherwise little that is new could be added to the exhaustive studies by Bischler-Causse (1993a).

Thalloid.smallish to medium-sized to large, flat and ungrooved, relatively delicate or firm and occasionally rather leathery, green to dark green or greyish green, along margins sometimes purplish, rarely all over dorsally and occasionally also ventrally; dorsal face with distinct po lygonal areolae, each w ith a pore; in crowded mats, some times in partial rosettes, hygrophytes.requiring high humidity and mostly unable to sustain life dry: growing on damp soil of vertical stream banks, at waterfalls, dams, weirs and canals, sometimes on wet rocks, rarely on rotting wood.
Branches broadly band-or narrowly ribbon-shaped, pseudodichotomously furcate, without lateral or apical inno vations from keel, ventrally thickened medianly and tapered toward margins, which are lobulate.crenulate.undulate or entire, apex notched, with median scale appendages recurved over edge.Dorsal epidermal cells generally unistratose.often without chloroplasts, walls thin or slightly thickened but lack ing trigones; air pores compound, encircled by several su perimposed concentric rings of cells, some above epidermis, others projecting into air chambers below, the latter in a shal low, single layer, densely packed with 2-4( 5)-celled assimilatory filaments; storage tissue compact, sometimes with a few sclerotic cells and/or mucilage cavities, also with scat tered oil cells each containing a single, large oil body, these present as well elsewhere in thallus and scales; numerous rhizoids ventrally, some smooth, others pegged, rarely with inner thickenings spirally connected.Ventral scales in 4 or more rows, covering part or all of ventral face and rarely projecting beyond m atin s, median scales bluntly triangular, constricted where joined to appendage, laminal scales smaller, sometimes in double rows, lacking an appendage, marginal scales rarely present.Cupules borne dorsally on thalli, hollowed, contracted below, flaring above, margin cili ate, lobed-ciliate.dentate or nearly entire, containing discoid gemmae that reproduce vegetatively.
Dioicous.Gametangiophores stalked.Stalks arising at apex of main and/or lateral branches, basally sometimes surrounded by large scales, generally without an append age, along their length bearing filiform scales, 2^\ rhizoid turrows and 0 -2 bands of air chambers with compound air pores.Antheridiophores with receptacular discs rather flat, lobed or divided into rays, antheridia and compound air pores on dorsal side, several rows of scales per lobe beneath.Archegoniophores w ith rece p tacles convex above, lobed or divided into ± Hat rays, dorsally with compound air pores, below with scales and archegonia.each one surrounded by calyptra and pseudoperianth, in groups that are enclosed by bivalved involucres, occurring alternate with the lobes or rays (in African species).Sporophytes consisting of foot, short seta (elongating later) and subglobose capsule, its unistratose wall with annular thickenings, dehiscing irregularly.Spores small, thin-walled, ± triangular-globular, ornamentation with nu merous thin, irregularly convoluted ridges or with few wide ridges separated by granules, the 2 faces similar or dissimilar.Elaters tapering at ends, bi-or trispiral.Chro mosome number: n = 9 (basically).
On the basis of differences in spore morphology, ger mination patterns and flavonoid patterns, the genus is sub divided into 3 subgenera: M anhantia, Chlamidium and Protomarchantia R.M. Schust.The latter is absent from the region.Key to local subgenera, sections and species la Thalli with margins plicate-crisped, crenulate or lobulate, dorsally with or without dark median band; epidermal pores with walls of cells bordering inner opening slightly or strongly projecting and pores then cruciate; scales in 4-6 rows, covering 3 á or all of ventral surface and then also extending beyond thallus margins; appendages o f median scales orbicular or reniform or ovate, marginal cells slightly or strikingly smaller than inner cells; laminal scales much wider than long; cupules with ciliate lobes at margins, externally with papillae; male receptacles peltate, shallowly dissected into 6 -10 broad lobes: membranous margins of rays crenulate or entire and then with very small cells; female receptacles deeply dissected into 9-11 terete rays, with or without papillae; stalks with single broad band of air chambers; margins of involucres with ciliate lobes; spores 8-16 pm in diameter, ornamentation on 2 faces similar, with numerous narrow convoluted ridges  4a Thalli 6.0-8.5 (-10.0)mm wide; dorsally without dark median band; appendages of median scales large.520-550 x 375-530 pm, inner cells also comparatively large, 75.0-87.[OXF, lecto., typo., fide Bischl. & Boisselier-Dubayle: 363 (1991) (photo, of typo, in PRE!)].
Marchantia polymorpha.w hich has been know n since classical times, is widespread.It has frequently been de scribed but until recently its taxonomy has been unre solved because proper lectotypification had not been done.Amell (1963) reported it in southern Africa from Golden Gate, near Clarens in the eastern (Orange) Free State and from Zimbabwe [Southern Rhodesia], near Odnazi River Bridge.Umtali.These specimens are not held at PRE or at BOL and up to now. the presence here of M. polymor pha under natural conditions has not been confirmed.Bischler-Causse ( 1993a) stressed the need for such con firmation.It is therefore considered worthy of note that female specimens of M. polymorpha with cupules have recently been collected at Johannesbuig Botanical Garden.Glen 3468 & 3728. in a shade house and also at Sterlig Nursery.Krugersdorp.Perold & Koekemoer CH 13640 (Figure 3).The plants are clearly introduced, but a de scription is nevertheless given.To complete the descrip tion and illustrations fresh male plants collected on a pavement in Ix'dbury.England.Perold & Koekemoer 3248.had to be used.since they grow as weeds in man-made habitats and agree in other respects with this subspecies, as distinguished by Bischler-Causse & Boisselier-Dubayle (1991).They are characterized by the fresh thalli being prostrate and bright green, with a dark, rather indistinct and discontinuous me dian band with elongated air chambers, by the dorsal air pores being 50.0-62.5fjm wide, the dorsal epidermal cells 3 5 -5 5 pm long and the median scale appendages having toothed margins and being 350-500 x 510-760 pm in size.
The other 2 subspecies of M. polymorpha, polymorpha and montivagans, have so far not been found in southern Af rica.They are distinguished by occurring in natural habi tats, with the former growing more or less erect, being dark green, with a conspicuous median dark band lacking air chambers, having small air pores, short dorsal epidermal cells and the median scale appendages having entire mar gins; the latter subspecies is prostrate, yellow-green, lacks a median band, the air pores are lai^er, the dorsal cells are of intermediate length and the median scale appendages are of average size and the margins toothed.The distin guishing characters of the subspecies are given, in case M. polymorpha subsp.polymorpha and M. polymorpha subsp.montivagans are found in southern Africa in the future.
Lectotypification of M. polymorpha was recently done by Bischler-Causse & Boisselier-Dubayle (1991) by means of a Dillenian illustration and by a specimen held in OXF (i.e. a typotype).This corresponds to the first of three Linnean varieties (Linnaeus 1753), namely var.[«], which was later called 'aquatica'.This first variety [<*] forms the basis for the application of the specific name (Isoviita 1970).However, since the lectotype of M. poly morpha var.polymorpha of Linnaeus corresponds to the taxon 'aquatica' (at any rank), it renders that name ille gitimate, because the epithet 'polymorpha' would be used for a taxon not including its type.The best procedure seemed, therefore, for Bischler-Causse & Boisselier-Dubayle to describe their three newly separated electro phoretic groups (in three enzyme systems: esterases, peroxidases and acid phosphatases) as subspecies, give two of them new names and select good, recent type specimens.M. polymorpha L. subsp.polymorpha thus cor responds to the taxon formerly called 'aquatica'; M. po\ymorpha L. subsp.ruderalis Bischl.& Boisselier-Dubayle corresponds roughly to the former polymorpha 'sensu stricto' and M. polymorpha L. subsp.montivagans Bischl.& Boisselier-Dubayle roughly to the former 'alpestris' .
On chemical evidence Markham et al. (1977) had pre viously concluded that the three taxa of M. polymorpha should be treated as varieties rather than as separate spe cies, since they all possess identical flavone glucuronides.
The time of going to press of Schuster's (1992) monu mental work pre-dated the publication by Bischler-Causse & Boisselier-Dubayle (1991) on the lectotypification of M. polymorpha.but judging by some ot the remarks con tained in it.it is by no means certain that he would have accepted it.He still subscribes to the genetic analyses of Burgeff (1943), although they have been shown to be out of date, and he therefore treats the segregates of M. po-Ixmorplui as distinct species.
As mentioned above, in southern Africa M. polymor pha subsp.ruderalis is only known from man-made sites, i.e. in nurseries.Its presence in natural habitats has not been confirmed.Asakawa et al. (1988) refer to the distri bution ol sescjuiterpenoids and cyclic bis-bibenzyls in southern African collections of M. polymorpha, but it is not known where the material was obtained from or who identified it.Magill & Schelpe (1979) and Arnold & De Wet (1993) list M. polymorpha as occurring in southern Africa, but these lists are based on erroneous information in the literature.
Marchantia polymorpha is very similar to M. ber teroana, but can be distinguished from it by the marginal scales which are always present and which mostly extend beyond the crisped, sometimes crenulate thallus margins: by the air pores not being cruciate: by the presence of numerous papillae on the rays of the female receptacle and by the appendages of the median scales bordered by larger cells.
Dioicous.Antheridiophore arising from apex of termi nal segment of main or short lateral branch, raised on stalk (Figure 4N), 2 3 -3 0 mm long, in transverse section rounded, diam eter ± 10 0 0 pm , cortical cells small, 10.0-15.0x 12.5-17.5pm. with thickened outer wall, medullary cells larger, mostly angular, 2 2 .5 -45.0 x 15.0-45.0pm.band of air chambers absent but with 2 rhizoid furrows, ± 162.5 x 100.0-125.0um; scales at base o f stalk large (Figure 4P).hyaline or purplish, roughly triangular or oblong, sometimes slightly bulging, lacking an appendage, up to 12(X) x 14(H) pm. cells in body of scale 4-6 -sided, often with sinuous walls, 47.5-87.5 x 224-25.0pm.along upper margins 1 or 2 rows of much smaller cells.12.5-25.0x 12.5-30.0pm. with up to 10 scattered oil cells throughout; scales along length o f stalk (Figure 4 Q) hyaline, filiform, sometimes only 3 cells wide but sometimes wider and up to 9 cells wide; receptacle (Figure 4M) up to 10 mm in diameter, shallow ly dissected into 8(9 ) ± symmetric lobes, basal sinus ± 80° w ide; mar gins of lobes membranous, brownish or hyaline, minutely crenulate.with I or 2 rows of small cells (Figure 4S).mostly rectangular across.15.0-20.0x 10.0-22.5 pm, in ner cells larger.52.5-87.5 x 37.5-40.0pm; median scales on ventral side of lobes (Figure 4R) hyaline.750-1375 x 1000-1875 pm. cells in body of scale 4-6-sided, up to 125 x 50 pm.thin-walled, at margins smaller.± 30.0 x 17.5 pm.appendage absent or present.± 267.5 x 200.0 pm.oblong, rounded apically.not or hardly constricted at join with scale, inner cells 40.0-42.5 x 15.0-22.5 pm.smaller at margins.Archegoniophore arising from apex of terminal seg ment of main or short lateral branch; raised on stalk 48-65 mm long, in transverse section (Figure 4 0 ) 1000 x 925 pm.constricted on inner side of single band of air cham bers.cortical cells small.12.5-20.0x 12.5-25.0pm.outer wall thicker, medullary cells angular, up to 60 x 45 pm. in between and at centre of stalk with smaller cells ± 25 x 20 pm. containing 2 rhizoid furrows, ± 240 x 105 pm; scales at base o f stalk (Figure 4T).brow nish or hy aline, without appendage, oblong or ovate, with apex rounded, large.1575-2000 x 800-1250 pm.inner cells 4-6-sided, walls mostly straight, sometimes sinuous.75.0-125.0x 27.5-42.5pm.margins apically occasionally slightly cre nulate.with rectangular cells arranged at right angles to margin, small.10.0-25.0x 12.5-25.0pm; scales along length o f stalk (Figure 4U) hyaline, filiform, up to 6500 pm long. 2 or 3(4) cells wide, their average size ± 112.5 x 25.0 pm; receptacle (Figure 4L) up to 10 mm in di ameter.nearly symmetric, dorsally with small round me dian projection, deeply divided into 9 linear rays, up to 2625 x 550 pm.basal sinus ± 45° wide, margins distally slightly decurved and terete in transverse section, lacking papillae toward apex; involucres with margins hyaline or purplish, with tapering ciliate lobes (Figure 4V Marchantia tabularis was described from specimens collected on Table Mountain and was placed in synonymy under M. berteroana by Schiffner (1896).Although Stephani (1898Stephani ( -1900) accepted Schiffner's decision, he still applied the epithet 'tabularis and was followed in this by Sim (1926).Amell (1963) gives only brief notes on M. berteroana.Bischler-Causse (1993a) recognized that M. contracta.collected by Krauss at Devil's Peak, also belongs here.M. berteroana is quite variable in size, but generally the plants arc large.Sometimes six rows of ventral scales arc present and some authors, e.g.Hiissel de Menéndez (1963) and Engel (1990) recognize these as belonging to a separate variety, namely var.polylepida.However, several authors (Campbell 1965;Bischler 1984) have pointed out that the number of rows of scales is too unstable to warrant the designation of a variety.Schuster (1992) has assigned M. berteroana to his new monotypic section.Berteroanae.on the absence ot marginal scales, on the cruciate inner openings of the epidermal pores w ith six rings of cells and on the tiny marginal cells of the median scale appendages.Bischler-Causse (1993c) is, however, not convinced that this splitting is necessary, since marginal scales are fairly frequently present and the pores are often similar to those in other species of subge nus Marchantia.
Mcirchantia berteroana generally grows on damp soil, and sometimes on wet rocks, at stream banks, near wa terfalls, along paths, in kloofs, passes, ravines, gorges, in forests under trees or in burnt-over areas.
It is widely distributed in the southern hemisphere, from South America, south to the Antarctic Peninsula and north to Costa Rica, islands of the Atlantic and south In dian Ocean, southern Africa, Australia, Tasmania, New Zealand.New Guinea.New Caledonia.Java and Sulawesi (Bischler-Causse 1993a).In southern Africa (Figure 3) it is known from the Western Cape, which has winter rain, and from Kwazulu-Natal as well as the Northern Province [Northern Transvaal] which have summer rain.Exact lo calities of two of these collections by Wilms and by MacLea are not known.This distribution indicates that the species seems to be indifferent to the seasonality of the rainfall, in contrast to several other members of the Marchantiales which are ± restricted to either winter or summer rainfall areas.
O f the 50 specimens examined 36% had cupules, 34c/c had antheridiophores and 46°7c archegoniophores; only 6 % had both.Specimens of M. berteroana are easily distinguished by the tiny marginal cells of the median scale appendages, by the cruciate dorsal pores and by the lobulate thallus margins.The membranous margins of the rays of the male receptacle also have very small cells.Otherwise it is quite similar to M. polymorpha, except for the latter having pa pillae on the rays of the carpocephalum.The ornamenta tion of their spores is also quite similar.Thallus branches rather narrow, from 2.4 to ± 10.0 mm wide, rarely more, margins nearly flat, entire, sometimes slightly undulate, rarely crisped.Dorsal epidermis with out papillae; air pores surrounded by (4-)5-7 concentric rings of cells, at inner openings with straight or convex walls, rarely with pronounced, rounded processes, and pores then cruciate: storage tissue often with scattered sclerotic cells.Scales in 4 rows, covering '/4 to 2/3 of ven tral face, with oil cells present or absent, median scales with appendages variously shaped, orbicular, ovate or tri angular, apically often acuminate, acute or apiculate, sel dom rounded; margins entire, crenulate-serrate, coarsely toothed or lobed; laminal scales as long as, or longer than wide, sometimes in 2 incomplete rows on either side of median scales, apically acute or obtuse, with papillae, up per cell walls lacking trigones.Cupules with margins cili ate, almost entire, or with ciliate lobes, externally without, or rarely with papillae.
Dioicous.Antheridiophores with receptacle symmetric or asymmetric, palmate or rarely peltate, rays shallowly or deeply dissected; stalks with 2(-4) rhizoid furrows, air chambers in a single band or absent.Archegoniophores with receptacle symmetric, or sometimes asymmetric; dis sected into 5-9 rays, flat or convex but never terete; scales of receptacle in African species apically with marginal cells rectangular and long axis parallel to margins; involu cre margins ciliate or crenulate to entire, rarely with ciliate lobes; stalks with 2-\ rhizoid furrows, air chambers in 1 or 2 bands.Spores larger than in subgenus Marchantia, 2 0 -3 5 pm in diameter; ornamentation on distal face gen erally with thick ridges separated by dense granules; on proximal face with coarse granules only, triradiate mark and thick wing usually present.Thallus with branches (3.5-)6.0-8.0(-11.0)mm wide, irregularly spaced, narrowly divergent.Dorsal epidermis without papillae: air pores with inner opening cruciate, inside walls of bordering cells strongly protuberant.M e dian scales with appendage oblong, ovate or suborbicular, apically rounded, acute or shortly apiculate.basally cor date, width across broadest part 650-750 pm.margins en tire, crenulate or slightly denticulate; with I, 2 or more oil cells.Cupules with margins triangularly lobed and cili ate, externally with 1 -or 2 -celled papillae.

Subgenus
Dioicous.Antheridiophore on stalk lacking band ot air chambers and basally surrounded by large scales without an appendage; receptacle peltate, shallowly dissected into 6 -1 0 broad, rounded lobes, dorsal surface without papil lae.Arche goniopho re on stalk having a single band of small air chambers, basally surrounded by large scales, their apices rounded, rarely with a short appendage; re ceptacle bearing prominent median projection dorsally, deeply divided into 8 or more convex lobes, basally costate, apically truncate or hardly broadened, emarginate; involucre margin with ciliate lobes.Spores 19-24 pm 111 diameter, ornamentation on distal face lacking areolae, mostly covered with a rather featureless, granular layer or with very irregular ridges, broken up or tolded in or con voluted; proximal face different, thickly winged, triradiate mark faint, covered with dense granules or centrally with narrow, irregular granular ridges.Only M. paleacea be longs to this section.The ornamentation of its spores is distinctive.It also differs from the other two sections in subgenus Chlamidium.by the shape of the female recep tacle and by the ciliate.lobed margins of the involucres and the cupules.
Marchantia paleacea has been known since the time of Micheli (1729).who described and illustrated it: but it was not accepted by Linnaeus (1753).After M. polymor pha. it was to become only the second species in the genus to be recognized from Europe, and was described by Bertolini (1817) from material collected in Italy.
It has been placed in subgenus Chlamidium on account of the four rows of ventral scales which are restricted to the median part of the thallus.It is assigned to the monotypic section Paleaceae because of the shape of the female receptacle, the structure of the margins of the involucres and the cupules.which have ciliate lobes (Bischler-Causse 1993a) with papillae externally.
The species has a circumtethyan distribution, ranging from the southern stales of the USA.Mexico and Central America, to the Mediterranean, the Caucasus, the Hima layas.and to the Far East (Bischler 1988).In Africa (and the neighbouring islands), it is known from Algeria.Ethio pia. the Azores.Terceira and Réunion.Bischler-Causse ( 1993a) states that its presence on the Canary Islands.Ma deira and in Morocco needs confirmation.A specimen from Madeira.Tavares (LISU) was seen by me.and its archegoniophores were studied and are illustrated in Fig ure 5L R. The presence of M. paleacea on Madeira is thus confirmed.Bischler-Causse ( 1993a) thought that the single specimen, Rankin 206 (BM).from the vicinity of Pilgrim's Rest.South Africa, that she had seen, might have been mislabelled.A computer printout at PRE, however, revealed that several other bryophytes were collected by Rankin in the same area, with collecting numbers both lower and higher than the one referred to.so that it was unlikely to have been mislabelled.I have recently also collected it near Pilgrim's Rest (Figure 3) on a steep earth bank of the Blyde River, where it grew down to the water's edge together with M. debilis.The plants were sterile unfortunately, as was Rankin's collection, but both had cupules.As noted above, archegoniophores from Ma deira were used for the description and illustrations, but no antheridiophores were available for study.
In the Far East a subspecies.M. paleacea subsp.diptera (Nees & Mont.)Hatt.. is recognized (Bischler-Causse 1989a).It is distinguished from subsp.paleacea by the epidermal pores of the thallus usually being surrounded by 7 or 8 rings of cells, by the frequent presence of non functional female receptacles and by the marginal cells of the median scale appendage having the long axis oblique to perpendicular to the margins (not parallel to).
Marchantia paleacea subsp.paleacea is regarded as morphologically stable and can be distinguished from the other species of subgenus Chlamidium by its cruciate epi dermal pores and its cupules which have margins with ciliate lobes.The appendage of the median scales is ovate to orbicular.Schuster (1992) regards M. berteroana as the closest ally to M. paleacea.because it also has cruciate epidermal pores and its cupules have margins with trian gular lobes bearing teeth (or cilia) as well.M. berteroana is however, classified in subgenus Marchantia.

M archantia section Chlam idium
Thallus with branches (6.0-)7.0-8.5 (-10.0)mm wide, generally rather remotely spaced and narrowly divergent.Dorsal epidermis without papillae: air pores with inner opening bordered by cells, their inside walls convex to nearly straight or w ith short, rounded processes.Median scales with appendage ovate to orbicular or broadly tri angular.apically rarely obtuse, mostly acute, sometimes shortly apiculate.basallv rounded or cordate, w idth across broadest part 375-530 pm.margins entire or sometimes bluntly toothed: with 1 or 2 oil cells, rarely more numer ous.Cupules with ciliate margins, cilia up to 6 or 7 cells long and 3 cells wide basally.exteriorly sometimes also with several cilia.Dioicous.Antheridioplwre on stalk which mostly lacks bands of air chambers but with 2 or 3 rhizoid furrows; basally surrounded by quite large scales, often with an appendage: receptacle palmate, shallowly to deeply dis sected into 6-8(-10) rays, dorsal surface with or without papillae.Archegoniophore on stalk having 2 bands ot air chambers and 2 rhizoid furrows: basally surrounded by quite large scales, often with an appendage and rather similar to median scales ot thallus; receptacle with or without small, median projection dorsally.shortly divided into 9-11 rather flat lobes, sometimes basally narrow, w id ening slightly toward truncate apex: involucre margins shortly to long ciliate.Spores 20-30 pm in diameter, or namentation on distal face with wide, irregular, smooth ridges forming incomplete areolae tilled with nodules; proximal face entirely covered w ith nodules.
Of the southern African taxa.only M. pappeana be ltings in this section.The ornamentation of its spores is D -F , air pore from above; E i, E2, from below; F, t.s.o f dorsal epidermal cells and part of air chamber.G, margin.H -J, scales: Hi, H :, laminal; Ii, I2, median; J 1-J 3, appendages of m edian scales.K i, K2, margins o f cupules; L -Q , receptacles: L i, L2, 9 from above; M, 9 from side; N, <f; O, t.s.o f 9 stalk; P, t.s. of <f stalk; Q, median scale o f <f.R -V , scales: R, alongtf stalk; S, foot of cr stalk; T 1-T 3, 9 receptacle; U, foot o f 9 stalk; V, along 9 stalk.W, margin o f ray; X, margin of involucre.A, G, H i, h , J2, K i, L i, L2, M, T 1-T 3, X, Koekem oer 1050, B, C, F. referred to as the chenopoda type; there are.however, two other spore coat ornamentation types in the section (Bischler-Causse 1989a).The section is distinct in the shape of the female receptacle and in the ciliate margins of the involucres and cupules.
Dioicous.Antheridiophore arising mostly from apex of term inal segm ent of main branch, raised on stalk.9_ 1 8(-32) mm long, diameter 775-925 pm. in transverse section (Figure 6 P) with one row of small cortical cells.
Although M. pappeana had already been described by Lehm ann in 1857 and was m entioned by Stephani (1898Stephani ( -1900)), the name has been neglected by subsequent authors and specimens in most herbaria, including PRE. are labelled as M. parviloba, M. planiloba or M. wilmsii.The species is listed as M. parviloba in Magill & Schelpe (1979).Several authors had suspected, however, that M. parviloba was synonymous with M. planiloba (Vanden Berghen 1965;Jones & Harrington 1983).Bischler-Causse (1993a) found that only seven of the 18 specimens cited by Stephani.belong to M. pappeana and of the 30 kept in his herbarium, only 11 belong here.Amell (1963) mistakenly considered M. pappeana to be a synonym of M. berteroana.He may.however, have been misled by a specimen in S (where Lehmann s origi nal collections are kept) which was labelled M. pappeana.but actually contains M. berteroana.as was shown by Bis chler-Causse ( 1993a).Amell (1963) merely surmised that M. parviloba would be found in the northern parts ot South Africa, but he had probably only seen specimens from Zaire [Congo].Tanzania [Tanganyika] and Zim babwe [Southern Rhodesia).
Marchantia pappeana often grows in the same locali ties as M. debilis.on vertical soil banks of streams, at waterfalls, at sluice canals, very rarely on rotting wood or on rocks, in open grassland or in forests, sometimes in deep shade.
It is widely distributed in tropical Africa.Bischler-Causse (1993a) reporting it from the Cape Verde Islands to Ethiopia and south to southern Africa, generally at an altitudinal range of I 000-2 500 m.In southern Africa (Figure 8) it is known from the Northern Province |North ern Transvaal | and Eastern Transvaal.Gauteng [PWV], Swaziland.Kwazulu-Natal.eastern [Orange] Free State and Lesotho.It has also been collected at Kirstenbosch Botanical Garden a number of times and the type speci men is from Promontorium Bonae Spei.
O f the 50 specimens examined, b2c/c had cupules, 20r/r had antheridiophores and 34ch had archegoniophores; only 6r/r had both.Morphologically the species is variable, ex hibiting this trait even among specimens from the same geographical area.Generally, however, it can be distin guished by being larger than M. debilis and by lacking a dark median line on the dorsal surface of the thallus; its median scale appendages are large and often marginallv toothed, with the inner cells large, presenting a Moose' appearance; its cupules have longer cilia: the female re ceptacle is shortly divided into rays and the involucral margin is ciliate: androgynous branches in the female re ceptacle are sometimes present.
Marchantia pappeana s u b s p .pappeana is d is tin guished from M. pappeana subsp.robusta.a close relative in South India and Sri Lanka, by the latter having numer ous sclerotic cells and mucilage cav ities in the thallus; oil bodies in the median scale appendages are.however, ab sent.Only M. debilis of the southern African taxa belongs to this section.Bischler-Causse (1993a) states that it is closest to the Asiatic species, M. emarginata subsp.tosana.The ornamentation of the spores is of the papillata type.The section differs from sect.Paleaceae and sect.Chlamidium in the shape of the female receptacle, with the lobes costate basally and broadened apically.
The syntypes of M. wilmsii cited by Stephani are McLea in Rehmann Hep.austro-afr.exs.I and 'Prope Lydenburg et Greytow n Dr W ilm s'.Bischler-Causse (1993a) states that the McLea specimens are male and correspond to M. pappeana; the Wilms specimens from Lydenburg are female with cupules, or are sterile and also belong to M. pappeana, whereas the Greytown specimens are male with cupules and contain M. debilis.Bischler-Causse (1993a) concludes that Stephani probably had M. pappeana in mind, and not M. debilis, since he clearly described M. pappeana under the epithet M. wilmsii.In Stephani's herbarium, she found that 13 of the 16 M. wilmsii' specimens belong to M. pappeana and only three to M. debilis.
It is indeed fortunate that Bischler.with her long and intimate experience with Marchantia species, was able to resolve the taxonomy of this species, since neither Vanden Berghen (1954. 1965). nor Amell (1963) nor Jones & Har rington (1983) managed to do so.Jones & Harrington (1983) regarded 'M.wilmsii' as the commonest Marchan tia species in tropical Africa and readily recognizable by the presence of the dark dorsal line.Specimens held at PRE. that belong here, were mostly identified as M. wilm sii.The species is also listed as such in Magill &Schelpe (1979) andin Arnold &De Wet (1993).
Marchantia debilis generally grows on damp soil on vertical stream banks or waterfalls, on mud (or occasion ally on stones) of stream beds, at weirs, or sluice canals, on stone dam walls kept wet by spray, and on soil overlying sandstone or granite, in open grassland or in forests, sometimes in partial shade.
It is widely distributed in Africa, Bischler-Causse (1993b) stating it to occur from Morocco to South Africa, as well as on Reunion and also in the eastern part of Madagascar.In southern Africa (Figure 8 ) it occurs in the summer rainfall areas of the Northern Province (Northern Transvaal I and Eastern Transvaal, Gauteng |PW V ], Swaziland, Kwazulu-Natal, eastern [Orange] Free State, Lesotho and Eastern Cape.
Sterile plants of M. debilis can be distinguished from M. pappeana, the species it has frequently been confused with, by the smaller size of the rather ribbon-like thallus, by the dark median line on the dorsal face of the thallus, by the smaller appendages of the median scales and by the shortly ciliate or almost entire margins of the cupules.Fertile plants should present no problem to identify as the smallish male and female receptacles, the latter with deeply divided lobes, are quite distinctive and the margin of the involucre is entire.