Tuatara: Volume 13, Issue 2, July 1965
Marchantia Species of New Zealand
Marchantia Species of New Zealand
Marchantia has Been Recognized for many centuries and in fact M. polymorpha is the original liverwort for because of its shape it was used by mediaeval herbalists as a remedy for diseases of the liver. The genus name was first used by the French botanist Marchant in 1713 in memory of his father. Marchantia is found in all countries and is especially rich in species in the tropics. The three species mentioned below which occur in New Zealand are confined to the Southern Hemisphere.
Key to the New Zealand Species
|A.||Ventral scales extending nearly to the margin of the thallus||1 M. berteroana|
|Ventral scales confined to the central region of the thallus||B|
|B.||Upper surface smooth||2 M. foliacea|
|Upper surface rough||3 M. macropora|
1. M. berteroana L. et L.
in Lehmann Nov. Stirp. Pug. 6:2, 1834.
Distribution and Nomenclature
M. berteroana was originally described from plants collected in Juan Fernandez but is now known to be widely distributed in southern regions. Herzog (1934) has shown that a form present in Columbia, which he has called var. polylepida, differs from the type of the species in having 6 rows of ventral scales instead of 4. The same form is found also in Chile and Argentina (Hassel de Menendez, 1962). For New Zealand, the species is listed under the name of M. tabularis by Hooker (1867), and under the same name also by Stephani but in this case with berteroana added as a synonym (Stephani, 1900). However, Schiffner has shown that the name berteroana has priority (Schiffner, 1896). Another species recorded for New Zealand and described by Stephani (1883), namely M. cephaloscypha, is considered by Evans after examination of an original specimen to correspond with M. berteroana (Evans, 1917).page 123
In New Zealand M. berteroana is widespread, especially near hot springs, on burnt-over country and in swampy areas. It shows a wide range of form under different environmental conditions. Some specimens are the largest of any belonging to the genus Marchantia, whereas others growing in more exposed situations are considerably smaller and approach in size robust specimens of M. foliacea. The expression of the ventral scales also is variable. These may be hyaline or reddish-brown in colour. In many specimens there are 6 rows, as in the var. polylepida of Herzog, but sometimes those of the marginal series wither early and in plants of exposed situations they may never appear. There seems to be justification for some designation for the plants with 6 rows of scales in order to avoid confusion with other species such as M. polymorpha, since the type of M. berteroana is described as having 4 rows; but, as far as the New Zealand plants are concerned, transplant experiments have shown that the number of rows is too unstable to warrant the designation of a variety.
Description of the Thallus
The thallus is up to 8 cm. long and 2 cm. wide with the margin wavy and crenulate. It grows irregularly, lying more or less parallel to the substratum, branching dichotomously at intervals of 1-5 cm., with sometimes a certain degree of overtopping, and also producing adventitious shoots from the median ventral region a short distance behind the apex. The upper surface is smooth, somewhat glossy, and in colour yellow-green to green or reddish-brown. Under a lens it can be seen to be dotted with closely crowded, whitish pores 0.1-0.2 mm. apart and to be very faintly marked out into polygonal areas. The under surface is lighter in colour and bears on each side of the mid-line 2 or 3 rows of hyaline, tawny, or reddish-brown scales, which extend outwards to within a distance of from 0.5-1.0 mm. from the thallus edge but never right to the edge, as well as numerous rhizoids. Following Leitgeb (1881) the scales from the centre outwards will be called median, laminar and marginal (Fig. 3). The median scales carry a colourless or reddish-brown, broadly ovate or cordate appendage, up to 1.2 mm. in length and 0.8 mm. in maximum width (Figs. 3, 9). Near the thallus apex the appendages, closely crowded and inflexed protectively over the growing-point, are visible on the upper surface. Each appendage is margined by 1 or 2 rows of small cells with thin walls, is either entire or is crenulate due to projecting cells, and as in the scale has a few cells with oil-bodies. Club-shaped mucilage cells project from the edge of young scales but later wither off. The scales of the outer rows also show a few cells with oil-bodies but lack appendages. Sometimes cells forming the upper half page 124 of each marginal scale have abundant mucilaginous contents and thickened angles (trigones). Sometimes, but not always, mucilaginous cells with only slightly thickened angles occur in the upper, outer portion of the laminar scales. The rhizoids are of 2 types, namely narrow rhizoids of diameter 13-16μ with thickened walls and conspicuous, peg-like, internal projections, and wider ones of diameter 32-68μ, which in some cases show rudimentary projections in the proximal portion but generally has smooth walls.
Cupules (gemma-cups) on the upper surface of the thallus are 4 mm. in diameter and 3 mm. high, cut on the rim into triangular lobes which are ciliate on their edges and drawn out at the top into fine points, often curved inwards (Fig. 5). A few oil-bodies occur in the cupule wall, and on its outer surface are short finger-like projections known as papillae. On the floor there arise disc-shaped gemmae, each attached by a minute stalk and showing 2 lateral growing-points. When mature, the gemmae break away from their stalks and, after dispersal by water or by splashing rain-drops, can grow into new plants.
Anatomy of the Thallus
In its structure the thallus shows differentiation into epidermis, photosynthetic layer and compact ventral tissue (Fig. 6). In transverse section it is 10 mm. deep in the central region and very gradually becomes thinner outwards into the wings. Oil cells, containing usually a single large brown oil-body as found in other Marchantia species, are scattered throughout. The epidermis consists of thin-walled colourless cells, which sometimes towards the edge of the thallus show projecting surface papillae (Fig. 7). It is interrupted by barrel-shaped air-pores enclosed by usually 6 tiers, each of 3-6 cells. The internal opening of the pore varies in appearance (Fig. 4), for cells of the lowermost tier alter in shape by swelling and shrinkage, as noted in Preissia by Goebel (1898) and described more fully by Walker and Pennington (1939). The movement is readily observable in material mounted in glycerine. The photosynthetic layer, 65μ deep, consists of one series of air chambers occupied by green filaments 3-4 cells high. The compact ventral tissue, 20-30 cells deep in the central region, consists of thin-walled cells indistinctly pitted.
Fig. 1: A female plant. × 1. Fig. 2: A male plant. × 1. Fig. 3: Under side of thallus. × 2. a. appendage, I. laminar scale, m. median scale, mg. marginal scale. Fig. 4: Air pores showing internal opening; in a, open; in b, closed. × 230. Fig. 5: Part of the rim of the cupule. × 75. Fig 6: Transverse section of part of the thallus. × 75. e. epidermis, p. photosynthetic layer, v. ventral tissue. Fig. 7: Transverse section of the thallus near the margin. × 200. p. papilla. Fig. 8: Spore. × 380. Fig. 9: Appendage. × 75. Cells with oil bodies are stippled. Fig. 10: Edge of the involucre. × 75.
The antheridiophore arises in August at the apex of a branch but usually comes to occupy a lateral position on the thallus due to rapid forward growth of vegetative branches. It has a stalk up to 3 cm. in height with 2 rhizoidal furrows but no air chambers, and a flat-topped head up to 18 mm. in diameter with 8 lobes green in colour except for a broad, colourless margin. Scales on the under side of the head are either colourless or reddish-brown.
The archegoniophore appears in September in a terminal position on the thallus. The stalk is up to 8 cm. high with 2 rhizoidal furrows as well as a band of photosynthetic tissue, and at the top shows a sparse development of slender, hyaline scales. The head is up to 12 mm. in diameter, slightly umbonate at the centre and with 9 linear rays slightly decurved (Fig. 1). On the under side between the rays lie the 8 receptacles, each protected by a hyaline, bilabiate involucre shortly lobed and fimbriate at the margin (Fig. 10). The receptacle at first carries archegonia and later several sporogonia, often 4-8. The pseudoperianth, which surrounds each sporogonium and its very thin calyptra, is hyaline, 1.5 mm. in length, and cut distally into pointed lobes. Between January and March the ripe capsules are projecting beyond the calyptra and the pseudoperianth. Each capsule has a wall strengthened wtih bands of thickening and contains bispiral elaters of length 350-540μ and maximum width 6μ, as well as smooth, spherical spores, 10μ in diameter and in colour a conspicuous buttercup-yellow (Fig. 8).
An Aberrant Form
A rather puzzling form thought to belong to M. berteroana occurs in some parts of New Zealand. Morphologically it maintains its distinctive features in cultivation but has not been induced to form antheridiophores or archegoniophores. The thallus is thin, with a wavy, crispate margin. Under a lens it appears blotchy, due to wide partitions between the areas of photosynthetic tissue. Papillae are plentiful on the upper surface, the internal opening of the air-pores is always surrounded by 4 cells and some of the tuberculate rhizoids have a crenulate wall.
2. M. foliacea Mitt.
in Hooker Fl. Nov. Zel. 2:168, 1855.
Distribution and Nomenclature
From an examination of the specimens on which Mitten based his description of M. foliacea, Evans has concluded that the material page 127 involved was presumably from New Zealand (Evans, 1930). Evans gives the distribution of the species as New Zealand, Tasmania, Chiloé and Juan Fernandez.
In New Zealand at the present time M. foliacea is widespread. It tends to grow on drier and more freely-draining sites than does M. berteroana but often the 2 species are in close proximity and even intermixed. It shows an extremely wide range of forms some of which maintain their identity during several years under cultivation. However, in no case was a specimen considered to be sufficiently distinct to justify the erection of another species. Stephani's description of the appendages to the median scales as entire and on another page as subentire (Stephani, 1900) has caused some confusion in identification. Although in some specimens they are entire or subentire, in others they are vaguely and irregularly dentate, as Evans (1930) has mentioned.
Description of the Thallus
The thallus is 0.5-7 cm. long and 2-12 mm. broad with a wavy, entire margin. It grows parallel to the surface of the soil and branches dichotomously at intervals of 1-3 cm. with sometimes the two branches developing at equal rates and sometimes one overtopping and dominating the growth so that the other comes to occupy an apparently lateral position. New thalli form from adventitious shoots arising ventrally (Fig. 11). The upper surface of the thallus is smooth and usually glossy, green to yellowish-green or blue-green in colour with a very narrow, hyaline or purple margin. Under a lens it appears faintly, or in some plants distinctly, marked out into polygonal areas, each with a central whitish air-pore. The air-pores are 0.2-0.5 mm. apart. The under surface is green when plants are growing under shady conditions where the humidity is consistently high, but in more exposed situations the colour is reddish-brown or purplish-brown either towards the margin or over the whole width. There are two types of rhizoids, tuberculate rhizoids of diameter 5-25μ some of which may have wavy walls, and smooth-walled rhizoids of diameter 18-43μ with only a few rudimentary internal projections. On each side of the mid-line there is a single row of scales (median scales) and in a few plants an ill-defined second row of smaller, scattered scales (laminar scales), but in all cases the scales are confined to the central region, with the result that ½ to ⅔ of the total width of the thallus is free of scales (Fig. 13). The scales may have a few cells with oil bodies, and are purple except in plants of very shaded situations when they are colourless. The median scales carry an appendage of variable size and shape, usually ovate to cordate with an acute apex but occasionally page 128 suborbicular or rectangular, 0.4-0.8 mm. long and 0.3-0.9 mm. broad, constricted at the line of junction with the scale and often [gap — reason: unclear] at an angle upwards and backwards at this point. The appendage is either purple or pale yellowish-brown in colour, [gap — reason: unclear]lly lacks oil bodies, and either has an irregular outline due to projections from some of the marginal cells or may be almost entire (Figs. 14-17).
The cupules containing the gemmae are 1.5 mm. high and [gap — reason: unclear] mm. in diameter; they have a ciliate rim due to fringing filamentous hairs 1-8 cells high and 1-2, occasionally 3-4, cells wide at the base (Fig. 18). The gemmae have 2 lateral growing-points and are green except for colourless marginal cells and scattered cells with oil bodies.
Anatomy of the Thallus
In its internal structure the thallus shows the usual differentiation into epidermis, photosynthetic layer and ventral tissue (Fig. 19). In some plants the thallus is thin throughout; in others there is a prominent midrib region gradually becoming thinner outwards towards the margin. Oil bodies are present in some of the cells. The epidermis consists of colourless or almost colourless cells and near the centre of the thallus is often bistratose. In some specimens it has thin walls throughout and in others it has evenly thickened walls towards the margin, in the lower layer elsewhere or in both layers. The air-pores are bounded by 6-7 tiers of cells (Fig. 20a). Since the 4-6 cells which surround the internal opening can alter in shape, as noted by Goebel (1906), the appearance of the pore varies (Fig. 20 b, c, d). The photosynthetic layer, 65μ deep, consists of a single series of air chambers occupied by green filaments 3-4 cells high. The compact ventral tissue is some plants is colourless and thin-walled throughout; in other plants there are scattered, brown, thick-walled, sclerotic cells as noted by Goebel (1906). The upper part and sides of the mid-rib region often constitutes a wide zone where the cells harbour non-septate hyphae and have purplish or brown, firm walls indistinctly pitted. The lowermost cells of the thallus may also have purple walls.
Fig. 11: Part of a male plant. × 2. a. adventitious shoot, c. cupule. Fig. 12: An 8-lobed antheridiophore. × 2. Fig. 13: Under side of the thallus. × 4. m. median scale. Figs. 14-17: Appendages from different plants. × 80. Fig. 18: Part of the rim of the cupule. × 75. Fig. 19: Transverse section of part of the midrib of the thallus. × 75. b. brown or purple zone, c. colourless zone with scattered sclerotic cells, e. epidermis, p. photosynthetic layer. Fig. 20: Air-pore. a. in vertical section. × 200; b, c, d. the internal opening. × 230. b. wide open, c. half-closed, d. closed. Fig. 21: Plant with developing archegoniophores. × 1. p. unfertilized head. Fig. 22: Head of mature archegoniophore. × 2. Fig. 23: Edge of involucre. × 75. Fig. 24: Spores. × 400.
The archegoniophores appear in August and September (Fig. 21). The stalk of the archegoniophore is up to 2 cm. in height, green for most of its length but tinged with purple at the base and carrying scattered, narrow, purple scales. In section it shows 2 rhizoidal furrows and a band of photosynthetic tissue. The mature head is almost flat and nearly circular in outline with a diameter of 8-12 mm. In colour the upper surface is either green all over or is margined with purple. At the periphery it is cut for ⅓-½ the distance to the centre into 7-11 broad, truncate rays, often upturned at the tip and, with the exception of the narrow basal pair, emarginate (Fig. 22). The basal sinus is deeper than the others. On the underside of the head are 6-10 receptacles alternating with the rays and each surrounded by a bilabiate involucre. Reddish-purple scales between the involucres give a purplish colour, augmented sometimes by purple edges to the involucres themselves. The involucre has a shallowly lobed, fimbriate edge (Fig. 23) and encloses a group of archegonia and later one or more sporogonia. The head of the young archegoniophore, as in other species of Marchantia, is hemispherical; as it flattens the 2 basal rays lengthen rapidly, producing for a time a tailed appearance which tends to persist in unfertilized heads where the other rays are poorly developed (Fig. 21). In November the yellowish-brown capsules are projecting beyond the involucres. They have bars of thickening on the wall and open at the top into about 6 lobes, thus exposing the mass of spores and elaters. The tetrahedral spores are 25-28μ in diameter and yellowish-brown when fresh, later shrinking somewhat and turning to brown. They have a tri-radiate marking and, as noted by Evans (1930), show vaguely reticulate ridges on the spherical face and at its periphery a wing with a wavy edge (Fig. 24). The elaters are bispiral, of length 340-750μ and maximum width 8.5μ, tapering gradually towards the tips.
3. M. macropora Mitt.
in Hooker Fl. Nov. Zel. 2:169, 1855.
Distribution and Nomenclature
M. macropora is known only from the North Island of New page 131 Zealand, where it grows as large colonies on shaded, dripping-wet banks, and from N.W. Nelson. First described by Mitten in 1855, it has always been recognised as a distinct species.
Description of the Thallus
The thallus is up to 3 cm. long and 5 mm. broad, branching dichotomously at intervals of 5-15 mm. and tending to form a semi-rosette on the soil surface due to wide divergence of the branches (Fig. 25). New thalli arise from adventitious ventral shoots and grow over the old ones which then turn purplish-brown and die off. The upper surface is green to dark-green in colour and rough in appearance; under a lens it is seen to be definitely marked out by either colourless or purplish-brown partition lines into polygonal areas, each of which includes a large, elevated air-pore rimmed with white or rarely with purple. The air-pores are 1 mm. apart. The underside of the thallus is sometimes green with a colourless or a reddish-purple margin but usually is wholly reddish-purple. Two kinds of rhizoids, a tuberculate type of diameter 16 to 19μ and a smooth-walled type of diameter 22-32μ, form a narrow central strand and to either side lies a row of purple median scales and in some specimens an ill-defined row of smaller laminar scales (Fig. 26). The median scales carry an ovate to almost circular appendage of purple or brown colour, usually entire or sub-entire with an acute apex, but sometimes with marginal projecting cells (Figs. 27, 28). In size the appendage is variable, ranging in length from 0.23-0.4 mm. and in breadth from 0.16-0.25 mm. Both the scale and the appendage lack oil bodies, but cells of the scale from which tuberculate rhizoids arise are themselves tuberculate. The laminar scales are elliptic to ovate and obtuse, of length 0.25 mm. and breadth 0.16 mm., in colour purple.
Cupules containing disc-shaped gemmae lie medianly on the upper surface of some thalli (Fig. 29). Each cupule is a small, but comparatively tall, cup widening to a diameter of 1.5 mm. at the top and having papillate projections 1-2 cells high on the rim (Fig. 30). The gemmae, which are green right to the edge, usually have 2 lateral growing points, occasionally a third in either a near-terminal or a lateral position, and rarely a fourth (Figs. 31, 32).
Anatomy of the Thallus
In section the thallus shows a mid-rib region 1 mm. wide and 0.5 mm. in depth and a thinner marginal region. Oil bodies occur in some of the cells. The epidermis is unistratose towards the margin and near the centre but elsewhere is bistratose (Fig. 33). page 132 Its cells contain small chloroplasts and near the edge of the thallus have thickened walls. It is interrupted by barrel-shaped air-pores, each surrounded by 8-10 tiers of cells. The outer circular opening is 0.12 mm. in diameter. The inner opening as noted by Stephani (1900) is of a distinctive pattern. Projecting inwards from the numerous cells of the 3 or 4 basal tiers are finger-like processes, the lowermost series being so long that they almost close the inner opening of the pore (Fig. 34). The projections contain small chloroplasts and like the wall of the pore are coated with resin. By trapping air they prevent flooding of the tissue beneath. The photosynthetic layer, up to 0.08 mm. in depth, consists of a single series of air chambers, occupied by branching green filaments 3-6 cells in height. The compact ventral tissue, 0.4 mm. in depth in the midrib region, has some sclerotic cells with thickened brown walls amongst the thin-walled cells (Fig. 33), and may harbour non-septate fungal hyphae; all of its cells have pitied walls.
M. macropora like all other species of Marchantia is dioicous. The antheridiophore arises in early spring in a terminal position on the thallus (Fig. 35). It has a pale green stalk with 2 rhizoidal furrows but without air chambers and a flat excentric head of diameter 6 mm. × 3 mm., deeply cut into 4, or sometimes only 2, palmate lobes with thin and often upturned edges. A few narrow scales scattered along the length of the stalk and larger ones at its base and beneath the receptacles are purple in colour. Antheridia arise in 4 oval receptacles on the head and are mature in September, after which time the antheridiophores wither away.
Fig. 25: Part of a plant. × 1. Fig. 26: Underside of thallus. × 4. m. median scale, I. laminar scale. Figs. 27 and 28: Appendages of ventral scales, × 75. Fig. 29: Part of the thallus with a cupule. × 8. Fig. 30: Part of the rim of the cupule. × 180. Fig. 31: Gemma with 2 growing-points. × 75. Fig. 32: Gemma with 3 growing-points. × 75. Fig. 33: Transverse section of the central part of the thallus. × 75. e. epidermis, p. photosynthetic layer, s. sclerotic cell in the ventral tissue. Fig. 34: Vertical section of an air-pore. × 80. Fig. 35: Antheridiophore. × 2. Fig. 36; Part of the edge of the involucre, × 380. Fig. 37: Head of an archegoniophore from above. × 2. Fig. 38: Head of an archegoniophore from below, × 2. Fig. 39: Spore, × 380.
The spores are tetrahedral, of diameter 26-32μ, with a very faint tri-radiate marking as well as irregular low ridges, and have at the boundary of the spherical face a narrow wing of wavy outline (Fig. 39). The elaters are bispiral, of length 300-650μ and maximum width 9μ, tapering gradually towards the tips.
Notes on Other Species which have been Recorded for New Zealand
1. M. cephaloscypha St.
Hedwigia 22:51, 1883.
As noted above, this name is considered by Evans (1917) to be a synonym of M. berteroana L. et L. and must therefore be rejected.
2. M. fusca St.
Sp. Hep. 1:174, 1900.
The description is based on a young female plant collected by Petrie in New Zealand. The original specimen has not been seen, but the description suggests a young stage of M. foliacea.
3. M. kirkii St.
Sp. Hep. 1:164, 1900.
An examination was made of 5 specimens, on which the original description was based, now belonging to the Stephani Herbarium at Geneva. These had been collected by Helms at Greymouth, by Kirk at Stewart Island, by Petrie in New Zealand and by an unnamed person in Auckland. Some of these are considered to be M. foliacea and the only one with a well-developed archegoniophore is considered to be M. berteroana. The description then is a composite one covering portions of 2 already established species. It is suggested that the name kirkii be rescinded.
4. M. laccriloba Steph. ms.
This manuscript name of Stephani's has been published by Bonner (1953). An examination was made of the type specimen, a male plant collected by L. S. Gibbs near Auckland in 1907, and now in the Stephani Herbarium, Geneva. It is considered that it belongs to M. foliacea. The name laceriloba, therefore, is considered redundant.
5. M. nitida L. et L.
in Lehmann Nov. Stirp. Pug. 4:11. 1832.
This species is recorded for New Zealand by Hooker (1867). However. Evans, after examining specimens collected in New page 135 Zealand and other islands of the Pacific and determined as M. nitida, has expressed the opinion that they are referable to other species (Evans, 1917). M. nitida is regarded either as a synonym of M. paleacea Bert. (Evans, 1917) or as closely resembling M. paleacea (Burgeff, 1943). Evans (1930) has expressed the opinion that M. paleacea is probably the nearest ally of M. foliacea. Doubtless there has been confusion between the species. It is considered that M. nitida is not present in New Zealand.
6. M. pileata Mitt.
in Hooker Fl. Nov. Zel. 2:169, 1855.
The description is based on a specimen with one archegoniophore. Two specimens collected by Colenso and labelled M. pileata in the herbarium of William Mitten were examined, and also part of a thallus collected and determined as M. pileata by Berggren. These are considered to correspond with forms of M. foliacea, in which case the name M. pileata is redundant.
7. M. polymorpha L.
Sp. Pl. 2:1137, 1753.
This species is listed as occurring in New Zealand by Frye and Clark (1937) on the authority of Evans (1930). However, it is not known to be established in New Zealand, although with such a cosmopolitan species, growing often in close association with human habitation, one cannot overlook the fact that it may be introduced at any time. One such plant has been seen in a greenhouse.
M. polymorpha in many respects resembles M. berteroana and, since both species are extremely variable, it is difficult to list reliable distinguishing features. The most dependable ones are found to be the lack of surface papillae on the head of the archegoniophore of M. berteroana, the narrow border of small cells on the scale appendages passing abruptly to larger cells, and the fact that the scales do not reach the edge of the thallus. The darkish midrib of most forms of M. polymorpha is also distinctive.
8. M. quadriloba Steph. ms.
This manuscript name of Stephani's has been published by Bonner (1953). It is based on a specimen with a mature archegoniophore collected by W. Gray from the Wairarapa in 1911. By courtesy of Dr. Bonner it was possible to examine this specimen. It is considered to belong to Asterella and not to Marchantia. The name M. quadriloba should therefore be rejected.
9. M. setchellii Pearson
Univ. Cal. Pub. Bot. 10:308, 1923.
The description is based on sterile plants with cupules collected by Setchell near Waimungu in 1904. By courtesy of the University page 136 of California a specimen was made available for examination. The plant is considered to correspond with ones already included under M. foliacea, in which case the name M. setchellii is redundant.
10. M. tabularis Nees.
Nat. eur. Leb. 4:71, 1838.
This name is used by Hooker (1867), but, as mentioned above, it has been shown by Schiffner (1896) to be antedated by the name of M. berteroana L. et L.
The writer is greatly indebted to Dr. C. E. B. Bonner for the loan of specimens from the Stephani Herbarium, to the New York Botanical Garden for the loan of two specimens of M. pileata from the herbarium of William Mitten, to the University of California for a specimen of M. setchellii, to Mrs. E. A. Hodgson and to the keeper of the herbarium at Botany Division for the loan of specimens from their herbaria.
List of References
Bonner, C. E. B., 1953. De Hepaticis. II. An unpublished section of Vol. 6 of Stephani's Species Hepaticarum: the genus Marchantia. Candollea 14: 101-112.
Burgeff, H., 1943. Genetische Studien an Marchantia, Jena.
Evans. A. W., 1917. The American species of Marchantia. Trans. Conn. Acad. 21: 201-313.
Evans, A. W., 1930. The thallose Hepaticae of the Juan Fernandez Islands, in Skottsberg. Nat. Hist. Juan Fern, and Easter Is. 2: 551-586.
Frye, T. C., and Clark, L., 1937. Hepaticae of North America. Univ. Wash. Pub. Biol. 6: 97-102.
Goebel, K., 1989. Organography of Plants. Eng. ed. Oxford.
Coebel, K., 1906. Archegoniatenstudien. Flora 96: 1-202.
Hassel de Menendez, G. G., 1962. Estudio de last Anthocerotales y Marchantiales de la Argentina. Op. Lill. 7: 1-297.
Herzog, T., 1934. Die Bryophyten der Andenreisen von C. Troll (Bolivia, Columbia, Panama). Hedivigia 74: 79-114.
Hooker, J. D., 1867. Handbook of the New Zealand Flora. London.
Leitgeb, H., 1881. Untersuchungen über die Lebermoose 6: 1-158. Graz.
Schiffner, V., 1896. Kritische Bemerkungen über Marchantia berteroana L. et L. und Marchantia tabularis N. ab. E. Oest. bot. Zeitschr. 46: 41-44. 100-103.
Stephani, F., 1883. Einige neue Lebermoose. Hedwigia 22: 49-52.
Stephani, F., 1900. Species Hepaticarum. 1. Geneva.
Walker, R., and Pennington, W., 1939. The Movement of the Air Pores of Preissia quadrata (Scop.). New Phyt. 38: 62-68.