THE PRESENT STATUS OF RHYNIA GWYNNE-VAUGHANII (K. AND L.) Y.L.

YVES LEMOIGNE Department de Biologie Vegetale, Universite de Lyon, (France)

cheids, surrounded by a zone of thin-walled singlefamilygenus,RhyniaceaeRhynia, compriseswith onea phloem. Cortex consisting of an inner THEspecies. It is known only from the and outer zone. Epidermis of aerial stems famous Devonian beds at Rhynie in with cuticularized outer wall and stomata. Scotland. Locality - Muir of Rhynie, Aberdeen• shire. HISTORY Horizon - Old Red Sandstone (not younger than the Middle Division of the The Muir Chert at Rhynie, containing Old Red Sandstone of Scotland). remains of Psilophytes, among them the In addition to these diagnoses Kidston Rhyniales, was discovered by Dr W. and Lang mentioned (1917, p. 765): Mackie in 1910. "Rhizome and aerial stems bore small In the first description of the fossil hemispherical projections which were more plants from this chert, Kidston and Lang or less closely placed without apparent regularity. On some of these bulges tufts (1917) recognized only two species, which of rhizoid-like hairs were borne, while in they called Rhynia gwynne-vattghanii and Asteroxylon mackiei. However, they were other cases the projections developed into adventitious branches, usually attached by aware of the presence of more plants which a narrow base. Some of these branches they intended to describe later. In this first description Kidston and Lang gave appear to have been readily detached, and the following diagnoses (p. 780): their occurence free in the feat suggests "Psilophytales: A Class of Pteridophyta that they served to propagate the plant characterized by the sporangia being borne vegetatively" . at the ends of certain branches of the stem Thus, in their first description Kidston without any relation to leaves or leaf-like and Lang recognized only one species of Rhynia. They explained the differences organs." in the structure of the stele as results of Rhynia gwynne-vaughanii, Kidston and Lang. n. g. and n. sp. differences in position of the sections in different parts of the vegetative body. "That the rhizomes, aerial stems, and Psilophyton princeps, Dawson (pars) sporangia were portions of the same plant RHYNIA, Kidston and Lang. n. g. might have been inferred from their asso• ciation in a bed composed of one type of Diagnosis - Plant gregarious, rootless plant only. Their continuity has, however, and leafless, underground rhizomes with been directly traced, and is established rhizoids, generally situated on large, down• by anatomical evidence" (Kidston & Lang, wardly directed protuberances of the cortex. 1917, p. 766, 1. 4-7). Aerial stems cylindrical tapering upwards, Three years later, in 1920, Kidston and about 8 inches in height, bearing small Lang published an emend.:nent of the genus hemispherical protuberances. Stems spar• Rhynia. They wrote: "In part I (1917) ingly dichotomous and also bearing lateral a general account was given of the silicified adventitious branches. Sporangium large, peat bed found at Rhynie, and one vascular cylindrical and terminating an aerial stem. plant was described in detail under the Sporangial wall thick, of mans layers of name of Rhynia gwynne-vaughanii. Further cells. Homosporous, spores developed in study has shown that they are two species tetrads about 65 [1. in diameter. Stele of Rhynia which we now distinguish as throughout the plant small, cylindrical, Rhynia gwynne-vaughanii and Rhynia consisting of a solid strand of annular tra- major" (Introduction). They further added, ;Ill 40 THE PALAEOBOTANIST

"As mentioned above, two species of Rhynia 12 mm. and a diameter of 4 mm. Sporangial have to be distinguished. Their similarity wall about 3-4 mm thick. Spores about in organization is so great that they are 65 fl. in diameter. not always readily separated from one Locality - Muir of Rhynie, Aberdeen• another, and in our former paper they were shire. described together u.nder the name Rhynia Horizon - Old Red Sandstone (not gwynne-vaughanii. The second species, younger than the Middle Division of the which we now separate as Rhynia major, Old Red Sandstone of Scotland). is larger in all its parts, and differs from After the publicRtion of the "Studies" Rhynia gwynne-vaughanii in the absence by Kidston and Lang numerous botanists of hemispherical projections and adventi• and paleobotanists have taken a great in• tious branches from the stems, in the greater terest in the Psilophytales, and all of them size of the stele and xylem strand, and in have wished to know something about the the much larger size of the sporangia and gametophytes of these plants, which for spores" (p. 603). In this second account a long time were regarded as the first Kidston and Lang gave new diagnoses (p. vascular plants and interpreted as the an• 610-611). cestors of the living vascular plants. I Rhynia - Plant gregarious, rootless and shall quote only a few authors and only leafless, consisting of subterranean rhizomes in so far as they have contributed to our attached by unicellular rhizoids, and erect, better understanding of these Devonian dichotomously branched, cylindrical aerial plants: stems. Stomata present. Stele consisting Bower (1935) has suggested that the of a zone of phloem surrounding a strand gametophytes of the earliest colonizers of of tracheids. Sporangia cylindrical, with• the land had probably a robust built out columella, terminal on aerial stems. (particularly the gametophytes of Rhynia). Homosporous. Spores with cuticularized Eames (1936) vaguely speculated that wall, developed in tetrads. "if gametophyte and sporophyte were much Rhynia gwynne-vaughanii: aerial stems alike in early land plants, some of the sterile tapering upwards, probably about 20 cm. fossil branching axes may perhaps be game• high, and ranging in thickness from 3 mm. tophytic" . to under 1 mm. Small hemispherical pro• Fritsch (1945) has with good reasons tuberances of superficial tissues of the stem suggested that "if embryos and gameto• occur, and sometimes, in place of them, phytes of Psilophytales are ever discovered adventitious branches, the stele of the it would not be astonishing to find that branch not being continuous with that of the latter were of the same general nature the main stem. Xylem strand of stele as those of Psilotales; the gametophytes slender, only sometimes showing a distinc• may even have been less red uced" . tion of smaller central and larger peripheral Merker (1959) in his paper entitled tracheids. Tracheids with broad annular "Analyse der Rhynien-Basis und Nachweis thickening. Sporangia about 3 mm long des Gametophyten" first criticized the ter• and 1·5 mm in diameter. Sporangial wall minology of Kidston and Lang, particularly about 2 mm. thick Spores about 40 fl. in because they used the term "rhizome" for diameter. the creeping axes. If the creeping axis Locality - Muir of Rhynie, Aberdeen• had simply been the horizontal subterranean shire. parts of the same plant as the erect aerial Horizon - Old Red Sandstone (not stems one should have expected, in Merker's younger than the MiddIe Division of the opinion, that they had been biCurcating Old Red Sandstone of Scotland). with one of the branches curving upwards, Rhynia major - Plant larger in all its in the same way as in Lycopodi~tm clavatum, parts than R. gwynne-vaughanii, aerial stems where aerial shoots curve up from the hori• tapering upwards, and ranging in thickness zontal creeping axes. Among the from 6 mm. to 1·5 mm. or less. No Rhyniales, however, there is a marked hemispherical projections or adventitious difference between the two parts: the aerial lateral branches. Stele large, xylem strand axis usually forms an almost right angle of numerous tracheids differentiated as to the horizontal one. Also, according to smaller central and larger peripheral tra• Merker, the creeping parts (the rhizomes cheids. Sporangia reaching a length of of Kidston and Lang) of Rhynia are often LEMOIGNE-THE PRESENT STATUS OF RHYNIA GWYNNE-VAUGHANII 41

decaying while the erect axis are not. On (f) The occurence of gametophyte-like the basis of observations and his "intuition" non-vascular axes in R. gwynne-vaughanii. (*) Merker said: "Neue Untersuchungen (g) The absence of actual organic connec• haben nun ergeben, dass die horizon tale tion between the indubitable axes of R. Basis der "Urlandpflanzen" kcin Rhizom gwynne-vaughanii and the sporangia as• sein kann, sondern das vermisste Prothal• signed to it. It thus appears that at least lium darstel1t, das dank seiner weitgehen those axes of R. gwynne-vaughanii which den Bestandigkeit dem vi:illig wurzellosen bear the 'hemispherical projections' or Sporophyten als Brutpflegeorgan und als 'adventitious branches' may well represent Halt in Boden diente" (p. 452).* the gametophytes of either of Psilophytales Two years later, in 1961, Merker main• described from Rhyn,ie" (Pant, 1962, p. tains again that the creeping parts 278). ("rhizomes") of Rhynia major and Rhynia "It is clear from the above account that gwynne-vaughanii are gametophytic. there is a close structural similarity between Pant (1962) published an important paper the gametophytes of Psilotales (more espe• on the problem of the gametophyte of the cially the vascular gametophytes of Psilophytales. He based his conclusions Psilotum) and the axes of R. gwynne• partly on the famous work of Hollaway vaughanii, and also between the develop• (1939) on the vascularized gametophytes ment and structure of 'adventitious of Psilotum. Pant m1.de it his working branches' in R. gwynne-vaughanii and the hypothesis that it should be possible to formation, development and structure of discover the gametophytes of the Psilo• the young sporelings, in Psilotales. Indeed phytales in the m1.terial already described. the resemblance between the fossil and the From this starting point and on the basis living structures is so close that it is hard of his own observations, he arrived at the to explain it on any other basis than by following conclusions: regarding even the fossil "parent axes" as "As a result of our studies it now seems gametophytic. This nature of the axes that the presumed absence of the gameto• of R. gwynne-vaughanii explain ipso/acto phytes of the Rhynie Psilophytales is not the nature of the curious 'adventitious because of the proverbial 'imperfection branches' which then satisfactorily fit in of the geological record' but due to as young sporophytes. On the other hand, erroneous interpretation. The following if we continue to regard them as 'adven• points are sign,ificant: titious branches', they would be without (a) The close structural similarity be• parallel in any other psilophyte or other tween the axes of R. gwynne-vaughanii plants (Pant, 1962, p. 295)". an,d the vascular gametophytes of Psilo• " ... It must, however, be admitted tttm. that the present evidence is mainly in,direct. (b) The possibility that at least some of Direct proof can be supplied only by the 'stomata', below which the 'hemi• demonstrating well preserved sex organs spherical projections' and 'adventitious (archegonia and antheridia) on these axes. branches' of this species are reported to The possible archegonial nature of at least be produced, could be archegonia whose some of the 'stomata' and the occurence necks had been shed already. of other archegonium-like structures is (c) The developmen,tal similarities be• perhaps some evidence of the kind but at tween, the 'hemispherical projections' of the present moment no clear antheridia R. gwynne-vaughanii and the young sporo• have been observed. Further work is in phytes of Psilotales. progress (Pant, 1962, p. 296)". (d) The clear demarcation between the tissues of the 'hemispherical projections' and the parent axes. OBSERVATIONS (e) The structural similarities between the 'hemispherical projections' or 'adven• Comparative studies on Pteridophytes titious branches' of R. gwynne-vaughanii had also led me to the idea that the and the young sporelings of Psilotales. gametophytes of the Rhyniales might have (*) "Das, was als Rhizom bezeichnet wurde, been vascularized. Further, the study of deutete ich, zunachst nur geflihlsmassig, als Pro• Kidston and Lang's publications had tha,llillm ". (p. 445, I. 26-28). directed my interest especially to the diffe- 42 THE PALAEOBOTANIST

TEXT-FIGURE 1 - Showing the morphological and anatomical characters of the gametophyte Rhynia gwynne-vaughanii. an, antheridium, ar, archegonium, ex, strand of xylem (protostelic), ml, phloem, 00, oosphere, rh, rhizoids, st, stomata.

rences which seemed to exist between is visible. Measurements were taken in Rhynia gwynne-vaughanii and Rhynia major; two archegonia: the canal was found to in particular it did not seem possible to be 310 fL long and the oosphere 70 [1. in dia• interpret the "adventitious axes" as organs meter. To a great extent the archegon,ium of vegetative propagation. Further, con• is enclosed in the tissue of the gametophyte, vinced of the importance which the dis• just as it is among the recent Pteridophytes, covery of the gametophyte of the Rhyniales and in contrast to the pedicellate arche• would have for our understanding of the gonia of the Bryophytes. The archegonial phylogeny of these and other Devonian canal (which, presumably, has arisen as plants, I started to study, from 1959 on• the result of lysis of a series of cells) wards, British, Belgian and French Collec• is surrounded by four rows of cells which tions of Psilophytes as well as the slides are elongated in the same direction as the prepared in my own laboratory from samples canal, each row seems to be formed of 5 or of Rhynie chert which I collected in 1964 6 cells above each other. The cells of the when members of the X International gametophyte, in contact with the opening Botanical Congress visited this famous loca• or in the vicinity of it, are also arranged lity under the guidance of Mr. A. G. Lyon in rows and elongated parallel to the canal, and Professor John Walton. The main so that these cells, together with neck cells results of these studies have, till now, formed form a protuberance. The mature arche• the contents of the following 6 publications: gonial protuberances are covered by an 1 - One deals with the discovery of amorphous substance (which no doubt re• archegonia borne by vascularized axes of presents a fossilized mucilage). The Rhynia gwynne-vaughanii Kidston and Lang oosphere (as seen in PI. 2, fig. 13 and 14) (Lemoigne, 1968a): these archegonia were is surrounded by a layer of cells in regular found in a slide in the Lang collection of arrangement. At maturity the cells of the Natural History Museum of Manchester. the neck of the archegonium and the They form small protuberances on the associated cells were evidently dissolved surface of the vascularized gametophytic and formed a mucilage similar to the axis. There are several such protuberances one found in Psilotum and Lycopodium on the same sectioned axis, all of them on complanatum. the same side of it. Each mature arche• Bierhorst has recently (1971) in his book gonial protuberance shows (PI. 2, fig. 11 entitled "Morphology of Vascular Plants" and 12) at its top a rosette of four cells. written: Between them is the opening of a straight "The stem of Rhynia gwynne-vaughanii canal leading down to an oosphere in the shows bumps along its surface, some of interior of the gametophyte. In one of which appear as undeveloped lateral the archegonia the nucleus of the oosphere branches. They entergrade with smaller LEM01GNE-THE PRESENT STATUS OF RHYNIA GWYNNE-VAUGHANII 43 and smaller ones down to small surface vaughanii were of a different kind. The eruptions involving relatively few cells. "vascularized protuberances" observed by The smaller ones seem to have a central Kidston and Lang were interpreted by channel leading to a large cell or intercel• them as organs of vegetative propagation; lular space below the surface. Lemoigne these organs were often thicker than the (1968a) called such structures archegonia axes bearing them and strongly attached and, therefore, assumed that some of the to them, although their vascular systems plants were gametophytes. His diagram• appear not connected. In my opinion matic reconstruction of one such structure they were either young sporophytes or appears in Fig. 6-1 G. The so called simple branches. archegonia were much more likely hyda• d) The gametophytic axes of R. gwynne• thodes or secretory structures of some kind. vaughanii mostly branched by very unequal Several other authors have in the past sug• bifurcation, but sometimes by trifurcation gested that some of the rhynialean axes giving rise to axes of different thickness. may have been gametophytes; some even said The gametophyte of R. gwynne-vaughanii that they 'probably were' gametophytes". seemed to branch sparingly; I have never It is surprising that Bierhorst has pre• observed erect ramifications (but have no ferred to reproduce my diagrammatical proof that they did not occur). drawing instead of my microphotograph 3 - A fourth paper with the title: of the archegonium, and I find it difficult "Organe assimilable a une antMridie et to accept that the drawing has been changed stomates epidermiques, portes par des axes so that the oosphere is replaced by a cavity. rampants du type Rhynia gwynne-vaughanii No doubt this change weakens my inter• Kidston et Lang" (1969b) was based on pretation of the entire structure as an the following observations: archegonium. a) On a transversal section (PI. 2. fig. 15 I am also surprised that Bierhorst, with and 16), rather thick and slightly oblique, his eminent knowledge of plant morphology of an axis with the structure of R. gwynne• in other fields, can regard these structures vaughanii K. and L. (slide No. 2427, as "hydathodes or secretory structures of Hunterian Museum Univ. Glasgow) there some kind". In my Laboratory two of is a kind of globular swelling of the epider• my assistants have carried out research mis, 200 fI< in diameter. It is not an on hydathodes and various kinds of glands, embryonic sporophyte (which would have and I can affirm that the structures des• been found in level with an archegonial cribed and interpreted in my papers as protuberance), nor is it a secretory gland archegonia of Rhynia gwynne-vaughanii are or any of the kinds of protuberances known really archegonia and certainly no kind of from the axes of Rhyniales: those bearing "hydathodes or secretory structures". rhiwids, or containing archegonia, nor can 2 - In a paper entitled "Contribution it be explained as a young branch or the a la connaissance du gametophyte Rhynia result of an attack by a parasite. From gwynne-vaughanii K. et L.: Probleme des all such structures it differs in shape and protuberances et processus de ramification" size. In fact, it has a great resemblance (1969a) I have shown that: to the antheridia of Psilotum, Botrychium a) Some of the protuberances borne by and 0Phioglossum. Although we know gametophytic axes of Rhynia gwynne-vau• nothing of the internal structure of this ghanii have been formed in connection with body it seems very likely that it represents archegonia; most, if not all, of the protu• an antheridium. berances that Kidston and Lang said they b) In several sections of R. gwynne• had observed under stomata are in fact va~tghanii (if the slides were thick and connected with archegonia (d. PI. 1, fig. 1; slightly oblique) I have seen stomata (the PI 2, fig. 11 and 13). two cells surrounding the ostiolum measured

b) Other protuberances, all of them on 90 fI< X 70 fI< together). These stomata are one side of an axis, bore rhiwids. This identical with the stomata in the epidermis type of protuberance have also been ob• of the sporophyte R. major K. and L. and served on axes of Rhynia major K. and L. also comparable to those of Anthoceros (d. PI. 1, fig. 4, 6, 7 and 9). (Bryophyta). Already Kic1ston and Lang c) "Vascular protuberances" are ramifi• reported the presence of stomata in R. cations. The branchings of R. gwynne- gwynne-vaughanii but only in those axes 44 THE PALAEOBOTANIST

which they regarded as aerial stems, while the rules of priority I propose to keep Rhynia they explicitly said they had never found gwynne-vaughanii as the name of only them in "rhizomes". Slide No. 2427 (Kid• species of Rhynia known to us. ston ColI. Glasgow) is particularly interes• New diagnoses of the genus Rhynia and ting because, in one and the same section its only species are proposed: of an axis, I found both a stomata and (Jass: PSILOTOPSIDA (plants with protuberances bearing rhizoids (PI. 1, fig. a vascularized gamctophyte and a sporo• 4 and 7). phyte which is simple) In my opinion the gametophyte R. order of the Psilotales gwynne-vaughanii K. and L. was neither + - family of the Psilotaceae, submerged in water nor subterranean, but • genus Psilotum. probably spreading out on the soil surface (as witnessed by the presence of stomata - family of the Tmesipteridaceae, and by the presence of rhizoids borne on • genus Tmesipteris, protuberances always situated on one side). - family of the Rhyniaceae 4 - The study of endophytic fungi in • genus Rhynia R. gwynne-vaughanii and R. major (1971) Rhynia gwynne-vaughanii (Kidston and has lead me to the following conclusions: Lang) Y. Lemoign,e Diagnosis: Sporophyte The axes of gametophytes (R. gwynne• and gametophyte distinct, vascularized, vaughanii) and sporophytes (R. major) har• having an epidermis with cuticularized boured several endophytic fungi which outer wall cells and stomata. All the differed from each other in morphological axis without leaves or spines. The game• and biological characters. One of these tophyte is a system of branched, vascularized fungi, which was common to the gameto• axis spreading on the ground, with rhizoids phytic and sporophytic phases of Rhynia, generally situated on hemispherical protu• produced respectively mycothallus and my• berances localized on the lower side. The corrhiza, an additional proof of the specific axis bear archegonial protuberances and identity of the Rhynia gwynne-vaughanii antheridia. Each mature archegonial pro• (Kidston and Lang) Y. Lemoigne. It is tuberance shows at its top a rosette of possible that long endocortical hyphae, four cells, between them the opening of cheifly intercellular, belong to the same a canal leading down to an oosphere symbiotic fungus. Among the other fungi in the interior of the gametophyte; observed, were one generally located in the oosphere is surrounded by a layer of cells the necrosis ZOnes (and producing clusters in regular arrangement. At maturity the of sporocysts); another invading superficial cells of the protuberance (cells of the neck cells (and closely related to the genus of the archegonium and associated cells) Rhizoctonia); and several other ones which dissolved and formed a mucilage. The an• produced sporocysts and spores varying theridia globular and they appear as a kind in size and structure; all were probably of globular swelling of the epidermis of parasites with a gradient in their virulence. about 200 [J. in diameter. All the axis are There were also saprophytic fungi in• protostelic. The gametophyte probably vading dead and decaying tissues. Such with chlorophylle. saprophytes appear commonly also in these The sporophyte is a system of naked sections of the sporophytic axis of Astero• branched protostelic or siphonostelic axis xylon macl~iei K. and L. that I have had creeping on the ground and bearing: the opportunity to study microscopically. - on the lower side rhizoids generally localized on protuberances, - on the upper side erect (simple or CONCLUSIONS branched?) naked protostelic axis. The sporangia, large, homosporous, borne Rhynia major K. and L., and, Rhynia lon,ely at the top of erect axes: the sporan• gwynne-vaughanii K. and L. have been gial wall thick, of many layers of cells. The considered as two distinct species of sporo• spores developed in tetrads about 65 [J. in phytes. However, they represent one diameter. species, R. gwynne-vaughanii being the, Locality - Muir of Rhynie, Aberdeenshire gametophyte and R. major the sporophyte, (Scotland) , both of them vascularized. According to Horizon - Devonian. LEMOiGNE-THE PRESE l' STATUS OF RHYNIA GWYNNE-VAUGHANII 45

Remarks the vasculiferous gametophytes. In my opinion considerable differences exist in 1) All characters known from Rhynia the gametophytes of Psilotum and Tmesip• gwynne-vaughanii are those of a Pterido• teris on the one side and Rhynia on the phyte and not of a Bryophyte. other side if we accept that Rhynia gwynne• 2) My observations confirm the correct-· vaughanii is the gametophyte of R. major. ness of Dr D. D. Pant's ideas. Psilotum and Tmesipteris have sub terrane• 3) The following points are still obscure: ous, though sometimes slightly vascularized we do not know for certain if the erect axes prothallia and the gametophyte of Rhynia of the sporophyte Were simple or branched, is in that case a dichotomously organized and if all erect axes (or, in case, if all their erect plant, provided with a haplostele, a ultimate ramifications) ended in sporangia. cortex, an epidermis with stomata, and 4) There is a close affinity between Rhynia a subterraneous rhizome". For F. P. and Psilotum. I do not think, however, JONKER the order Psilotales (genera Psilo• that there is any phylogeneJ ic relationship tum and Tmesipteris) shows more affinity with the Anthocerotales. to the phylum Lycopodiophyta in his opinion 5) In a recent paper, entitled "The the order Psilotales is to be derived from Taxonomic position of the Psilotales in the Protolepidodendraceae) the light of our knowledge of devonian I am astonished that the morphology plant life" (Palaeobotanist , 20 (1) 33-88, of the gametophyte of Rhynia gwynne• 1973), p. 35, F. P. JONKER writes: vaughanii is not the same for F. P. JONKER " ... Rhynia consequently shows an almost as for me (In my opinion the gametophyte isomorphic alternation of generations, quite was not a "dichotomously organized erect unknown up till noWin order Pteridophytes. plant ... with a subterraneous rhizome"). I am astonished that this leads Lemoigne On the other hand I have considered not (1968) to the conclusion that his discoveries only one but a group of comparisons have made it clear that both Psilotum and between Psilotum- Tmesipteris and Rhynia. Tmesipteris belong together with Rhynia I think that Psilotaceae, Tmesipteridaceae in the same order Psi10tales, of the Psilo• and Rhyniaceae are in the same phylum phyta. He argues this by pointing to Psilophyta.

REFERENCES

BOWER, F. O. (1935). Primitive Land Plants. Idem (1968b). Les genres Rhyuia Kidston et London. Lang du Devonien et Psilotum Seward actuel BlERHORST,D. W. (1971). Morphology of Vascular appartiennent-ils au meme phylum ? Bull. Plants. New York & London. Soc. Bot. Fr. 115: 425-440. EAMES, A. J. (1936). Morphology of the Vascular Idem (1969a). Contribution it la connaissance du Plants. Lower Groups (Psilophytales to Fili• Gametophyte Rhynia gwynne-vaughanii Kidston cales). New Yor/I. et Lang: Probleme des protuberances et pro• FRITSCH, F. E. (1945). Studies in the comparative cessus de ramification. Bull. Soc. Linn. Lyon. morphology of the algae. IV. Algae and the 4. archegoniate plants. Ann. Bot. (N.S.) 9: 1-29. Idem (1969b). Organe assimilable it une antheridie HOLLOWAY, J. E. (1939). The gametophyte, et stomates epidermiques portes par des axes embryo and young rhizome of Psilotum tri• rampants du type Rhynia gwynne-vaughanii quetrum Seward. Ann. Bot. (N.S.) 3: 313-336. Kidston et Lang. C. R. Acad. Sci. Paris. KIDSTON, R. & LANG, W. H. (1917). On Old Red 269D: 1393-1395. Sandstone Plants showing Structure from the Idem (1970). Nouvelles diagnoses du genre Rhynia Rhynie Chert Bed Aberdeenshire. Part 1. et de l'espece Rhynia gwynne-vaughanii, Bull. Rhynia Gwynne- Vaughanii Kidston and Lang. Soc. Bot. Fr. 117: 397-320. Trans. R. Soc. Edinburg. L, 1, 24: 761-784. LEMOIGNE,Y & BOULLARDB., (1971). Les Champi Idem (1920). On Old Red Sandstone Plants ons endophytes du " Rhynia gwynne-vatlghanii " showing Structure, from the Rhynie Chert Bed, K. et L.: Etude morphologique et eJeductions Aberdeenshire, Part II. Additional Notes on sur leur biologie. Botaniste. LIV: 49-89. Rhynia Gwynne- Vaughanii Kidston and Lang; MERKER, H. VON (1958). Zum fehlenden Gliede with Descriptions of Rhynia major, n. sp., and del' Rhynien Flora. Bot. Notiser. 111: 608-618. Hornea Lignieri, n.g., n. sp. Ibid. L. II: 603-627. Idem (1959). Analyse del' Rhynien. Basis und LEMOIGNE, Y. (1968a). Observation d'archegones Nachweis des Gametophyten. Ibid. 112: 441• portes par des axes du type Rhynia gwynne• 452. vaughannii Kidston et Lang. Existence de PANT, D. D. (1962). The gametophyte of the Gametophytes vascularises au Devonien. C.R. Psilophytales. Proc. Summer School Bot. A cad. Sci. Paris. 266: 1655-1657. Darjeeling: 276-301. 46 THE PALAEOBOTANlsl' EXPLANATION OF PLATES

PLATE 1 10. Epidermis with stomata of the sporophyte. X 40. Rhynia gwynne-vaughanii (Kidston and Lang) Y. Lemoigne PLATE 2 1. Two transversal sections of the axis of the Rhynia gwynne-vaughanii (Kidston and Lang) gametophytes. We can see, on the left, a section Y. Lemoigne with 3 archegonial protuberances. X 20. 2. A part of the transversal section of an axis of 11. Transversal section of an axis of the gameto• the sporophyte. X 25. phyte showing a beautiful archegonial protuberance vs - vascular strand. (A). X 40. 3. Part vs of the fig. 2, vascular strand (proto• 12. Part (A) of the fig. 11. Archegonial protube• stele) with xylem, in the center, and phloem, of rance showing at its top a rosette of four cells, an axis of the sporophyte. X SO. between them is the opening of a canal leading 4. Transversal section of an axis of the gameto• down to an oosphere (00) in the interior of the phyte with 2 protuberances bearing rbizoids. gametophyte. X 300. X 25. 13. Transversal section of an axis of the gameto• 5. Stomata of the epiderm of the gametophyte. phyte; two archegonial protuberances (A) can be X 100. seen. X 30. 6. Transversal section of an axis of the sporo• 14. Part of the fig. 13: an archegonial protube• phyte: 2 protuberances with rhizoids can be seen rance with an oosphere (00) surrounded by a on the right of the lower part of the figure (P). layer of cells in regular arrangement. X 75. X 12. 15. Part of the fig. 16: a globular antheridium. 7. A part of the transversal section of an axis X 60. of the gametophyte. X 40. 16. Transversal section of an axis of the gameto• st: stomata. phyte showing one antheridium (a). X 30. p: protuberance bearing rhizoids. 17. Diametral section of an axis of the gameto• phyte: we see very well the vascular elements of 8. A stomata of the sporophyte. X 200. the phloem. X 40. 9. Part of the fig. 6: the two protuberances 18. Longitudinal view of the elements of the with rhizoids. X 30. phloem of Psilatum nudum. X 300. THE PALAEOBOTANIST, VOL. 22 LEl\IOIG E - PLATE 1 LEMOIGNE - PLATE 2 THE PALAEOBOTANIST, VOL. 22