VOLUME 4 DECEMBER 1956 PART i REINWARDTIA BEING A CONTINUATION OF T H E BULLETIN DU JARDIN BOTANIQUE DE BUITENZORG (BULLETIN OF THE BOTANIC GARDENS, BUITENZORG) EDITORS A N W A R I DILMY (Herbarium Bogoriense) AND C. G. G. J. VAN STEENIS (Flora Malesiana) Published by HERBARIUM BOGORIENSE KEBUN RAYA INDONESIA Reinwardtia Vol.4, Part 1, pp. 1-118, BOGOR, December 1956 R E I N W A R D T . I A Published by Herbarium Bogoriense, Kebun Raya Indonesia Volume 4, Part 1, pp. 99-104 (1956) SCYPHOSTEGIA BORNEENSIS STAPF Anatomy of Stem and Leaf in Relation to its Taxonomic Position C. R. METCALFE * . S U M M A R Y From an examination of anatomical characters it appears that the genus Scyp'hostegia is not related to Monimiaceae and Moraceae but re- presents a separate family related to Flacourtiaceae. INTRODUCTION As the taxonomic position of Scyphostegia has been disputed, an ana- tomical examination of the stem and leaf was undertaken at the suggestion of Dr Van Steenis in the hope that the microscopical structure of these organs would afford evidence concerning the affinities of the genus. As was only to be expected with a, genus that exhibits so many characters in the morphology of the inflorescence and flower that are both distinctive in themselves and which cannot readily be matched, in any of the well established families of Dicotyledons, anatomical evidence likewise points to the somewhat isolated position of the genus. It is thus reasonable to follow Hutchinson (2) in recognising that the genus merits the status of a distinct family. As is shown below,' however, there is little anatomical evidence to suggest that Scyphostegia is related either to the Monimiaceae or Moraceae. The facts indicate rather that its nearest existing relations are to be found amongst the Flacourtiaceae, although there is no parti- cular genus in this family, amongst those of which the anatomy has been investigated, that appears to have a specially close relationship. The possibility of a taxonomic relationship of Scyphostegia to the Flacourtia- ceae rests rather on the fact that Scyphostegia exhibits a combination of characters that are also to be found in a number of genera and species that are well established as members of the Flacourtiaceae. In this article the anatomy of the leaf and stem of Scyphostegia is described, and the evidence that suggests that the genus has affinities with the Flacourtia- ceae, rather than with the Monimiaceae or Moraceae,. is discussed. LEAF. Hairs; none seen. Adaxial epidermis, in surface view, con- sisting of variously shaped cells with thin, curved/but not sinuous walls. * Jodrell Laboratory, Royal Botanic Gardens, Kew. . — 99 — 100 R E I N W A R D T I A [VOL. Abaxial surface also composed of variously shaped cells, with thin walls but these are slightly sinuous. Stomata confined to the abaxial surface; abundant; paracytic (rubiaceous), each stoma accompanied on either side by a subsidiary cell parallel to the pore. Mesophyll dorsiventral, with 2—3 rows of short to tall palisade cells, and a broader zone of slightly spongy parenchyma. In some leaves, e.g. in a leaf from the specimen collected by J. and M. S. Clemens 26062, the layer of cells immediately below the adaxial epidermis is differentiated as a distinct hypodermis, but this hypodermal layer was less clearly apparent in material from the Penang Botanic Garden. The height of the palisade cells also varies in different leaves. Some of the mesophyll cells, especially those towards the adaxial surface, are filled with amorphous, probably tanniniferous, contents that stain readily with haematoxylin. Structure of the large lateral veins obscure in transverse sections of the leaf because of their oblique course in relation to the long axis of the leaf, but each vascular stand is encircled by a fibrous sheath. Smallest vascular bundles deeply embedded in the mesophyll, and often accompanied by only a few fibres, mostly on the abaxial side, each small bundle being surrounded by a rather irregular sheath of thin-walled cells. Large, solitary, clustered crystals occur sporadically throughout the mesophyll tissue. Midrib with a longitudinal ridge that projects prominently from the abaxial, and another that projects slightly from the adaxial surface, the ridges consisting mostly of slightly collenchymatous tissue. Vascular sys- tem of the midrib surrounded by a narrow, circular, but abaxially flatte- ned cylinder of fibrous cells with wide lumina, and only moderately thickened walls. Vascular tissue consisting essentially of adaxial and abaxial parts. The abaxial part appears either as a cylinder of xylem that is somewhat concave on its adaxial side, or as an arc that is not quite closed adaxially. The cylinder or arc of xylem surrounds a central, pith- like tissue, and is itself surrounded externally by thin-walled phloem. The adaxial part of the vascular tissue consists of a collateral strand of xylem and phloem that lies on the adaxial side of the cylinder or arc that has just been described, the phloem of the collateral strand being almost con- tinuous with the phloem on the adaxial side of the abaxial cylinder. The xylem of the adaxial strand abuts directly, or almost directly, on to the fibrous cylinder by which the whole vascular system is surrounded. Bran- ches from the adaxial strand pass out into the mesophyll at intervals. The vessels, wherever they occur in the xylem, are mostly in radial multi- ples. PETIOLE, in transverse sections immediately at the base of the lamina, exhibiting a vascular structure not unlike that of the midrib, but there is no fibrous cylinder surrounding the vascular system. The abaxial vas- cular cylinder, or almost completely closed arc, that occurs in the midrib, has the form of a deeply U-shaped strand in the distal part of the petiole. Situated between the arms of the U there is an adaxially flattened cylin- der of xylem and phloem, formed by the amalgamation of the adaxial vascular arc of the midrib with the adaxial part of the abaxial cylinder. 1956] C. R. METCALFE: Seyphostegia Borneensis Stapf 101 The vascular cylinder between the arms of the U consists externally of xylem that surrounds the phloem which has the form of a number of closely placed strands, the somewhat triangular ground tissue surrounded by the phloem consisting of parenchyma. At a lower level in the petiole, the vascular system has the form of an abaxial cylinder of xylem and phloem, accompanied adaxially by an irregularly shaped and complex mass of xylem and phloem. Towards the base of the petiole the adaxial mass of xylem and phloem has the form of a rather irregular arc which is, at this level, continuous with the main abaxial vascular strand, so that the whole vascular system appears in transverse section as a some- what uneven cylinder. Towards the base of the petiole the whole vascular system is surrounded by a narrow cylinder of fibrous cells with fairly thick walls and wide lumina, the fibrous ring being similar to that which surrounds the vascular system in the midrib. Cluster crystals are abun- dant in the ground tissue, especially at the centre of the petiole, and smaller, but similar crystals in the phloem. The exact appearance of the vascular system in the petiole, and to some extent in the midrib, varies from section to section, and there also appear to be minor variations from leaf to leaf. STEM, (a) Stem 2 mm in diameter. Stem more or less rectangular in transverse section. Hairs; none seen. Phloem and xylem in the form of cylinders of about equal width. Large cluster crystals occur in the cortex and near the phloem fibres, and smaller but similar cluster crystals in the phloem. Other particulars as in (b) below. (b) Stem 3 mm in diameter. Cork originating in the epidermis; consisting of thin-walled markedly rectangular cells. Amorphous, (tanniniferous?) deposits present in some of the cork cells. Primary cortex about 7 cells wide, consisting mostly of thin-walled parenehymatous cells, but outer cells locally smaller than those elsewhere, and somewhat collenchymatous. Outer boundary of the phloem marked by a continuous sclerenchymatous ring, consisting of thick- walled fibres with narrow lumina and irregularly shaped sclereids with wider lumina. Phloem and xylem in the form of closed cylinders traversed by narrow rays. Phloem devoid of sclerenchyma apart from the ring at the outer periphery. Vessels solitary and in short radial multiples of 2—4 or occasionally more; even those vessels that are solitary are located on definite radii from the stem centre. Individual vessels 31—58µ. in internal radial diameter. Inner part of the primary xylem consisting of specially small elements that are stained more readily by haematoxylin than by safranin, and are therefore apparently less lignified than those of the rest of the xylem. The occurrence of these unlignified portions of xylem abutting on the pith suggests that there is considerable centrifugal development of xylem before the primary xylem is wholly lignified, and there may be some centripetal lignification of the xylem. Pith somewhat stellate in outline, with 4 arms; parenehymatous; thick-walled and ligni- fied at the periphery, and thin-walled and less lignified at the centre. The 102 R E I N W A R D T I A [VOL. 4 thickening and lignification of the cells continue centripetally as the stem grows older, and the pith ultimately becomes homogeneous in ap- pearance. Crystals similar to those described under (a) above, but less numerous. (c) Secondary xylem, 1 cm in diameter. Vessels sometimes solitary, but mostly in radial multiples of 2—4, or occasionally more; a few irregular multiples also present. Individual vessels in each multiple flattened where in contact with one another; those not pressing against one another are circular or oval in outline. Vessels 40—100 JA in internal radial diameter. Vessel members with simple, but very oblique, perforations; lateral pitting alternate, pits crowded to rather sparse, mostly rounded in outline and with circular to horizontally oval apertures. Fibres constituting practically the whole of the ground tissue of the wood; with fairly thick walls and oval to circular lumina; with numerous, fine, transverse septa, and rather large bordered pits with slit- shaped apertures in the radial, but not in the tangential walls. Parenchyma absent, apart from occasional paratracheal cells. Rays very densely crowded, not conspicuous in transverse sections; mostly uniseriate, but a few partly bi- or triseriate; uniseriate rays composed mostly of tall, narrow cells, but some rays, especially those that are more than uniseriate, are markedly heterogeneous; at least 9—28 cells high, and sometimes appearing higher owing to fusions between rays. TAXONOMIC AFFINITIES It seems, from the anatomical evidence, that Scyphostegia has no very close affinities with well established families. This is also empha- sized by the distinstive morphology of the inflorescence and flower. Hith- erto the most commonly expressed opinion has been that the genus has affinities with the Monimiaceae, although it has always been felt that the affinities cannot be very close. Hutchinson (2), on the other hand, has taken the view that the genus should be in a distinct family related to the Moraceae. This discrepancy of view largely depends on varying interpretations of the morphology of the flowers and inflorescence, which, in turn have been partly due to lack of adequate material. Hutchinson, now that more material has been at his disposal, has changed his views about the relationship of Scyphostegia to the Moraceae. The varying interpreta- tions of the morphology of the flower and inflorescence have been summa- rized by Swamy (6), who, however, does not make any constructive sug- gestions concerning the affinities of the genus. A study of the anatomy of the stem and leaf fails to provide any convincing evidence that the genus has any close affinities with either the Moraceae or Monimiaceaee. On the contrary the anatomical evidence suggests rather remote affinities with the Flacourtiaceae or with the Euphorbiaceae. The suggestion of a relationship with the Euphorbiaceae is, however, of doubtful signifi- 1956] C. R. METCALFE: Scyphostegia Borneensis Stapf 103 cance, as the Euphorbiaceae themselves constitute a large heterogeneous group, in which the range of anatomical structure is correspondingly great. Furthermore some genera of Euphorbiaceae are themselves not unlike some of the Flacourtiaceae, at least so far as their wood structure is concerned. It must be emphasized that there is no particular genus in the Fla- courtiaceae to which Scyphostegia is especially similar. The point is rather that Scyphostegia exhibits a number of characters that occur in certain genera of Flacourtiaceae, and this combination of characters suggests that Scyphostegia may have affinities, although these may be somewhat remote, with the Flacourtiaceae. The characters that suggest this relation- ship include the following: — In the leaf, the paracytic (rubiaceous) stomata and the occurrence of adaxial hypoderm. The midrib structure of Scyphostegia. is not unlike that of certain Flacourtiaceae such as Dipentodon. On the other hand, petiolar vascular structure of the type that occurs in Scyphostegia, has not yet been recorded in the Flacourtiaceae. The superficial origin of the cork in the stem of Scyphostegia, and the thin- walled cells of which it is composed, have their counterparts in the Fla- courtiaceae. This applies also to the radial multiples of small vessels in the wood; the sparse wood parenchyma; the uniseriate rays composed of hign, upright cells; the ociurrence of vestically fused rays the septate wood are common to both Scyphostegia and the Flacourtiaceae. fibses, with pits limited to the radial walls. Specially large cluster crystals The first anatomical objection to the inclusion of Scyphostegia in the Monimiaceae came from Perkins and Gilg (5) who pointed out that the leaves of Scyphostegia, unlike those of the Monimiaceae, do not contain secretory cells. Baehni (1), and, more recently, Money, Bailey and Swamy (4) and Swamy (6) have reminded us of this fact. In addition, the last 3 authors have pointed out that Scyphostegia differs from the Monimia- ceae in having trilacunar nodes, and tricolpate pollen grains. A perusal of Metcalfe and Chalk's "Anatomy of the Dicotyledons" (3) reveals further anatomical reasons for believing that there are no close affinities between Scyphostegia and the Monimiaceae. For example the stomata in Monimia- ceae are usually anomocytic (ranunculaceous) in contradistinction to the paracytic rubiaceous) stomata of Scyphostegia. The Monimiaceae also differ from Scyphostegia in having crystals that are usually needle- shaped; vessels that are seldom in radial multiples; a less complex vas- cular structure in the petiole. The rays in the wood of the Monimiaceae are variable in form, but uniseriates of the type that occur in Scyphostegia are unknown. 104 R E I N W A R D T I A [VOL. 4 Turning now to the Moraceae it may be noted that the family as a whole generally differs from Scyphostegia in not usually having paracytic (rubiaceous) stomata, whilst laticiferous canals, unknown in Scyphostegia, are characteristic of many members of the Moraceae. The wood of the Moraceae differs from that of Scyphostegia in having vessels that are mostly solitary; parenchyma that is typically paratracheal, and usually aliform or confluent. Uniseriate rays are uncommon in the family, and, where they do occur, they are not of the same type as those in Scypho- stegia. On the other hand the wood of Scyphostegia resembles that of both the Moraceae and Monimiaceae in having septate fibres, but this character, although of diagnostic value because of its restricted occur- rence, is to be found sporadically throughout the Dicotyledons, and it occurs in families between which there are no close affinities. Taking all of these facts into consideration, the anatomical evidence seems to suggest that Scyphostegia can best be treated as a distinct family the Scyphostagiaceae, having some taxonomic affinities with the Flacour- tiaceae. REFERENCES (1) BAEHNI, C. (1938): in Ber. schweiz. bot. Ges. 48: 22—28. (2) HUTCHINSON, J. (1926): Families of Flowering Plants 1: Dicotyledons, London. (3) METCALFE, C. R. & CHALK, L. (1950) : Anatomy of the Dicotyledons, 2 vols. Oxford. (4) MONEY, L. L., BAILEY, I. W. & SWAMY, B. G. L. (1950); in Journ. Arnold Arbor. 31: 372—404. (5) PERKINS, I. & GILG, E. (1901) ; in Engler, Pflanzenreich Heft 4 (Monim.) : 117. (6) SWAMY, B. G. L. (1953) : in Proc. Nat. Instit. Sci. India 19: 127—142. MATERIAL EXAMINED Sample 927 from the Botanic Gardens, Penang. Herbarium specimens collected by J. and M. S. Clemens, reference no. 26062. ACKNOWLEDGEMENTS The author is indebted to Mr J. W. Purseglove, Director of the Botanic Garden at Singapore, and to Mr H. Ritchings, Horticultural Officer at the Botanic Gardens at Penang, through whose courtesy it was possible to obtain material of Scyphostegia preserved in formalin acetic alcohol. Thanks are also due to Dr J. Hutchinson for his kindly interest and advice. The microscope slides examined during the investigation were prepared at the Jodrell Laboratory by Mr F. Richardson. REINWARDTIA Published by Herbarium Bogoriense, Kebun Raya Indonesia Volume 4, Part 1, pp. 105-112 (1956) NOTES ON INDONESIAN FRESHWATER ALGAE II. Ichthyodontum, a new desmid genus from Sumatra. ARTHUR M. SCOTT * and GERALD W. PRESCOTT ** SUMMARY Described and figured are Ichthyodontum, a new genus belonging to the desmidiaceous algae, with /. sachlanii, a new species with its new variety parorthium, showing a peculiar bipolarity. From southern Sumatra. I c h t h y o d o n t u m Scott & Prescott, gen. nov. Cells elongate-cylindric and rectangular in front view, the poles truncate and bearing at each angle a blunt spine or tooth which may be either vertically or laterally directed, the apical margin with a shallow median notch or depression; semicells slightly swollen at the base, with a circumferential supraisthmian row of blunt teeth, the two series of teeth intermeshing and completely enclosing the shallow median incision; side view of cell elongate subfusiform; basal view broadly elliptic. Cellulae a fronte visae elongato-cylindricae reetangularesque, polis truncatis et in utroque angulo spinam obtusam vel dentem verticaliter lateraliterve directum ferentibus, margine apicali incisuram mediam non profundam vel depressionem praebente; semicellulae ad basim subinflatae dentibus obtusis in ordine circumferentiali supraisthmiali praeditae, den- tibus amborum ordinum implexis et incisionem median non profundam omnino includentibus; cellula a latere visa elongato-subfusiformis; a basi visa late elliptica. Ichthyodontum sachlanii Scott & Prescott, spec. nov.—Fig. 1 Cells of medium size, length 6 to 7 times the width, in front view elongate-cylindric and decidedly curved, apices truncate with a shallow median subcircular notch with a prominent tubercle at each side on the margin, each apical angle bearing a stout upwardly directed tooth that is prolonged into a sharp fine spine; semicells slightly swollen at the base with one lateral margin more inflated than the other, and bearing a supraisthmian row of 10 longitudinal folds (5 showing) which bear each a prominent basally directed tooth, the teeth of one semicell intermeshing (not interlocking) with those of the other, thus completely enclosing the shallow median incision of the cell; cell wall sparsely punctate and having *2824 Dante St., New Orleans 18, La., U.S.A. ** Dept. of Botany, Michigan State University, East Lansing-, Mich., U.S.A. — 105- Rein.Vol 4, Part 1, pp 1-118_Page_01 Rein.Vol 4, Part 1, pp 1-118_Page_51 Rein.Vol 4, Part 1, pp 1-118_Page_52 Rein.Vol 4, Part 1, pp 1-118_Page_53 Rein.Vol 4, Part 1, pp 1-118_Page_54