FLORAL MORPHOLOGY AND EMBRYOLOGY IN SOME TAXA OF THE CANELLACEAE

BY N. PARAMESWARAN (Department of Botany, Presidency College, Madras-5) Received January 22, 1962 (Communicated by Dr. T. S. Sadasivan, r.n.sc.)

INTRODUCTION ThE Canellace~e has not been investigated from the point of view of embryology or floral morphology. Schnarf (1931) lists this family as inviting embryological study along with Lactoridace~e, Himantandrace~e, Eupomatiace~e, Gomortegace~e, Monimiace~e and Hernandiaee~e. Rather extensive taxonomic deliberations combined with scanty anatomical studies of the taxa of the Canellaceze have yielded data which are conflicting in them- selves as to the exact placement of the family in the systems of classification. The general trend has been to adjudge the Canellace~e to the Parietalean com- plex with various degrees of relationship to families like the Violace~e, Bixace~e, Flacourtiace~e and Koeberliniace~e. A comparative morphological study of the family combined with an intensive study of wood anatomy has con- vinced the present author that the Canellace~e is to be located in the Ranalian group of families withmonocolpate , " ethereal oil cells" and trilacunar node (Group B of Money, Bailey and Swamy, 1950). On the evidence ob- tained from wood anatomy Wilson (t960) has concluded that the family is more nearly related to Eupteleace~e, Dilleniace~e, Eupomatiacea~, Illiciace~e and Schisandrace~e of the woody Ranales than to the families of Parietales. The present study sums up the data obtained from an investigation of floral anatomy and embryology in relation to the systematic position of the Canellace~e.

MATZR;AL AND METHODS Melchior and Schultze-Motel (1959) recognize six genera and twenty as constituting the taxa of the family. The genera are , , , , Capsicodendron and . In the embryological study presented here, fresh and killed materials of Canella alba Murray, obtained through the courtesy of the Director, Atkins 167 168 N. PARAMESWARAN

Gardens, Cienfuegos, Cuba and those of Sprague and of Engl. obtained through the courtesy of the Sylviculturist, Forest Department, Lushoto, Tanganyika, were used. Materials for anatomical study were obtained from herbarium specimens. Of these, Cinnamosma madagascariensis Danguy was obtained from the herbarium specimen supplied by the Director, National Museum of Natural History, Paris. I am thankful to the above institutions and personnel for the gift of materials used in the present study. Customary methods of dehydration and embedding were followed. Iron-alum ha~matoxylin in combination with erythrosin or fast green was used for staining.

OBSERVATIONS Floral anatomy The exomorphic features of the in the Canellace~e are rather uniform and stabilized. The norm may be taken to represent a trimerous calyx, the basal part having united in the form of a cup; one or two whorls of , the number of which is subject to slight variation within each ; a syngenesious andrcecium in which the component are variable in number (generally in multiples of five) and a superior gyncecium constituted of two to six carpels. The are numerous on parietal placentae and semi-anatropous. While the petals are free in most of the genera, those of the genus Cinnao mosma exhibit a particular trend of specialization in having undergone lateral fusion for a greater length. The pattern of floral vascularization appears to be as stabilized as the exomorphie features with little variation, thereby rendering it possible to visualize a norm. The variations concern the degree of proliferation of the vascular strands of the pedicel corresponding to the number of appendages borne by the . A major variation in the exomorphic feature is, as mentioned above, the gamopetalous condition in Cinnamosma. With these considerations in mind, the vascular anatomy of Warburgia stuhlmannff (representing norm), of Cinnamosma madagascariensis (representing variation) and of Canella alba has been described in the following paragraphs. The terminologies employed in the description are patterns as seen in successive serial transverse sections from the base to the apex of the flower, and the terms do not imply develop- mental connotations, Floral Morphology & Embryology in Some Taxa of Canellaceae 169 In the pedicel of the flower of Warburgia stuhlmannii the vasculature occurs in the form of a ring; a careful examination indicates that the ring is made up of more or less discrete strands (Fig. 1), the number varying between 10 and 24 in different taxa. The median and marginal traces for each of the calyx lobes arise from independent "gaps" (Fig. 2). Within the calyx, the bundles proliferate and anastomose freely. It may be indicated at this point

Flo. 1-12 170 N. PARAMESWARAN that the origin of vascular bundles that supply the calyx lobes is reminiscent of the trilacunar condition of the vegetative nodes of the Canellace~e.

Immediately above the level of calyx the axial vasculature is broken up into a number of concentrically placed bundles (Figs. 3-5). The outermost series, the number of which corresponds to that of petals, constitutes the main supply to the corolla lobes. Within the the bundle trifurcates into one median and two marginals. At still higher levels in the petal the marginals generally undergo bifurcation. This latter feature appears to be particularly so in reference to the outermost petals which are relatively larger than the innermost.

Vasculature to the androecium is constituted by the outer ring of bundles that encloses the centrally situated group of five larger bundles (Figs. 3-5). Although the androecium morphologically appears to belong to a single , anatomically there is clear evidence to indicate that it is constituted of two whorls, the number of stamens in each being equal. Thus, in the given example, a set of five bundles deviates centrifugally at a lower level (the outer whorl) and another set of same number of bundles but disposed along alternating radii become separated at a successive level (Figs. 3-5). Soon, however, the bundles of both the whorls align themselves along one and the same circumference (Figs. 5-7) and contribute a single strand to each (Figs. 8, 9, 11).

After the vasculature to the outer whorls of floral parts is completed, only five relatively large bundles are left in the axis (Fig. 6). Each one of these breaks up into a larger median and two smaller lateral traces, the latter more centrifugally so as to confront the respective median bundles (Figs. 7, 8). The branches of the lateral traces vascularize the ovules (Fig. 9). At the top of the , i.e., above the level of attachment of the ovules, the median bundles of the carpel undergo further proliferation, the ends of which form anastomoses with similar strands of the ventral bundles (Fig. 10).

In Cinnamosma madagascariensis also the manner of vascularization of the floral parts is identical to the pattern just described for Warburgia. However, in the former species the petals are fused to form a tube. In spite of this external manifestation, the vascular supply remains the same as in Warburgia. In other words, cohesion of petal members is not reflected in the vascular supply. Thus, fifteen bundles representing the median and marginal traces of five petals which have undergone lateral fusion are discernible at successive levels of the gamopetalous corolla. Floral Morphology & Embryology in Some Taxa of Canellaceae 171

In reference to Canella there is a difference of opinion whether the inner whorl of perianth is to be considered sepaline or petaline in nature. In view of this ambiguity it should be emphasized here that the vascular ground plan of Canella is similar to the one described for the norm. However, two important features are to be noted: Firstly, the individual members of the outermost whorl are supplied with two vascular strands from the eustele of the pedicel (Fig. 13). These strands arise from independent " gaps " and occupy the median position in the basal part of the lobe. They soon proli- ferate into numerous traces which spread uniformly in the lobe (Figs. 14--18). This situation is in contrast to the" trilacunar " vascular supply to the corres- ponding structures in the other genera of the family. Secondly, the vascular supply of the inner perianth members in Canella is exactly similar to the single trace condition that obtains in the remaining genera of the family. Thus, it would appear appropriate to designate the inner whorl of perianth as pelaline in conformity with the similar vasculature available in the other genera of the family.

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F]os. 13-18

Megasporogenesis and female gametophyte.--In both the species studied, the is bitegmic and crassinucellate (Figs. 25, 27). The differentiating ovule from the placenta soon undergoes a curvature of about 45 ° so that the axis of the nucellus comes to lie at right angles to that of the funicle (Fig. 27). Continued growth results in a shallow curvature of the ovule at the time of fertilization (Fig. 25). The situation becomes more pronounced during post- 172 N. PARAMESWARAN fertilization development and the mature of the family are conspicuously curved. Both the inner and outer integuments arise more or less simul- taneously from the base of the nucellus. The outer integument grows at a relatively faster rate and envelops the inner one. On the antiraphe side the outer integument attains an exaggerated development so that it asym- metrically overhangs on the raphe side (Figs. 22, 27). The archesporial cell becomes differentiated in the subepidermal layer. It divides by a periclinal wall giving rise to a primary parietal cell and a primary sporogenous cell (Fig. 19). The former undergoes rapid divisions in periclinal plane to build up a rather extensive parietal tissue, as a result of which the developing megaspore or female gametophyte appears to be deeply embedded in the nucellus (Figs. 25, 27). The formation of a linear tetrad of megaspores resulting from the meiotic divisions of the megaspore mother cell has been seen in Warburgia stuhlmannii (Fig. 22). The chalazal megaspore germinates and builds up an eight-nucleate -sac (Figs. 23-25, 28). The antipodal cells persist at the time of fertilization and the polar nuclei fuse to form the secondary embryo-sac nucleus in Canella alba (Fig. 28). In Warburgia stuhlmannii also it is likely that the formation of the secondary embryo-sac nucleus is completed before triple fusion, although in Fig. 25 the polar nuclei are represented before fusion. The position of the secondary embryo-sac nucleus is invariably nearer to the egg apparatus. In both the species of Canellace~e studied at present, the synergids characteristically exhibit the so- called" filiform apparatus ". The nucleus of the cell occupies a basal position imbedded in densely staining cytoplasm. In very mature stages the apical part of the cell may show a vacuole, but such a structure is conspicuously absent in the basal part (Fig. 26).

Microsporogenesis and male gametophyte.--The andrcecium of the Canellace~e is, as is well known, syngenesious (Figs. 11, 12). A somewhat cylindrical column forms, so to say, the ' base' for the origin of the micro- sporangia. The primordium of pairs of anther thec~e arises in the form of longitudinal ridges on the surface of the column. As seen in transection, the elevated parts appear as protuberant groups of cells. Each group consti- tutes the primordium of a pair of thec~e. The archesporial cell becomes differentiated in the hypodermal layer at the outer corners of the protuberant groups of cells (Fig. 29). This cell divides periclinally giving rise to the outer primary parietal cell and inner primary sporogenous cell (Fig. 30). The primary parietal cell, by continued periclinal divisions (Fig. 31) forms five cell-layered wall tissue; in the meantime, the primary sporogenous cell also undergoes divisions, thereby increasing in bulk. The innermost of the wall Floral Morphology & Embryology in Some Taxa of Canellaceae 173 19 2O !

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Flos. 19-28 t74 N. PARAMESWARAN layers differentiates itself as the tapetum, while the outermost (the subepJ- dermal layer) organizes itself into the endotheeium (Fig. 32). This layer becomes morphologically distinct, though incipiently, at the same time as the tapetum. The cells of the endothecial layer soon become filled with a yellowish infiltration and the future position of the banded thickenings also become blocked out at this stage itself as may be witnessed by the radially aligned striations (Fig. 32). At maturity, the banded thickenings appear very conspicuous (Figs. 47, 49). The epidermis also persists in the mature anther wall (Fig. 47) and it may be seen in a slightly crushed condition even after the of the sporangia. These features are seen also in some species of Cinnamosma as could be judged from the siccate materials. The epidermal cells in Warburgia stuhlmannii and Warburgia ugandensis become conspicuously protuberant (Fig. 49). In the remaining taxa of the family, the epidermal cells become crushed at maturity. The endothecial cells in transections clearly demonstrate that the banded thickenings are developed on all the radial walls (Fig. 50). The tapetal cells become binucleate by the time the microspore mother cells embark upon meiosis. From this stage the nuclear behaviour (in Canella alba) in the cells is varied: (1) the two nuclei divide into four (Figs. 40--42); (2) the two nuclei may fuse to give rise to a single tetraploid one (Fig. 43) ; (3) the four nuclei undergo fusion again to result in a single octaploid nucleus (Fig. 44). Another feature in the behaviour of tapetal cells is also noteworthy. The inner tangential wall of these cells, both in Canella alba and Warburgia stuhlmannii, undergoes structural modifications before final disintegration. Either side of the wall becomes studded with minute protuberances of more or less spherical contour (Figs. 45, 46). These appear and persist throughout the active stage of the tapetum. This situation recalls the condition that has been described for the tapetal cells of Magnolia youlan, Lilium tigrinum (Kosmath, 1927), Moringa oleifera (Puri, 1941), dustrobaileya (Bailey and Swamy, 1949), etc. In these the puberulous protuberances occur only on the outer face of the tangential wall, whereas in the Canellace~e such a feature is present on both surfaces (Fig. 45). The microspore mother cells (Fig. 32) divide meiotically to produce tetrahedral quartets (Figs. 33, 34). Occasionally other tetrad configurations also occur. At the time of division of the microspore nucleus the tetrad alignment remains undisturbed. Such stages clearly indicate that the genera- Floral Morphology & Embryology in Some Taxa of Canellaceae 175

29 30

35 34 "-I 36 37

8 39 40 41 42 -$"~'~"~50

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• ",x 44

F~o~. 29-50 1T6 N. PARAMESWARAN tive cell is cut off towards the proximal pole of the pollen grain (Fig. 36). In the shedding condition, however, the position of the generative cell is variable (Fig. 39). In Canella alba there is a well-differentiated stomium region of thin-walled cells along the median line of each thecum. The dehiscence of the anther takes place along this line and the longitudinal halves of the endothecium reflect back (Fig. 48). While some of the pollen may escape to the exterior during this process, others become lodged in the now vase-shaped cavities of the thec~e (as seen in transectional view). Such pollen grains exhibit a remarkable tendency for germination. The vegetative nucleus by this time appears to have become greatly elongated and the sperms are also associated with it; these structures occupy the terminal part of the pollen tube (Fig. 35). The initiation of the germinal furrow takes place more or less simul- taneously with the division of the microspore nucleus. At first there appears a meridional fold on the proximal face of the pollen grain. This strip is left out during the deposition of the exine. Thus, the germinal furrow is placed on the distal pole of the pollen grain (Figs 37, 38). It is needless to say that the pollen tube is put forth from any locus on the colpa.

DISCUSSION Morphology of floral structures Calyx.--The outermost whorl of perianth in the Canellace~e is typically sepaline. This view is strengthened by the nature of vascular supply. In most genera, each receives three traces from the stele of the pedicel, each trace being related to one " gap ". Thus, this condition simulates the trilacunar structure of the vegetative nodes of the family. The only exception is in Canella where two traces that are related to a corresponding number of "gaps" constitute the vasculature of the sepal. This situation does not contradict the morphologically sepaline nature of the concerned structures, particularly in view of the subsequent behaviour of the main traces within the lobes. As in the remaining genera the traces undergo rather extensive branching, and the branches distribute themselves uniformly throughout the lamina. Corolla.--In contrast to the , the petal in all genera is uniformly supplied with a single trace from the stele of the pedicel. This trace trifurcates into a median and two laterals immediately after the level of insertion of the petals. This feature is so stereotyped that the gamopetaly in Cinnamosma does not in any way affect the norm. Floral Morphology & Embryology in Some Taxa of Caneliaceae I77

Attention has already been drawn to the diversity of opinion expressed in regard to the morphological nature of the inner whorl of perianth in Canella. While the original description of the genus and species treats the inner whorl as constituting of petals and the outer one as sepals, Bentham and Hooker (1862-1867) designate the members of the inner whorl as sepals and those of the outer as bracteoles. Even on the basis of exomorphic comparative morphology this view seems to be unjustifiable. From the point of view of vascular anatomy of the concerned structures, the untenability of Bentham and Hooker's view becomes much more emphasized. In Canella also the sepaline and petaline vasculature presents distinctive methods, and it may be stressed that the inner whorl of perianth of Canella possesses identical pattern of vascular supply as in the remaining genera. Thus, the outer and inner whorls of perianth in Canella are homologous with the corresponding structures occurring in all the other taxa of the family.

Andrcecium.--The syngenesious condition of the andr~ecium is an important diagnostic feature of the family. The fusion appears to have phylogenetically taken place along the lateral margins of adjacent members, so as to form a hollow cylinder. Although from the point of view of external morphology all the stamens appear to belong to a single whorl, a study of vascular anatomy clearly indicates that both cohesion and adnation have combined to produce the syngenesious structure. The evidence for this view is clearly portrayed in those instances where the number of stamens per andr~ecium occurs in multiples of five. In such cases, the vasculature for each whorl arises not only at successive levels but also along alternating radii. Each stamen receives one trace which traverses the hypothetically median part of the structure. Thus, the anthers are typically quadrilocular and the number of vascular traces in the andr~ecium reflects the number of stamens that have become fused. Therefore, there is no evidence in favour of Payer's contention that the stamens are bilocular (Baillon, 1871).

Gynavium.--Although the gyncecium of the Canellace~e is unilocular, it has been assumed, perhaps rightly, that more than one carpel has gone into its construction. The number of placentze per gyncecium may be taken as an indication of the number of carpels involved. The basis for this procedure is evidenced by the number of vascular traces that occur in the pedicel after the remaining whorls of the flower have been vascularized. These bundles soon trifurcate into the median and lateral traces of the component carpels. The laterals of the adjacent carpels draw nearer to each other and remain in this juxtaposed condition in the wall of the ovary. These bundles represent the placental vasculature which, in turn, supply the ovules. i78 N. PARAMESWARAN

The phylogenetic processes involved in the construction of the gynceeium of the Canellace~e may bc visualized without recourse to extensive series of complicated hypothetical stages. All that has to be done is to project back- wards, so to say, the structure of the canellacean gyn0ecium to the condupli- cate carpels, their number corresponding to that present in the gyn0ecia of the family. Each carpel component of the gyn~ecium appears to represent a single modified conduplicate carpel; these carpels have 'opened out' so that the margins of the adjacent members come in contact with one another, and ultimately the contiguous tissues undergo fusion. The result would bc exactly what it is in the Canellace~e (Fig. 51). 0 0

5{ Fro. 5! .--The placentation in the family has been described as parietal by all taxonomists. The is unilocular throughout the taxa with 2-5 parietally placed placentae on which the hemianatropous ovules are arranged in two series. As prescribed by Purl (1952) the parietal placenta- tion is characteristic of a multicarpellary, syncarpous, unilocular gynoecium with placentm borne on fused margins of different carpels; the placentm derive their vascular supply from the ventrals of different carpels, the ventrals being oriented on different radii from those of dofsals. The canellacean placentation strictlyfalls within this category as borne out by vascular anatomy. It may be remarked here that the vascular traces for the different lobes of the perianth whorl.arise at successively higher levelsof'the pedicelcortes-- Floral Morphology & Embryology in Some Taxa of Canellaceae 179 ponding to the level of insertion of the individual lobes, thereby revealing the basically cyclic arrangement of the perianth lobes. Furthermore, a careful analysis of the perianth parts indicates that there is a less defined but definite gradation between the outer and inner perianth members in so far as the shape and size are concerned. Whether from the point of view of external morphology a given flower possesses a spiral or cyclic arrangement is often difficult to decide, because of the progressive condensation of a spiral to appear as cyclic. In the Canellace~e this is the situation and only studies of vascular anatomy of the flower afford a clue to the true nature of the basic pattern of arrangement of the floral parts on the axis. It may also be inci- dentally mentioned here that Warburg (1895) became impressed with the united nature of stamens and the spirocyclie arrangement of petals in Cinnamodendron which prompted him to favour a ranalian relationship. Embryology While it is realized that the information presented here on the embryology of the family is ,too meagre to allow any dependable comparisons with other families, the amount of data that has become available is worthy of considera- tion in formulating the embryological features of the family. These are as follows: Ovule bitegmic and crassinucellate; parietal cell gives rise to a massive tissue; embryo-sac develops following the Polygonum type. Archesporium in the anther hypodermal; tapetum of the secretory type with nuclear divisions and fusions; the inner tangential wall of the tapetal cells exhibit puberulous thickenings. Division of the microspore mother cells is simultaneous; the generative cell is cut off toward the proximal pole; shedding stage two-celled. The innermost layer of the inner integument and the outermost layer of the outer integument constitute the seedcoat; the cells of the latter layer become infiltrated with black contents that impart a similar colour to the seeds. Mature contains copious oily with somewhat curved embryo occupying the axial part of the seed. Seeds of Cinnamosma exhibit a particular trend of modification in possessing a ruminate seedcoat (Parameswaran, 1961). Suggestions have been put forward in the past that the Myristicacea~ is related to the Canellace~e (Bessey, 1915; Wettstein, 1935; Vestal, 1937). It is also to be noted that the syngenesious nature of the andrcecium in the two families long ago attracted the attention of taxonomists. We are prone to suspect that this phenomenon in the two families has occurred indepen- dently. One of the main reasons for casting doubt has been the unisexual condition of the Myristicace~e in contrast to the bisexual flowers of the Canellace~e. This character makes it possible that the syngenesious condition in a unisexual flower could have been attained through a wholly different B2 180 N. P~Aa~AN method than the attainment of a similar condition in a bisexual flower. In fact, in the Myristicace~e the andrcecium is columnar and solid, while in the Canellace~e it is tubular. Although the anther tapetum in both the families conforms to the secretory type, that of the Myristicace~e remains uninucleate (Joshi, 1946), while the concerned cells in the Canellace~e exhibit nuclear divisions followed by secondary fusions. Also the peculiar structural modifi- cation of the inner tangential wall of the tapetum in the Canellace~e is not shared by the Myristicace~e. The seeds of the Myristicaee~e are arillate whereas those of the Canellace~e do not possess any appendages. On the other hand, the two families exhibit certain common features or trends. In addition to the bitegmic crassinucellate ovules containing a female gametophyte deve- loped according to the Normal type, the microspore mother cell divides according to the simultaneous method, in both the families the generative cell is cut off towards tile proximal pole (Joshi, 1946). All the genera of the Myristicace~e possess ruminate seedcoat and the presence of this particular feature is noted in one genus (Cinnamosma) of the Canellace~e. It may also be remarked incidentally that the vessels of the Canellace~e are more primitive than those of the Myristicace~e; however, the paratracheal parenchyma and uniseriate condition of the rays in the Canellace~e are shared by certain members of the Myristicace~e also. It may also be noted that the rays in the phloem flare out in both the families. The tanniferous tubes of the Myristicace~e do not have a counterpart in the Canellace~e (Garratt, 1933). Thus, there appear to be a large number of common features and trends in the families Myristicace~e and Canellace~e, just as there are important differences. It is the latter set of characters that has made the families what they are. In other words, these two families appear to present relatively a greater degree of relationship between themselves than they do with the remaining families of woody Ranales possessing monocolpate pollen, "ethereal oil cells" and trilacunar node. However, it must be emphasized that the similarity between the two families is not of the type whereby one family could be derived from the other. On the other hand, it appears that these two families have diverged from a common ancestor. Until such ancestors are discovered and in view of the limitation of our knowledge in regard to the trends and features in all the concerned families of Ranales, it is advisable to treat the two families as a closely related group just as the "magnoliaceous triumvirate" of families or the Piperace~e-Saururace~e group. SUMMARY The study of floral anatomy in the Canellace~ reveals a basically cyclic arrangement of the various floral parts. Floral Morphology & Embryology in Some Taxa of Canellaceae 181

The ovule in the family is bitegmic and crassinucellate. The archesporial cell produces a parietal cell, which in turn divides to form a massive parietal tissue. The embryo-sac development conforms to the Polygonum type. The andreecium is syngenesious in the Canellace~e. The tapetum has a parietal origin in the anther. The behaviour of the tapetal cells during microsporogenesis is peculiar and worthy of note. There is a 'fibrous' endothecium. Microspores are produced in tetrahedral quartets. The pollen is two-celled at shedding stage and possesses a single colpa. Dehiscence of the anther is longitudinal. Floral anatomy and embryology combined with a study of wood anatomy speak for a Myristicacean alliance of the Canellace~e.

ACKNOWLEDGEMENTS It is a rare privilege and great pleasure to record my sincere gratitude and deep appreciation to Professor B. G. L. Swamy for his critical guidance and stimulating discussions during the course of study on the Canellace~e. The author is also grateful to the Government of India for the award of a Senior Research Scholarship during the tenure of which this and other items of research were carried out.

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EXPLANATION OF FIGURES FIos. 1-12. Watburgia stuhlmanniL Figs. 1-11 represent successive transections of the flower to illustrate the course of vasculature. The approximate levels of these figures are shown by corresponding markings in Fig. 12. All figures, × 8. FIGS. 13-18. Canella alba. Successive transections of the flower to illustrate the course of vasculature. All figures, × 13. FIos. 19-28. Figs. 19-26. Warburgia stuhlmannii. Fig. 19. Young nucellus showing primary parietal and primary sporogenous cells, × 203. Fig. 20. Megaspore mother cell and origin of integuments, × 203. Fig. 21. Dyad stage, × 203. Fig. 22. Linear tetrad. Note the accelerated growth of the outer integument on one side, × 203. Figs. 23-24. Two, and four-nucleate embryo-sac, × 203. Fig. 25. L.s. of ovule at the time of fertilization show- ing the topography of the female gametophyte in relation to the ovule. Note the overhanging lobe of the outer integument, × 203. Fig. 26. Egg apparatus enlarged from previous figure, × 300. Figs. 27 and 28. Canella alba. Fig. 27. L.s. of young ovule containing the mega- spore mother cell, × 203. Fig. 28. Mature embryo-sac. × 203. Ftos. 29-50. Figs. 29-36, Figs. 38-48, Fig. 50. Canella alba. Fig. 29. Transection of a sector of young anther primordium showing the hypodermal origin of the archesporium, × 300. Fig. 30. The same; the archesporial cell has divided into the primary parietal and primary sporogenous cells, × 300. Fig. 31. Porielinal division in the primary parietal cell, × 300. Fig. 32. Transection of a sector of young anther showing from outside: epidermis, endothecium three wall layers, tapetum and group of microspore mother cells, × 300. Fig. 33. Same olderstage after formation of microspore tetrads, × 203. Fig. 34. Apollen tetrad, × 514, Fig. 35. A germinated pollen enlarged from Fig. 48, × 514. Fig. 36. Microspore tetrad after division of the microspore nucleus into generative and vegetative cells, × 514. Fig. 38. A sectional view of mature pollen showing germinal furrow, × 514. Fig. 39. Mature two- celled pollen grain, × 514. Figs. 40-45. Nuclear belaaviour in tapetal cells, all × 300. Fig. 46. Puberulous thickenings of the inner tangential wall of a tapetal cell as seen from surface, x 745. Fig. 47. Endothecium and the persistent epidermis, x 300. Fig. 48. Germinating pollen grains lodged in the dehisced anther thecm, x 53. Fig. 50. Endothecial cells in surface view showing thickenings on radial walls, X 200. Figs. 37 and 49. Warbutgia stuhlmannii. Fig. 37. Mature pollen grain, × 514. Fig. 49. Endothecium and the persistent epidermis, x 745. FIG. 51. Phylogenetic derivation of tlae gyn~r.cium in the Canellace~e. The upper row represents the situation where the gyr oecium is composed of two carpels; the lower row repre- sents the situation wherein the gyn~cium is composed of five carpels. (Schematic representation.)