A CONTRIBUTION TO THE FLORAL ANATOMY AND EMBRYOLOGY OF

By L. L. N a r a y a n a Department o f Botany, Osmania University, Hyderabad-!

(Received for publication on November 29, 1962)

I ntroduction

T h e Linaceae have not received much attention from the point of view of floral anatomy, the only work being that of Saunders (1937). Information on the embryology of the family is meagre and this has been summarized by Schnarf (1931). Kappert (1933) reported poly- embryony in usHatissimum. Soueges (1924, 1937) described the embryo development in and . Johan­ sen (1950) classified the embryo development in this family under the Linum variation of Solanad type. Subsequently, Mauritzon (1934) studied the embryology of Radiola linoides. Doraisami and Gopinath (1945) studied the development of the female gametophyte, endosperm and embryo in Linum mysorense. In view of the scanty information on the floral anatomy and embryology of Linaceae, this study was undertaken and the present account deals with the floral morphology of Durandea penlagyna (Warb.) K. Schym., mystax Linn., Desf., L. rubrum Rafin and Reinwardtio trigyna Planch.

M aterials a n d M ethods

The materials were fixed in formalin acetic alcohol. Customary methods of dehydration, infiltration and embedding were followed. Sections were cut at a thickness of 5-12 microns and stained in Eherlisch Haematoxylin. The herbarium material of Durandea was soaked in water for 24 hours. It was then boiled in a weak solution of KOH for 2-3 hours and later washed in running water for about 2 hours. It was fixed in formalin acetic alcohol for 24 hours and then treated in the usual way.

F lo ra l A natom y

The flower is pedicillate, regular, bisexual, heterochlamydeous and pentamerous. The sepals and petals show quincuncial and contorted aestivation respectively (Text-Figs. 4, 5, 9, 10, 14, 15, 17, 18, 24-27, 34 2 . m m II.U

Text-Fios. 1-20. T.S. of flower from base upwards. F i^ . 1-10, Durane4a pentagyna. Figs. 11-20. , ^ 37, 44, 45, 49). The 10 stamens of Durandea and Hugonia are of two heights, the antepetaJous ones being shorter (Text-Fig. 10). In Linum species and there are 5 fertile antesepalous stamens

tmm It 2t

Text-Figs. 21-39. T.S. of flower from base upwards. Figs. 21-29. Linum frandiflorum. Figs. 30-39, L, rubrum. VText-Fiqs. 40-55.^; Figs. 40-49, 55. Reinwardtia trigyna. Figs. 40-49. T.S. of flower from base upwards. Fig. 55. Mature pollen grain. Figs. 50, 52, 53. Linum gramUflorum. Fig, 50. T.S. of anther lobe showing microspore mother cells, tapctum and wall layers. Fig. 52. P.M.C. showing cytokinesis. Fig. 53. Pollen te tj^ . Figs. 51, 54. Hugonia mystax. Fig. 51. Anther lobe show ing 1-nucleate poUen grams and tapetal layer. Fig. 54. Pollen grain showing ‘O N Q ’. alternating with 5 sterile non-vascular filiform staminodes (Text-Figs. 27, 39, 47). The filaments in all the species are basally connate (Text- Figs. 5, 6, 8, 9, 18, 26. 35-37, 46).

The syncarpous gynoecium consists of 5 carpels in Durandea and Linum species (Text-Figs. 7-9, 27 29, 37, 38). 5-3 in Hugonia (Text- Figs. 19, 20) and 3 in Rcinwardtia TText-Figs. 47, 48). The number of loculi corresponds with the number of carpels in Durandea and Hugonia (Text-Figs. 8, 9, 19, 20). Fn Linum species and Rcinwardtia as each locule is divided into two chambers by a sterile septum, the number of loculi at the base of the ovary is double the number of carpels (Text- Figs. 27, 36. 37, 47). But, the septum is incomplete towards the top of the ovary and at this level the number of loculi corresponds with the number of carpels (Text-Figs. 28, 29, 38, 48). Each locule bears two pendulous ovules (Text-Figs. 7, 9, 19, 20, 28, 29. 37, 38, 47, 48).

The pedicel shows a ring of vascular bundles in Durandea and L. ruhrum (Text-Figs. 1, 30) and a siphonostele in the rest (Text-Figs. 11, 21, 40). Fn Durandea and L. grandiflorum the conjoint sepal laterals and sepal midribs arise in two alternating whorls (Text-Figs. 2, 22); in Hugonia they are close together (Texi-Fig. 12). In L. ruhrum and Reinwardtia the sepal traces (Text-Figs. 31, 41) divide radially forming a median and two lateral bundles (Text-Figs. 32, 42). The petals are single-traced and they arise independently from the main stele alter­ nating with the sepal midribs (Text-Figs. 3, 13, 23, 24, 33, 34, 43, 44). The traces supplying the perianth members divide further forming smaller bundles in the respective organs (Text-Figs. 3-6, 8-10, 13-15, 17, 18, 23-27, 33-37, 43-49). The traces for the 10 stamens in Hugonia arise in two alternating whorls, the antesepalous ones being organized first (Text-Figs. 14, 15). They emerge out and at the periphery of the thalamus they present a horse-shoe-shaped outline (Text-Fig. 16). In Durandea on the other hand the traces for the antepetalous stamens become demarcated first (Text-Fig. 4) and thus, the androecium is obdiplostemonous. Tn Linum species and Reinwardtia only 5 staminal traces arise on the sepal radii and these feed the fertile stamens (Text-Figs. 25. 27, 34-37, 44-47). The sterile filaments representing the antepetalous stamens are devoid of vascular supply (Text-Figs. 27, 39, 47). At about the level of separation of the staminal tube, the dorsal carpellary traces are organized (Text-Figs. 6, 18, 26, 36, 46). In Durandea, each dorsal carpellary trace divides to form two lateral branches, which again divide into two each (Text-Figs. 6-8). In Hugonia the dorsal carpellary traces divide into numerous branches in the ovary wall (Text-Figs. 18-20). Alternating with these the common median laterals are organized (Text-Figs. 18-20). The main stele then closes to form a ring which in turn splits into as many ventral bundles as there are carpels and they lie opposite the loculi (Text-Figs. 7, 19, 20). In Linum species the emerging staminal traces divide tangentially demarcating an inner ring of bundles, the common median laterals (Text-Figs. 25, 26, 35). At a higher level the dorsal carpellary traces are organized (Text-Figs. 26, 36). The common ventral bundles lie along the septal radii (Text-Figs. 27-29, 37, 38). In Reinwardiia the

Text-Fios. 56-70. Figs. 56-58, 64, 67, 68, 70. Reinwardiia trigyna. Figs. 56-58. Stages in the development of ovule. Fig. 64. L.S. of ovules showing M.M.C. Fig. 67. 8-nucleate embryo-sac; note early differentiation of antipodals. Fig. 68. Organized- 8-nucleate embryo-sac. Fig. 70. Micropylar parts of embryo- sac showing egg apparatus and secondary nucleus surrounded by well-differentiated endothelium. Figs. 59, 65, 66. Hugonia mystax. Fig. 59. Mature ovule. Fig. 65. M.M.C. and parietal tissue ; note poorly differentiated endothelium. Fig. 66. Megaspore tetrad and parietal layers. Figs. 60, 69. Linum rubruni- Fig. 60, MLature ovule. Fig. 69. Micropylar parts of mature embryo-sac showing egg apparatus and secondary nucleus surrounded by well-differentiated endothelium. Figs. 61, 62, 63. Linum grandiflorum. Fig. 61. Mature ovule. Fig. 62. Andiesporium. Fig. 63, Two megaspore mother cells. median laterals arise as common bundles, but become split up radially as they enter the ovary wall ('Text-Figs. 45-48). The common ventral bundles lying on the sepal radii divide into two at the level where the ovular traces are given off (Text-Fig. 48). In all the members the ventral bundles are used up in the ovular supply. Only the dorsal car- pellary traces extend to the tips of the stylar branches (Text-Figs. 10, 39, 49).

MlCROSPOROGENESlS AND M a LE GAMETOPHYTE ,

A fully differentiated anther shows an epidermis and four wall layers (Text-Figs. 50, 51). Of these, the innermost develops into the secretory tapetum, whose cells become binucleate (Text-Figs. 50, 51). II is absorbed as the microspores are formed in the anthers. In Hugonia, however, the tapetal cells persist in the anthers even after uni­ nucleate pollen grains are formed (Text-Fig. 51). The cells of the hypo- dermal wall layer undergo radial elongation, develop fibrous thicken­ ings and function as the endothecium. The middle layers get crushed during the development of the anther.

Cytokinesis takes place by peripheral furrowing (Text-Fig. 52) and tetrahedral pollen tetrads are formed (Text-Fig. 53). The pollen grains are 3-colporate in Linum and Hugonia (Text-Fig. 54), while in Reinwardtia they arc non-aperturate (Text-Fig. 55). They are 3-celled at the shedding stage (Text-Fig. 55). The exine ornamentation is different in the genera studied. It is verrucose with the verrucae of the same size in Linum rubrum and Hugonia (Text-Fig. 54) and of different sizes in L. grandiflorum and Reinwardtia (Text-Fig. 55). Starch grains are present in the mature pollen grains. ‘ONCUS’-like structures are present in the pollen grains of Hugonia (Text-Fig. 54).

O v u l e

The ovule is crassinucellar, bitegminal and anatropous (Text- Figs. 56-61). The ovule primordium arises on the placenta as a small cushion-like outgrowth. The integumentary primordia are formed by the time the archesporium is differentiated. It soon bends upwards during development and the mature ovule becomes anatropous with the micropyle pointing upwards (Text-Figs. 58-61). The integuments are free (Text-Figs. 57-61). The outer integument consists of two layers of cells in Linum species and three layers of cells in Hugonia and Reinwardtia. The inner integument shows a variable number of layers; it is thus 4-5-layered in Hugonia, 9-12-layered in Linum species and 6-8- layered in Reinwardtia. A common feature noticed in all the species is the difTerentiation of an endothelium from the innermost layer of the inner integument (Text-Figs. 58-61, 65, 69, 70); in Hugonia it is not so prominent (Text-Fig. 65). In mature ovules although the outer integument extends slightly beyond the level of the inner, the micropylar canal is formed by the inner integument only (Text-Figs. 58-61). The nucellus is elongated (Text-Figs. 59, 61). As the ovule develops, an outgrowth arises from the placenta and it soon arches over the micropyle to form the obturator (Text-Figs 56-61).

Text-Figs. 71-77. Figs. 71, 72, 74, 76. Reinwardiia trigyna. Fig. 7J. Ferli- iized egg and free endosperm nuclei. Fig. 72. Seed cleared in chloral hydrate show­ ing chalazal endosperm haustorium and dicotyledonous em biyo; the lines represent groups of thick-walled cells in the outer layer of the inner integument. Fig. 74. Dissected embryo-sac from mature seeds showing chatazal haustoria. Fig. 76. Haustoria in sectional view. Figs. 73, 75, 77. Linum grandiflorum. Fig. 73. Dissected embryo-sac showing peg-like chalazal haustorium. Fig. 75. Dissected embryo-sac from mature seeds showing chalazal haustorium. Fig. 77. Haustorium in sectional view.

M egasporogenesis a n d F emale G a m etoph yte

The hypodermal archesporium is single-celled (Text-Fig. 62) A multi-cellular archesporium was also observed. The archesporia! ccll divides into an upper primary parietal cell which forms a parietal tissue of 4-6 layers and a lower megaspore mother cell (Text- Figs. 64-66). Two megaspore mother cells were occasionally noticed (Text-Fig. 63). The megaspore mother cell undergoes meiosis and gives rise to a linear tetrad of megaspores (Text-Fig. 66). The chalazal megaspore functions and after undergoing three successive free nuclear divisions gives rise to an 8-nucleate embryo-sac (Text-Figs. 67, 68). The egg apparatus consists of two hooked synergids which show fili­ form apparatus and an egg (Text-Figs. 69, 70). The polar nuclei fuse before fertilization (Text-Figs. 69. 70). The antipodal cells are ephe­ meral. During development, the embryo-sac enlarges and crushes the parietal tissue as well as the cells of the nucellar epidermis in the micropylar region and some of the nucellar cells along the sides and below it (Text-Figs. 58-61, 67). The embryo-sac of Hugonia and Reinwarc/tia arc packed with starch grains (Text-Figs. 68, 70).

E n d o spe r m

The primary endosperm nucleus divides earlier than the zygote, and undergoes free nuclear divisions (Text-Fig. 71). As the endosperm nuclei increase in number, there is a widening of the embryo-sac in the micropylar region (Text-Fig. 73). The lower end of the embryo-sac elongates by crushing some nucellar cells below. In Linum species, the lower end of the enlarging embryo-sac is in the form of a small peg- iike projection at this stage (Text-Figs. 73, 77). In Reinwardtia, the lower end becomes tubiform and reaches the funicular vascular bundle (Text-Fig. 72). Some free endosperm nuclei migrate into this region, which in turn ultimately become surrounded by cell walls (Text-Figs. 76. 77). The lower end of the embryo-sac thus appears to function as a haustorium. It persists even in mature seeds and could be observed by clearing the seeds in chloral hydrate (Tcxl-Figs. 72, 74, 75).

E mbryo

The first division of the fertilized egg is transverse and results in a terminal cell ca and a basal cell ch (Texl-Fig. 78). Both ca and cb divide transversely and four cells /, /'. m and ci arranged in a linear row are formed (Text Fig. 79). Cell 1 divides vertically giving rise to juxta­ posed cells (Text-Figs. 80, 81). Cell /' also divides similarly (Text- Figs. 81-83), while m divides transversely giving rise to d and / (Text- Figs. 82, 83). ci divides transversely giving rise to n and n' (Text- Figs. 80-82). The cells of the tier / undergo another vertical division and the resulting four cells divide by oblique walls (Text-Fig. 83). From this region the cotyledons and stem tip are developed. The deriva­ tives of the tier /' give rise to the hypocotyi region. Cell d divides once 5>nd the daughter cell next to the embryonal mass becomes the hypo­ physeal cell (Text-'Fig. 84). The derivatives of the hypophyseal cell give rise to the root portion. Further divisions in the tiers / and /' lead to the development of the globular embryo (Text-Fig. 85). The tiers n and n form the suspensor (Text-Fig. 85), which in Linum consists a filament of 6-9 cells (Text-Fig. 85). The mature embryo is dicotyledonous (Text-Fig. 86). 8 ^ 0 1

Text-Figs. 78 90. Figs. 78-85, 87, 89. Reinwardlia trigyna. Figs. 78-85. Stages in the embryo development (for abbreviations see text). Fig. 87. T.S. seed. Fig. 89. Section of seedcoat. Figs. 86, 88, 90. Linum grandlfiorum. Fig. 86. Mature embryo. Fig. 88. T.S. Seeds. Fig. 90. Section of scedcoat. U’ncl endosperm.; ent, endothelium; inner integument; o.i., outer integument.)

The development of the embryo in Reinwardtia is also similar except that the suspensor is made up of 4-6 cells. F r u it an d Seed

The fruit in Linum and Reinwardtia is a capsule. Both the integu­ ments take part in the formation of the seed coat. The cells of the outer integument in Linum species enlarge in the radial direction, whiic in Reinwardtia they become tangentially flattened (Text-Figs. 89, 90). Tn both genera these cells become filled with starch grains, though they are more abundant in Linum species. The outer epidermis of the inner integument in Linum species develops into a continuous layer of thick- walled cells (Text-Figs. 88, 90). In Reinwardtia these thick-walled cells are in isolated groups (Text-Figs. 87, 89). Seeds cleared in chloral hydrate show these isolated groups of thick-walled cells in the form of lines converging towards the micropylar region (Text-Fig. 72). The endothelium persists in the mature seed as a layer of deeply stain­ ing cclls (Text-Figs. 87 -90). The tissue between the two epidermal layers of the inner integument becomes compressed during the deve­ lopment of the seed. A single layer of endosperm is present in the mature seeds of Reinwardtia. while in Linum sfJecies there are up to four layers of this tissue (Text-Figs. 88, 90). The seeds are thus endospermous.

D iscussion

In Linaceae the flowers are fundamentally pentanierous, pentacyclic with a tendency towards reduction in the number of floral parts, parti­ cularly the androecium and gynoecitim. Radiofa (Saunders, 1937), however, has tetramerous flowers. In all the taxa studied, the calyx is quincuncial and the corolla con­ torted. The sepals in Durandea, Hugonia and Linum grandiflorum are 3-traced. The sepal laterals show connation though the sepals are externally free. In Linum ruhrum and Reinwardtia each sepal trace as it emerges divides into a median and two lateral branches. The petals are single-traced. The androecium consists of 10 stamens of two heights in Durandea and Hugonia and only five in the rest of the species. They are basally connate. The traces for the 10 stamens arise in two distinct whorls in Durandea and Hugonia; in the latter, while the traces for the ante- sepalous stamens are the first to arise, in the former the traces for the antepetalous stamens appear earlier. Thus, the androecium in Durandea is obdiplostemonous. In the other species the surviving stamens belong to the antesepalous whorl. The antepetalous stamens are represented by sterile non-vascular filaments. This is an example where the organs are persisting while their vascular supply has suffered complete reduction. A parallel situation is seen in the androecium in Oxalidaceae^ and Meliaceae (Narayana, 1958). In Oxalis^ species and Averrhoa bilimbi,^

‘ Author's unpublished woik. the androecium consists of 10 basally connate stamens of two heights as in Durandea and Hugonia. In Averrhoa carambola, the androecium is represented by 5 antesepalous stamens, while the antepetalous stamens are reduced to staminodes. Their vascular supply, however, has not suffered reduction. In Meliaceae, the androecium consists of 10 stamens which unite to form the characteristic staminal tube. But the genus Cedrela (Narayana, loc. cit.) shows only 5 free stamens and they belong to the antesepalous whorl. The antepetalous whorl is completely suppressed. Their traces, however, have not suffered reduction and they fade out in the receptacle. In Aglaia (Narayana, loc. cit.), the antepetalous whorl of stamens as well as their traces are completely suppressed. A reduction in the number of carpels is noticed in the family Linaceae. The carpels in Hugonia and Linum species and Reinwardtia are 5-traced. There is adnation between the common median laterals and the staminal traces in Linum species, in ReitiWcrdtia, the median laterals show neither connation nor adnation. Judging from the posi­ tion of the ventral bundles the placentation in Durandea and Hugonia is axile and parietal in the rest.

According to Schiirhoff (1924) the anther tapetum does not form a periplasmodium. He, however, reported the formation of a slimy substance. Mauritzon (1934) reported in Radiola linoides a secretory tapetum and the present studies confirm this feature. The members of the family exhibit a diversity in the structure and ornamentation of the exine. Erdtman (1952) described*the family as eurypalynous. The pollen is shed at the 3-celled stage as in the investigated species of the family (Schnarf, 1931; Mauritzon, /oc. c;7.).

Both tenuinucellar and crassinucellar ovules were reported in the family. Schnarf (1931) mentioned that the ovules are crassinucellar and quickly become tenuinucellar. Doraisami and Gopinath (1945) reported the occurrence of a parietal cell in Linum mysorense. In the species studied, there is a parietal cell which gives rise to a parietal tissue of 4-6 layers. An endothelium, reported by earlier investigators (Mauritzon, 1934; Doraisami and Gopinath, loc. cit.), is present in the species studied. The presence of the obturator seems to be a characteristic feature of the family.

The archesporium in the ovule is single-celled. However, a multi- cellular archesporium was also reported (Mauritzon, 1934; Doraisami and Gopinath, 1945). The embryo-sac develops according to the Poly­ gonum type (Maheshwari, 1950) as in the other investigated species (Schnarf, 1931; Mauritzon, loc. cH.\ Doraisami and Gopinath, loc. cit.). The aritipodals are ephemeral—a feature also reported by earlier workers (Mauritzon, loc. cit.; Doraisami and Gopinath, loc, cit.). Schiirhoff (1924) reported Helobial type of endosperm in the species of Linum studied by him. Mauritzon (1934) in Radiola linoides and Doraisami and rropinath (1945) in Linum mysorense reported free nuclear type. The present study supports these findings. Chalazal endosperm haustoria are present in Linum species and Reinwardtia. While in Linum species the haustorium is short and peg-like, in Rein­ wardtia it is long and caecum-like reaching the funicular vascular bundle, [n both genera it persists in the mature seed. In Reinwardtia, a layer of endosperm is present in the mature seed and 3-4 such layers persist in Linum species. The embryo development conforms to the Solanad type as in Linum catharlicum, Radiola Hnoides (Soueges, 1924, 1937) and Linum mysorense (Doraisami and Gopinath, 1945). Both integuments take pan in the formation of the seedcoat. In Linum species the cells of the outer eoidermis of the inner integument develop thick walls. In Reinwardtia. a continuous thick-walled layer is absent. The endothelium persists as a layer of deeply staining cells. Seeds are endospermic. Bentham and Hooker (1862-93) and Gundersen (1950) include Erythroxylaceae also under Linaceae and placea it in the order . But these are recognised as distinct families by Engler and Prantl (1931). Hutchinson (1926) recognized these as distinct families, but placed Linaceae under Geraniales and Erythroxylaceae under . However, in his recent work (Hutchinson, 1959) he transferred Linaceae also to the Malpighiales. The members of the families Linaceae and Erythroxylaceae have resemblances and differences. The flower in these families is penta- merous and pentacyclic. Obdiplostemony is common to both the I'amilies. A tendency towards reduction of floral parts and their traces is present in the family Linaceae. Although the plan of floral structure in both the families is similar, the Erythroxylaceae differ from the Linaceae in the appendaged petals and a 3-carpellary ovary with one fertile carpel bearing a solitary ovule (Narayana, 1960). The embryo- logical characters of the two families resemble closely. An obturator, noticed in the investigated species of Linaceae, is absent in Erythro­ xylaceae (Narayana, loc. cit.). Palynological characters of the two families differ from one another. Erdtman (1952) described Linaceae as eurypalynous and Erythroxylaceae, stenopalynous. Hence, the two families resemble each other closely but at the same time the differences seem to justify their separation into distinct families. On anatomical grounds Metcalfe and Chalk (1950) separated Erythroxylaceae and Linaceae into distinct families. Heimsch (1942), who made a comparative study of the two families observes: “The Erythroxylaceae should not be united with Linaceae, because of the general lack of scalariform basal perforations, but the family is most closely related to Linaceae and Humiriaceae on the basis of occurrence 01 tracheids and other xylem characters.” The above remarks show that the Linaceae and Ei7throxylaceae are closely related but at the same time show certain distinctive features on the basis of which they ca t be separated from one another. S um m ary

The comparative floral morphology and embryology of 5 taxa of Linaceae have been studied. The flower is pentamerous with a tendency towards reduction in the number of floral parts. The sepals in Durandea and Hugonia are 3-traced and the laterals showconnation. The petals are single-traced. The carpels show reduction from 5-3. A false partition divides the loculus in Linum and Reinwardtia. The common median laterals show adnation with staminal traces in Linum species. The ventrals in Durandea and Hugonia lie opposite the loculi and in Linum and Rein- wardiia along the sepal radii. Only the dorsal carpellary traces extend into the stylar branches. The secretory tapetum consists of binucleate cells. Pollen grains are 3-celled at the shedding stage. The ovules are crassinucellar, bitegminal and anatropous. An endothelium is differentiated. The embryo-sac develops according to the Polygonum type. Anti- podals are ephemeral. The endosperm is free nuclear and chalazal endosperm haustoria are present. The embryo development confirms to the Solanad type. Both integuments take part in the development of the seedcoat. Seeds are endospermic. The affinities of Linaceae with Erythroxylaceae arc discussed.

My thanks are due to Prof. M. R. Suxena, Professor of Botany, Osmania University, for his kind encouragement and interest. I am indebted to Dr. K. Subramanyam, Deputy Chief Botanist, Botanical Survey of India, for going through the manuscript and valuable criti­ cism. My thanks are also due to Dr. C. Venkata Rao, Reader in Botany, Andhra University, for his helpful suggestions and criticism. Finally, I wish to express my indebtedness to Dr. W. A. Van Heel for the material of Durandea pentagyna.

R eferences

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N a r a v a n a , 1.. L. 1958. Floral anatomy of Meliaceae—1. J. Indian hot. Soc. 38: 288-95. I960, Studies in Erythroxylaceae—1. Proc. Indian Acad. Sci. 51 B: 270-75.

S a u n d e r s , E. R. 1937. Floral Morphology. Vol. 1, Cambridge.

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* ScHURHOhE, P. N. 1924. Zytologische Unlersuchungen in der Reihe der Geraniales. Jh. wiss. Hot. 63: 707-59. SdUEOES, R. 1924. Erabryogenie des Linacees. Developpement de I’embryon chez le Liniim catharticum L. C.R. Acad. Sci., Paris 178: 1307-10. ------1937, Ddveloppement de I’embryon chez le Radiola linoides Roth. B14II. Soc. hot. Fr. 85: 297-306.

* Not seen in original.