A CONTRIBUTION TO THE VASCULAR ANATOMY OF THE NODE IN CERTAIN SPECIES OF THE ^

SHASHI KSHETRAPAL AND Y. D. TIAGP

Department of Botany, Universiiy of Rajasthan, Jaipur

ABSTRACT

A comparative study of nodal a’latomy of 44 spi^c ics ol'thc order Gcntiaualc!.. comprising the families Oleaceae. Salvadoraceae. Anocyiiacoar. Asdcpi-xd.iccai', Loganiaceae and Gentianaceac has been made. Inversely orienti

INTRODUCTION Gcntianales. Customary methods of The nodal anatomy of the Gcntianales microicchnique were employed. Study has received Hltle attention, notwilh- of .serial sections of the nodal region of the stancling several features of morphological stem was supplemented with dissections of interest, such as the presence of extra- cleared nodal regions under a stereoscopic axillary shool and inversely oriented cor­ binocular. tical bundles in several laxa beside its general application for determining rela­ OBSERVATIONS tionships. Dming a comprehensive Oleaceae : The leaves are arranged in movpho-anatomical study of this order an oppoistc-dccussatc manner. The stem (Kshetrapal, 1967), a wide range of varia­ contains an etiophloic siphonosiele. In tion in the nodal types was observed. the majority of ta.xa of this family, in­ Part of this work was published earlier cluding Jasminum, LtQUslrum :nul Fr/ixinus, (Kshetrapal and Tiagi, 1967 ; Kshetrapal, the node is of unilacunar, l-lraccd typi; 1973). Relevant lileralutr on the topic (Figs. 1-3, 8, II). The vasctdar supply would be referred to under discussion. of axillary shool is constituted by two traces. In .Nydanthvs, although the node MATERIAL AND METHOD is of uiiilacim;u-, I-traced typ'*. the leaf is The present study is based on an 3-traced, the marginal traces arising by examination of the nodal anatomy of the fusion of branches ft ora ihe dor.sal 44 species of the diflercnt families of the trace uf the leaf and the inversely oriented

1. .Accepted for publication on November 5, I980. 2. Deptt. of Botany, University of Udaipur, Udaipur. cortical bundles (Figs. 4-6). In Schrebera, interesting feature of the node of certain the single leaf trace undei^gois precocious Asclepiadaceae is the presence of gene­ divisions (Fig. 7) and forms a more or rally one, sometimes two extra-axillary less complete ring in the base of petiole. peduncles of the inflorescences. Their In Osmanthus armatus, the node is of tri- vascular supply is pinched off from the lacunar, 3-traced type (Fig. 9). In 0 . main stele, generally on one side (Figs. aquifolium, the node is of unilacunar, 3- 30-32, 34, 36, 37) but sometimes on both traced type (Fig. 10). sides as in Gyrmema ylvestre (Fig. 33) and Salvadoractae : In Salvadora, the nodal has nothing to do with the vascular traces structure is of unilacunar, 1-traced type and gaps of the leaves and their axillary (Fig. 12). Azima Utraamtha possesses a shoots. unilacunar, 2-traced node. Each spine Loganiaceae : The node is uni­ which is a modified leaf is vascularized formly of the unilacunar, 1-traced type. by two discrete vascular strands that are In certain taxa such as Buddleia (Fig. 39) related to a single gap in the stele of the and Nicodemia (Fig. 40), interpeiiolar axillary shoot (Figs. 13-15). stipules are present. A stipule receives Apocynaceae : The node in this family two traces from the marginal bundles of is uniformly of the unilacunar, J-traced the different leaves of the pair on the same type (Figs. 16-18, 21-26) with Kopsia side. In Mitreola oldenlandioides (Fig. 38) fruticcsa being the only exception. In this and Strychnos nux-vomica (Fig. 41), the species (Figs. 19-20), divergence of the stipular line is a very inconspicuous ridge two dorsal traces of the leaves causes two and is without any vascular supply. gaps on the opposite sides in the stele. Gmlianaceae : In the vast majority Earlier than this and in a plane at right of taxa of this family, the node angle to the plane of the two dorsal is of unilacunar, 1-traced type (Figs. 42, traces, two more traces, each from a 47, 53, 55). In certain species, such separate gap diverge out from the stele as Swertia chirata, the node is trilacunar, on the opposite sides. Each of these traces 3-traced for one and unilacimar, 3-traced radially splits into two and furnishes one for the other member of a pair of leaves marginal trace on the same side to each (Fig. 54). The nodal anatomy of Eni- leaf of the pair. Thus, it is a modification costemma verticillatum (Figs. 45, 46) is simi­ of the trilacunar type with ab initio com­ lar to that of Kopsia fruticosa o f Apocyna- pounding of two marginal traces of the ceae. The stem of Hoppea and same side belonging to the different leaves has four inversely oriented cortical of the pair. Only four gaps are therefore bundles (Figs. 43, 48, 50). In the nodal present in the nodal region in this species. region the cortical bundles furnish traces Asclepiadaceae ; Ih c taxa of this which reinforce ihe marginal traces of family uniformly possess a unilacunar, leaves (Figs. 44, 49, 51, 52) and the leaf 1-traced type of node (Figs. 27-37). An is 3-traced.

Figs. 1-26. Tra'isverse sections of the nodal region, showing llie mode of origin of vascular supply to the leaves and axillary shoots. Figs. 1-2. Jasminum mullifhrum ; Fig. 3. J . sambae ; Figs. 4-G. ^fytanthes arhor-tristU ; Fig. 7. Schrtbera swietenoides ; Fig. 8. Fraxirm bmgeana ; Fig. 9. Osmanthus armatus ; Fig. 10. Osmanthus aguifoUum ■, Fig. l \ . Ligustrum robustum ; Vig. 12. Salvadora persica \ Figs. 13-15. Azima tetracantha; Fig. 16. AUamanda cathartica ; Fig. 17. Carissa paucinervia ; Fig. 18. Thevetia neriefolia ■ Figs. 19-20. Kopsia fruticosa ; Fig. 21. Tabernatmontana divaricaia ; Fig. 22. Holarrhena antidysenterica ; Fig. 23. Vatlaris solana- « a ; Fig. 24. Wrightia tinctoria ; Fig. 25. Nmum indi(um ; Fig. 26. Ichnocarpus frutesctns.

DISCUSSION coalesce to give rise to a bilacunar con­ A unilacunar, 1-traced node is of dition (Kumar, 1976). widespread occurrence in the Cientianales. Inversely oriented cordcal bundles are Exceptions are few. It is only in Azima known to occur in several genera of the ktracmtha that the node is of the uni­ Gentianales, such as Nyctantkes (Majumdar, lacunar, 2-trace type (Kshetrapal and 1936, 1941 ; Fotidar, 1939) and Canscora Tiagi, 1967), a type which is of wide­ and Hoppea (Kshetrapal, 1967, 1973). spread occurrence in the Ranalian families Grovil (1973) who reinvestigated Myctanthes and now regarded as the primitive type considers them as consisting of the aggre­ among the Angiosperms (Bailey, 1956). gation of descending leaf traces. How­ A typical trilacunar node occurs in ever, it appears that they form a separate Omanthus armatus. However, in Omanlhus system in the cortex which in the nodal aquifolium, the node is of unilacunar, region, not only furnishes the marginal 3-traced type. In certain species of traces of the leaves but also reinforces Swertia, the node may be trilacunar in the independently arising dorsal traces. relation to one and unilacunar in relation The occurrence of similar type of inversely to the other leaf at a node. Post (1958) oriented cortical bundles in Calycanthus reports variation in the number of traces (Smith, 1928 ; Tiagi, 1963) is an elegant going to a leaf at different nodes of the example of parallel evolution. same in certain species of Swertia An interesting feature of the node of and Frasern. In the subfamily Menyan- certain Asclepiadaceac is the presence thoideae of the , the node is of generally one, sometimes two extra- of the multilacunar type (Takhtajan, axillary peduncles of the inflorescences. 1966). Its morphology has been a subject of In the genera Kopsia and Enicostemma, debate. The extra-axillary position of the the marginal traces of the same side of the floral peduncle has been explained either two leaves of the pair arise ab initio com­ due to sympodial development, the in­ pounded, thus reducing the number of florescence axis being always terminal in gaps and traces diverging from the stele this case or due to subsequent displace­ from six to four. More or less similar ment from axillary position during deve­ nodal types have been reported in Sar- lopment (Rendle, 1938). Vascular ana­ candra (Swamy and Bailey, 1950) and tomy of the node lends no support to Chloranthus (Swamy, 1953). In Geranium either of these explanations. The vascular nepaknse, the node is of the trilacunar, supply of the extra-axillary peduncle is 3-traced type but sometimes the gaps of pinched off ^om the main stele, generally the median and one marginal traces on one but sometimes on both the sides

Figs. 27-55. Transverse sections of the nodal region, showing the mode of origin of vascular supply to the leaves and axillary shoots. Figs. 30-34., 36-37. also show the mode of origin of vascular supply to their extra-axillary peduncles. Fig. 27. Hemidesmus indicus ; Fig. 28. CrypUtUpis bucJmani; Fig. 29. Crypioslegia grand flora ; Fig. 30. Oxystelma secamone ; Fig. SI. Calotropis procera \ Fig. 32. Asdepias curassavica ; Fig. 33. Gymmma sylvestre ; Fig. 3 1. Marsdenia roylei; Fi.g 35. Dregta volubilis ; Fig. 36. Ctropegia fiirsuta ; Fig. 37. Telomna pallida ; Fig. 38. Mitreola oldetilandioidts ; Fig. 39. BuddUia asialica ; Fig. 40. Micodemia diversifolia ■, Fig. 41. Strychim nux-vomica ; Fig. 42. Exacum pedunculatum ■, Fig 43-44. Hoppea dichatoma; Figs. 45-46 Enicostemma verticillatum ; Fig. 47. C^ntaurium roxhurghii ; Fig. 48-49. ; Figs, 50-52. Canscora decussata ; Fig. 53. Swertia paniculata ; Fig. 54. Swertia chirata ; Fig. 55. HaUnia elliptiea. % 8 ^ S 0 as in Gymuffui ^Ivestn and has nodiing aritr (AntiamUu, Ph.D. thesis, Univ. Saugar, to do %vith the vascular traces and gaps Saugar. of the leaves and their axillary shoots. Kshbtrapai-, s. 1973. Vascular anatomy of the node and flower of Ho/iua dichatoma Willd. It is clear, therefore, that the extra- Bot. Gat. 134 s 1-4. axillary pediinde is an accessory shoot at K sh jb tr a pa l, s. a n d Y. D. T ia o i. 1967. A con- a node. According to Deshponde and tributioo to the nodal anatomy of Aximti Ittra- Joneja (1962), the axillary bud in Ltpta- auUha. U m k. Bot. Bull. Acad. Sin. « i 171-183. daenia fyrolechnica is furnished with a K u m a r , A. 1976. A new type of nodd organisa­ tion in Angiosperms. Acta bot. Indica. 4 i 76-77. single trace. This seems rather uncon­ Majumdax, G. p. 1936. On the occurrence of vincing. Further, their observation that four discrete cauline bundles in the stem of the axillary bud gives rise to an accessory Nyctamhes orbor-tristis L. Proc. ‘Z3rd Ind. Sci. Congriss. bud, the former developing into an in­ 298. florescence and the latter into a v^etative M a ju m d a k , G. p. 1941. Anomalous structure of branch abo does not appear to be correct the stem of Myctanthes arbor-tristis. J . Indian bot. Soc. 20 I 119-122. because in all the species studied by us, Post, D. M. 1958. Studies in the Gentianaceae 1. the stele of the accessory bud diverges Nodal anatomy of Frasira and Swtrtia pennnis. independently from that of the main Bot. Caz. 1201 1-14. stem. Renole, a . B. 1933. The CUssffication o f Flowering . Vol. 2. Dicotyledons. Cambridge. REFERENCES SufTH, G. H. 1928. Vascular anatomy of Ranalian flowers II. Ranunculaceae (contd.), Menisperm*

B a il e y , I. W. 1956. Nodal anatomy in retrospect. aceae, Calycanthaceae, Annonaceae. Bot. Gaz. J . Arnold Arb. 37 i 269-287. 8 S t 152-177. D e b h p a n d e , B. D. a n d P. J o n e j a . 1962. Studies in SwAMY, B. G. L. 1953. The morphology and Aaclepiadaceae I. Morphology and embryo­ relationships of the Chloranthaceae. J . Arnold logy of LeplaJaenia pyrotechnica. Decne. Phyton. Arb. 34 I 375-408. 19 I 73-84. SwAM Y, B. G. L. AND I. W. B a i l e y . 1950. Sarcandra, G o v i l , C. M. 1973. Seedling and nodal anatomy a vessel-less genus of the Chloranthaceae. J . of Jfyctanthes arbor-lristis L. J . Indian bat. Soc. ArnoU. Arb., 31 i 117-129. 5 2 I 113-118. T a k h t a ja n , a . L. 1966. Systemsa el Fhylogenia Magno- Fotidar, a. N- 1939. The primary vascular liophytorum. Moscow and I.eningrad. system of the stem of Nytanthis arbor-trislis L. Jf. T ia g i, V. U. 1963. Vascular anatomy of the Indian bot. Soc. 18 t 43-45. flower of certain species of Calycanthaccae. Proc. K s k e t r a p a l , s . 19 6 7 . Morphological studies in the Ind. Acad. Sci. (India). 33B : 224-234.