Proe. indian Aead. Sci., Vol. 85 B, No. 2, 1977, pp. 57-66.

Petiolar anatomy of certain members of

M. L. TRIVZDI, SHebA AND VEronA ~A

Department of , Punjabi University, Patiala 147002

MS received 1 September 1976; in revised form 14 October 1976

ABSTRACT

The petiolar anatomy of sixteen belonging to iourteen genera of Bignoniaceae has been studied. Two aspects, namely, the vascular pattern in the slender part of the and the mode of vascular supply from the primary rachis to leaflets or secondary rachii, are taken into consideration. On the basis of the ~asculature as seen in tran.,ecticn of the slendeI part, four main types of petioles have been recognized, while thereare three patterns of vascular supply. A key also has been devised to identify these sixteen species.

1. INTRODUCTION

PETIOLAR anatomy has received considerable attention of anatomists from time to time. One of the most comprehensive works on this aspect is by Watari} on Leguminosae. Howard ~' also has surveyed the petiole vasculature i n a large number of dicot families and found this structure to be of great taxonomic value. Carlquist 3 favoured correlated study of node-petiole structure. Howard ~ also advocated the study of the stem node--continuum The present study deals with the petiolar anatomy of certain Bignoniaceous members. The nodal anatomy of some members has already been studied by the present authors. 5

2. MATERIALSAND METHODS

Materials for the present study were collected from growing in the Botanical Garden and the University Campus. The growing shoot tips with young were fixed in F.A.A. Normal procedures for paraffin embedding were followed. Transections were obtained at 8-10 t, and stained with safranin-light green combination. The following species were studied:

57 58 M. L. TRIVEDI, SHAILAJA AND VEENA KHANNA 1. alliaceum (Lain.) Miers. 2. purpurea Lodd. 3. grandiflora K. Schum. 4. Doxantha unguis-cati Rehd. 5. 1-Iaplo- phragma adenophyllum (Wall) P. Dop. 6. mimosifolia D. Don. 7. pinnata DC. 8. MiUingtonia hortensis Linn. 9. cerifera Seem. 10. venusta (Ker-Gawl.) Miers. 11. campanulata Beauv. 12. Stenolobium stans Seem. 13. argentia Britt. 14. Tabebuia pentaphylla Hemsl. 15. capensis Lindl. 16. Tecoma jasminoides Schum.

3. OBSERVATIONS

Bignoniaceae members bear compound leaves. It is a very impor- tant character by which the can be distinguished from other associated families of the Personales. The leaves are pinnately compound with odd number of pirmae borne on primary, secondary or even tertiary rachii. Palmately compound and simple leaves are also met with in a few cases. The petiolar anatomy has been studied from two different viewpoints. Firstly, to see the topographic arrangement of the vascular bundles in the slender part of the petiole, slightly below the attachment of first pair of leaflets. Secondly, to trace the pattern of vascular supply from main rachis to leaflets or the secondary rachii, as the case may be. The following types are observed on the basis of the number of vascular bundles and their topographic a~:'angement, in the petiole.

TYPE [ WITH FIVE VASCULAR BUNDLES" In three traces (one medium and two laterals) depart from a common gap irt the stem to enter the base of the petiole. The two lateral traces soon bifurcate and thus five traces are formed. In the middle of petiole, the transection shows five bundles arranged in such a manner that they can be designated as one dorsal (DB), two laterals (LB, LB') and two ventrals (VB, VB'). Thus, the arrangement is expressed as 1 + 2 + 2 (figure 1). II WITI-I SEVEN VASCULAR BUNDLES: In Tecoma jasminoides five traces pass througk a common gap and enter the base of the petiole. A little higher up, the lower laterals sh,ow bifurcation resulting in seven dis- tinct vascular bundles. These are labelled as one dorsal (DB), four laterals (LBI, LB2 and LBI', LB./) and two ventrals (VB, VB'). Thus, the topo- graphic arrangement is 1 + 4 + 2 (figure 2). A similar topograpkic arrangement (1 + 4 + 2) is met with in Doxantha ungius-cati, Bignonia purpurea, Stenolobium stans arid where the nodal condition is unilacunar, triple-traced. This arrange- PETIOLAR ANATOMY OF BIGNONIACEAE 59

ment is achieved by the bifurcation of lateral traces and further forking of the lower derivatives. Thus, seven vascular bundles are formed. TYPE III WITH THIRTEEN VASCULAR BUNDLES: In Tabebuia pentaphylla the transection through the nodal region shows three traces passing through the single gap. The lateral traces bifurcate and ultimately the number of vascular bundles in the middle of the petiole increases to thirteen. These have been labelled as one dorsal (DB), eight laterals (LB1, LB2, LB3, LB4 and LB(, LB~', LB3', LBj)and four ventrals (VB1,VB2 and VBI', VB2') 1 ÷ 8 + 4 arrangement (figure 3). A similar topographic arrangement (1 ÷ 8 + 4)is observed in Adeno- calymma alliaceum, hortensis and Kigelia pinnata. In tIaplo- phragma adenophyllum the petioles he.ve 3 + 6 + 4 arrangement (figure 4). TYPE IV WITH FIFTEEN VASCULAR BUNDLES" In Spathodea companulata at the nodal region the procambial arc with seven vascular traces enter the base of the petiole. Later, a pair of laterals on either side is added from the axial cylinder to supplement the vascular supply of the petiole. Higher up, the number of vascular bundles becomes 15 which are labelled as dorsal

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Figures 1-7.1. T.S. petiole of Pyrostegia venusta. 2. T.S. petiole of Tecoma ]asminoides. 3. T.S. petiole of Tabebuia pentaphylla. 4. T.S. petiole of Haplophragma adenophyllum. 5. T.S. petiole of Spathodea campanulata. 6. T.S. petiole of Tabebuia argentia. 7. T.S. petiole of .

B2~eb. 77 60 M. L. TRIVEDI, SHAILJA AND VEENA KHANNA (DB), eight laterals (LB1, LB~, LB3, LB4 and LBI', LB(, LB3', LB4') and six ventrals (VBx, VB2, VBz and VBI', VB(, VB3'). Thus, the arrangement can be expressed as 1 + 8 + 6 (figure 5).

In Tabebuia argentia, Jacaranda mimosiJolia and Tecoma capensis also the petioles have fifteen vascular bundles. Howevel, the topographic arrangement in T. argentia is 3 + 6 + 6 (figure 6) while in the other two members the arrangement is 3 + 8 + 4 (figure 7).

On the basis of the manner of vascular supply to the leaflets(or secondary rachii in ease of multipinnate leaves) the following three types have been recognised : 1. L AND V TYPE: In Tecoma jasminoides, as already describeds there are seven vascular bundles (figure 2). The supply for the first pair of leaflets is given off from the laterals (LB2, LB~') which enter as such accompanied by vascular traces from ventrals (VB and VB') on their res- pective sides (figure 8). Thus only five vascular bundles are left in the main rachis after the supply to the first pair of leaflets. The remaining vascular elements of the ventrals bifurcate and the upper half of each ventral takes lateral position (figure 9). The supply for the second pair of leaflets is given off in a manner similar to the first one, but here the laterals are the product of the ventrals themselves (figure 10). The remaining vascular elements, i.e., dorsal (DB), two laterals (LBa, LBI') and ventrals (VB, VB') enter the terminal leaflet (figure 11).

In the present investigation, a large number of plants show this type of vascular supply where the laterals and the ventlals are the contributors. Of these, Pyrostegia venusta has five vascular bundles in the petiole while Doxantha unguis-cati, lJignonia purpuria, Stenolobium stans and have seven. In Adenocalymma alliaceum, Tabebuia pentaphylla and Millingtonia hortensis also, where the transection of petiole show, thirteen vascular bundles, the supply departs from laterals and ventrals only. A similar vascular pattern is met with in Spathodea eampanulata, Tecoma capensis and Tabebuia argentia where fifteen vascular bundles are observed in transection of petiole. 2. L Alqo R TYPE: A transection through the middle of the petiole of Jacaranda rnimo~ifolia reveals the presence of fifteen vascular bundles. These are labelled as three dorsals (DB1, DB, DBI'), eight laterals (LBz, LB2, LB3, LB4 and LBx', LB~', LB3', LB~') and four ventrals (VB1, VB~ and VB(, VB~'). Beside~, two ridge bundles (RB, RB') are seen in the ridges (figure 12). PETIOLAR ANATOMY OF BIGNONIACEAE 61

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Figures 8-17. 8, 9. Transections through primary rachis of Tecoma jasminoides at different levels of first nodule. 10. T.S. through the racbis at second nodule of Tecoma jasminoides. 11. T.S. through the base of petiole of the terminal leaflet of Tecoma iasminoides. 12 T.S. petiole of .. 13. T.S. primary rachis of J. mimosifolia at first nodule. 14. T.S. petiole of Campsis grandiflora. 15, 16. T.S. primary rachis of C. grandiflora at different levels of the first nodule. 17. T. S. through the base of petiole of terminal leaflet of C. grandiflora. 62 M.L. TRIVEDI, SHAILJA AND VEENA KHANNA

The supply for the first pair of secondary rachii departs from the lateral (LB4) and ridge bundle RB on one side and from LB4' and RB' on the other. The lateral LB4 and LB4' leave the ring as such while only traces from the ridge bundles accompany them (figure 13). After the supply for the first pair of secondary rachii has departed, the dorsal bundle DB trifur- cares. Thus, again the number of vascular bundles in the intemodular region is restored to fifteen. The supply at the subsequent nodules departs in a similar manner, i.e., from the lowermost lateral accompanied by traces from the ridge bundle. The mode of vascular supply of the leaflets from the secondary rachii is similar to the supply of secondary rachii from the primary one. In Kigelia pinnata, where the leaf is unipinnate, the vascular supply of the leaflets is given off in the manner similar to that of Jacaranda. 3. L, V AND R TYPE: In Campsis grandiflora the transection through the petiole shows seven vascular bundles. These are labelled as one dorsal (DB), four laterals (LB1, LB2, LBI', LB2'), two ventrals (VB, VB'). Besides these, two ridge bundles (RB, RB') are seen in the ridges (figure 14).

At the first nodule, the laterals (LB2, LB2'), ventrals (VB, VB') and the ridge bundles (RB, RB') give out traces, one each on either side, to supply the leaflets (figure 15). At the base of the petiole of the leaflet, all these traces fuse to form an arc. The bundles of the rachis take their original position (figure 16). This process is repeated for other pairs of leaflets at higher nodules. The petiole of the terminal leaflet has the same 1 q- 4 + 2 arrangement of vascular bundles (figure 17). The vascular supply of the leaflets in ttaplophragma adenophyllum is given off in a similar fashion.

4. DISCUSSION

The petiolar structure in dicots has been divided into various types by different authors. De Candolle 6 proposed two main types based on vascular outline as seen in transection, namely, ' open ' and ' closed ' types. The former has an arc of vascular elements while the latter has a ring of fused or dissected vascular bundles. Later, Petiff also followed the same termino- logy with a slight modification in the usage of ' closed' type. Hare s proposed

' U-shaped ', ' I-shaped' and ' O-shaped" petioles and also correlated their functional importance. Metcalfe and Chalk 9 recognised nine types of petioles as seen in transection. The petiolar structure in the members, investigated in the present work, corresponds to the 'closed' type of De CandollO and 'O-shaped' type of Hare. 8 According to Metcalfe and PETIOLAR ANATOMY OF BIGNONIACEAE 63

Chalk 9, Bignoniaceous petioles fall under the types ' F' and ' G '. However the members considered here can be grouped in ' G' type as all the petioles show dissected ring of vascular bundles. However, this condition is seen in the primary stage. The petioles show secondary growth when the complete vascular cylinder is formed. Petit's 7 view that herbaceous plants have 'open' type while woody plants have 'closed' type of petioles, does not hold true in Bignoniaceous genera as the closed but dissected system is present both in herbaceous and woody species.

The petiole structure in the present work has been further classified into four types on the basis of number and general topographic arrange- ment of major vascular bundles, namely, dorsal, lateral and ventrals. These types are :

Type I with five vascular bundles and 1 q- 2 + 2 arrangement. Type II with seven vascular bundles and 1 + 4 + 2 arrangement. Type III with thirteen vascular bundles. This type is further sub- divided into two types : (a) with 1 q- 8 -k 4 arrangement, (b) with 3 + 6 -k 4 arrangement.

Type IV with fifteen vascular bundles: This type is further subdivided into three types: (a) with 1 -k 8 + 6 arrangement, (b) with 3 -b 6 -b 6 arrangement, (c) with 3 -b 8 ,-b 4 arrangement.

From the observations it becomes clear that types I and II are prevalent in non-arborescent species, viz., Pyrostegia venusta, Campsis grandiflora Tecoma jasminoides and Stenolobium stans. Of these Pyrostegia has five vascular bundles, while the rest have seven. On the other hand, the types III and IV are present predominantly in arborescent members, viz., Tabebuia pentaphylla, Millingtonia hortensis, Kigelia pinnata, Haplophragma adeno- phyllum, Spathodea campanulata, Jacaranda mimosifolia and Tabebuia argentia. However, in Adenocalymrna alliaceum and Tecoma capensis which are non-arborescent members, the petioles have thirteen and fifteen vascular bundles respectively.

Beside the central vascular cylinder, in Campsis grandiflora, Kigelia pinnata, Jacaranda mimosifolia and tlaplophragma adenophyllum the petioles have a pair of prominent ridge bundles situated in the ridges on the adaxial side. The presence of ridge bundles in Leguminosae has been considered of some use for taxonomic purposes? Here also an attempt has been made to use the presence or absence of ridge bundles in categorising Bignoniaceous genera. 64 M.L. TRIVEDI, SHAILJA AND VEENA KHANNA

In addition to ridge bundles, a few vascular elements are prominently seen on the adaxial side between the ridge bundles except in Campsis grandi- flora where the petiole is devoid of these additional ventral bundles. How- ever, these are absent where the ridge bundles are not found. The vascular pattern, particularlY in compound leaves, where the supply departs from the primary rachis to the component structures (depen- ding on the type of compound nature) forms an interesting part of petiolar anatomy. Watari t studied this aspect and recognised three main types with further subdivisions. The vascular supply from the primary racki to leaflets or the secondary rachii as the case may be, studied, in sixteen members in the present work can be grouped into three main types. The most complicated pattern of vascular distribution is observed in tIaplophragma adenophyllum and Campsis grandiflora where the laterals, ventrals and ridge bundles are important in supplying the leaflets. A comparatively simpler pattern is observed in Kigelia pinnata and Jacaranda mimosifolia where the supply goes from laterals and ridge bundles. The simplest and the most common type is observed in rest of the members where laterals and ventrals supply the corresponding appendages. The vasculature of petiole has beert used for taxonomic purposes by various workers. Tamura, 1° on the basis of observations on the petiole structure in members of Ranunculaceae, supported the removal of Paeonia from Ranunculaceae. Howard ~ used the petiole vasculature for identi- fication of certain horticultural taxa. One i~dvantage of such anatomical criteria is that these can be utilised even when the is in the vegetative stage or the material available is sterile. In the present study also an attempt is made to provide an artificial key for the identification of the sixteen members of Bignoniaceae, most of them garden plants. The following key is primarily based on the presence or absence of ridge bundles, number of vascular bundles in the slender part of the primary rachis (before the onset of secondary growth), their topographic arrangement, the mode of vascular supply and the nodal structure. The last criterion is taken from the earlier work of the present authors3

ARTIFICIAL KEY FOR IDENTIFICATION OF MEMBERS STUDIED

Ridge bundles present ...... 1 Ridge bundles absent ...... 2 1. Supply from ridge bundle and lateral ...... 3 2. Supply from ridge bundle, lateral and ventral ...... 4 PETIOLAR ANATOMY OF BIGNONIACEAE 65

. Number of bundle in slender part thirteen.. Kigelia pinnata Number of bundle in slender part fifteen .... Jacaranda mimosifolia

. Number of bundle in slender part seven .... Campsis grandiflora Number of bundle in slender part thirteen..ttaplophrogma adeno- phyllum

. Number of bundle in slender part five ...... Pyrostegia venusta Number of bundle in slender part seven .... 5 Number of bundle in slender part thirteen..6 Number of bundle in slender part fifteen .... 7

. Nodal condition unilacunar triple-traced .... 8 Nodal condition unilacunar multi-traced .... Tecoma jasminoides Nodal condition unilacunar an arc ...... Parmentiera cerifera

. Climber ...... 9 Non-climber ...... Stenolobium stans

. Trifid clawlike [ present ...... Doxantha unguis-cati Trifid but simple) tendrils present ...... Bignonia purpurea

° Nodal condition unilacunar triple-traced .... 10

10. Unipinnate leaf ...... Adenocalymma alliaceum Bipinnate leaf ...... Millingtonia hortensis

. Topographic arrangement 1 + 8 + 6 ...... Spathodea campanulata Topographic arrangement 3 + 8 + 4 ...... Tecoma capensis Topograpkic arrangement 3 + 6 + 6 ...... Tabebuia argentia

ACKNOWLEDGEMENTS

The authors are thankful to Prof. S. K. Pillai and Prof. B. D. Deshpande of B.I.T.S., Pilani, for their keen interest in the present work and to Prof. S. S. Bit of Punjabi University, Patiala, for providing necessary facilities. 66 M.L. TRIVEDI, SHAILJA AND VEENA K.HANNA

REFERENCES

1. Watari, S., J. Fac. Sci. Univ. Tokyo Sect. 3 4 225 0934).

2. Howard, R. A., Adv. Hort. Sci. 37 (1962). 3. Carliquist, S., Comparative Holt, Reinart & Wintson, New York (1961).

4. Howard, R. A., J. Arnold Arbor. 55 125 (1974). 5. Trivedi, M. L., Khanna, Veena and Shailja, Proc. Indian Acad. Sci. 1384 31 (1976).

6. *Candolle, C. De, Mem. Soc. Pttvs. Itist. Nat. Geneva 26 427 (1879).

7. *Petit, L., C.R. Acad. ScL Paris 103 767 (1886).

8. *Hare, C. L, Proc. Linn. Soc. London 155 223 (1943).

9. Metcalfe, C. R. and Chalk, L., Anatomy of the Dicotyledons Vol. II Clarendon Press, Oxford (1950). 10. Tamura, M., Sci. Rep. Osaka Univ. 11 19 (1962).

* Original not seen.