J. A. Inamdar, Sr. Avita & N. V. Rao

Leaf architectural studies in some Paeoniaceae

Feddes Repertorium Band 94 Heft 3—4 Seite 191—199 Berlin, April 1983

Sardar Patel University, Department of Biosciences Vallabh Vidyanagar, Gujarat, India




With 1 plate and 1 figure


Summary

Pinnate camptodromous-eucamptodromous or brochidodromous venation pattern is observed. The number of secondary veins as well as their angle of divergence varies from species to species and even within the same species. The marginal ultimate venation is looped or incomplete. The areoles are well developed. Tracheids uniseriate, biseriate or grouped; isolated veins, isolated tracheids, loop formation and extension cells are observed. The major veins are tri- to multiseriate and ornamented with parenchymatous bundle sheath cells. The leaf architectural studies add one more evidence for separation of the tribe Paeonieae from the Ranunculaceae.


Zusammenfassung

Es wurden camptodrome, eucamptodrome oder brochidodrome Nervatur-Muster bebaohtet. Sowohl die Zahl der Sekundärnerven als auch der Divergenzwinkel variieren von Art zu Art ebenso wie innerhalb einundderselben Art. Die äußerste randliche Nervatur ist gekrümmt oder unvollständig. Die Areolen sind gut entwickelt. Die Tracheiden sind einreihig, zweireihig oder liegen in Gruppen zusammen; isolierte Gefäße und Tracheiden, gekrümmte Formierungen und Extensionszellen wurden beobachtet. Die Hauptnerven sind drei- oder vielreihig und mit parenchymatischen, angehäuften Scheidezellen umhüllt. Die Untersuchungen des Blattbaus geben einen weiteren Beweis fur die Abtrennung des Tribus Paeoniaceae von den Ranunculaceae.


Introduction

The term "leaf architecture" is difined by Hickey (1973) to denote the placement and form of those elements constituting the outward expression and leaf structure, including venation pattern, marginal configuration, leaf shape and gland position. The leaf architectural studies is gaining significance in phylogeny and classification of angiosperms. Dilcher (1974) used these characters for diagnosis of fossil and living material. The taxonomic significance of vein-islet areas and vein endings are discussed by Levin (1929) and stbain (1933). hickey (1973) and melville (1976) classify le architecture of dicotyledonous and angiosperms leaves respectively. Surprisingly, le detailed study of leaf architecture and venation pattern in the unigeneric family Paeoniaceae is unknown.


1. Materials und Methods

The material fixed in FAA was obtained through the courtesy of Director, Royal Botanic Gardens, Kew, England for the present study. Leaves were cleared using trichloro-acetic acid and phenol in 2:1 ratio following the method of Rao et al. (1980), stained in Safranin '0' or Kores stamp pad ink (Kores India Ltd., Bombay) and made permanent by the customary methods. The absolute vein-islet number and absolute vein termination number are calculated following gupta (1961). Terminologies described by Hichey (1973) are adopted here.

Photomicrographs were taken with the help of Carl Zeiss photomicroscope 1 using yellow or violet filter and ORWO NP 15 film. The qualitative and quantitative leaf features are charted in Table 1 and ..


2. Observations

A. Morphology

The leaves are compound and palmately tripartite in all the species studied except Paeonia suffruticosa, where the leaves are pinnately compound. The lamina is asymmetrical in P. potanini and P. trollioides. It is symmetrical in other species studied. Obovate narrow obovate; wide obovate and oblong types of leaf forms have been recorded. They are with acute apex (Plate XIX, 15, 16) and decurrent base. Margin: is entire (P. arietina), lobed to entire (P. latiflora, P. suffruticosa, P. veitchii) or incised into cuneate segments which are dentate or bluntly toothed (P. potanini, P. trollioides). Texture: it may be coriaceous or subfleshy. Species wise details are given in table 1.


B. Major venation pattern

The venation pattern in most of the cases is "pinnate-eucamptodromous" however, "pinnate-brochidodromous" type is too observed (Fig. 1/1). Primary vein: There is single primary vein or midvein which is straight and moderately thickened in all the species studied. Secondary vein: The secondary vein arise on either side of the primary vein in alternate fashion (Fig. 1/1, 3, 4, 6, 10, 12). The number of secondary veins on one side of the primary vein varies in different species. The range is between 3—4 in P. arietina, P. lactiflora and P. potanini and 2—3 in other species. The angle of divergence of the 2° vein is acute wide in P. potanini, acute moderate or acute narrow and varies from species to species and even within the same species from base to apex in the other species. In P. arietina the basal secondaries are more acute than the apical ones. The relative thickness of the secondary vein is moderate. The secondary veins show branching in P. potanini, P. trollioides and P. veitchii and the lobes of the leaflets are supplied with the branches of secondary veins. The secondaries are interconnected by a number of other categories of veins. Intersecondary veins which are intermediate in thickness between second and third degree veins are simple, common in P. arietina, rare in P. suffruticosa and P. veitchii and absent in other species.

The tertiary veins orginate from the secondary veins and are mostly thinner than the secondaries. They may be acute or obtuse and alternating and oblique (tending to an obtuse or rarely an acute angle to the midvein). The tertiary veins exhibit random reticulate pattern. The major veins are as a rule triseriate to multiseriate.

leaves into uni-, bi-, triveined depending upon the number of strands entering the base of the lamina. According to them Paeonia species fall under univeined type.

- liEWS (1929) has emphasized the taxonomic value of vein-islet areas on the basis of

• his study of the genera Barosma, Cassia, Digitalis and Erythroxylon. According to him the vein-islet number is nearly constant for a species and it can be used as a valuable specific character. Later hall & melville (1951, 1954) pointed out that ; the number of veinlet terminations either alone or in conjunction with the other histo-'• logical characters can be used as a taxonomic criterion especially in genera with very small number of species. vebghese (1969) on the basis of the study on the venation pattern in some Scrophulariaceae pointed out that the number of vein-islet and vein-; lets are more or less constant for a species. nicely (1965) reported significant varia-S tions within the same leaf as regard the size and shape of areoles and number of vein \ endings in each vein-islet. The veins surrounded by parenchymatous bundle sheath )are termed as ornamented by seghal & paliwal (1974). Such ornamentation is a i common feature for major veins only in the species studied of the genus Paeonia. s? hick.ey (1974) classified the vein endings into none, simple or branched. During ! the present observations simple or branched once or twice vein endings are observed.. ^The tracheids which are present at the tips'are either uni-, biseriate or grouped. The I? occurrence of isolated veins for the first time was reported by kasapligil (1951). "(Later the presence of isolated veins have been noticed in Circaester (foster 1956) »and Euphorbia (hebbest 1972). The isolated veins or tracheids are observed in P. {potanini, P. trollioides and P. veitchii. haba (1962) reported some elongated cells : termed as,,extension cells" between one vein and vein ending of another vein. Similar ; cells are found in P. potanini only.

Taxonomic significance

The tribe Paeonieae of the Ranunculaceae is separated into a distinct family Paeoniaceae. The floral, wood anatomical, embryological, stoinatal and vessel elements studies have justified this separation (see woesdell 1908; ktjmazawa 1935; eames 1953; maheswaki 19C3; avita & inamdab 1980a, 1980b). The tribe Paeonieae has been given a family status by the workes of davezag (1957), hutchinson (1959) and takhtajan (1966). Leaf architectural tudies of the Ranunculaceae and Paeoni-aceae justify the separation (see Table 3).


Acknowledgement

One of us (sb. avita) thanks the university grants commission for the award of a teacher fellowship under faculty improvement programe.

 

 

 

 


References

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Address of the authors: J. A. Inamdab, sb. Avita & N. V. Rao, Deparment of Biosciences, Sardar Patel University, Vallabh Vidyanagar 388120, Gujarat. India.

Manuskript eingegangen am 8. 6. 1981.