Planta Med 1965; 13(2): 247-256
DOI: 10.1055/s-0028-1100119
© Georg Thieme Verlag Stuttgart · New York

DETERMINATION OF AVERAGE VEIN–ISLET, VEINLET TERMINATION AND STOMATAL NUMBERS OF A LEAF

B. Gupta, B. C. Kundu
Further Information

Publication History

Publication Date:
15 January 2009 (online)

Summary

In the identification of leaf drugs, palisade ratio, stomatal index, vein–islet number, veinlet termination number and stomatal number are generally used. However, it was shown that the total number of vein–islets, veinlet terminations and stomata of a normal mature leaf of a particular species, irrespective of the size of the lamina, is constant, and for this reason the concentration of the tissues per unit area in large and small leaves of the same species varies widely. It is very difficult to count the total numbers of these tissues from a whole leaf blade; these have been determined first by finding out their average concentration per unit area and then multiplying these numbers by area of the lamina. As there is no easy and dependable method for the determination of the average values, a method is presented here.

In view of some vagueness in the existing methods for the counting of vein–islet or veinlet termination numbers some modifications have been suggested. The efficiency of counting the number from 4 sq. mm. area have been determined by analysing the counts taken from 1 to 10 sq. mm. area. The variation becomes too high if it is counted from an area which is less than 4 sq. mm.

The concentration of different tissues varies from place to place in a leaf, but there is a pattern in this variation. The concentration may be high at one end and gradually decreases to the other. For the determination of the average number of these tissues an easy method has been evolved. This can be obtained by counting the number from 5 points from one lateral half of the leaf, which are nearly equidistant from one another and are placed midway between the margin and the midrib. If secondary veins run through any of these areas, the points may be shifted a little. From the average of these five numbers and the area of the half leaf the absolute number can be determined. Absolute vein–islet number, absolute veinlet termination number, absolute stomatal number or any other absolute number can be determined from the above mentioned 5 points of the leaf.

In the determination of the stomatal number, it is not known what should be the minimum area wherefrom the counting should be taken. Stomata were counted from 0.1 to 1.0 sq. mm. area of several solanaceous leaves from 10 different places in each leaf. It was noted that fairly uniform results can be obtained if stomata are counted from an area which is not less than 0.4 sq. mm. where the percentage of coefficient of variation may not be too high.

Zusammenfassung

Basierend auf Zählungen, die an Solanaceen–Blättern durchgeführt wurden, wird die Methodik zur Festlegung der Blattinselzahl (vein–islet number), der Zahl der Nervenendigungen (veinlet–termination) und der Spaltöffnungszahl erörtert.

Der Verfasser weist darauf hin, daß eine hinreichende Konstanz dieser Werte auf folgende Weise erreicht werden kann:

Zur Festlegung der Blattinselzahl und der Nervenendigungen sollen mindestens 5 Flächen von jeweils 4 mm2 ausgezählt werden. Zur Bestimmung der Stomatazahl sind 5 Flächen von jeweils 0,4 mm2 auszuzählen.

Die fünf Zählflächen sollen etwa gleich weit voneinander entfernt und auf der Mitte zwischen Blattrand und Mittelnerv liegen.

Aus den Zählwerten werden die absoluten Werte für die gesamte Blattfläche berechnet.

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