Biosci<?nr.f» Research Communications 
Vol 15. No 6. December 31. 2003 
Printpd in Nigeria

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13RC 2003048/15608

Comparative leaf micromorphological characters of the 
Nigerian species of Rauvolfia Linn (Apocynaceae)

A.B. Kadiri* and A.R. Ayodclc**

‘ Department of Botany and Microbiology, Botany Research I .aboralory, l Ini versity of I .agos, I .agos. Nigeria.

ABSTRACT: Leaf micromophological characters of Rauvolfia Linn. (Apocynaceae) have been studied and 
compared. The leaf is usually glabrous and hypostomatic. Stomatal type is mostly paracytic but epidermal 
cell shape is either polygonal or irregular while epidermal cell number is lower on the abaxial surface. 
Mean stomatal size varies from 1.40.pm x 0.60pm in /?. macrophylla to 2.30pm x 0.60pm in R. vomitoria 
and mean cell wall thickness is either identical on both surfaces in R. macrophylla and R. cq/fira or 
dissimilar on either surface in other species. Other features that show variation are anticlinal wall pattern, 
stomatal and cell inclusions. Using these micro-characters, the species can be recognised even when the 
leaves are fragmentary. Rauvolfia has therapeutic properties for the treatment of neuropsychiatric disorder 
and it can be used as aphrodisiac and genital excitant.

Key words: Leaf morphology; Taxonomy; Apocynaceae; Rauvolfia

Introduction

Rauvolfia Linn. (Apocynaceae) is an economic genus containing about one hundred species in the 
World out of which filleen and four species are presented in Africa and Nigeria respectively (2,6,7,8,9). 
The Nigerian species are R. caffra Solid., R. vomitoria Afzel., R macrophylla Stapf, and R. mannii Stapf.

Lvans (6) had reported that only one species R. serpentina (L.) Benth. ex Kurz which is restricted to 
Asia, contains most of (he active medicinal substances. However, further studies on the genus have 
revealed that the African species particularly R. vomitoria has the highest medicinal value than any species 
elsewhere (9,13,15.17),

Furthermore, other Nigerian species apart from R. vomitoria also contain (he medicinally active 
ingredients but in varied concentrations. (2,6,9,17). An excellent account of the medicinal properties of the 
genus has been documented (2,6,9,13,15, 17). Rauvolfia contains hypotensive alkaloids which arc non­
toxic but have cumulative action. These alkaloids are reserpine, yohimbine, rescinamine, serediuc, 
reserpiline, raumitorine, serpenlinine, alstonine, rauvanine, ajmalicine and rauvoxine which are useful for

Department of Botany and Microbiology, University of Ibadan, Ibadan, Nigeria.

(Received October 6, 2003)

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the elimination o f Schizophrenia in neuropsychatrie patients, they also have a symphatholytic action and are 
much used in the treatment of hypertension; besides, the above compounds are used as a remedy for the 
opacities of the cornea, epilepsy, skin diseases, chest pains, internal disorder, restoration of hair loss, 
combating convulsion, as aphrodisiac and genital excitant.

Rauvoljia species are also important as avenue trees, shade bearers, for live fence and mixing drink 
hence its name swizzle-stick. Anatomical data have been used by various workers to show taxonomic 
relationship and delimit taxa (1,5,11,12,14,16). Anatomical report on Rauvolfia has been mostly on the 
stem and root with scanty account on epidermal morphology (6 ,11,12).

This study describes the significance of, an discusses the extent to which foliar epidermal characters 
may be used for identifying sterile plants of each species of Rauvolfia which until now is the form in 
which the medicinal ones ate obtained from the local markets or collected by the herbal traders. Apart from 
responding to the call o f Cunningham (3) and Martin (10) on the importance of wild or non-cultivated 
plants in the lives of a large portion of the world’s populations, the study also aims at checking the 
adulteration of these medicinal plants. Moreso, it also suggests the need for phytochemical screening of the 
hitherto sterile species: R. macrophylla and R. manni for their therapeutic properties.

Material and Methods

Dried leaf material obtained from the Forestry Research Institute of Nigeria Herbarium (F ill) was used 
for the study. Method follows Akhil & Subhan (1), Ogundipe (14), and Olowkudejo & Ayodele (16) with 
some modification initiated by the author. About 2cm2 portion was cut out from the standard median 
position of the leaf lamina of each specimen and boiled in water for thirty miutes in order to revive it. F.ach 
specimen was then soaked in Concentrated Trioxonitrate (V) acid (UNO,) in a capped specimen bottle for 
10-24 hours to macerate the tnesophyll. l’issue disintegration was indicated on the leaves by bubbles and 
the epidertnides were transferred into Petri-dishes containing water. Fpidermides were separated with 
forceps and a mounting needle and cleared of debris with soil hair brush. Specimens were washed in 
several changes of water and dehydrated through 50%, 70%, 90%, 100% grades of alcohol to harden the 
cells. Fhe specimens were mounted in glycerin after being stained in Safranin O for live minutes. Slides 
were covered with cover slips and then ringed with nail vanish to prevent dehydration. Specimens were 
observed at X 400 and drawings of the epiderntides were made from Wild M12 microscope fitted with 
camera lueida.

Result tint! Discussion

All the Nigerian species are represented in the Southern part of the country but three species are present 
in the middle-belt areas with only one representative in the Northern Nigeria (Fig. I).
The epidermal cells are either irregular or polygonal on the adaxial surlace but they are uniform on the 
abaxial surfaces of the species (Fig.2a-h),straight anticlinal wall pattern accompany the polygonal cells on 
the adaxial surface while the abaxial cells usually have curved to undulate anticlinal walls (Fig. 2a-h). 
Metcalfe & Chalk (I 1,12) reported crystals in the Apocynaceae. In this study, crystals are present in all 
species except in R. mannii. Raphides were recorded on the abaxial surface of R. macrophylla (Fig.2b) and 
on the adaxial surfaces o f R. caffra and R. vomitoria (Fig. 2e,f) Sandy crystals were also found on the 
abaxial surface o f R. vomitoria (Fig. 2h).

Metcalfe & Chalk (1 1,12) reported that the leaf is paracytic and pubescent in the general account of the 
family Apocynaceae. In the present study, the leaf was found to be hypostomatic with mostly paracytic 
stomata sometimes ac companied by anomocytic stomata. Epidermal cell length is longer on the abaxial 
surface than adaxial surface in R. vomitoria and R.macrophylla whereas it is vice-versa in other species 
(Table I). Mean epidermal cell number varies from 9 and 5 in R. mannii and R. caffra to 2 1 and 15 in R. 
vomitoria on the adaxial and abaxial surfaces respectively. Usually, epidermal cell number on the abaxial 
surface is lower than the adaxial surface. Mean cell wall thickness is identical on both surfaces in all 
species except R mannii and R. vomitoria.

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Fig. 1:

I

Map of Nigeria showing distribution of Rauvolfia species

R. vomitoria 2 ” R mannli 3 *> R cqffra 4 R macrophylla

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E p id o rm id e s  of the fo u r Nigerian s pecies  o f Ratrvofffa
Drawing of adaxiai surface of the leef of R  m arop/iyia  showing polygonal cells with straight anticlinal wails. Scale par =* 0.44um
Drawing of aboxiai surface of the leaf of R m acro p nyla  snowing irregular cell with curved anticlinal waits and peracyffc stomata. Sca le  bar -  0.44. pm
Drawing of aaaxiai surface of the :eaf R  mtmn4 showing polygonal cells with straight to curved anticlinal walls. Scale bar = 0 .4 4  pm
Drawing of abaxia! surface of the ieaf of R  manna showing irregular cells with undulate to sinuate anticlinal waits and paracytic stomata. Scale bar = 
0.«*4 pm
Drawing of adaxial surface of the leaf of R  caffra showing polygonal ceils with straight to curved walls and rap hides in som e ceils. Scale bar = 0.44pm
Drawing of abaxial surface of the leaf of R. cafTra showing irregular ceils ’with undulate to sinuate anticinel walls and panacytic stomata
Drawing of adaxial surface of the leaf of R  vom tona  showing polygonal cells with straight wails and containing rap hides. Scale bar =  0.44um  
Drawing of abaxial surface of the leaf of R. vomJtona showing irregular cells wit. > curved arrttciinaJ walls, paracytic stomata and crystal oxalates. Scale bar 
= 0.44pm

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Table 1: Epidermal features of the leaf of Rauvolfia in Nigeria.

Taxa Cell Length Cell Width Cell Number Cell wall Stomatal length Stomatal width Stomatal Anticlinal Epidermal
(pm ) (u rn ) thickness (pm) (um) Number. wall cell shape

(pm ) pattern
R.
macrophvl ad 15(25=3.1) 32 10(18.29=2.5) 23 19 (21=0.8)23 0.5(0.5=0.04)0.6 St P
la Stapf. ab 17(21.5=1.6)25 6(10.25=1.3)13 13(14=0.3)14 0.4(0.5=0.04)0.6 1.1(1.4=0.1)17 0.560.6=0.1 >0.8 3(3=0.2)4 Cv Irr

R.mannii ad 24(31.75=3.7)40 20(23.75=1.5)28 8(9=0.2)9 0.4(0.5=0.04)0.6 - - - SLCv lrr
Stapf. ab 23(27.5=2.1) 33 10(15.25=2.4)23 5(5=05)6 0.3(0.4=0.04)0.6 1.5(1.9=0.2) 2.3 0.5(0.5=0.03)0.6 1(2=0.1)2 Ud/'Sn Irr

R. caffra ad 23(31.25=3.0) 40 20(22.25=0.9)25 7(9=0.6)9 0.3(0.4=0.04)0.5 - - - St/Cv P
Sond. ab 20(25.25=2.0)30 10(15.5=1.8)20 5(5=0.3)6 0.3(0.4=0.04)0.5 1.5(1.5=0.03) 1.7 0.2(0.4=0.1) 0.6 4( 5=0.2 )5 Ud'Sn Irr

R. ad 15(21.75=^2.2)27 12(15=2.5)26 17(21=1.2)23 0.3(0.5=0.04)0.6 _ . . St p
vomitoria 
A feel.

ab 22(24.5=1.2)28 5(11.75=2.8)19 13(15=0.6)17 0.2(0.3=0.03)0.6 1.8(23=0.2)2.7 0.5(0.6=0.1)0.8 2(2=05)3 Cv lrr

Ud = Undulate. Cv = Curved. St = Straight. P = Polygonal. Irr = Irregular, ad = Adaxial ab = Abaxial. Sn = sinuate

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The smallest inean stomata number of 2 was recorded in R. matmii and R. vomitoria whereas highest 
values of 5 was recorded in R. caffra. Mean stomata! width is 0.60pm in R. macrophylla and R. vomHoria,
0.50pm in R. mannii and 0.40pm in R. caffra. The longest stomata of 1.80 (2.3 A 0.2) 2.70pm x 0.50 (0.6 
± 0 .1 ) 0.80pm were recorded in R. vomitoria whereas the shortest stomata of 1.10 (1.4 ± 0.1) 1.70pm x
0. 20.(0.4 ±0.1) 0.60pm was found in R. macrophylla (Table I). From this study, it is revealed that the 
species show a remarkable affinity and a high level of interrelationship.

Evans (6) reported that R. caffra resembles R. vomitoria in its therapeutic use based on the studies of 
their root anatomy. Apart from R. vomitoria and R. caffra it is therefore suggested that other species 
discussed in this study should be screened for their therapeutic properties. Akhil & Subhan (I), Ogundipe 
(14), Olowokudejo & Ayodclc(l6).have reported that micromorphological data are a good source of 
taxonomic information and have been used to delimit taxa and recognise useful plants.

Key to (he four Nigerian species of Rauvolfta (Linn.)

1. Epidermal cell shape polygonal on adaxial surface
2. Mean cel! wall thickness identical on both surfaces
3. Epidermal cell number up to ....... R. macrophylla
.3. Epidermal cell number less than 10 ........ R. caffra
2. Mean cell wall thickness different on either surface
4. Cell inclusions present ............................ R. vomitoria
I . Epidermal cell shape irregular on adaxial surface
4. Cell inclusions absent.............. .............. R. matmi

References

1. Akhil, H and Subhan, C.N (1997). Foliar epidermal characters in twelve species of Uvmamomum Schaeffer 
(Eauracene) from North Eastern. India. Phvtomorphohgy 47(2): 127-1.34.

2. Iturkill, II.M (1985). The Useful Plants of West Africa V . I.(A-D). Whilcfrairs Press ltd. Kent. 960 pp.
.3. Cunningham, A. B. (2001). Applied Ethnohotany. Earthscan Publication Ltd. London. 300pp
4. Dal/.icl, J.M. (1937). The Useful Plants o f West Tropical Africa. Crown Agents for the Colonies. London.

612pp.
5. Davis, P it. and IIcywood, V I1. ( 196.3). Principles of Angiosperm Taxonomy R.F,. Krcigncr Publishing Co. New 

York. 556pp.
6. Evans, W.C. (1996).Trease and Evans' Pharmacognosy. W.I3. Sanders Co. I ,td. London. 612pp.
7. Ileywood. V.ll. (ed)(l978). Flowering Plants o f the. World Oxford University Press. Oxford. 336pp.
8. Hutchinson, .1. and Dal/icl. J.M. (196.3). Flora of West Tropical Africa Vol. 2: Crown Agentsfor Overseas

Government and Administrations. London. 544pp.
9. Lambo, I . A. (1984). Medicinal Plants in Tropica! West Africa. Cambridge University Press. Cambridge. 375pp.
10. Martin, G.J. (1995). Etlinohotany: A methods manual. Chapman & Itall. London 268pp
11. Metcalfe, C.R. and Chalk, L. (1950). Anatomy o f the Dicotyledons. Clarendon Press, Oxford. 1500pp.
12. Metcalfe, C.R. and Chalk. L. (1979). Anatomy of the. Dicotyledons (2nd ed) V.l Clarendon Press, Oxford. 276pp.
1.7. OAU/STRC. (1985). African Pharmacopoeia. OAU/STRC Scientific Publications No. 2 V.l Lagos, Nigeria.

256pp.
14. Ogundipe, 0.1. (1992). Leaf Epidermal Studies in the genus Datura Linn. (Solanaceae), Phytomorphology. 

42(.7&4):209-217.
15. Oliver, 13. (I960). Medicinal Plants in Nigeria. College of Arts. Science and Technology. 138pp.
16. Olowokudejo, J.l). and Ayodclc, A.E. (1997). Systematic importance of leaf and epidermal characters in West 

Africa species of family Myrtaceac. Pot. Soc. Pl ot. Her. 2, 68:35-72
17. Samba Mtirty. A.V.S.S. and Subrahmanyam, N.S. (1989). A Textbook of Economic Polony. Wiley Eastern I,id. 

New Delhi. 875pp.
18. I hisellon-Dyer, W.T. (1904). Flora of Tropical Africa. L. Reeve and Co. Ltd. Kent. 646pp.

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