Diversity of medicinal plants
The Ankaratra Mountain is rich in medicinal plants. The majority of species encountered are almost medicinal. Two hundred and thirty five species are surveyed in the studied area (Appendix 1). They are distributed in 173 genera and 82 families. This work has revealed that 203 of them, distributed in 172 genera and 82 families, are traditionally used for therapeutic purposes.
The Dicotyledons are the most diversified and account for 167 species which are distributed in 143 genera and 64 families. The Monocotyledons are represented by 23 species distributed in 17 genera and 8 families. The Pteridophytes which are the least diversified encompass 13 species distributed in 12 genera and 10 families (Table 1).
Table 1: Synopsis of the medicinal species in the Ankaratra Massif
|
Species
|
Genera
|
Families
|
DICOTYLEDONS
|
167
|
143
|
64
|
MONOCOTYLEDONS
|
23
|
17
|
8
|
PTERIDOPHYTES
|
13
|
12
|
10
|
Total
|
203
|
172
|
82
|
These species are encountered in four types of habitats, namely herbaceous savannah which house the highest number of species (35.5%), the rainy forest of the mountain holds 31.5% of species, the degraded forest with 17.2% of species, and the shrub savannah with 13.3% of the species (Figure 5A). Consequently, the species with herbaceous habit are prevalent in Ankaratra, with a percentage of 53.2%. The trees and shrubs represent 29.1 and 10.8%, respectively. The lianas only accounted for 7.4% of the all species (Figure 5B). The greater part of the medicinal species inventoried are endemic with a percentage of 73.9%. They largely have priority over the introduced species, which have a percentage of only 7.2% (Figure 5C).
Figure 5: Percentage of species according to ecology (A), life forms (B) and endemism (C); (FD: degraded forest, FH: humid forest, SH: grassy savanna, SA: shrub savanna, H: grass, a: shrub, A: tree, L: liana, AE: indigenous endemic, I: introduced, NE: indigenous not endemic)
At the genus level, the first four most diversified genera in terms of medicinal species are composed of savannah and endemic species. The most diversified genera have a high percentage of species. Helichrysum is the most diversified with 14 species, which represent 8.8% of the all species inventoried. It is followed by Senecio and Salvia with 7 (3.9%) and 4 (2.3%) species respectively, and Pimpinella and Gerbera with 3 (1.7%) species each. The species of the genera Helichrysum, Salvia and Pimpinella are all endemic, which is not the case for Senecio and Gerbera.
Regarding the most diversified families in traditional medicine, the richest families in medicinal species are the most diversified ones inventoried on the floristic standpoint. The Asteraceae accounts for more than half of the families of medicinal plants inventoried during this work (63.4% or 52 species). It is followed by the Rubiaceae which represents 17% or 14 species, while the Poaceae is found at the rate of 14.6% or 12 species, and the Lamiaceae and the Apiaceae go for 13.4% (11 species) and 12.2% (10 species), respectively.
The most cited taxa in traditional medicine
The quotation frequencies of the species, as calculated using the Singh formula, vary between 4.2% and 100%. Among the first ten most cited species, the first eight such as Tetradenia goudotii, Clematis pimpinellifolia, Billburttia capensoides, Micromeria flagellaris, Agauria polyphylla, Helichrysum benthamii, Hubertia faujasioides, Lycopodiella cernua, have each a quotation frequency of 100%. Those of Pimpinella perrieri and Inulanthera brownii reach 95.8% (Table 2, Figure 6). Among these species, nine belong exclusively to Madagascar and six are aromatic plants.
Table 2: Top ten most cited species
Scientific names
|
Frequency of citation (%)
|
Tetradenia goudotii Briq.
|
100
|
Clematis pimpinellifolia Hook.
|
100
|
Billburttia capensoides Sales & Hedge
|
100
|
Micromeria flagellaris Baker
|
100
|
Agauria polyphylla Baker
|
100
|
Helichrysum benthamii R. Vig. & Humbert
|
100
|
Hubertia faujasioides (Baker) C. Jeffrey
|
100
|
Lycopodiella cernua (L.) Pic. Serm.
|
100
|
Pimpinella perrieri Sales & Hedge
|
95.8
|
Inulanthera brownii (Hochr.) Källersjö
|
95.8
|
Moreover, the first twelve most cited genera have the maximal quotation frequency of 100%. Four of them belong to the most represented genera regarding the inventoried species. They are Helichrysum, Senecio, Pimpinella, Micromeria, Salvia, Vernonia, Hubertia, Agauria, Geranium, Indigofera, Vaccinium, Buddleja. All of the representatives specific to these genera are endemic and all the species of the four genera (Helichrysum, Pimpinella, Micromeria, Salvia) are aromatic.
Figure 6: most used species: Tetradeniagoudotii (A), Billburttiacapensoides (B), Helichrysumbenthamii (C) and Inulanthera brownii (D)
Concerning the quotation frequency of the families, 15 families have the maximal quotation frequency of 100%. They are Asteraceae, Apiaceae, Rubiaceae, Lamiaceae, Ericaceae, Poaceae, Ranunculaceae, Euphorbiaceae, Fabaceae, Lycopodiaceae, Hypericacee, Malavaceae, Geraniaceae, Scrophulariaceae and Asphodelaceae.
Relation between the quotation frequency and the endemism, biological forms and ecology
The variance analysis of the quotation frequency of the species in relation to the endemism, to the biological forms and to the ecology is presented in the figure 7. These results show that:
- The endemic autochthon species are more cited than non endemic autochthon and introduced ones with a highly significant difference (p<0,0001),
- The herbaceous species and the shrub species are more cited than the trees and the liana with a highly significant difference (p<0,0001),
- The species from herbaceous savannah are most cited than those from other kinds of vegetations.
Figure 7: Analysis of variance of the frequency of citation of species depending on endemism (A), life forms (B) and ecology (C); (FD: degraded forest, FH: humid forest, SH: grassy savanna, SA: shrub savanna, H: grass, a: shrub, A: tree, L: liana, AE: indigenous endemic, I: introduced, NE: indigenous not endemic)
Diseases treated with plants
Sixteen diseases categorized using the international classification of diseases are treated with plants in Ankaratra (Figure 8). The first mostly cited disease (FC=29.9%), the Symptoms, signs and abnormal clinical and laboratory results, not classified elsewhere (SYMP), is the one which requires particular knowledge, and is treated with the great number of species (165 species or 81.2%). The two following groups are among the diseases frequently encountered in Madagascar, namely some infectious and parasitical diseases and the digestive tract diseases with quotation frequencies of 13.7% and 10.7%, respectively. The plants associated to these diseases correspond to 97 species (47.7%) and 93 species (45.8%), respectively. The quotation frequency of the five diseases such as the respiratory tract diseases (18 species or 8.8%), the eyes diseases and their appendages (9 species or 4.4%), the nervous system diseases (22 species or 10.8%), the mental and behavior disorders (2 species or 0.9%), the ear diseases and the mastoid apophysis (4 species or 1.9%) do not exceed 1%.
Figure 8: Diseases treated with plants corresponding species rate (SYMP: Symptoms, signs and abnormal results of clinical and laboratory examinations, not elsewhere classified, MIP: Certain infectious and parasitic diseases, MAD: Disease of the digestive system, INC : Unclassifiable, MAR: Disease of the respiratory system, MPT: Diseases of the skin and subcutaneous cellular tissue, LTE: Traumatic injuries, poisonings and certain other consequences of external causes, MSO: Diseases of the osteoarticular system, muscles and connective tissue, MAG: Diseases of the genitourinary system, MEN: Endocrine, nutritional and metabolic diseases, GAP: Pregnancy, childbirth and the puerperium, MAC: Diseases of the circulatory system, OEA: Diseases of the eye and its appendices, MSN: Diseases of the nervous system, TMC: Mental and behavioral disorders, ORA: Diseases of the ear and mastoid process)
Important species for every disease
The fidelity level varies from 5.2 to 100%. Only species that are cited at least by three informants are considered in their identification.
The traditional healers give a huge importance to 8 endemic species with a fidelity level value of 100%:
- Cantharanthus lanceus, Helichrysum bojerianum and Helichrysum fulvescens used to treat some infectious and parasitical diseases,
- Oncostemum bojerianum and Psiadia lucida indicated to look after the Symptoms, signs and abnormal results of clinical and laboratory analysis, not classified elsewhere,
- Pteridium aquilinum and Gerbera bojeri reputed to be efficient respectively against the skin diseases and the sub-cutaneous cellular tissue, and Traumatic injury, poisoning and certain other consequences of external causes..
- Kniphofia ankaratrensis and Solanecio angulatus well known on the treatment of Endocrine, nutritional and metabolic diseases,
One hundred and seven species are cited at least by three informants. Concerning each of diseases treated with the plants, the first five species having the highest fidelity level are to the number of 64 and presented in the table 3. This table shows that:
- The fidelity level of species used to treat some infectious and parasitical diseases, and Symptoms, signs and abnormal results of clinical and laboratory analysis not classified elsewhere, the inclassables diseases, the skin diseases and the sub-cutaneous cellular tissue and the digestive tract diseases exceed 50%. The informants have more knowledge on these diseases and most of them agreed the uses of these species.
- The fidelity level of species used for caring pregnancy, childbirth and puerperium, the eye diseases and its appendices, the ear diseases and the mastoid apophysis do not reach 50%. The informants have few knowledge about these diseases and that the majority of them diversify the uses of these species.
Table 3: Top five species with the highest fidelity level (FL) by disease
Scientific names
|
Diseases
|
FL (%)
|
Cantharanthus lanceus (Bojer ex A.DC.) Pichon
|
Certain infectious and parasitic diseases
|
100
|
Helichrysum bojerianum DC.
|
100
|
Helichrysum fulvescens DC.
|
100
|
Helichrysum chermezoniiHumbert
|
85.7
|
Helichrysum cf fulvescens DC.
|
80
|
Garcinia verrucosa Jum. & H. Perrier
|
Pregnancy, childbirth and the puerperium
|
40
|
Indigofera bojeri Baker
|
40
|
Hypericum japonicumThunb.
|
33.3
|
Crassula ankaratrensisDesc.
|
25
|
Pyrostria italyensis (Cavaco) A.P. Davis &Govaerts
|
25
|
Stoebe pachyclada Humbert
|
Unclassifiable
|
100
|
Aphloia theiformis (Vahl) Benn.
|
88.2
|
Croton mongueBaill.
|
87.5
|
Dioscorea hexagona Baker
|
83.3
|
Pityrogramma calomelanos (L.) Link
|
83.3
|
Gerbera bojeri (DC.) Sch. Bip.
|
Traumatic injuries, poisonings and certain other consequences of external causes
|
100
|
Maesa lanceolata Forssk.
|
60
|
Plectaneia thouarsii Roem. &Schult.
|
50
|
Athrixia debilis DC.
|
44.4
|
Micromeria sphaerophylla Baker
|
40
|
Pteridium aquilinum (L.) Kuhn
|
Diseases of the skin and subcutaneous cellular tissue
|
100
|
Kosteletzkya velutina Garcke
|
87.5
|
Asplenium cancellatum Alston
|
80
|
Indigofera thymoides Baker
|
66.7
|
Cyperus betafensis Cherm.
|
50
|
Hypericum japonicum Thunb.
|
Diseases of the circulatory system
|
66.7
|
Dombeya lucida Baill.
|
50
|
Melicope madagascariensis (Baker) T.G. Hartley
|
50
|
Indigofera thymoides Baker
|
33.3
|
Pyrostria madagascariensis Lecomte
|
33.3
|
Euphorbia emirnensis Baker
|
Disease of the digestive system
|
66.7
|
Eragrostis cylindriflora Hochst.
|
66.7
|
Centella tussilaginifolia (Baker) Domin
|
57.1
|
Pimpinella ebracteata Baker
|
50
|
Aloe capitata Baker
|
50
|
Scientific names
|
Diseases
|
FL (%) Level
|
Micromeria sphaerophylla Baker
|
Diseases of the genitourinary system
|
80
|
Clematis mauritiana Lam.
|
50
|
Dianella ensifolia (L.) DC.
|
33.3
|
Buddleja madagascariensis Lam.
|
33.3
|
Pilogyne emirensis (Baker) W.J. de Wilde &Duyfjes
|
33.3
|
Anthospermum emirnense Baker
|
Disease of the respiratory system
|
76.9
|
Osmunda regalis L.
|
66.7
|
Hypericum japonicum Thunb.
|
66.7
|
Poa ankaratrensis A. Canus & H. Perrier
|
50
|
Ilex mitis (L.) Radlk.
|
40
|
Helichrysum plantago DC.
|
Diseases of the eye and its appendices
|
27.3
|
Dombeya lucida Baill.
|
25
|
Radamaea montana Benth.
|
22.2
|
Helichrysum stenoclinoides (Baker) Humbert
|
16.7
|
Centella tussilaginifolia (Baker) Domin
|
14.3
|
Kalanchoe campanulata
|
Diseases of the ear and mastoid process
|
12.5
|
Kalanchoe pumila Baker
|
12.5
|
Phellolophium madagascariense Baker
|
6.3
|
Hubertia faujasioides (Baker) C. Jeffrey
|
5.9
|
Anthocleista madagascariensis Baker
|
Diseases of the nervous system
|
75
|
Panicum dregeanumNees
|
75
|
Elionurus tristis Hack.
|
33.3
|
Tarenna angolensis Hiern
|
33.3
|
Panicum subalbidum Kunth
|
33.3
|
Kniphofia ankaratrensis Baker
|
Endocrine, nutritional and metabolic diseases
|
100
|
Solanecio angulatus (Vahl) C. Jeffrey
|
100
|
Impatiens baronii Baker
|
40
|
Polygala ankaratrensis H. Perrier
|
40
|
Eragrostis cylindrifloraHochst.
|
33.3
|
Salvia parvifolia Baker
|
27.3
|
Equisetum ramosissimumDesf.
|
Symptoms, signs and abnormal results of clinical and laboratory examinations, not elsewhere classified
|
85.7
|
Inulanthera brownii (Hochr.) Källersjö
|
83.3
|
Billburttia capensoides Sales &Hedge
|
80
|
Hubertia faujasioides (Baker) C. Jeffrey
|
70.6
|
Senecio resectus Bojer
|
57.1
|
Drosera madagascariensis DC.
|
Mental and behavioral disorders
|
72.7
|
Hypericum bojerianum H. Perrier
|
20
|
Relationship of the fidelity level to endemism, biological forms and ecology
The results of the variance analysis of the fidelity level versus the endemism, biological forms and ecology are summarized in figure 9. It shows that:
- The endemic species are of great importance in the treatment of diseases. The variance analyses of the fidelity level versus the degree of endemism of medicinal plants display a significant difference (p=0.0001) (Figure 9A). The endemic species have a high fidelity level, so they are very important for use to treat the diseases in comparison with autochthon but non-endemic species and those which are introduced. Among the 54 species having a fidelity level more than 50% and employed for the treatment of the first six diseases, only five species, namely Clematis mauritiana, Ranunculus multifidus, Equisetum ramosisimum, Osmonda regalis and Lycopodiella cernua are not endemic.
- The informants give much importance to herbaceous species which have a very significant difference (p=0.0001) (Figure 9B).
- The species from herbaceous savannah are more important in their health care than that of others. Nevertheless, the difference with those from rainy forest is not significant (Figure 9C).
Figure 9: Fidelity level according to endemism, life forms and ecology (FD: degraded forest, FH: humid forest, SH: grassy savanna, SA: shrub savanna, H: grass, a: shrub, A: tree, L: liana, AE: indigenous endemic, I: introduced, NE: indigenous non-endemic)