Introduction

Many drugs listed as traditional medicines were primarily derived from plants. Diverse wild medicinal plants including herbs, lianas and trees or their related parts like leaves, stems, roots, fruits and flowers are used in traditional medicinal systems (Marshall 2011). Although there is no record for exact total number of medicinal plants around the world, about half million plants around the world are considered as medicinal plants and the numbers and share of each country vary (Schippmann et al. 2002). Medicinal plants have favourable future because most of their medical activities have not been explored yet and their medical activities could be vital in the treatment of many diseases (Hassan 2012).

The genus Salacia comprises several medicinally important species (S. chinensis, S. oblonga, S. malabarica, S. macrosperma, S. reticulata etc.) and is known as Saptrangi in Ayurveda medicine and used as medicine for the treatment of Diabetes. Genus Salacia belongs to family Celastraceae. Salacia species are widespread in tropical and subtropical regions including North Africa, South America and East Asia, particularly in China (Spivey et al. 2002). The Genus Salacia consists of about 131 species in the world (http://www.theplantlist.org/).

In India genus Salacia is represented by 21 species, of which 15 species are known to occur in Peninsular India and it is distributed in Karnataka (rare in semi-evergreen forests of Western Ghats), Kerala (coastal forests of Kollam, Western Ghats of Pathanamthitta and Idukki districts) and Sothern Orissa (Ramamurthy and Naithani 2000). Among them, eight species are recorded from Karnataka (Herbarium JCB 2016). To get more evidence about the current variation in Karnataka and other states of India, it will be necessary to establish organised national germplasm collections, and to describe accessions according to a proper descriptor list. The variation that is observed among individuals can be the result of their genetic structure, the effect of the environment and the interface between these factors. Therefore, morphological variation will be due to some degree of genetic variability, but it will also be intertwined with variation caused by various environmental factors. However, in the lack of direct genetic methods, morphological variation of a group of traits is frequently used to determine the population structure of a species (Hughes 2001).

The descriptors of Salacia species have not yet been fully defined. It would be very useful to establish a descriptor list for each of the economically important Salacia species in order to classify all important and genetically controlled traits. Descriptors are essential for the determination of cultivars and conservation of the germplasm. For this purpose it would be very helpful to have consistent data about the variation within species.

The main objective of this paper was to prepare the list of morphological traits, which could be used in description of the Salacia species of Western Ghats of Karnataka, and as selection criteria in genetic breeding. To our knowledge there are no previously published chromosome numbers for the species S. chinensis and S. oblonga. This paper also provides the first report of the chromosome numbers of these species.

Material and method

Descriptor analysis

The descriptor list is based on the documented observations of the phenotypic variation within various germplasm collections of natural populations of Salacia species during the period 2014–2018. It included 6 species collected from different geographical regions of Western Ghats of Karnataka (Table 1).

Table 1 Salacia species in the Western Ghats: IUCN status and distribution
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The assessment of morphological factors was based on the observation of variation of particular trait within individuals (e.g., the shape of leaf apex was determined on 5 or more leave on the same plant) and or within different plant of same species. The observations of variation within the same individual was more frequently used because the number of individuals was limited for same species. The species were identified at the beginning of flowering. Colours were observed when plants are fully exposed to sun. The list of morphological traits that can be used as descriptors for Salacia species are given in Table 2.

Table 2 The taxonomic and morphological traits that can be used as descriptors of Salacia genotypes
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Somatic chromosome preparation

Somatic chromosomes were examined using root tips collected from seedlings. Mitotic squash preparations were made by pre-treating root tips in with 0.002 M 8-hydroxyquinoline for 2–3 h, a saturated aqueous solution of paradichlorobenzene for 4–5 h fixing was done with freshly prepared Carnoy fluid (ethanol alcohol: glacial acetic acid = 3:1), after washing with distilled water three times hydrolyzed in 1 M HC1 for 8 min at room temperature, and stained with 1% aceto-orcein for 15 min. Then the root tips were heated slightly and squashed on glass slide and were observed under microscope and photographs were taken. The experiment was repeated three times (Xin-Hua et al. 2010).

Result and discussion

Distribution of Salacia species in the Western Ghats

In the Western Ghats, most of the Salacia species are distributed in semi evergreen to evergreen habitats. Altitude wise S. chinensis and S. malabarica were exclusively found in higher elevation (1001–1700 m) (Tripathi et al. 2015). S. chinensis and S. macrosperma are the most widely distributed species in the Western Ghats. Among the six species indigenous in the Western Ghats, S. chinensis is an economically important and widely cultivated plant in Southern Western Ghats.

Conservation status

Literature review revealed that Salacia species in the Western Ghats have not been evaluated critically for their distribution and conservation and a comprehensive revision on the conservation status of the Salacia species appears to be vital. According to Majid et al. (2016), Mastiholi et al. (2018) S. chinensis is an endangered plant. However detailed literature survey and the guidelines of IUCN Red List revealed S. chinensis is rare in semi-evergreen forests of Western Ghats, S. macrosperma is rare in southwest India in wet forests of Western Ghats (Hassan, Kodagu, Shimoga, Uttar kannada) (http://flora-peninsula-indica.ces.iisc.ac.in), S. malabarica, S. oblonga and S. reticulata are endangered species (http://www.bsienvis.nic.in) (Table 1).

Taxonomy

The overall characteristics of the plants of the genus are as follows; scandent or sarmentosa shrub (Dandy 1969; Mabberley 2005) or small tree (Roopa et al. 2017; Ramakrishna et al. 2016). Among the different phylogenic analytical strategies, morphology in all its aspects, from micromorphology to embryology, palynology, seed, fruit, floral, stem and leaf morphology still remains to be the most indispensable tool. Till to date no identification keys have been reported for Salacia species across the globe based on morphological features of tree, leaf, stem, flower, fruit and root.

Diversity in tree morphology

Shape of the plant for all the six species i.e. S. chinensis, S. malabarica, S. oblonga, S. macrosperma, S. reticulata and S. gambleana was similar, all the six species showed compact plant shape.

Diversity in leaf morphology

Young leaves of four out of six species showed light green colour whereas leaf colour of S. malabarica and S. oblonga was green colour. Mature leaves were dark green in colour for all six species. Leaf shape of S. chinensis was elliptic, S. malabarica was oblong elliptic, S. oblonga was elliptic oblong, S. macrosperma was broadly elliptic, S. reticulata was elliptic oblong and leaf shape of S. gambleana oblanceolate. Leaf apex shape was acute for S. chinensis and S. gambleana, acute to obtuse for S. malabarica and S. oblonga, acuminate for S. macrosperma was abruptly acuminate for S. reticulata. Leaf base shape was obtuse to wedge for S. chinensis, round to wedge for S. malabarica, cuneate for S. oblonga, entire to crenulated for S. macrosperma, acute for S. reticulata and attenuate for S. gambleana. Leaf blade shape of four out of six species was elliptic whereas S. chinensis leaf blade shape observed was narrowly ovate to round and S. gambleana leaf shape observed was ovate. Leaf margin was dentate for S. chinensis, entire to undulate for S. malabarica and S. gambleana, undulate to serrate for S. oblonga, serrate for S. macrosperma and toothed for S. reticulata. Leaf length was maximum in S. malabarica (15 cm) and lowest in S. macrosperma (10 cm). S. malabarica showed the highest leaf width (7 cm) whereas S. gambleana showed the lowest leaf width (4 cm). Petiole length was maximum in S. oblonga (1.2 cm) and the lowest in S. reticulata (0.3 cm). S. malabarica showed the highest leaf blade length (5 cm) whereas S. gambleana showed the lowest (2.2 cm) (Fig. 1).

Fig. 1
figure 1

Variations in leaf apex shape, leaf blade shape and leaf base shape of different species of Salacia. a Leaf shape, b leaf apex and base shape of S. chinensis; c leaf shape, d leaf apex and base shape of S. malabarica; e leaf shape, f leaf apex and base shape of S. oblonga, g leaf shape, h leaf apex and base shape of S. macrosperma; i leaf shape, j leaf apex and base shape of S. reticulata; k leaf shape, l leaf apex and base shape of S. gambleana

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Diversity in stem morphology

Colour of the stem exterior of four out of six species was grey, whereas it was greenish grey for S. chinensis and greenish yellow for S. oblonga. Colour of the stem cortex of five out of six species was cream whereas colour of the stem cortex of S. reticulata was white. All six species showed acute branching and strangling stem. Five species showed green colour epidermis whereas S. reticulata showed white colour epidermis. Maximum stem length was in S. malabarica and S. oblonga (8 m) and minimum in S. chinensis (4 m). Maximum stem diameter was in S. malabarica (35 cm) and minimum in S. chinensis (20 cm).

Diversity in flower morphology

Type of inflorescence of four out of six species was verticil whereas it was raceme for S. oblonga and S. gambleana. Corolla shape of five out of six species was stellate whereas it was companulate for S. oblonga. Flower colour was greenish yellow for S. malabarica and S. oblonga, yellowish green for S. chinensis, green for S. macrosperma, greenish white or greenish yellow for S. reticulata and whitish yellow for S. gambleana. Sepal shape observed was oblong to obovate for S. chinensis, elliptic for S. malabarica, circular to oblong for S. oblonga, ovate for S. macrosperma and S. reticluata and oblong to obtuse for S. gambleana. Anther thecae colour was orange for five out of six species and yellow for S. oblonga. Calyx lobe was triangular for S. chinensis, minute ovate and entire for S. malabarica, orbicular ciliate for S. oblonga, oblong for S. macrosperma and S. reticulata and obtuse for S. gambleana (Fig. 2).

Fig. 2
figure 2

Pictorial depiction of flowers of different species of Salacia. aS. chinensis, bS. malabarica, cS. oblongadS. macrospermaeS. reticulatafS. gambleana

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Diversity in fruit morphology

Immature fruit colour of four out of six species was green. Immature fruit colour of S. malabarica and S. oblonga was light green and dark green respectively. Mature fruit colour was red for S. chinensis, dark orange for S. malabarica, orange for S. oblonga, orange red for S. macrosperma, pinkish red for S reticulata and light orange for S. gambleana. Fruit shape was round for S. reticulata and S. oblonga, round to ovate for S. chinensis, ovoid for S. malabarica, ovate for S. macrosperma and oblong for S. gambleana. Fruit apex shape was round for S. malabarica, S. oblonga and S. reticulata, obtuse for S. chinensis, S. macrosperma and S. gambleana. Fruit surface was smooth for S. chinensis and S. macrosperma, tuberculate for S. oblonga and S. reticulata, slightly tuberculate for S. malabarica and rugose for S. gambleana. Fruit mesocarp colour observed was pale yellow for S. chinensis, light orange for S. malabarica and S. gambleana, white for S. oblonga and for S. macrosperma and S. reticulata was green and light yellow respectively. Fruit diameter was maximum in S. oblonga (5 cm) and minimum in S. chinensis 1 cm (Fig. 3).

Fig. 3
figure 3

Picture representing fruit clustering habit of different species of Salacia. aS. chinensis, bS. malabarica, cS. oblonga, dS. macrosperma,eS. reticulata, fS. gambleana

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Diversity in seed morphology

Dry seed shape of S. chinensis was round, S. malabarica was oblong, S. oblonga was ellipsoid, seed shape of S. macrosperma was ovoid seed shape of S. reticulata and S. gambleana was oval and flat oblong respectively. Seed colour of S. chinensis was brown, S. malabarica was light orange, S. oblonga was cream, seed colour of S. macrosperma and S. reticulata was grey and seed colour of S. gambleana was light brown. Seed length and seed width was maximum in S. gambleana, i.e., 2 cm and 1 cm respectively, and seed length and seed width was lowest in S. chinensis, i.e., 0.6 cm and 0.5 cm respectively. Seed weight was maximum in S. gambleana (1.8 g) and minimum in S. reticulata (150 mg).

Diversity in root morphology

Four species showed irregular shape of roots, whereas shape of root of S. chinensis and S. oblonga was conical–cylindrical. Colour of root cortex of S. malabarica, S. macrosperma, and S. reticulata was yellow S. chinensis, S. oblonga and S. gambleana was brown. For all six species texture of root epidermis and cortex thickness was rough and intermediate, respectively.

Key to the Salacia species of the Western Ghats

Morphological characters among the Salacia species of the Western Ghats were evaluated systematically to construct an identification key, which will be a valuable tool for identification of the Western Ghats species in the field.

Group I

  • 1a Plant height tall—2

  • 1b Plant height very tall—2

  • 2 Shape of the plant compact—3

  • 3a Type of the plant climbing shrub—4

  • 4a Flowering and fruiting season December–April—S. chinensis

  • 4b Flowering and fruiting season February–June—S. malabarica

  • 3b Type of the plant shrub—5

  • 5a Flowering season March–August—S. oblonga

  • 5b Flowering and fruiting season January–June—S. macrosperma

  • 3c Type of the plant scandent shrub—6

  • 6a Flowering and fruiting season February–August—S. reticulata

  • 6b Flowering and fruiting season March–August—S. gambleana

Group II

  • 1 Type of leaf placement opposite—2

  • 2 Type of leaf arrangement pinnately compound—3

  • 3 Colour of leaf vein green—4

  • 4 Orientation of petiole horizontal—5

  • 5 Midrib appearance prominent—6

  • 6 Leaf upper surface pubescence glossy—7

  • 7 Leaf lower surface pubescence non glossy—8

  • 8 Leaf venation reticulate—9

  • 9 Leaf venation appearance prominent—10

  • 10 Petiole colour green—11

  • 11 mature leaf colour dark green—12

  • 12a Colour of young leaf light green—13

  • 13 Leaf shape elliptic, leaf apex acute, base obtuse, edge jagged, margins dentate—14

  • 14a Leaf blade shape narrowly ovate or round, leaf length 5–11 cm, leaf width 3–5 cm—S. chinensis

  • 14b Leaf blade shape elliptic—15

  • 15a Leaf shape broadly elliptic, apex acuminate, base entire/crenulated, edge wavy, margins serrate, leaf length 4–12 cm, leaf width 2–6 cm—S. macrosperma

  • 15b Leaf shape elliptic oblong, apex abruptly acuminate, base acute, edge jagged, margins toothed, leaf length 6–12 cm, leaf width 3–6 cm—S. reticulata

  • 14c Leaf blade shape ovate—16

  • 16 Leaf shape oblanceolate, apex acute, base attenuate, edge smooth, margins entire, leaf length 6–12 cm, leaf width 3–4 cm e—S. gambleana

  • 12b Colour of young leaf green—17

  • 17b Leaf shape oblong elliptic, apex obtuse, base round/wedge, edge smooth, margins entire–leaf length 8–16 cm, leaf width 5–7 cm—S. malabarica

  • 17b Leaf shape elliptic oblong, apex acute/obtuse, base cuneate, edge wavy, undulate/serrate leaf length 6–14 cm, leaf width 3–5 cm—S. oblonga

Group III

  • 1 Growth habit of stem strangling—2

  • 2 Angle of branching acute—3

  • 3 Colour of epidermis green—4

  • 4a Colour of stem exterior greenish grey—5

  • 5 Branching habit erect—6

  • 6a Colour of stem cortex cream, stem length 4 m, stem diameter 20 cm—S. chinensis

  • 6b Colour of stem cortex cream, stem length 5 m, stem diameter 23 cm—S. gambleana

  • 4b Colour of stem exterior grey—7

  • 7 Colour of stem cortex cream—8

  • 8 Branching habit dichotomous—9

  • 9a Stem length 8 m, stem diameter 35 cm—S. malabarica

  • 9b Stem length more than 5 m, stem diameter 22 cm—S. macrosperma

  • 9c Colour of stem cortex white, stem length 6 m, stem diameter 24 cm—S. reticulata

  • 4c Colour of stem exterior greenish yellow—10

  • 10 Colour of stem cortex cream, stem length 8 m, stem diameter 32 cm—S. oblonga

Group IV

  • 1 Inflorescence branching unbranched—2

  • 2 Flower position axial—3

  • 3 Corolla shape stellate—4

  • 4 Anther thecae colour orange—5

  • 5a Type of inflorescence verticil—6

  • 6a Number of flowers per inflorescence 3–6, flower colour yellowish green, petal shape broadly ovate, sepal shape oblong or obovate and calyx lobe triangular—S. chinensis

  • 6b Number of flowers per inflorescence 8–12, flower colour greenish yellow, petal shape elliptic, sepal shape elliptic and calyx lobe minute ovate entire—S. malabarica

  • 6c Number of flowers per inflorescence 4–6, flower colour green, petal shape ovate acute, sepal shape ovate and calyx lobe oblong—S. macrosperma

  • 6d Number of flowers per inflorescence 2–8, flower colour green, petal shape ovate, sepal shape ovate and calyx lobe obtuse—S. reticulata

  • 5b Type of inflorescence raceme—7

  • 7a Anther thecae colour orange, number of flowers per inflorescence 2–4, flower colour greenish yellow, petal shape ovate, sepal shape circular oblong and calyx lobe orbicular ciliate, pedicle sessile—S. oblonga

  • 7b Anther thecae colour orange, number of flowers per inflorescence 2–4, flower colour whitish yellow, petal shape oblong, sepal shape oblong/obtuse and calyx lobe obtuse—S. gambleana

Group V

  • 1 fruit hairiness absent—2

  • 2 fruit flavour moderately sweet—3

  • 3 Strips in mature fruits absent—4

  • 4a Number of fruits per fructoscence 2—5

  • 5a Immature fruit colour light green—6

  • 6 Mature fruit colour dark orange, fruit shape ovoid, fruit apex shape round, surface slightly tuberculate—S. oblonga

  • 5b Immature fruit colour green—7

  • 7a Fruit apex shape obtuse—8

  • 8a Mature fruit colour red, fruit shape round/ovate, surface smooth, fruit diameter more than 3 cm—S. chinensis

  • 8b Mature fruit colour light orange, fruit shape oblong, surface rugose, fruit diameter 4 cm—S. gambleana

  • 8c Mature fruit colour orange/red, fruit shape ovate, surface smooth, fruit diameter 1.7 cm—S. macrosperma

  • 7b Fruit apex shape round—9

  • 9 Mature fruit colour pinkish red, fruit shape round, surface tuberculate, fruit diameter 5 cm—S. reticulata

  • 4b Number of fruits per fructoscence 3—10

  • 10 Immature fruit colour dark green—11

  • 11 Mature fruit colour orange, fruit shape round, fruit apex shape round, surface tuberculate, fruit diameter 5 cm, pedicle sessile—S. oblonga

Group VI

  • 1a Seed colour grey—2

  • 2 Seed width 0.6–0.65–3

  • 3 Seed diameter 0.8–0.9—4

  • 4a Dry seed shape ovoid, seed length 0.95 cm, dry seed weight 300 mg, number of seeds per fruit 3—S. macrosperma

  • 4b Dry seed shape oval, seed length 0.7 cm, dry seed weight 150 mg, number seeds per fruit 1–4—S. reticulata

  • 1b Seed colour light brown—5

  • 5 Dry seed shape flat oblong, seed length 2 cm, seed width and diameter 1 cm, dry seed weight 700 mg, number of seeds per fruit 2 or many—S. gambleana

  • 1c Seed colour brown—6

  • 6 Dry seed shape round, seed length 0.6 cm, seed width 0.5 cm and diameter 0.75 cm, dry seed weight 380 mg, number of seeds per fruit 1—S. chinensis

  • 1d Seed colour light orange—7

  • 7 Dry seed shape oblong, seed length 1.5 cm, seed width 0.9 cm and diameter 1 cm, dry seed weight 1 g, number of seeds per fruit 4—S. malabarica

  • 1e Seed colour cream—8

  • 8 Dry seed shape ellipsoid, seed length 1.5 cm, seed width 0.95 cm and diameter 1.6 cm, dry seed weight 1.2 g, number of seeds per fruit 3–4—S. oblonga

Group VII

  • 1a Root shape conical–cylindrical—2

  • 2 Colour of root cortex–brown—3

  • 3 Texture of root epidermis rough, cortex thickness intermediate—S. chinensis, S. oblonga

  • 1b Root shape irregular—4

  • 4a Colour of root cortex yellow—5

  • 5 Texture of root epidermis rough, cortex thickness intermediate—S. malabarica, S. macrosperma, S. reticulata

  • 4b Colour of root cortex brown—6

  • 6 Texture of root epidermis rough, cortex thickness intermediate—S. gambleana

Western Ghats Salacia species

Salacia chinensis L.

Evergreen tree up to 4 m high; climbing/strangling shrub, branching habit erect.

Leaves: elliptic, leaf blade shape narrowly ovate/round, leaf apex shape acute, leaf base shape obtuse/wedge, leaf edges jagged/serrated, margins dentate, 5–11 × 3–5 cm.

Flowers: inflorescence verticil, 3–6 flowers on axillary fascicles, petal 0.37 × 0.3 cm, pedicle 0.4–0.6 cm long, flower colour yellowish green, petals broadly ovate, sepal shape oblong or obovate, sepal length up to 0.1 cm, anther thecae colour orange, calyx lobe triangular.

Fruits: immature fruit colour green, red when ripening, fruit 1 cm in diameter, fruit shape round/ovate, apex shape obtuse, fruit surface smooth, pericarp thin, flesh thickness thin.

Seeds: one seeded, colour brown, round shape, 0.6 × 0.5 cm.

Flowering season: December

Fruiting season: January–April

Field identification characters

  • Leaves elliptic in shape, 5–11 cm long

  • Flower yellowish green, 3–6 flowers on axillary fascicles

  • Fruit orange when ripening, one seeded

Salacia malabarica Gamble

Evergreen tree up to 8 m high; climbing shrub, branching habit dichotomous.

Leaves: oblong elliptic, leaf blade shape elliptic, leaf apex shape acute/obtuse, leaf base shape round/wedge, leaf edges smooth, margins entire/undulate, 8–16 × 5–11 cm.

Flowers: inflorescence verticil, 8-12 flowers on axillary fascicles, petal 0.25 × 0.15 cm, pedicle 0.8–1.5 cm long, flower colour greenish yellow, petal elliptic, sepal shape elliptic, sepal length up to 2 mm, anther thecae colour orange, calyx lobe minute ovate entire.

Fruits: immature fruit colour light green, dark orange when ripening, fruit 3 cm in diameter, fruit shape ovoid, apex shape round, fruit surface slightly tuberculate, pericarp thick, flesh thickness medium.

Seeds: 4 seeded, colour light orange, oblong shape, 1.5 × 0.9 cm.

Flowering season: February–April

Fruiting season: April–June

Field identification characters

  • Leaves oblong elliptic in shape, 8–16 cm long, branching habit dichotomous

  • Flower greenish yellow, 8–12 flowers on axillary fascicles

  • Fruit dark orange when ripening, 4 seeded

Salacia oblonga Wall ex Wight and Ern Var.

Evergreen tree up to 8 m high; shrub, branching habit erect.

Leaves: elliptic oblong, leaf blade shape elliptic, leaf apex shape acute/obtuse, leaf base shape cuneate, leaf edges wavy, margins undulate/serrate, 6–14 × 3–5 cm.

Flowers: inflorescence raceme, 2–4 flowers on axillary fascicles, petal 0.25 × 0.2 cm, pedicle sessile, flower colour greenish yellow, petal ovate, sepal shape circular, oblong, sepal length up to 1.5 mm, anther thecae colour yellow, calyx lobe orbicular ciliate.

Fruits: immature fruit colour dark green, orange when ripening, fruit 5 cm in diameter, fruit shape round, apex shape round, fruit surface tuberculate, pericarp thick, flesh thickness medium.

Seeds: 3–4 seeded, colour cream, ellipsoid shape, 1.5 × 0.95 cm.

Flowering season: March–May

Fruiting season: May–August

Field identification characters

  • Leaves elliptic oblong in shape, 6–14 cm long

  • Flower greenish yellow, 2–4 flowers on axillary fascicles

  • Fruit orange when ripening, fruit surface tuberculate, 3–4 seeded

Salacia macrosperma Wight

Evergreen tree up to 5.5 m high; stout climbing shrub, branching habit dichotomous.

Leaves: broadly elliptic, leaf blade shape elliptic, leaf apex shape acuminate, leaf base shape entire/crenulate, leaf edges wavy, margins serrate, 4–12 × 2–6 cm.

Flowers: inflorescence verticil, 4–6 flowers on axillary fascicles, petal 0.3 × 0.2 cm, pedicle 0.5–7 cm, flower colour green, petal ovate acute, sepal shape ovate, sepal length up to 1.5 mm, anther thecae colour orange, calyx lobe oblong.

Fruits: immature fruit colour green, orange red when ripening, fruit up to 2 cm in diameter, fruit shape ovate, apex shape obtuse, fruit surface smooth, pericarp thin and flesh thickness thin.

Seeds: 3 seeded, colour grey, ovoid shape, 0.95 × 0.65 cm.

Flowering season: January–April

Fruiting season: April–June

Field identification characters

  • Leaves broadly elliptic in shape, 4–12 cm long, branching habit dichotomous

  • Flower green, 4–6 flowers on axillary fascicles

  • Fruit orange red when ripening, 3 seeded

Salacia reticulata Wight

Evergreen tree up to 6 m high; strangling woody shrub, branching habit dichotomous.

Leaves: elliptic oblong, leaf blade shape elliptic, leaf apex shape abruptly acuminate, leaf base shape acute, leaf edges jagged, margins toothed, 6–12 × 3–6 cm.

Flowers: inflorescence verticil, 2–8 flowers on axillary fascicles, petal 0.3 × 0.2 cm, pedicle 0.4–5 cm, flower colour greenish white/greenish yellow, petal ovate, sepal shape ovate, sepal length up to 1 mm, anther thecae colour orange, calyx lobe entire.

Fruits: immature fruit colour green, pinkish red when ripening, fruit up to 6 cm in diameter, fruit shape round, apex shape round, fruit surface tuberculate, pericarp thick, flesh thickness medium.

Seeds: 1–4 seeded, colour grey, oval shape, 0.7 × 0.6 cm, branching habit dichotomous

Flowering season: February–April

Fruiting season: April–August

Field identification characters

  • Leaves elliptic oblong in shape, 6–12 cm long

  • Flower greenish white/greenish yellow, 2–8 flowers on axillary fascicles

  • Fruit pinkish red when ripening, fruit surface tuberculate, 1–4 seeded

Salacia gambleana Whiting and Kaul

Evergreen tree up to 5 m high; scandent shrub, branching habit erect.

Leaves: oblanceolate, leaf blade shape ovate, leaf apex shape acute, leaf base shape attenuate, leaf edges smooth, margins entire/undulate, 6–12 × 3–4 cm.

Flowers: inflorescence raceme, 2–4 flowers on axillary fascicles, petal 0.3 × 0.15 cm, pedicle 0.4–5 cm, flower colour whitish green, petal oblong, sepal shape oblong/obtuse, sepal length up to 1.5 mm, anther thecae colour orange, calyx lobe obtuse.

Fruits: immature fruit colour green, light orange when ripening, fruit up to 4 cm in diameter, fruit shape oblong, apex shape obtuse, fruit surface rugose, pericarp thick, flesh thickness medium.

Seeds: 2 or many seeded, colour light brown, flat oblong shape, 2 × 1 cm.

Flowering season: March–May

Fruiting season: June–August

Field identification characters

  • Leaves oblanceolate in shape, 6–12 cm long

  • Inflorescence raceme, flower greenish whitish green, 2–4 flowers on axillary fascicles

  • Fruit light orange when ripening, fruit surface rugose, 2 or many seeded

Somatic chromosome numbers

The first aspect to be noted about Salacia chromosomes is that they are not a very good material for analysis because they are very small and difficult to spread, especially the somatic ones. Moreover, the dense cytoplasm, especially in somatic cells, turns chromosome counting a rather difficult task. Chromosome counts are listed in Table 3 and chromosome complements are illustrated in Fig. 4. In Celastraceae the base chromosome number includes x = 8, 9, 10, 12, 14, 15, 17 and 23. In Celastraceae the polyploidy appears to be relatively common (Kubitzki 2004). In this study S. chinesis and S. oblonga were determined as having 2n = 28 chromosomes (Fig. 4), although in some preparations absolute counts proved difficult. This is the first report on the chromosome number in the genus Salacia. However, attempts were made to study the karyomorphology in the taxon but because of the stringency of chromosomes it was not possible. This count is in agreement with Mangenot and Mangenot (1957) somatic count of Salacia lucida Oliv. is 2n = 28.

Table 3 Species studied of Salacia and their chromosome number
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Fig. 4
figure 4

Somatic chromosomes at mitotic metaphase in the a, bSalacia chinensis 2n = 28 and c, dSalacia oblonga 2n = 28

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Conclusions

Salacia species are important components of the flora of the Western Ghats and also an economically important group. The study of descriptor analysis indicates that Western Ghats of Karnataka is a good source of diversity for Salacia. However, the collection surveys indicated that even though many species exist, the population density is dangerously low and is reduced to one or two trees due to the fact that seeds fail to produce seedlings because of numerous physiological and environmental factors making multiplication, maintenance and survival of these species very difficult. Field surveys revealed that 6 species are indigenous to the Western Ghats of Karnataka out of which S. macrosperma is rare to the region. Though the root product of Salacia is available in local markets, the awareness of Salacia as a tree is very rare. In this study, descriptors of fruit, leaf, root, stem, seed and tree morphology for six species of Salacia has been discussed in detail. It is also important to determine the chromosome numbers of other Salacia species including these two species with wide distribution in order to reveal the diversity of the chromosome numbers and ploidy levels in the genus Salacia.