Phytopharmacology of Holy basil (Ocimum tenuiflorum, Ocimum sanctum) Part 2

Phytopharmacology of Holy basil
(Ocimum  tenuiflorum, Ocimum sanctum) Part 2

Morphology of holy basil
(Ocimum tenuiflorum, Ocimum sanctum)

Macroscopic characteristics


Geniosporum tenuiflorum (L.) Merr.
Lumnitzera tenuiflorum (L.) Spreng. 
Moschosma tenuiflorum (L.) Heynnh.
Ocimum anisodorum F. Muell.
Ocimum caryophyllinum F. Muell.
Ocimum hirsutum. Benth.
Ocimum inodorum Burm. f
Ocimum monachorum. L.
Ocimum sanctum. L.
Ocimum scutellariodes Wild. Ex Benth
Ocimum subserratum B. Heyne ex Hook f.
Ocimum tomentosum Lam.
Ocimum villosum Roxb. nom.illeg.
Plectranthus monachorum (L.) Spreng [30]



                   Holy basil (Ocimum tenuiflorum, Ocimum sanctum)

Tulsi, Holy basil (Ocimum tenuiflorum, Ocimum sanctum) is an aromatic perennial plant native to India and wide spread as a cultivated plant throughout the Southeast Asian tropics. It is an erect, softly hairy, herbaceous (the plant that does not have much wood), much branched plant attaining 30 to 90 cm height. Three main morphotypes cultivated in India and Nepal are Raam Tulsi, Krishna Tulsi and Vana Tul (wild variety) [31] 


        Tap root with multiple fibers                   Dry roots

As Tulsi, Holy basil (Ocimum tenuiflorum, Ocimum sanctum) is a dicot plant its root system is tap root. There is however a lot of confusion on internet, whether it is tap root or fibrous root. According to experts, Tulsi (Ocimum tenuiflorum) being a dicot plant its root for sure is ‘tap root’. [32]

Root is wiry, branched, hairy, soft, blackish-brown externally and pale violet internally [33]


                                                                                           Stem of green Tulsi                                                       Stem of urple Tulsi     

Its stem is erect, herbaceous, woody, square, hairy, much branched, 30 to 60 cm tall and depending on variety light green to purple in color outside and cream colored internally; lower parts sub-serrate, higher parts slightly furrowed and more densely pubescent. [34], [35]




                Green Tulsi                                                          Purple Tulsi

Leaves green or dark purple in color; the variety with green leaves is called Shri Tulsi and with reddish leaves is called Krishna Tulsi. Leaves are simple, opposite, elliptic to elliptic-oblong blades, 3 to 6 cm long, 1 to 2.5 cm wide, cuneate (wedge shaped) at base, obtuse to acute at apex, entire, serrated margins, pubescent (hairy) on both surfaces; petiole thin, cylindrical, green with purplish tinge, thinly pubescent (hairy) and dotted with narrow inconspicuous adaxial (facing towards stem) groove, 1 to 3 cm long; venation reticulate (veins are irregularly distributed) [36], [37]



            Green Tulsi: Fresh flowers                           Green Tulsi: Mature flowers


                                         Purple flowers of Tulsi

Flowers are terminal, slender racemes or panicles, 4 to 12 cm long, 1 to 1.5 cm wide; bracteoles 2 to 3 mm long, ovate, acuminate, ciliate; flowers in verticils, on pedicels 2 to 4.5 mm long; calyx 2.5 cm long at anthesis (the flowering period of a plant, from the opening of the flower bud), in fruit up to 5 mm long, glabrous within, the upper lip suborbicular (nearly circular), reflexed (bent or curved backward or downward), short-apiculate (ending abruptly in a small distinct point),  the lower lip longer than upper lip, the teeth 4, lanceolate; corolla pale pink, white or pale lavender, to 4 mm long; filaments of stamens exserted (protruded), slender, the upper of each with a small, bearded basal appendage. [38]
The purplish flowers ease placed in close whorls on elongate racemes, bracts about 3 mm longer than calyx, slender, pubescent; calyx ovoid or campanulate (bell shaped) 3 to 4 mm, having two lips, upper lip obovate (oval with narrower end at the base), shortly apiculate (ending abruptly in a small distinct point), lower lip longer than upper lip having 4 mucronate (ending abruptly in a short sharp point) teeth, central two large lateral two short; corolla about 4 mm long, pubescent [39]   


Tulsi fruit

 Fruit, a group of 4 nullets, each with one seed, enclosed in an enlarged, membranous veined calyx; nutlets broadly elliptic, 0.8 to 1.2 mm long, slightly compressed or nearly smooth to minutely pitted, purple-green to brown in color marking at the place of attachment of thalamus [40], [41]

                                                Tulsi seeds

Seeds round to oval, small, many, yellow to reddish or black in color, 0.1 cm long, slightly notched at the base, having tough coat which pops around the seed on wetting [42], [43]

Microscopic characteristics
Transverse section shows single layered epidermis followed by cortex, consisting of seven or more layers of rectangular, round to oval polygonal, thin-walled parenchymatous cells filled with brown content, inner layers of cortex devoid of contents; phloem consisting of sieve elements, thin walled, rectangular parenchyma cells and scattered groups of fibres, xylem consists of vessels, tracheids, fibres and parenchyma; vessels pitted; tracheids fibres long, pitted with pointed ends; fibres thick walled and with pointed ends. [44]
Transverse section of stem shows a single layered epidermis with uniserriate (one cell wide), multicellular covering trichomes having 5-6 cells, occasionally a few cells collapsed; cortex consists of 10 or more layers of thin walled, rectangular parenchymatous cells; phloem consists of sieve elements, thin-walled, rectangular parenchyma cells and fibres; fibres found scattered mostly throughout phloem, in groups; xylem occupies major portion of stem consisting of vessels, tracheids fibres and parenchyma; vessels pitted; fibres with pointed ends; centre occupied by pith consisting of round to oval, thin-walled parenchymatous cells [45]
Section of petiole shows somewhat cordate (heart shaped) outline, consisting of single layered epidermis composed of thin-walled, oval cells having a number of covering and glandular trichomes; covering trichomes multicellular 1 to 8 celled long, rarely slightly reflexed at tip; glandular trichomes short, sessile with 1 to 2 celled stalk and 2 to 8 celled balloon shaped head, measuring 22 to 27 μ in diameter; epidermis followed by 1 or 2 layers and 2 or 3 layers of thin-walled, elongated, parenchyma cells towards upper and lower surfaces respectively; three vascular bundles situated centrally, middle one larger than other two; xylem surrounded by phloem.  [46]  

Transverse section of the leaf through its midrib shows that upper epidermis consists of a layer of small, quadrangular transparent cells with thin walls and thin smooth cuticle. On tangential view, these cells are polygonal with straight or wavy walls. Lower epidermis consists of a layer of small, quadrangular transparent cells with thin walls and thin smooth cuticle. Trichomes bent, consisting of 2 to 6 cells; glandular trichomes short, Laminaceae type, consisting of 1 stalk cell and 2 to 4 cells with rounded heads. Pallisade parenchyma consists of layer of long cylindrical cells containing chlorophyll; spongy parenchyma consists of polygonal cells with thin, straight or slightly wavy side walls. Vascular bundles collateral type with cholenchyma cells. Stoma diacytic (also called caryophyllaceous or cross-walled type), on upper and lower epidermis
[Note: Diacytic stoma remains surrounded by a pair of subsidiary cells. The common wall of the subsidiary cells is at right angles to guard cells) [47]

Epidermis and trichomes similar to those of petiole; both anomoctyic and diacytic type of stomata present on both surfaces, slightly raised above the level of epidermis; palisade single layered followed by 4 to 6 layers of closely packed spongy parenchyma with chloroplast and oleoresin [48]
[Note: Anomocytic means having irregular cells]

Greenish in color, shows thin-walled, parenchymatous cells, a few containing reddish brown contents, unicellular and multicelluar trichomes either entire or in pieces; thin-walled fibers, xylem vessels with pitted thickenings, fragments of epidermal cells in surface view having irregular shape, oil globules rounded to oval, simple as well as compound starch grains having 2 to 5 components, measuring 3 to 17 μ in diameter [49]

Parts used
All parts of the plant are edible. For medicinal purpose leaf and seeds are used, but sometimes stem is used.
Some Ayurvedic practitioners recommend using all parts of the plant

41. Malav et al, Morphological variability in holy basil (Ocimum tenuiflorum L.) from India, Genet resour Corp Evol
46. 47.


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