Snake Plant (mother-in-law’s tongue,): Introduction, Classification, Taxonomy, Distribution, Morphological Characters, Phytochemistry, and Uses
Introduction
Dracaena trifasciata belonging to the family Asparagaceae, is a perennial herb, native to tropical West Africa, but widely grown as an ornamental plant in houses, gardens and thickets in many parts of the world. The plant is commonly known as mother-in-law’s tongue, snake plant, viper’s bowstring hemp or Saint George’s sword, because of the shape and sharp margins of its leaves that resemble snakes. It is also known as the “viper’s bowstring hemp” because it is one of the sources of plant fibres used to make bowstrings.
Classification
Kingdom: Plantae
Order: Asparagales
Family: Asparagaceae
Genus: Dracaena
Species: D. trifasciata
Binomial name: Dracaena trifasciata (Prain) Mabb.
TAXONOMY
The genus Dracaena Vand. ex L. (subfamily Nolinoideae; family Asparagaceae; order Asparagales) consisting of around 120 species. The taxonomic position of the genera Sansevieria and Dracaena has been debated for a long time and the two genera are still differentiated in the APG IV system of flowering plant classification (APG IV). However, recent molecular phylogenetic studies included the species formerly placed in Sansevieria within Dracaena. The species has two infraspecific taxa namely, Dracaena trifasciata subsp. trifasciata and Dracaena trifasciata subsp. sikawae (R.H.Webb & Yinger) Takaw.-Ny. & Thiede. Numerous variegated foliage cultivars have been developed with yellow or silvery-white stripes leaf margins and popular are Compacta, Goldiana, Hahnii, Laurentii, Silbersee, and Silver Hahnii
Distribution
Native to tropical West Africa – Cameroon, Central African Repu, Congo, Nigeria, Zaïre. Introduced into Andaman Islands, Bangladesh, East Himalaya, Fiji, Florida, India, Jamaica, Malaya, Mauritius, Mexico Southeast, Mexico Southwest, Myanmar, Queensland etc
Morphological characters
1. Evergreen perennial herb, 0.5-1.0 m in height; rhizome horizontal; sympodial, producing leafy shoots at intervals, aerial shoots in a single clump.
2. Leaves simple, tuft thick, upright fleshy to rigidly coriaceous, both surfaces shinning smooth, dark green, with numerous very conspicuous, light or greyish green irregularly confined transverse bands,
3. A narrow dark green margin, tapering to apex, acute, apiculate, linear-lanceolate or ensiform, 52.5-76.9 cm in length and 3.5-5.5 cm in breadth.
4. Inflorescence raceme;
5. Flowers in fascicles of 3- 7, membranous bract, each flower with a minute bract; pedicel cylinder, actinomorphic, regular, bisexual, trimerous, hypogynous.
6. Tapels 3+3, united at the base, tapel tube short, cylindrical, pale yellowish green; limbs linear or narrowly lanceolate, revolute, pale greenish white, inferior.
7. Stamens 3+3, epipetalous, filaments filiform, pale yellowish green; anther dithecous, dorsifixed, longitudinal dehiscence, sagittate at base, inferior.
8. Ovary 3-carples, 3 loculi, with anatropous ovule in each locule, axile placentation; style filiform, pale yellowish green, stigma 3 lobed, exserted, superior.
9. Fruit berry, globose, orange in colour when ripe. Seeds broadly ovoid, with horny endosperm
Phytochemistry
The leaves contain β-sitosterol, ruscogenin, neoruscogenin, and two spirostan sapogenins 25S-ruscogenin and sansevierigenin. Phytochemical analysis of the whole plant of S. trifasciata has resulted in the isolation of 12 steroidal saponins and 4 pregnane glycosides and identified as 1β,2β-dihydroxypregna-5,16-dien-20- one-1-O-α-L-rhamnopyranosyl-(1→2)-O-[β-D-xylopyranosyl- (1→3)]-β-D-glucopyranoside, 1β,2β-dihydroxypregna-5,16-dien-20- one1-O-α-L-rhamno- pyranosyl-(1→2)-O-[β-D-xylopyranosyl- (1→3)]-α-L-arabinopyranoside
Uses
Traditionally, it has important therapeutic use against acne, fungal infections, skin itches, ulcers, earache, allergies, helminths, jaundice, pharyngitis, urinary diseases, analgesic and antipyretic. It is used as a protective charm against evil or bewitchment in Africa and cultivated for its fibre in several tropical countries. A study by NASA found that D. trifasciata is one of the best plants for improving indoor air quality by passively absorbing various types of pollutants in the air; hence it could produce a great refresher.