In this article we will discuss about:- 1. Characters of Musaceae 2. Distribution of Musaceae 3. Economic Importance 4. Affinities 5. Important Type.
Characters of Musaceae
Plants large herbs with false stem, or trees, leaves large, compound inflorescence with large often petaloid bracts; Flower zygomorphic, hermaphrodite or unisexual, perianth 3+3, petaloid, often united, stamens 3+2 and staminode, gynoecium tricarpellary, syncarpous, inferior, trilocular with 1 to indefinite ovules in each locule, fruit berry or capsule, seed endospermic, often with perisperm.
A. Vegetative characters:
Plants are gigantic herbs, perennial, may attain a height of 5 meters.
Adventitious arising from rhizome.
Underground rhizome, perennating, branched, from which the many naked leaves spring. The sheaths of the leaves are rolled round one another below, and form, what looks like an aerial stem. The aerial pseudo stem is tall, stout and un-branched.
Ravenala has woody arboreal stem reaches nearly 30 metres in height.
Large and oval, simple, stalk and sheath long and broad, blade oblong, end blunt; leaf blade when young is convolutely rolled up; midrib stout, parallel veins running from it to the edge, pinnate parallel venation.
B. Floral characters:
The aerial stem terminates in an inflorescence. Simple or compound, spike or panicle, or panicle spadix with several woody or leathery bracts, large, sometimes coloured; each spathe enclosing clusters of flowers in two rows, which are arranged in uniparous cyme.
Large, brightly coloured, generally trimerous, unisexual or bisexual, when monoecious, male flowers usually at the upper end of the inflorescence and the female at the lower bracts; zygomorphic, epigynous, incomplete, plenty of honey present.
Tepals 5, in two rows of three each, or coherent, petaloid, unequal in shape and size, superior. In Musa five tepals united into a tubular structure while the sixth posterior tepal is free and boat shaped.
In hermaphrodite and male flowers stamens six, – all fertile (Ravenala), usually 5 fertile one posterior stamen is absent or staminode (Musa), filament filiform, free, stiff and attractive, anthers bithecous, linear, introrse, dehiscence by vertical slits.
Tricarpellary, syncarpous inferior, trilocular, ovule one and basal (Heliconia) or numerous with axile placentation; style single, filiform; stigma trilobed.
In male flower rudiments of ovary in the form of nectary is often present.
Elongated berry (Musa), capsule (Ravenala), schizocarpic (Heliconia).
Hard, arillate, deeply coloured, endospermic or non-endospermic, yellowish perisperm. In cultivated varieties seeds are absent and propagation by rhizomes.
Entomophilous due to coloured spathe and honey. Sometimes ornithophilous (by birds).
Distribution of Musaceae:
The family is commonly known as Banana family. It is a small family comprising of 2 genera and 42 species by Willis and 5 genera and 150 species by Lawrence and 6 genera and 225 species by de Wit (1965). In India the family is represented by a single genus Musa and 10 species. It is distributed in tropical Africa, Asia and Australia.
Economic Importance of Musaceae:
The genus Musa is of great economic value and possesses several very important species and varieties. It is extensively cultivated in tropics and subtropics for its edible fruits.
The fruit of Musa paradisiaca subspecies sapientum (Banana H. Kela) when ripe is eaten as fruit.
The unripe fruits of banana are dried and ground to form plantain-meal. The green bananas are used as vegetables.
Banana is a good source of digestible starch. The ripe fruits are used as diet in dysentry. It is also used in preparation of alcoholic drinks-banana wine.
The roots and stems of M. paradisiaca are used as tonic in blood and veneral diseases. The juice of flowers mixed with curds is used in dysentry and menorrhagia. The sap of stem is used in nervous diseases like hysteria and epilepsy. The banana powder is used in dysentry.
From the sheathing leaf bases of Musa textilis, a very useful fibres are extracted, which are woven into abaca cloth. The fibre is called manila hemp or abaca.
After distillation, the fruit pulp is used in dyeing of cotton, leather and even wood. After burning of dried fruit skin of Musa sapientum the ash or residue so obtained is very rich in potash and is largely used in soap industry.
The leaves of Musa are used as plates in S. India.
Affinities of Musaceae:
Musaceae shows some resemblance to Orchidaceae but it differ from latter in habit and absence of pollinia. Engler considered Musaceae as the ancestral stock of Orchidaceae.
Bentham and Hooker placed Musaceae as tribe of family Scitamineae. Engler and Prantl gave it a rank of family and in its genera like Strelitzia, Heliconia and Ravenala are included. Hutchinson placed Strelitzia and Ravenala in a separate family Strelitziaceae.
Cronquist (1968) included Strelitzia and Heliconia in two separate families. Strelitziaceae and Heliconiaceae respectively.
Cronquist (1968) and Takhtajan (1969) included Musaceae in order Zingiberales along with Strelitziaceae, Lowiaceae, Heliconiaceae, Zingiberaceae, Costaceae, Cannaceae and Marantaceae.
Common plants of the family:
1. Musa paradisiaca – sub sp. sapientum-banana of commerce, in Sanskrit it is called kadli.
2. Ravenala madagascariensis – Commonly called traveller’s tree or traveller’s palm.
3. Orchidantha – flowers brightly coloured with one enlarged petal called labellum.
4. Strelitzia reginae – a bird of paradise due to its perianth in the form of flying bird.
Division of the family and chief genera:
Winkler (1930) divided the family into following three sub-families:
Sub-family I. Strelizioideae:
Leaves half alternate, Flowers bisexual at the axil of a large spathe. Fruit woody capsule or schizocarpic capsule e.g. Ravenala, Strelitzia and Heliconia.
Sub-family II. Musoideae:
Leaves spiral. Flowers bisexual or by abortion of essential members unisexual. Fruit berry or leathery indehiscent. Aril absent e.g. Musa.
Sub-family III. Lowioideae:
Leaves half alternate. Flower bisexual, solitary or in few flowered inflorescence. Sepals connate. Large medium petal forming labellum e.g. Orchidantha.
Important Type of Musaceae:
Musa paradisiaca (Fig. 103.1):
A perennial, tall, tree like herb.
Underground, rhizomatous, perennating sheathing leaf bases rolled upon one another to form a pseudoaerial stem.
Radical, simple, alternate exstipulate, large, broadly elliptical, entire obtuse, leaf base sheathing may be upto 6 feet in length, breaking transversely at maturity, unicostate parallel venation.
Racemose spadix covered by thick violet pink spathe.
Ebracteate, ebracteolate, sessile, some unisexual other hermaphrodite, zygomorphic, incomplete, trimerous, epigynous, cream white.
Tepals 6, two whorls of 3 each, gamophyllous, superior; only one posterior tepal of inner whorl is free, innermost and boat-shaped, prolonged into an apical appendage; the rest five united to form a tubular structure, whorls valvate, cream white.
Stamens 5, in two shorls, outer whorl of 3 and inner whorl of 2 stamens, posterior stamen of inner whorl is a staminode, filament long flattened, anther bithecous, adnate and introrse, superior.
In pistillate or hermaphrodite flower-tricarpellary, syncarpous trilocular, inferior, axile placentation, ovules many, abortive, ovary triangular; style long, simple; stigma capitate.