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The below mentioned article provides an overview on Order Personales, Family–Acanthaceae. After reading this article you will learn about: 1. Introduction to Order – Personales 2. Explanation on Family-Acanthaceae 3. Economic Importance.
Introduction to Order – Personales:
According to Hutchinson this is the 78th order of the phylum Angiospermae, subphylum Dictoyledones and division Herbaceae. This order comprises of six families, i.e., Scrophulariaceae, Acanthaceae, Gesneriaceae, Orobanchaceae, Lentibulariaceae, Columelliaceae, of which the Acanthaceae has been described in the present text in detail.
Bentham and Hooker have placed the families Scrophulariaceae and Acanthaceae along with six others including the Pedalineae and the Acanthaceae in their ninth order the Personales of class Dicotyledones division Gamopetalae, and series Bicarpellatae. Engler and Prantl have included the Scrophulariaceae and the Acanthaceae along with other eighteen families such as Convolvulaceae, Verbenaceae, Labiatae, Solanaceae, Pedaliaceae, etc., in their sixth order the Tubiflorae of class Dicotyledoneae and subclass Sympetalae.
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Corolla nearly always zygomorphic with stamens fewer than the corolla lobes. Mostly herbaceous; leaves alternate to opposite.
Explanation on Family-Acanthaceae:
There are about 240 genera and 2,200 species in this family.
Distribution:
The members of this family are mostly found in tropical to subtropical forests especially in the damp and marshy places.
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Habit:
Usually they are herbs or shrubs. Trees are rarely found. Some are however xerophytic, such as, Barleria, Blepharis, Acanthus, etc. Some plants are climbing in habit, e.g., Mendoncia, Thunbergia and other allied plants.
Thunbergia alata is a herbaceous twiner; Peristrophe bicalyculata, Andrographis paniculata, Runzia parviflora, Ruellia prostrata, Justicia simplex, Hemigraphis sp; Haplanthus sp., etc., are typical examples of herbs. Several plants are undershrubs, e.g., Barleria cristata, Ruellia tuberosa, Justicia betonica, Strobilanthes coloratus, Eranthemum pulchellum, etc.
Some good examples of shrubs are, Barleria alba, Barleria prionitis, Adhatoda vasica, etc. Acanthus ilicifolius is a halophyte and represents mangrove vegetation.
Leaves:
The leaves of usual mesophytes are simple, usually opposite decussate, entire, exstipulate, thin and delicate. In xerophytes the leaf blade is more or less spiny.
The characteristic anatomical feature of the family is the presence of cystoliths in the epidermal cells of leaves and stems. Sometimes double cystoliths are found. The cystoliths are calcium carbonate crystals.
Inflorescence:
The inflorescence is of cymose type. The dichasial cyme passes into monochasial one in the higher branching. Sometimes the flowers are found to be arranged in the short axillary clusters. Spikes and racemes are also frequently found. Bracts and bracteoles generally well developed and often brightly coloured.
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These bracts, etc., add to the beauty of the inflorescence. In Mendoncia sp., and Thunbergia sp., the bracteoles are large and form an involucre around the corolla tube. The flowers of Dicliptera sp., are found to be arranged in axillary peduncled cymes. The flowers of Phialacanthus griffithi are arranged in typical cymes.
The flowers of Strobilanthes discolor are found to be arranged in panicled cymose heads whereas in Strobilanthes anisophyllous these are arranged in cymose heads. In the species of Barleria, the flowers are either solitary or arranged in short spikes, or pairs.
In the species of Thunbergia the flowers are found to be arranged either in cymose or in racemose types of inflorescence. This way, there is great variation in the types of inflorescence in various members of the family.
Flower:
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The structure of flower is very uniform. The flowers are bracteate; bracteolate, hermaphrodite, complete, zygomorphic (irregular) and hypogynous. Usually the flowers are tetramerous or pentamerous, but generally there is a reduction to 4 or 2 in the androecium, and there are two carpels in the gynoecium.
Calyx:
It consists of five, sometimes four or rarely three sepals. Usually they are gamosepalous. In Thunbergia the sepals are reduced to narrow beam. In this case large bracteoles serve the purpose of protection. The aestivation is either contorted or imbricate.
Corolla:
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Usually it consists of five or sometimes four gamopetalous petals. The corolla is often bilabiate, e.g., in Ruellia in such cases the upper lip of the corolla is erect and bifid at the apex and the lower lip is horizontal and three-lobed forming the landing-platform for the insects.
Usually the corolla possesses a large or short slender corolla tube which passes above into an equally five lobed limb, e.g., in Thunbergia. The inner side of the lip of the corolla possesses dense hairs. These hairs often extend to the mouth of the corolla.
In Acanthus and other allied genera the upper lip of corolla is altogether absent. Here, the corolla is found to be cut upto the base of the corolla tube. The aestivation is either contorted or imbricate.
Androecium:
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Usually there are 4 didynamous stamens. In certain cases only two stamens are found. Very rarely the number of fertile stamens reaches to five, e.g., Pentstemonacanthus. In the cases where there are only four stamens, the fifth posterior stamen reduces to a staminode or disappears completely.
In the Imbricatae group of the family, there are only two stamens. In such cases, firstly the posterior stamens reduce to staminodes or disappear completely. However, in Brillantaisia the anterior pair of stamens reduces to staminodes.
The filaments are generally quite free and project out from the mouth of the corolla tube. The stamens of Thunbergia, are however short and remain inside the corolla tube. The stamens are inserted in the corolla, i.e., epipetalous. The anthers may be two or one celled.
In the cases where one celled anthers are found, a rudiment of the second cell may be seen, whereas, in the case of two-celled anthers the cells are equal and more or less separated by a connective. Sometimes the lower cell of the anther becomes spurred. The shape and size of pollen grains are quite different from genus to genus.
Gynoecium:
The gynoecium consists of two carpels, syncarpous. The ovary superior, bilocular, two or more ovules are found in each loculus. The Placentation is axile. The style is long and slender and projects out from the mouth of the corolla tube. There are two small stigmas; the posterior stigma is usually reduced.
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Fruits:
Usually the fruit is bilocular capsule, which dehisces loculicidally. In Mendoncia the fruit is drupe.
Seed:
In Nelsonia, the seeds are small and many. In Nelsonia and Thunbergia, the funicle of the seeds forms a papilla, the seeds are rounded. In the Acanthus and allied genera, e.g., Ruellia, the funicle of the seeds forms a hook-like projection, known as jaculator, in which the seed rests. These hook-like jaculators make the fruits burst and the seeds become dispersed in different directions. The seeds are exalbuminous.
Pollination:
The pollination takes place through the agency of insects.
Description of some important plants in semi-technical language:
1. Barleria prionitis:
Habit:
A prickly bushy shrub.
Root:
Tap and branched.
Stem:
Erect, branched, woody, slightly angular, solid, glabrous, green.
Leaf:
Simple, opposite, decussate, upper leaves short petioled, lower leaves long petioled, interpetiolar spines, lanceolate, entire acute, unicostate reticulate venation.
Inflorescence:
A terminal spike, lower flowers arranged in cymes.
Flower:
Sessile, bracteate (leaf bracts), bracteolate (six bracteoles-two large and four small narrow and spiny at the tips), hermaphrodite, zygomorphic, hypogynous.
Calyx:
4 sepals, polysepalous, slightly connate at the base, sepaloid, arranged in two whorls of two each, two outer bigger and inner smaller, inferior, imbricate aestivation.
Corolla:
5 petals, gamopetalous, slightly bilabiate, upper lip consisting of four lobes and the lower of single lobe, inferior, imbricate aestivation, yellowish in colour.
Androecium:
4 stamens, two stamens large and two small, epipetalous, sometimes fifth stamen is represented by staminode, anthers bicelled dorsifixed.
Gynoecium:
2 carpels (bicarpellary), syncarpous, ovary superior, bilocular, axile placentation, one ovule in each loculus style terminal, stigma slightly elongated, ovary situated on a honey secreting disc.
Fruit:
An elongated capsule.
2. Ruellia sp:
Habit:
An erect wild annual herb, common in the gardens near moist places.
Stem:
Erect, branched, herbaceous, cylindrical, solid green.
Leaf:
Simple, opposite, decussate, sub-sessile, ovate, entire, acute, glabrous, unicostate reticulate venation.
Inflorescence:
Cymose, dichasial cyme.
Flower:
Pedicellate, bracteate, bracteolate, hermaphrodite, zygomorphic, funnel shaped, bluish pink, complete, hypogynous.
Calyx:
5 sepals, gamosepalous (connate at the base), acute, sepaloid, valvate asetivation, inferior.
Corolla:
5 lobes, funnel shaped, gamopetalous, bluish-pink, twisted aestivation, inferior.
Androecium:
4 stamens, polyandrous, epipetalous, anthers bicelled, basifixed, introrse.
Gynoecium:
2 carpels (bicarpellary), syncarpous, ovary superior, bilocular, axile placentation, one ovule in each loculus, style slender, stigma single.
Fruit:
An elongated capsule with tapering end, jaculators present.
3. Justicia sp:
Habit:
An undershrub, commonly grown as hedge plant.
Stem:
Erect, branched, cylindrical, solid, herbaceous or somewhat woody, glabrous.
Leaf:
Simple, opposite decussate, cauline, petiolate, lanceolate, entire, acute, glabrous, unicostate reticulate venation.
Inflorescence:
Racemose and cymose mixed.
Flower:
Sessile, bracteate (bracts lanceolate), hermaphrodite, zygomorphic, complete, hypogynous.
Calyx:
5 sepals, gamosepalous, connate at the base and free above, green, inferior.
Corolla:
5 petals, gamopetalous, bilabiate, upper lip consists of two lobes, lower of three lobes, yellowish white with pink or violet dots, imbricate aestivation, inferior.
Androecium:
2 stamens, free, epipetalous, inserted on the upper part of the corolla, filaments long, anthers bicelled, basifixed.
Gynoecium:
2 carpels (bicarpellary), syncarpous, ovary superior, bilocular, axile placentation, two ovules in each loculus, style filiform, stigma bifid.
Fruit:
A capsule.
4. Peristrophe bicalyculata Nees:
Stem-aerial, erect, angular, branched, solid, pubescent, green, herbaceous. Leaf-cauline and ramal, opposite decussate, simple, exstipulate, petiolate, ovate, acute, hairy, unicostate reticulate. Inflorescence-cymose, branched or panicled cyme.
Flower-bracteate, two bracts (anterior and posterior), bracteolate, 4 bracteoles, bracts and bracteoles persistent, pedicellate, bisexual, complete, zygomorphic, pentamerous, hypogynous, cyclic.
Calyx-5, polysepalous, valvate. Corolla-5, gamopetalous, bilabiate 2/3, valvate, purple. Androecium-2, polyandrous, epipetalous, filaments long, dithecous, basifixed, introrse. Gynoecium-2, bicarpellary, syncarpous, superior, bilocular, 2 ovules in each locule, axile, style filiform stigma bifid. Fruit-capsule,
Economic Importance of Family-Acanthaceae:
The family is of little economic value. Some plants are used as hedge plants and some are ornamental. Some plants possess medicinal properties.
A list of few important plants is given below:
1. Adhatoda vasicw, Syn. Justicia adhatoda; Eng.-Malabar nut; Verna.-Arusa, Adulasa-An Ayurvedic drug is obtained from its leaves, which is used in cough, chronic bronchitis and rheumatism. The twigs and leaves are used as green manure. The plant is also used as an antiseptic and insecticide. This is an evergreen shrub commonly found in Northern India.
2. Barleria alba; This is a shrub grown as an ornamental.
3. Barleria cristata; This is an ornamental small shrub. The juice of the leaves is given in cough.
4. Barleria prionitis; Verna.-Katsareya-A plant with medicinal properties. The dried bark is given in the cough.
5. Barleria trigosa; Verna.-Nila kusum-The root is used as a remedy of severe cough.
6. Andrographis paniculata; Verna.-Kiryat. The leaves possess medicinal properties. The plants are grown as ornamental herbs.
7. Asteracantha longifolia; Verna.-Tal makhana-This is a medicinal plant. Its leaves, roots and seeds are given in jaundice, rheumatism and dropsy.
8. Ruellia prostrate; the plants possess medicinal properties. They are used as a remedy in ear troubles.
9. Ruellia tuberose; This is herb or a small shrub, grown as an ornamental.
10. Justicia betonica; An undershrub, grown as hedge plant.
11. Thunbergia alata; It is a herbaceous twiner; grown as an ornamental, as it flowers throughout the year.
12. Thunbergia coccinea; This is grown as an ornamental.
13. Thunbergia fragrans; Grown in the gardens as ornamental.
14. Thunbergia grandiflora; Verna.-Kukua lata-This is an ornamental; the leaves are edible.
15. Aechnanthera wallichii; The lower surface of the leaves is used in making a kind of cloth by natives.
16. Runzia parviflora; Verna.-Pindi-The juice of its leaves is given to children in small-pox.
17. Peristrophe bicalyculata; Verna.-Atrilal.-Used as an antidote for snake bite.
18. Peristrophe bivalvis; Syn. P. tinctoria; A shrub; a yellow orange dye is obtained from its leaves and young stems.
19. Ecbolum viride; Syn. E.linneanum- Verna.-Udajat-An ornamental shrub, grown in the gardens. The roots are given 4s a remedy for jaundice and rheumatism.
20. Phlogacanthus thyrsiftorus; Verna.-Lal bahuk.-The flowers are used as vegetable. The fruits and leaves are given in fevers. The leaves of Tubiflorus are used as a washing soap.
21. Rhinacanthus communis; Verna.-Palakjuhi.-The leaves and roots are used as a remedy for skin diseases, e.g., ring-worm.
22. Jacobinia tinctoria; This is a diffused shrub and grown as an ornamental in the gardens.
23. Crossandra infundibuliformis; Verna.-Priya darsa- This is a shrub grown as an ornamental.
24. Asytasia gangetica; Syn. Justicia gangetica; A herb, grown as an ornamental.
Systematic Relationships:
Bentham and Hooker have included eight families in the order Personales.-These families are Scrophulariaceae, Orobanchaceae, Lentibulariaceae, Columelliaceae, Gesneraceae, Bignoniaceae; Pedalineae, and Acanthaceae.
Engler and Prantl have included all these families in the Tubiflorae along with other twelve families. Hutchinson has included these families in his Personales. He however, puts the family Pedaliaceae in the order Bignoniales which is not related to the Personales.
Hallier considered the Scrophulariaceae to be one of the primitive families of the Tubiflorae. Bessey considered the family as an advanced member of his Scrophulariales, derived perhaps from the Bignoniaceae.
Many botanists have thought that the Acanthaceae has been derived from the Scrophulariaceae. Hutchinson considered the Acanthaceae to be most advanced among his Personales.
