Classification of Campanulatae: 2 Families | Dicotyledonae

In this article we will discuss about the classification of Campanulatae. According to Hutchinson, Campanulatae consists of two families:- 1. Campanulaceae 2. Compositae.

Family # 1. Campanulaceae:

Campanulaceae are annual or perennial herbs, undershrub’s or rarely shrubs, very rarely trees; milky latex often present. Leaves are simple, exstipulate, alternate or rarely opposite. Inflore­scence racemose or cymose, often paniculate or clustered in heads, rarely solitary and axillary.

Flowers are bisexual, actinomorphic or zygomorphic, pentamerous, epigynous or semi-epigynous and usually with 2 bracteoles. Calyx lobes 5, valvate or open in bud. Corolla funnel-shaped or bell-shaped, regular, 5-lobed, valvate, or irregular and bilabiate, the upper lip being resupinate to 180°.

Stamens as many as petals and alter­nate to them, free or variously united and syngenesious; filaments often wider at base. A nectar-secreting epigynous disc is usually present.

Ovary of 2-5 united carpels, inferior or semi-inferior, 2-5-celled, rarely 6-10-celled or one celled; ovules many, anatropous on axile or parietal placentas; style simple or branched. Fruit a capsule or berry. Seed with a small embryo and copious fleshy endosperm.

Clermontia is a small tree while Codonopis and Cyphia are twiners. Cyanea of Hawai has a palm like appearance. In Phyteuvia the small flowers are aggregated in heads. In Lobelia, Pratia, Cyphia, etc. the corolla is zygomorphic.

In the subfamily Lobelioideae sepals, petals and stamens are 6-10. In Michauxia and Phyteuma the petals are almost free to the base. Stamens are more or less completely unified in Cyphia. The ovary in Merciera is unilocular.

The floral formula is represented as:

Articulated latex tubes are present in the stem in many species. Bi-collateral bundles sometimes occur. The flowers are protandrous. The style pushes up the pollens to be easily collected by the insect visitor. The nectar in the epigynous disc is protected by the broad bases of the filaments forming a dome-like structure over it.

Campanulaceae contains about 1,500 species under 61 genera and is distributed mainly in the temperate and subtropical parts of the world with a few in the tropics. It is well represented in India having several species of Campanula in the hills, a few species of Lobelia in the plains and at low elevations in the hills and some other genera.

Wahlenbergia marginata A. DC. (Syn. W. gracilis Schrad) and Sphenoclea zeylanica Gaertn. are quite common all over India in the plains, the latter in marshy habitats.

Campanulaceae has a close affinity with Compositae and the 2 families are placed under the same order by many workers. In both families herbs predominate, corolla more or less similar, syngenesious androecium in some genera of Campanulaceae, similar arrange­ment of exposing the pollens, inferior ovary, more or less similar style and stigma and compact head-like inflorescence in some Campanulaceae.

It is allied to Rubiaceae where too the small flowers are aggregated in compact type of inflorescence, the corolla is tubular and the ovary inferior. Many workers consider that Campanulaceae and the families included in the order Campanulatae originated from Rubiaceae or the order Rubiales.

Campanulaceae appears to be a much advanced family in the scalie of evolution, being predominantly herbs, having a special arrangement for cross pollination by insects, gamopetalous corolla, anthers usually united, inferior ovary, etc. Inclusion of Compositae the most highly evolved family, by Engler in the same order with Campa­nulaceae appears to be justified.

Some authors trace the affinity of Campanulaceae with Cucurbitaceae having similar calyx and often similar corolla, syngenesious androecium (with tendency of synandrium in some cases), inferior ovary and bicollateral vascular bundles, in some genera of Campanulaceae. However, the flowers in Cururbitaceae are unisexual while in Campanulaceae they are bisexual.

The family is divided into 3 subfamilies as mentioned below:

Subf. I. Campanuloideae:

Flowers actinomorphic; anthers free.

Subf. II. Cyphioideae:

Flowers zygomorphic; filaments of stamens more or less united.

Subf. III. Lobelioideae:

Flowers bilabiate, anthers united; carpels 2.

The subfamily Lobelioideae is raised to the rank of a distinct family Lobeliaceae by some authors, e.g., Hutchinson and Takhtajan and the genus Sphenoclea is placed by some in a distinct monotypic family Sphenocleaceae.

Characters of these 2 families when treated as distinct are given below:

Lobeliaceae:

Herbs, undershrubs or shrubs, rarely trees, often with milky juice. Leaves alter­nate, simple, exstipulate. Flowers hermaphrodite or unisexual, epigynous, bilabiate. Calyx adnate to the ovary, 5-lobed.

Corolla gamopetalous, bilabiate; lips resupinate due to twisting of the pedicel; lobes valvate. Stamens 5, epipetalous or not; filaments free, anthers cohering into a tube round the style.

Ovary more or less inferior, 2-3- locular (rarely 1-locular); style simple or 2-3-lobed and surrounded by a ring of hairs; ovules ∞; placentation axile. Fruit a capsule or fleshy and indehiscent. Seeds small and numerous, with small straight embryo and copious endosperm.

Sphenocleaceae:

Herbaceous plant of marshy area, stem hollow. Leaves simple, alternate, exsti­pulate. Inflorescence a dense cylindric spike. Flowers regular, bracteate, bisexual, pen­tamerous. Calyx gamosepalous; lobes 5, valvate. Corolla gamopetalous, 5-lobed, campa- nulate, valvate, stamens 5, epipetalous, anthers free.

Ovary semi-inferior, bicarpellary, 2-locular; ovules many in each locule, pendulous from axile placentas. Capsule circum- scissile, seeds many, with plenty of endosperm.

Only one species Sphenoclea zeylanica Gaertn found in India and S. E. Asia. This genus appears to be anomalous when placed in Campanulaceae and some workers transfer it to Phytolaccaceae. Takhtajan segregates Sphenocleaceae as a distinct family and Cronquist supports this treatment.

Economically Campanulaceae (sensu lato including Lobeliaceae and Sphenocleaceae) is not very important. Many species of Campanula are cultivated as garden annuals and are known as Canterbury-bells, Hair bells, etc.

Some species of Lobelia and Siphocampylos are also cultivated for their showy flowers. The young roots and shoots of some Campa­nula are edible and the tender leaves and shoots of Specularia are used in salad.

Some species are strong poisons, e.g. Lobelia inflaia Linn. L. tupa Linn., Laurentia longiflora (Linn.) E. Wimm. etc. In small doses L. inflate -the Indian tobacco, cures whooping cough and gives relief in spasmodic asthma. The milky juice of Isotoma longiflora Linn., also a strong poison, contains couchouc.

Family # 2. Compositae (Asteraceae):

Compositae  are herbs, under shrubs or shrubs; sometimes with milky latex, rarely aromatic, usually unarmed. Leaves are radical or cauline, simple or rarely compound, pinnately or palmately lobed, alternate or opposite, rarely whorled, exstipulate.

The inflorescence is a capitulum surrounded by an involucre of bracts. Flowers are actinomorphic or zygomor­phic, bisexual or unisexual, epigynous. Calyx represented by pappus consisting of scales or hairs, persistent.

Corolla tubular or bilabiate, ligulate in the marginal ray florets. Stamens 5, filaments attached to the corolla tube, anthers syngenesious, bilobed, connective often prolonged. Carpels 2, syncarpous, forming a unilocular inferior ovary; ovule solitary, basal, with one integument; style short with 2 recurved or spreading stigmas. Fruit a cypsela; seeds without endosperm.

The capitulum inflorescence may be heterogamous or homogenous. In the former the ray florets are either female or sterile and the disc florets are bisexual. Ray florets are zygomorphic, with a ligulate corolla or rarely bilabiate; disc florets are-actino­morphic.

In homogamous capitulum all flowers are usually bisexual and similar, actino­morphic or zygomorphic, rarely all unisexual. A capitulum may have few flowers or numerous and often not less than a thousand. It may be simple or compound, arranged in heads, corymbs or paniculate. The involucre may be uniseriate, biseriate or multi- seriate. In a compound capitulum each smaller capitulum has its own involucre.

The axis of the capitulum (usually called receptacle) is usually flat or convex but may be cone-like or elongate (Rudbeckia, Spilanthes) or concave and cup-like (Epaltes). The pappus is regarded as modified calyx but Small interpreted these as trichomes of the ovary. Ramiah and Sayeduddin supported Small.

The plants are usually herbs or shrubs but rarely also climbers, e.g. Mikania and very rarely are trees, e.g. Wilkesia (Sandwich Isl.), Leucomeris (Nepal),Vernonia arborea Buch. Ham. (India), etc. Tuberous roots are found in few genera, e.g. Dahlia, Helianthus etc., where the tubers store reserve food in the form of inulin grains.

In the armed species the lobes of the leaves and the involucral bracts are spine tipped, e.g. Cirsium, Cnicus, Carthamus, etc. One-flowered capitulum occurs in Lagascea, some species of Vemonia, etc.

In Hoplophyllum, a xerophytic genus, the leaves are modified into spines. The stem is flat and leaf-like in Baccharis. Capitula of Xanthium are unisexual, the female consists of 2 florets in an urnshaped 2-beaked involucre clothed with hooked bristles.

In Schoenia the disc florets are sterile and the ray florets are bisexual. In Lactuca, Cichorium, etc. all florets are ligulate while in Multsia all florets are bilabiate. In Silybium the stamens unite by anthers as well by filaments.

The bracts in Elveria are accrescent and act like wings giving the capitulam a samara-like appearance.In Wilkesia the floral bracts are prominent and the involucre of bracts is wanting. In Millenia one bract is larger than the others and covers the capitulum in fruit.

A ring-like tubular nectary is present at the base of the style. In many genera vascular bundles are present in the cortex and in pith. Anomalous secondary thickening occurs in some cases. In the African genus Metalasia the vascular bundles are in several successive rings.

The pollination mechanism in Compositae is noteworthy. Numerous flowers can be pollinated by one insect in a single visit to a capitulum. The ligulate ray florets make the capitulum conspicuous for attracting the insects while the disc florets often incons­picuous, get the benefit.

The nectar is easily accessible to the insects and is protected from rain. The protandrous condition of the androecium is another help for cross pollination. The pollens are carried up and preserved by the stigma of the same flower to be easily carried away by the insect visitor. Arrangement of self-pollination also exists if cross-pollination fails.

The family consists of more than 19,000 species under 950 genera and is the largest among the dicotyledonous families if not among the whole of angiosperms. They are found in almost all parts of the world from sea-level to the alpine region, from the tropics to the arctic zone, from the arid region to very humid tracts.

A few are true aquatics and some are halophytes. In India about 700 species are found among which Situcio, Vtrnonia, Blumea, Saussurea etc. are represented with large number of species.

Agtratum conyzoides Linn., Blainvillea acmella (L.) Philip., Caesulia axillarisKoxh., Echinops echinata Roxb., Ecliptaprostrata (L.) Linn., Siegesbeckia orientalis Linn., Sphaeranthus indicus Linn., Xanthium strumarium Linn., Tridaxprocumbens Linn., Lagascea mollis Cav., Grangea maderaspatana (L.) Poir., Gnaphalium luteoalbum Linn., Eupatorium odoratum Linn., Emilia sonchi- folia (L.) DC., Elephantopus scaber Linn. etc. are very common in the plains.

Anaphalis contorta Hk. fArtemisia nilagirica (CI.) Pamp., Saussurea candicans Clarke are common in the hills. Tragopogon gracile Don are common in the Himalayas between elevations of 2000 to 3000 mtr.

Floral formula for a bisexual flower:

The family is divided into 2 subfamilies and 13 tribes of which 12 are under one subfamily and the 13th is under the other.

Subf. 1. Tubuliflorae:

Corolla of disc Horeis not ligulate; laticilerous vessels absent.

Tribe (i) Vernonieae:

Capitula homogamous; corolla tubular; anthers sagittate: pappus hairy; stigmatic branches long with papillae all over the inner surface.

Tribe (ii) Eupatorieae:

Capitula homogamous; corolla tubular; pappus bristle or scale-like; anther-base not sagittate; stigmatic branches papillose on margin only.

Tribe (iii) Astereae:

Capitula heterogamous with female or neuter ray florets: anthers not sagittate; stigmatic arms flat.

Tribe (iv) Inuleac:

Capitula homo- or heterogamous; all of only central florets tubular; pappus hairy or bristly; anthers tailed; stigmas with marginal papillae.

Tribe (v) Heliantheae:

Capitula heterogamous with female or neuter ray florets; involucral bracts not membranous at margin; pappus not hairy; anther base not pro­longed; ray florets often with 3 petals; disc florets paleaceous, i.e. with bracteoles.

Tribe (vi) Helenieae:

Like Heliantheae but disc florets without palea.

Tribe (vii) Anthemideae:

Like Heliantheae but involucral bracts scarious at margin and pappus small, annular or absent.

Tribe (viii) Senecioneae:

Capitula homo- or heterogamous; involucral bracts with scarious margin and with extra scales; pappus hairy.

Tribe (ix) Calenduleae:

Capitula heterogamous with female ray florets and small disc florets; floral bracts absent; pappus absent; anther-base pointed; stigma entire.

Tribe (x) Arctotideae:

Capitula heterogamous; ray florets female or neuter, ligu­late; pappus not hairy or absent; anther-base pointed or not; style thickened at base or with a ring of hairs.

Tribe (xi) Cynareae:

Capitula homogamous or heterogamous; ray florets not ligu­late, female or neuter; involucral bracts spiny; base of anther tailed.

Tribe (xii) Mutisieae:

Capitula homo- or heterogamous; ray florets with bilabiate corolla; disc florets regular with deeply seated corolla-limb.

Subf. II. Liguliflorae:

All florets in the capitula with ligulate corolla; laticiferous vessels present.

Tribe (xiii) Cichorieae:

Capitula homogamous; anthers sagittate.

Compositae is related to Campanulaceae and Goodeniaceae having 5-merous flowers and inferior ovary. In the 3 families the arrangement for collecting the pollens is elabo« rate. In Campanulaceae the stamens often have syngenesious anthers.

In Goodeniaceae also anthers are sometimes united and the ovary is bicarpellary. Compositae is also allied to Stylidiaceae, both having inferior bilocular ovary and on this character it comes near to Rubiaceae.

The affinity of Compositae with Valerianaceae and Dipsacaceae is also traced from’dense inflorescence and inferior ovary. It is presumed that Compositae and the other families in the order Campanalatae originated from Rubiaceae.

The family is generally regarded as occupying the highest position among the angiosperms or at least among the dicots in the course of evolution as is evident by the presence of largest number of species and by the cosmopolitan distribution from the arctic to the tropical zone.

The highest position reached by the family is due to the following advanced characters:

(a) The herbaceous habit.

(b) The capitulum inflorescence with numerous inconspicuous florets surroun­ded by a ring of ligulate marginal florets that make the whole capitulum very promi­nent and showy for attracting insect visitors for pollination. Aggregation of so many flowers in a small space makes it possible to pollinate a large number of them by an insect in a single visit.

(c) Reduction and modification of calyx.

(d) Cohesion of stamens in the form of syngenesious anthers or completely; protandry of the androecium.

(e) Reduction of carpels to 2 and in the number of ovules to one only; inferior ovary.

(f) Easily accessible nectar which is protected against rain.

(g) Arrangement for cross pollination and prevention of self-pollination till last moment with certainty of the same when cross pollination fails by curling back of stigmas and coming in contact with pollens of the same flower.

(h) Distribution of fruit with help of the pappus that act as parachute mechanism.

The family includes a few plants of economic importance some of which are culti­vated as ornamental plants, e.g. Dahlia pinnata Cav., Chrysanthemum coronarium Linn, and other species of the same genus, Zinnia pauciflora Linn., Z- elegans Linn., Tagetes patula Linn., T. erecta Linn. (Marigold), Helianthus annuus Linn. (Sun flower), Aster tripolium Linn., Calendula officinalis Linn., Gaillardia species, Cosmos bipinnatus Cav., etc. Species of Helichrysum and Heliptarum produce the so called “Everlasting flowers” where the bracts of the involucre are brightly cloloured and dry and papery. These do not change long after the fruits mature.

Artemisia cina Berg, is the source of santonin. Centratherum anthelminticum O. Ktze. is the Someraj of Indian Kavirajes the seeds of which have anthelmintic properties. Leaves of Eupatorium ayapana Vent, stop internal haemorrhage.

The juice of Wedelia calendulacea Less, promotes the growth of hairs. Eclipta prostrata Linn, possess the same property and the juice is also used in tattooing. Saussurea lappa Clarke, the Kuth or Kustha is used medicinally in various ways and also in the preparation of a hair tonic.

The juice of Enhydra fluctuant Lour.—Hingcha, Hilomochika kills worms and induces sleep.

Lactuca sativa Linn, is cultivated for the leaves which are used as salad. Cichoriwn endivia Linn, is the Endive which is also a salad plant. C. intybtis Linn, is also used simi­larly and the roots of which are much used as a beverage after roasting.

The tuberous roots of Helianthus tuberosus Linn.—the Jerusalem Artichoke are edible. The young shoots of Scolynus hispanicus Linn, and S. maculatus Linn, are eaten as asparagus. The roasted seeds of Helianthus annuus Linn, are also eaten.

Flowers of Carthamus tinctorius Linn, yield a dye and an oil is extracted from the seeds of this and of Guizotia abyssinica Cass. Pyrethrum, an insecticide, is obtained from Tanacetum cinerariefolium Schr. (Syn. Chrysanthemum cineraiefolium Vis.) Parthenium argentatum A. Gray yields rubber.