Unit III: Angiosperm Systematics

Characters of Asteraceae:

Mostly herbs or shrubs or rarely trees; leaves alternate rarely opposite, exstipulate rarely stipulate; inflorescence capitulum or head surrounded by involucre of bracts; ray and disc florets, flower tubular or ligulate, flowers bi- or unisexual or outer male or female, pentamerous, actinomorphic or zygomorphic, caryxpappus, corolla gamopetalous, petal lobes 5, stamens 5, epipetalous, usually dithecous, filament free and anthers united i.e. syngenesious, introrse, ovary unilocular, inferior, with basal placentation, style slender stigma bifid; fruit cypsela.

A. Vegetative characters:

Habit: Herbs (Ageratum, Lactuca, Dahlia, Sonchus), shrubs (Inula, Senecio) rarely trees (Vernonia arborea and Leucomeris). Many of the plants are xerophytes (Proustia), hydrophytes (Cotula) some are semiaquatic (Caesulia axilaris).

Root: Tap root, sometimes modified into tubers (Dahlia).

Stem: Erect, or prostrate, herbaceous or woody (Artemisia), hairy, sometimes with latex. Stem tubers are also present (Helianthus); tubers are edible (H. tuberosus); cylindrical; glabrous, solid or fistular, stem may be leaf-like (Baccharis).

Leaf: Alternate rarely opposite (Zinnia, Dahlia) or whorled; leaves may be radical, petiolate or sessile, exstipulate, mostly simple sometimes scale-like (Senecio), unicostate or multicostate reticulate venation.

B. Floral characters:

Inflorescence: A head or capitulum, consisting of a few or large number of flowers or florets closely arranged on an axis surrounded by involucral bracts. The whole head or capitulum is apparently similar to a single flower because the involucral bracts perform the function of protection.

In Helianthus the outer or peripheral, ligulate and zygomorphic florets are called ray-florets; whereas inner or central, tubular and actinomorphic ones are called disc-florets.

In capitulum or head the form of flowers and distribution of sex also varies.

Distribution of sex: The flowers of a head may be all hermaphrodite (Ageratum), or ray-florets are female or neuter and inner ones hermaphrodite, or male; rarely the complete head bears unisexual flowers.

Flower: Bracteate, sessile, (Sonchus, Ageratum), complete or incomplete, hermaphrodite or unisexual, pentamerous, tubular (actinomorphic) or ligulate (zygomorphic), epigynous and inconspicious.

Ray-florets

Zygomorphic, ligulate, pistillate, or neuter or sometimes also bisexual, epigynous.

Calyx: Modified into pappus or absent or scale-like.

Corolla: Petals 5, gamopetalous, highly coloured, ligulate, strap-shaped, valvate.

Androecium: Absent.

Gynoecium: Either absent or if present then bicarpellary, syncarpous, inferior, unilocular with basal placentation, one anatropous ovule; style one; stigma bifid.

Fruit: Absent; if present cypsela.

Seed: Non-endospermic.

Disc florets

Flower: Bracteate, sessile, complete, hermaphrodite, actinomorphic, pentamerous, epigynous and tubular.

Calyx: Modified into pappus or scale, persistent.

Corolla: Petals 5, gamopetalous, tubular, coloured.

Androecium: Stamens 5, epipetalous, syngenesious, dithecous, introrse, dehiscing longitudinally.

Gynoecium: Bicarpellary, syncarpous, inferior, unilocular with single anatropous ovule, basal placentation; style simple, long, stigma bifid.

Fruit: Cypsela.

Seed: Non-endospermic.

Pollination: Entomophilous.

Economic Importance of Asteraceae:

1. Food: Leaves of Lactuca sativa are used as salad. The roots of Helianthus tuberosus are edible.

2. Oil: The seeds of Helianthus and Artemisia yield oil.

3. Medicinal: Solidago used in dropsy. Artemisia yields santonin which is used as vermifuge. The roots of Taraxacum used in bowel disorders. The juice of Emillia sonchifolia leaves has cooling effect and is used in eye inflammation and also for night blindness. Eclipta alba used as tonic in spleen enlargement. Centipeda orbicularis is used in cold and toothache.

4. Rubber: It is obtained from Solidago laevenworthii and Taraxacum.

5. Insecticide: The capitula of Chrysanthemum roseum and C. cinerriefolium are dried, powdered and used as insecticide.

6. Ornamental: Zinnia, Dahila, Cosmos, Chrysanthemum, Calendula, Helichrysium, Aster Helianthus etc. are well known garden plants.

7. Weeds: Xanthium, Blumea, Sonchus, Vernonia are the common weeds.

Characters of Asclepiadaceae:

Plants herbs, shrubs, mostly twiners and rarely trees; leaves opposite, simple, entire margin rarely alternate; inflorescence cymose or racemose; flowers hermaphrodite, pentamerous; calyx of 5 sepals, imbricate; petals 5, gamopetalous, corona arising as outgrowth of petals or stamens; stamens 5, fused with stigmatic disc forming gynostegium; pollens forming pollinia; carpels bicarpellary, syncarpous, ovaries and style free, only stigma fused to form disc, marginal placentation, fruit follicles.

A. Vegetative characters:

Habit: Perennial herbs (Asclepias) or shrubs (Calotropis, Leptadenia), climbers (Cryptostegia, Daemia), succulent (Stapelia) with latex.

Root: A deep branched tap root.

Stem: Herbaceous, week and climbing or succulent, woody below (Calotropis), erect, twiner or climbers (Cryptostegia) cylindrical, rarely hairy and solid, latex present.

Leaves: Simple, petiolate, exstipulate, entire, opposite rarely whorled, waxy; in Dischidia rafflesiana leaves are modified into pitchers, reduced or absent (Periploca), succulent in Hoya.

B. Floral characters:

Inflorescence: Mostly umbellate cymes (Calotropis) or dichasial cyme ending in monochasial cyme.

Flower: Bracteate or ebracteate, pedicellate, complete, hermaphrodite, actinomorphic, rarely zygomorphic (Ceropegia), pentamerous, hypogynous.

Calyx: Sepals 5, polysepalous or gamosepalous-fused near the base, quincuncial aestivation, sometimes valvate.

Corolla: Petals 5, gamopetalous, 5 lobed, twisted aestivation or valvate, corona may be scaly or hairy out growth from petals – corolline corona in Cryptostegia, Cryptolepis or form staminal tube i.e. staminal corona in Calotropis and Asclepias.

Androecium: Stamens 5, synandrous, gynostegium (stamens fused with stigmatic disc to form gynostegium), anthers dithecous, epipetalous, coherent; the pollen grains of each half anther usually agglutinated into granular mass of tetrads or waxy pollen called pollinium (Asclepias, Calotropis). Thus each stamen has two pollinia.

The pollinia of two adjacent anther halves are connected together at the black, dot-like gland called corpusculum by appendages called – retinacula. The two pollinia (of adjacent anther halves), two retinacula and a corpusculum together form a single translator. So in all there are 5 translators.

Gynoecium: Bicarpellary, syncarpous, ovaries free, superior, enclosed in staminal tube, ovules many on marginal placentation, each carpel is unilocular; style 2, free, distinct; stigmas united to form a pentangular disc with which anthers are fused to form gynostegium.

Fruit: An etaerio of two, often widely divergent follicles; in some one follicle is abortive.

Seed: Many small, compressed with long silky hairs.

Pollination: Entomophilous, translator mechanism.

Distribution of Asclepiadaceae:

The family Asclepiadaceae is commonly known as ‘Milk weed family’. In includes 320 genera and 2,000 species of world wide distribution, but mostly confined to tropics and sub-tropics. In India 332 species belonging to 35 genera are found.

Economic Importance of Asclepiadaceae:

1. Food: Gymnema lactiferum yields latex which is used as food in Ceylon.

2. Fibres: Some plants like Daemia extensa, Calotropis procera, C. gigantea, Marsdenia and Leptadenia etc. yield silky fibres which axe used for making ropes, mat, stuffing pillows etc.

3. Medicinal: The source of medicine in the family is latex from which alkaloids are extracted. The roots of Oxystelma esculentum are specific for jaundice. This roots of Pentatropis are used in gonorrhoea. Hemidesmus indicus is used in leucorrhoea, rheumatism and in snake bites. Daemia extensa is used in cough; asthma and diarrhoea.

4. Rubber: Cryptostegia grandiflora is a natural source of rubber in India.

5. Poison: Some species of Asclepias are important as live-stock poison. The sap of Matelea has been used as an arrow poison.

6. Ornamental: Asclepias, Cryptostegia, Hoya, Huernia, Ceropegia, Periploca etc. are cultivated for ornamental purposes.

Characters of Apocynaceae:

Herbs, shrubs and trees, often twining, usually with white latex; leaves are alternate, simple, exstipulate, usually opposite or whorled, entire margin with latex; flowers’ hermaphrodite, actinomorphic, hypogynous; calyx free or united; corolla gamopetalous, 5 lobed, campanulate or funnel-shaped, valvate or twisted; androecium epipetalous, introrse; gynoecium bicarpellary, syncarpous, ovary superior, united by the styles only; fruit-follicle or berry; seeds with crown of hairs.

A. Vegetative characters:

Habit: Herbs (Catharanthus), shrubs (Carissa, Nerium), twinners (Vallaris), tree (Alstonia) with latex.

Root: A much branched tap root system.

Stem: Usually herbaceous (Catharanthus) erect, woody, solid, branched, green or succulent with latex.

Leaves: Simple, opposite (Catharanthus) or whorled (Nerium), petiolate or sub-sessile, exstipulate, margin entire, unicostate reticulate venation.

B. Floral characters:

Inflorescence: Usually cymose either terminal or axillary, may be cyme (Carissa) or umbellate cyme (Rauwolfia).

Flower: Bracteate or ebracteate, pedicellate, complete, hermaphrodite, actinomorphic, tetra or pentamerous, often with corona.

Calyx: Sepals 5, rarely 4, gamo- or polysepalous, deeply lobed, small, often glandular at the base, imbricate or valvate.

Corolla: Petals 5, gamopetalous forming a corolla tube which may be long or short, corona present (hairy scales or outgrowth), usually twisted, sometimes imbricate, rarely valvate.

Androecium: Stamens 4 to 5, epipetalous, alternipetalous, filament short, free, dithecous, connate to stigma, dehiscing longitudinally, introrse.

Gynoecium: Bicarpellary, syncarpous ovaries are free below but united by style only, superior style short, enclosed in a tube formed by the corolla; stigma thickened distally; when ovaries are free each ovary is unilocular with marginal placentation but when ovaries are fused then axile placentation.

Fruit: A drupe (Thevetia), berry (Carissa), follicle (Nerium, Amsonia).

Seed: Endospermic, hairy or winged.

Pollination: Entomorphilous.

Distribution of Apocynaceae:

It is commonly known as Oleander family. It comprises 180 genera and 1500 species out of which 84 species or 30 genera are present in India. The members are most abundant in tropics and sub-tropics.

Economic Importance of Apocynaceae:

1. Vegetables: The pulpy fruits of Carissa carandus (H. Karaunda) are edible and also pickled.

2. Medicinal: The root of Rauwolfia serpentina (H. Sarpgandha) are used in lowering blood pressure, sedative, stimulator for uterine contraction and in mental diseases. The juice of leaves is used for removal of opacities of the cornea of the eyes. Anti-cancerous drugs are extracted from Catharanthus roseus. The bark of Alstonia scholaris is a febrifuga. Holarrhena antidysentrica yields a drug which is a cure for amoebic dysentery.

3. Rubber: Many species of Hancora, Dyera, Urceola are the sources of rubber.

4. Poisonous: The seeds of Thevetia contain Thevetine a poisonous glycoside. The latex of Acokanthera is used for poisoning arrows. The bark and wood of Nerium indicum provide rat-poison.

5. Ornamental: Nerium, Catharanthus (syn. Vinca), Thevetia, Wrightia, Allamanda are cultivated in gardens as ornamentals.

Characters of Solanaceae:

Plants herbs, shurbs rarely trees; leaves alternate, flowers solitary or in cymes; axillary or terminal; flowers pentamerous, actinomorphic, hypogynous, hermaphrodite, calyx persistent, gamosepalous, corolla gamopetalous, campanulate; stamens epipetalous; gynoecium bicarpellary, syncarpous, ovary obliquely placed, axile placentation; swollen placentae; ovules many in each locules; fruit capsule or berry.

A. Vegetative characters:

Habit: Mostly herbs (Petunia, Withania), shrubs and trees.

Root: A branched tap root system.

Stem: Aerial, erect, climbing (Solanum jasminoides), herbaceous, or woody, cylindrical, branched, solid or hollow, hairy, or glabrous, underground stem in Solanum tuberosum.

Leaves: Cauline, ramal, exstipulate, petiolate or sessile, alternate sometimes opposite, simple, entire pinnatisect in Lycopersicon, unicostate reticulate venation.

B. Floral Characters:

Inflorescence: Solitary axillary, umbellate cyme, or helicoid cyme in Solanum.

Flower: Bracteate or ebracteate, pedicellate, complete, hermaphrodite, actinomorphic, pentamerous, hypogynous.

Calyx: Sepals 5, gamosepalous, tubular or campanulate, valvate or imbricate, persistent, green or coloured, hairy, inferior.

Corolla: Petals 5, gamopetalous, tubular or infundibuliform, valvate or imbricate aestivation, scale or hair-like outgrowth may arise from the throat of the corolla tube, coloured, inferior.

Androecium: Stamens 5, epipetalous, polyandrous, alternipetalous, filaments inserted deep in the corolla tube, anthers dithecous, usually basifixed or dorsifixed, introrse, inferior.

Gynoecium: Bicarpellary, syncarpous, ovary superior, bilocular, unilocular in Henoonia, axile placentation placentae swollen, many ovules in each loculus, ovary obliquely placed; in some cases nectariferous disc is present; style simple; stigma bifid or capitate.

Fruit: A capsule or beery.

Seed: Endospermic.

Pollination: Entomophilous.

Distribution of Solanaceae:

The family is commonly called ‘Potato family’. It is a large family well distributed in tropics and sub-tropics, though a few members are found in temperate zone. The family includes 2,000 species belonging to 90 genera. In India it is represented by 70 species of 21 genera.

Several members are cultivated through out the world for their great economic importance; among them are Solarium tuberosum (Potato), Solanum melongena (Bringal), Lycopersicon esculentum (Tomato) etc.

Economic Importance of Solanaceae:

The family is of great economic importance.

1. Food: Many members viz., Solanum tuberosum (Potato), Solanum melongena (Brinjal), Lycopersicon esculentum (Tomato), Capsicum (H. Mirch) etc. are used as vegetables. Physalis peruviana (H. Rasbhari) produces edible berries.

2. Medicinal: Atropa belladona contains alkaloid Atropine; this is used in Belladona plaster. Atropine is used in eye testing. Nicotiana tabacum (tobacco) yields Nicotine. Hyoscyamus niger, Solanum nigrum, Datura (H. Dhatura), Withania somnifera (Ashwagandha) are used medicinally.

3. Narcotics: Tobacco is obtained from leaves of Nicotiana tabacum and variously used in cigars, bidi, chewing, jarda etc.

4. Ornamentals: Petunia, Cestrum, Lycium, Salpiglossis, Schizanthus are cultivated in gardens for ornamentals.

Characters of Verbenaceae:

Plants herbs, shrubs or trees, leaves simple, exstipulate, opposite or whorled; inflorescence cymose, racemose or spike, flowers hermaphrodite, zygomorphic, hypogynous, calyx gamosepalous, persistent; corolla 5 lobed, gamopetalous sometimes 2 lipped, stamens four, didynamous, unequally paired, epipetalous; carpels two, syncarpous, superior, axile placentation, fruit drupe.

A. Vegetative characters:

Habit: Mostly annual or perennial herbs, may be shrubs or trees (Tectona) or rarely woody climbers or halophyte (Avicennia) in tropical shores.

Root: Tap, branched, pneumatophore in Avicennia.

Stem: Erect, herbaceous or woody, young branches quadrangular, in some branches spiny.

Leaves: Simple or palmately or pinnately (Peronema) compound, opposite or whorled, exstipulate, entire or divided.

B. Floral characters:

Inflorescence: Cyme or racemose spikes often with an involucre of coloured bracts; cymose is usually dichasial (Clerodendron).

Flower: Zygomorphic, hermaphrodite, rarely unisexual by abortion (Aegiphila), hypogynous, pentamerous or tetramerous (Physopsis), rarely actinomorphic (Physopsis) complete.

Calyx: Sepals 5 lobed, gamosepalous, persistent, bell shaped or tubular, rarely 4 to 8 valvate, inferior.

Corolla: Petals 5 or 4 lobed, gamopetalous petals unequal, tubular or cylindrical, bi-lippod, imbricate, inferior.

Androecium: Stamens 4, didynamous, fifth stamen may be staminode or absent rarely 5 present (Tectona), epipetalous, bithecous, filaments free, dorsifixed, introrse, dehiscence longitudinal.

Gynoecium: Bicarpellary, syncarpous, rarely carpels 4 (Duranta) or 5 (Geunsia) superior in early stage bilocular but soon divided into 4 or many loculed by false septa, axile placentation or free central in Avicennia; style terminal, stigma entire or bilobed.

Fruit: Drupe rarely schizocarpic capsule enclosed by persistent calyx.

Seed: Non-endospermic with a straight embryo.

Pollination: Entomophilous.

Distribution of Verbenaceae:

The family is commonly called Verbena family. It includes 77 genera and 3,020 species, out of which 21 genera and 125 species occur in India. The members of family are inhabitants of tropical and subtropical regions, they also extend into temperate lands.

Economic Importance of Verbenaceae:

The family is of fairly great economic importance.

1. Timber: The wood of Tectona grandis (Teak, H. Sagwan) is extremely hard and lasting. The wood is largely used in manufacturing of ships and good quality furniture. Teak is grown in forests of Burma, Madhya Pradesh and Assam. The wood of Gmelina arborea is used in making drums, sitars and other musical instruments.

2. Medicinal: The roots of Clerodendron are used in asthma and cough. The decoction of leaves of Lantana camara is given in tetanus and rheumatism. The leave’s juice of Gmelina arborea is used in gonorrhoea, cough and ulcers.

3. Oils: Lippia alba produces a valuable oil.

4. Tanning: The bark of Avicennia is used in tanning.

5. Febrifuge: The leaves of Vitex negundo serve as febrifuge. The branches of this plant are kept over stored grains to keep off insects.

6. Ornamental: Lantana, Verbena officinalis, Duranta, Congea tomentosa, Callicarpa, Clerodendron, Petrea are cultivated in gardens.

Characters of Lamiaceae:

Sweet aromatic smell due to essential oils present in sessile glandular hairs; stem rectangular in cross section, leaves opposite decussate rarely alternate, simple, exstipulate with hairs; inflorescence verticillaster; flowers zygomorphic, hermaphrodite, hypogynous, bracteate; calyx gamosepalous, persistent; corolla bilabiate; stamens 4 epipetalous, didynamous; gynoecium 2 four celled by false septum, syncarpous, axile placentation, gynobasic style, seated on lobed disc; fruit schizocarpic carcerulus.

A. Vegetative characters:

Habit: Plants are mostly aromatic herbs or shrubs (Leonotis, Pogostemon). Tree habit is found in the Brazilian genus Hyptis and climbing habit in American species of Scutellaria.

Root: Tap, branched, rarely adventitious (Mentha).

Stem: Aerial, herbaceous, rarely woody, erect or prostrate, quadrangular, hairy, branched, solid or hollow, sometimes underground suckers (Mentha).

Leaves: Opposite decussate, rarely whorled, simple, petiolate or sessile, exstipulate, hairy with aromatic smell, entire, pinnatifid (Perovskia), unicostate reticulate venation.

B. Floral characters:

Inflorescence: Very commonly verticillaster consisting of a pair of condensed dichasial cymes at each node; often the verticillasters are grouped together in a thyrsus form; rarely solitary (Scutellaria).

Flower: Pedicellate or sessile, bracteate, complete, zygomorphic rarely actinomorphic (Mentha, Elsholtzia), hermaphrodite, rarely unisexual (Nepeta, Thymus), pentamerous hypogynous.

Calyx: Sepals 5, gamosepalous, bilabiate (Salvia, Thymus) campanulate (Teucrium), persistent, valvate or imbricate aestivation. When a bilabiate calyx is present the arrangement of the sepals may be (1/4) as in Ocimum or (2/3) as in Calamintha.

Corolla: The corolla possesses a tubular base which widens towards the mouth. Petals generally 5, gamopetalous and the five teeth are sub-equal and mostly bilabiate. In Mentha a four lobed corolla arises due to the fusion of two upper teeth. When a distinct bilabiate condition is found the arrangement of the petals may be gamopetalous 2/3 i.e. two petals in the posterior upper lip and three in the anterior lower lip (Salvia, Nepeta, Leucas etc.).

In Ocimum, Coleus, Plectranthus etc. the petals arrangement is gamopetalous 4/1 i.e. four petals in the posterior upper lip and only one petal in the anterior lower lip. In extreme cases the arrangement may be gamopetalous 0/5 i.e. all the five petals forming the lower lip so that the corolla becomes one lipped. Aestivation in the petals is valvate or imbricate.

Androecium: Typically only 4 stamens, didynamous (2+2) and posterior stamen is reduced or represented by a staminode; in Calamintha only two perfect stamens are found, two are imperfect and the fifth reduced. In Salvia only two stamens on the anterior side are found; they are characterised by peculiarly long connectives which help in insect pollination stamens generally introrse and dithecous.

Gynoecium: Bicarpellary, syncarpous, superior, situated on hypogynous honey secreting disc; bilocular becomes tetralocular by the formation of false septum; axile placentation, one ovule in each loculus; style gynobasic (arising from the base of the ovary), stigma bilobed. The gynoecium character is thus uniform without any variation.

Fruit: Usually schizocarpic carcerulus or achenes or nutlets rarely drupaceous.

Seed: Non-endospermic.

Distribution of Lamiaceae:

It is commonly called Mint family. The family includes 260 genera and 3200 species of world wide distribution. In India it is represented by 400 species.

Economic Importance of Lamiaceae:

1. Food: Tubers of Stachys sieboldi are edible. Leaves of Mentha viridis, Ocimum basilicum, Melissa officinalis etc. are used as condiments.

2. Medicinal: Many plants of this family are used in medicines. Ajuga bracteosa, Leucas cephalotes are used in fever. Mentha piperata and Thymus serphyllum give Menthol and Thymol respectively, which are extensively used in medicines. Leaves of Ocimum kilimandus charicum give camphor.

Ocimum sanctum and other species of Ocimum are used in various ailments.

3. Ornamental: Several species of Salvia, Coleus, Ajuga, Leonotis, Dracocephalum, Thymus, Lavandula etc. are cultivated in gardens for ornamental purposes.

4. Perfumes: Aromatic oil is extracted from Thymus, Lavandula (Lavender oil), Rosmarinus (Rosemary oil), Calamintha, Pogostemon etc.

5. Dye: Fruits of Lycopus europaeus yield red dye.

Introduction to Euphorbiaceae:

Hypogynous; actinomorphic; unisexual; petals usually absent, if present sometimes quite sympetalous (Jatropha)-, syncarpous with 1-2 ovules pendulous from the inner angle; stamens various; seeds often with a conspicuous caruncle; endosperms mostly copious; stipules mostly present.

There are about 283 genera and 7,300 species in this family.

Distribution: The plants of this family are found throughout the world. However, they are not found in arctic regions. In our country the family is represented by several genera such as, Euphorbia, Ricinus, Phyllanthus, Croton, Pedilanthus, etc. In the desert regions of Africa and elsewhere the family is represented by cactus-like plants of different species of Euphorbia.

Heath like Euphorbias are quite common in Australia. In Britain only two genera, i.e., Euphorbia and Mercurialis are found, which are represented by sixteen and two species respectively.

Habit: The plants exhibit great variation in their habit. The plants may be herbs, shrubs or trees. Euphorbia hirta, E. thymifolia, E. helioscopica, E. peplus; E. heterophylla, E. cristata, E. elegans; Phyllanthus niruri, Croton sp., Acalypha indica, etc., are annual or prennial herbs. Euphorbia pulcherrima, E. splendens, are beautiful shrubs. Pedilanthus sp., and Jatropha sp., are shrubby plants.

Euphorbia royleana, E. tirucalli are cactus like shrubs. Ricinus communis (Arand) is a tall annual and becomes small tree-like in habit. The tree habit of the family is represented by Phyllanthus emblica (Amla), Bischofia javanica, Putranjiva roxburghii, etc.

Havea brasiliensist (rubber tree) is a large tree 60 to 100 feet in height and 8-12 feet in girth. Species of the genus Tragia are tropical climbers. Majority of the members of the family possess large laticiferous vessels which contain latex.

Root: Tap and branched. The roots of Manihot utilissima and M. palmata are tuberous and rich in starch.

Stem: Herbaceous or woody, erect, very rarely climbing as in a tropical genus Tragia. The species of Xylophylla possess flat phylloclades. The stem is branched. It may be cylindrical, angular or flat. Usually solid but sometimes hollow as in Ricinus communis. Many stems possess spines. In many Euphorbia sp., the stems become fleshy, green and cactus like in appearance.

Leaves: The form and position of leaves are variable. The arrangement is usually alternate but sometimes they are opposite, e.g., Euphorbia hirta. In Pedilanthus the leaves are arranged alternately in the lower region of the plant whereas opposite in the floral region.

Usually the leaves are simple but in some they are deeply incised, e.g., Ricinus, Manihot, etc. In many Euphorbias the leaves are scaly and caducous. In many cases the leaves are reduced to spines. In few cases the leaves are replaced by cladodes. Usually the leaves are stipulate. In Jatropha sp., the stipules become branched and hair-like. In many Euphorbia sp., they are represented by glands or spines.

Inflorescence: The inflorescence varies greatly. It may be racemose or cymose or sometimes complex. In Euphorbia, the inflorescence is peculiar but very characteristic and known as cyathium. This is the modification of a cyme. In cyathium inflorescence a large number of male flowers each represented by a stalked stamen are found arranged around a central stalked female flower. The female flower consists of gynoecium only.

The complete inflorescence looks like a single flower. The bracts are being arranged like a perianth. The bracts are so united that they form a cup-like structure. In Acalypha the inflorescence is catkin type. In Croton and Ricinus the flowers are arranged in terminal racemes. In Jatropha the inflorescence is of cymose type and the flowers are arranged in terminal cymes. In Manihot the flowers are being arranged in racemes.

Flowers: The flowers are always unisexual. They are much reduced and may be monoecious or dioecious. In Euphorbia sp., each male flower is represented by a single stalked stamen. The flowers are incomplete, regular, actinomorphic and hypogynous.

Perianth: Occasionally, both calyx and corolla are present, e.g., Croton. In majority of cases either calyx or corolla or both are absent. In Ricinus communis the calyx is present and the corolla absent. In Euphorbia hirta both the whorls of calyx and corolla are absent. In Jatropha sp., both calyx and corolla are present.

In Acalypha indica the perianth is represented by four minute sepaloid petals. In Phyllanthus only sepaloid perianth is present. In Euphorbia the perianth is absent or represented by tiny scaly structures.

The perianth consists of 4 to 5 petals. The calyx and corolla consists of 4 or 5 sepals or petals. The aestivation is valvate or imbricate.

Androecium: The number of stamens varies from one to many. Usually as many stamens are present as many perianth leaves. In Euphorbia a single stalked stamen represents a single male flower. In Ricinus sp., usually five stamens are present, each stamen is profusely branched. In Jatropha they are arranged in two whorls each of five stamens.

In many the stamens are indefinite, e.g., Croton. The filaments may be free or united. The anthers are dithecous. They dehisce either by apical pores or by transverse or longitudinal slits.

Gynoecium: Three carpels (tricarpellary), syncarpous; the ovary is trilocular, superior. Each locule contains one or two pendulous, anatropous ovules. The placenation is axile.

Fruit: The fruits are schizocarpic. The fruits break violently and dehisce into one seeded cocci. Such type of fruit is termed regma which is characteristic of Ricinus sp. The sp., of Trewia and Bridelia bear drupe fruit. Phyllanthus emblica also bears drupe.

Seeds: The seed is endospermic. In Ricinus caruncle develops from the micropyle. The cotyledons either lie flat or are folded within the endosperm.

Pollination: Usually entomophilous, i.e., through the agency of insects. Only cross- pollination takes place. In many species the leaves and bracts become coloured and showy to attract the insects. Sometimes anemophily is also found.

Economic Importance of the Family – Euphorbiaceae:

1. Acalypha hispida; An ornamental herb.

2. Acalypha wilkesiana- (Eng. -Garden Acalypha). Grown in the gardens as ornamental plant.

3. Bischofia javanica; (Eng.-Bishop wood; Verna-Bhillar)- A tree. A red dye, obtained from the bark is used to stain rattan baskets. The bark is also used as a tan. The wood is extremely resistant to water effect and therefore, largely utilized in the construction of bridges and boats.

4. Bridelia retusa, (Verna.-Ekdania, Khaja)-A tree, found in Rajasthan, Madhya Pradesh, the Western Peninsula and Bihar. The bark is used for tanning. The fruits are edible and the leaves are used as fodder.

5. Cleistanthus collinus (Verna-Garari)-A small tree, found in Tamil Nadu, Malabar, Bihar, Orissa and Madhya Pradesh. The bark, leaves and green fruits are used as tan.

6. Croton aromaticus; An aromatic shrub or small tree found in Andhra Pradesh produces a gum-resin, which is used in varnishes.

7. Croton oblongifolius; (Verna-Chuka) – The seeds yield an oil, which is used as a purgative and also as an insecticide.

8. Croton tigllium; (Verna-Jamalgota)-A shrub or small tree, native of South East Asia but cultivated in Assam, Bengal and South India. The seeds are the source of croton oil, which is used as a purgative.

9. Baccaurea courtallensis: Found in the Western Ghats. The fruits are edible.

10. Baccaurea sapida- (Verna-Lathua)-Found in Assam, Bengal and Andaman Islands The fruits are edible.

11. Chrozophora prostrata (Verna-Subali)-The root ashes are given to the children for cough treatment. The seeds are used as a purgative.

12. Baliospermum montanum; (Verna-Danti)-The seeds are used as a strong purgative. The decoction of leaves is used in asthma.

13. Euphorbia milii; Syn. E. splendens; A small climbing shrub; native of Madagascar. Grown in gardens as ornamental.

14. Euphorbia pulcherrima-, Syn. Poinsettia pulcherrima’, Eng-Poinsettia; (Verna.-Lal Patta)-A shrub, native of Central America. Grown as an ornamental.

15. Euphorbia tirucalli, (Verna.-Tohar)-Succulent spineless small tree, native of Africa. The roots are used for poisoning fish and birds.

16. Euphorbia hirta, (Verna.-Dudhi)-The plant is of medicinal value and used in many diseases of children and adults.

17. Euphorbia thymifolia; (Verna.-Chhoti dudhi)–The juice of leaves and seeds is used as a strong purgative. The juice is also used for remedy of ringworms and other skin diseases. It is an antidote for snake bite.

18. Euphorbia royleana- (Verna.-Thar)-The plants are used in hedges. The latex is used medicinally in several ways.

19. Euphorbia antiquorum- (Verna.-Tridhara, sehund)-The decoction of stem is used as a remedy of gout. The juice of the plant is also used as a strong purgative. The root bark is also used as a purgative.

20. Glochidion zeylanicum; (Verna.-Kumbalm)-The leaves are used in itches.

21. Securinega leucopyrus; Syn. Phyllanthus leucopyrus; Flueggea leucopyrus (Verna.- Hartho)-A large shrub or small tree, found in Uttar Pradesh, the Punjab, Maharashtra and Tamil Nadu. The fruits are edible.

22. Jatropha curcas; (Verna.-Safed arand)- A shrub or small tree, native of tropical America, now cultivated in Travancore. The seed oil is used for manufacturing candles, soaps and as a lubricant and for illumination. The seed oil is also used as a purgative. The tender shoots are edible. Oil also used as biodiesel.

23. Jatropha gossypifolia; (Verna.-Bherenda)-A shrub, native of Brazil. Cultivated as an ornamental.

24. Jatropha hastate; Grown as an ornamental for bright crimson flowers.

25. Jatropha padagrica; (Eng.-Gouty stemmed Jatropha)-Native of Panama, grown for its bright scarlet flowers.

Characters of Liliaceae:

Herbs rarely shrubs, stem underground rhizome, corm or bulb; leaves alternate, flowers actinomorphic, trimerous, hypogynous, perianth 6 in two whorls of 3 each, free or fused; stamen 3+3, epiphyllous, antiphyllous; gynoecium tricarpellary, syncarpous, ovary superior, axile placentation, two to many ovules per loculus; fruit capsule or berry; seed endospermic.

A. Vegetative characters:

Habit: Mostly herbs (Asphodelus), perennating by rhizome (Aloe), bulb (Lilium, Tulipa, Allium), tree (Dracena), climber (Asparagus, Smilax), xerophytic plants like Yucca, Aloe; cladodes in Asparagus and Ruscus.

Root: Fibrous adventitious, sometimes tuberous (Asparagus).

Stem: Herbaceous, or woody, solid or fistular, underground; aerial climbing or erect; underground stem may be corm, bulb or rhizome. In Ruscus and Asparagus aerial stems bear phylloclades (modified leaf-like branches), corm (Colchicum); secondary growth in Yucca. Dracaena, Aloe.

Leaves: Alternate, opposite or whorled, radical and cauline, exstipulate, sessile or petiolate, sheathing leaf base; shape is variable scale-like (Asparagus), thick succulent and mucilaginous in Aloe, broad in Phormium tenax. In Smilax stipulate and stipules are modified into tendrils. Venation is usually parallel but reticulate in Smilax and Trillium.

B. Floral characters:

Inflorescence: Variable-solitary (Tulipa, Fritillaria), panicled raceme (Asphodelus), cymose umbel (Allium, Smilax), solitary axillary (Gloriosa).

Flower: Pedicellate, actinomorphic or zygomorphic (Lilium, Hemerocallis), hermaphrodite or unisexual in Smilax, Ruscus; hypogynous, complete or incomplete (in unisexual flowers), trimerous rarely 2 or 4-merous (Maianthemum, Paris).

Perianth: 6, in two words of three each, polyphyllous (Lilium, Tulipa) or gamophyllous (Aloe, Asparagus) and of various shapes; petaloid or sepaloid; imbricate in bud, usually valvate aestivation, perianth may be scarious or membranous.

Androecium: Stamens 6 or 3 (Ruscus), 8 in Paris; polyandrous, epiphyllous, antiphyllous, filaments long, anthers versatile or basifixed, dithecous, introrse or extrorse. In Ruscus outer whorl of stamens is reduced to staminodes.

Gynoecium: Tricarpellary, syncarpous, ovary superior or half inferior, trilocular or unilocular with two ovules, axile placentation, style simple; stigma trilobed or 3-parted.

Fruit: A berry (Asparagus, Smilax), capsule (Asphodelus).

Seed: Endospermic; endosperm horny or cartilagenous.

Pollination: Entomophilous rarely self-pollination.

Distribution of Liliaceae:

It is commonly called “Lily family”. It includes 250 genera and 4000 species, which are world wide in distribution. In India it is represented by 169 species.

Economic Importance of Liliaceae:

1. Food: Allium cepa (Onion), Allium sativum (Garlic) and Asparagus are edible and used as food.

2. Medicinal: Smilax, Aloe, Gloriosa, Veratrum, Colchicum, Scilla and Urginea yield useful drugs. Rat poison is obtained from Urginea and the bulbs of Scilla. Aloe vera yields “Aloin”. The roots of Asparagus (H. Satavaer) yields a tonic. From Colchicum, colchicine is obtained.

3. Fibres: Yucca, Phormium tenax yield fibres of commerce.

4. Resin: Dracaena and Xanthorrhoea yield resin. From the acrid resin of Xanthorrhoea sealing wax is prepared.

5. Ornamentals: The common cultivated garden plants are Tulipa, Lilium, Gloriosa, Aloe, Ruscus, Dracaena, Asparagus, Yucca, Hemerocallis etc.

Characters of Poaceae:

Mostly herbs, stem jointed, fistular, cylindrical; leaves simple, alternate, sheathing, sheath open, ligulate; inflorescence compound spike; flowers zygomorphic, hypogynous, protected by palea; perianth represented by 2 or 3 minute scales (lodicules); stamens 3, versatile; carpel one, style 2 or 3, stigmas feathery, basal placentation; fruit caryopsis; testa fused with pericarp.

A. Vegetative characters:

Habit: Herbs, annuals or perennials or shrubs, sometimes tree like (Bambusa, Dendrocalamus).

Root: Adventitious, fibrous, branched, fascicled or stilt (Zea mays).

Stem: Underground rhizome in all perennial grasses, cylindrical, culm with conspicuous nodes and internodes, internodes hollow, herbaceous or woody, glabrous or glaucous, vegetative shoots are arising from the base of aerial stem or from underground stems are called tillers.

Leaves: Alternate, simple, distichous, exstipulate, sessile, ligulate (absent in Echinochloa), leaf base forming tubular sheath, sheath open, surrounding internode incompletely, ligule is present at the junction of the lamina and sheath, entire, hairy or rough, linear, parallel venation.

B. Floral characters:

Inflorescence: Compound spike which may be sessile or stalked. Each unit of inflorescence is spikelet. The spikelets are arranged in various ways on the main axis called rachilla. A compound inflorescence may be spike of spikelets (Triticum), panicle of spikelets (Avena).

The spikelet consists of a short axis called rachilla on which 1 to many sessile or short stalked flowers are borne. The florets may be arranged in alternate or opposite manner on the central axis.

At the base of rachilla two sterile scales, called glumes, are present. The glumes are placed one above the other on opposite sides. The lower one is called first glume and the upper is called second glume. Both the glumes are boat shaped and sterile. Above the glumes a series of florets are present. Each floret has an inferior palea or lemma and above it a superior palea. The lemma frequently bears a long, stiff hair called awn.

Flower: Bracteate and bracteolate, sessile, incomplete, hermaphrodite, or unisexual (Zea mays), irregular, zygomorphic, hypogynous, cyclic.

Perianth: Represented by membranous scales called the lodicules. The lodicules are situated above and opposite the superior palea or may be absent, or many (Ochlandra), or 2 or 3.

Androecium: Usually stamens 3, rarely 6 (Bambusa, Oryza) and one in various species of Anrostis, Lepturus; polyandrous, filaments long, anthers dithecous, versatile, linear, extrorse; pollen grains dry.

Gynoecium: Monocarpellary, according to some authors carpels 3, of which 2 are abortive, ovary superior, unilocular with single ovule, basal placentation, style short or absent; stigmas two feathery or papillate and branched.

Fruit: Caryopsis (achene with pericarp completely united or adherent with the seed coat) or rarely nut (Dendrocalamus) or berry (Bambusa).

Seed: Endospermic and containing a single cotyledon called scutellum, which is shield shaped and pressed against the endosperm.

Distribution of Poaceae:

The family is commonly known as grass family. It is one of the largest among the angiospermic families. It consists of 620 genera and 6,000 species. The members are cosmopolitan in distribution. The plants represent all the 3 ecological types as hydrophytes, xerophytes and mesophytes. In India it is represented by 850 species.

Economic Importance of Poaceae:

The family stands first and foremost in respect of economic importance in whole of Angiosperms. The staple food grains of the population of world is derived from Oryza sativa (Rice) and Triticum aestivum (Wheat). They are cultivated from time immemorial.

Food: Triticum aestivum, Oryza sativa, Zea mays (Maize), Hordeum vulgare (Jaw), Sorghum vulgare (Jowar), Avena sativa (Oats), Pennisetum typhoides (Bajra) are cultivated for cereals and food grains.

Fooder: Many grasses as Cynodon dactylon, Panicum, Cymbopogon, Agrostis, Poa are grown for fodder.

Sugar: Saccharum officinarum (Sugarcane; H. Ganna) is cultivated for gur and sugar.

Building material: Some species of Bambusa e.g. B. tulda, B. vulgaris are used for scaffolding, thatching huts etc.

Furniture: Species of Dendrocalamus (H. Bent), Arundinaria, Melocalamus are used in manufacture of furniture.

Aromatic grasses: Many grasses yield scented oils which are used in perfumery viz. Vetiveria zizanioides (H. Khus khus) yields vetiver oil from the roots. The roots are also woven into curtains. Andropogon odoratus (Ginger grass), Cymbopogon citratus (Lemon grass), Cymbopogon martini (Geranium grass), Cymbopogon jawarancusa etc. also yield oil.

Medicinal: Phragmites karka, Cymbopogon schoenanthus etc. are medicinal.

Secale cereale is cultivated for infection of its inflorescence by Claviceps purpurea for production of Ergot and for extraction of ergotine. Ergotine is an excellent remedy for uterine contraction.

Paper: It is manufactured from certain species of grasses and bamboos.

Ornamental: Rhynchelytrum repens, Cortaderia selloana and some species of the tribe Bambusoideae are ornamentals.

Besides these a number of grasses are grown to form fine lawns, play grounds etc.