Euphorbiaceae: General characters, Distribution, Important plants, Economic importance and Floral diagram
Posted on : 15-11-2019 Posted by : Admin

 

General Information

Common name: Spurge family

Number of genera: This family includes 300 genera and about 5000 species

Propagation type: Fruit or seed

Distribution: The members of this family are cosmopolitan in distribution but, they are more abundant in warmer parts or tropical regions of the world. They are almost absent in Arctic region. In India this family is represented by 61 genera and 336 species. All these species are distributed in tropical and sub-tropical Himalayas and mountain ranges of south India.

 

Vegetative characters

Habitat: Generally, plants belonging to this family are Mesophytic or xerophytic in habitat

Habit: This family shows a great range of characteristics in vegetative and floral structures. Members of this family are mostly shrubs (for example Jatropa, Ricinus, Euphorbia sps.) or trees (for example Emblica officinalis, Hevea brasiliensis) and rarely herbs (for example Acalypha, Phyllanthus).

The species of Tragia are climbers. Several species of Euphorbia (like E. royleana, E. neriifolia and E. trigona) are cactus like in habit with thick, fleshy stems and with leaves reduced to spines. These plants contain milky latex in special laticiferous vessels.

Root system: These plants show tap root system. Exceptionally, Manihot has tuberous roots which are rich in starch. Few species of Manihot are edible.

Stem: Several species of Euphorbia are cactus-like in habit with thick and fleshy stems and leaves reduced to spines. These plants often contain milky latex with special laticiferous vessels.

Leaf: The leaves are usually alternate or rarely opposite (Choriophyllum) or whorled (Mischodon), simple, entire or deeply palmately lobed (Ricinus and Jatropa) or compound (Bischofia). The leaves are variegated in Croton.

The stipules are usually present and in Jatropa they are represented by ciliate glands. The venation is pinnate or palmate as in Ricinus. In species of Euphorbia, leaves fall off early and photosynthesis is carried by green stems.

 

Floral characters              

Inflorescence: Inflorescence is complex and highly variable. In Phyllanthus, the flowers are solitary or auxiliary. In Croton, the inflorescence is panicle. In Acalypha, it is catkin and in Jatropa the flowers are arranged in terminal cymose clusters.

The first branching is usually racemose and the subsequent branchings are cymose. The partial inflorescence is a cyathium which appears as a single flower. Each cyathium is surrounded by an involucre of four or five connate bracts and between these large coloured glands a petaloid appendage is present (Splendens).

In the middle of cyathium, there is a single female flower represented by a tricarpellary gynoecium. In the axil of each bract a number of male flowers are arranged in scorpioid cymes. The oldest flower is nearest to the centre and thus the maturation is centrifugal.

In Euphorbia both male and female flowers are naked, whereas in anthostema both have a tubular perianth. In the remaining genera of this tribe, male flowers are naked and female flowers have rudimentary perianth.

Flower: The flowers are unisexual, bracteates, actinomorphic, regular, pentamerous or trimerous (Phyllanthus), monochlamydeous and hypogynous. The flowers are rarely perigynous as in Bridelia.

• In Croton the corolla is distinct in the male flowers whereas it is inconspicuous or absent in the female flowers. Flowers are often apetalous.
• In Jatropa both calyx and corolla are present with five members each. The petals may be united or free.
• In Manihot the calyx becomes petaloid.
• In Ricinus male flowers have five sepals and the female flowers have only three sepals.
• In Trewia and Mercurialis there are only three or four sepals.

Perianth: Perianth is mostly in one whorl, green or rarely petaloid (Manihot). Rarely perianth is in two whorls as in Jatropa or absent as in Euphorbia. In Jatropa, both calyx and corolla are present. Both calyx and corolla are five membered with united petals. Aestivation is valvate or imbricate type.

Androecium: The Androecium show variable number of stamens. In male flowers they range from one to many arranged in one to ten whorls. Filaments are free or united. The anthers are monothecous or dithecous, erect and dehisce longitudinally or transversely.

For example,

• One in Euphorbia
• Three in Breynia
• Three to five in Phyllanthus
• Eight in Acalypha
• Ten in two alternate whorls with the members of the outer whorl opposite the petals as in Jatropha
• Fifteen in Crozophora
• Eight to twenty in Mercurialis
• Fifteen to thirty in Codiaeum
• Eighty to hundred in Croton

Filaments are free or united. In Phyllanthus cyclanthera besides filaments the anthers are also united into a ring-like common anther. In Ricinus, branched stamens are present opposite to the sepals. Here anthers are borne on the ultimate branch. The anthers are dithecous, erect and dehisce longitudinally or transversely. A rudimentary ovary is often present in the male flower.

 

Gynoecium: The gynoecium is tricarpellary, syncarpous with superior, trilocualr ovary. One or two collateral, pendulous, anatropous ovules in each locule in axile placentation are present. At the base of the ovaries nectarines are present.

Pollination: Unisexual flowers necessitate cross pollination and here pollination is entomophilous taking place with the help of insects. This is due to the presence of brightly coloured glands or bracts, petaloid calyx or nectar. Certain taxa, such as Mercurials with long thread like styles are anemophilous.

Fruit: Fruit is usually three chambered, schizocarpic splitting into three one-seeded cocci. Rarely drupe (Phyllanthus) or berry (Bischofia).

Seed: Seeds are with fleshy endosperm and straight embryo. The seeds are often with a conspicuous caruncle. Seeds are dispersed by birds and animals. Some seeds are also dispersed by explosive mechanism of the capsules.

  

Important plants of Euphorbiaceae

The following is a list of some important members of family Euphorbiaceae, arranged alphabetically.

1. Acalypha  hispida (Chinille plant)
2. Acalypha indica (Copper leaf)
3. Aleurites foldii (Tung oil)
4. Codiaeum variegatum (Croton)
5. Emblica officinalis (Amla)
6. Euphorbia antiquorum (Bomma jemudu)
7. Euphorbia milii (Crown of thorn)
8. Euphorbia nerifolia (Aku jemudu)
9. Euphorbia tirucalli (Milk bush)
10. Euphornia pulcherrima (Poinsettia)
11. Hevea brasiliensis (Para rubber tree)
12. Jatropa gossypifolia (Jatropa)
13. Jatropa panduraefolia (Garden jatropa)
14. Mallotus philippensis (Kumkuma)
15. Pedilanthus tithymaloides (Red bird cactus)
16. Phyllanthus niruri (Nela usiri)
17. Ricinus communis (Castor oil)
18. Spanium indicum (Castor bean)

 

Economic Importance of Euphorbiaceae

Plants of Euphorbiaceae are economically very important. They provide food, drug, rubber and oil

Edible plants

• The large and fleshy tuberous roots of Manihot are rich in starch and form valuable food stuff. It is extensively cultivated in tropics. Some cultivars are with high HCN content (Bitter cassava) and others which low content (Sweet cassava). The poisonous juice is squeezed outand is used as antiseptic and preserving meat.
• The fruits of Emblica officinalis are rich source of vitamin-C. They are used to make pickle and in treatment of scurvy.

Rubber

• Hevea brasiliensis (Para rubber tree) is the best natural source of rubber. The tree is tapped by making plant cuts on the trunk and the latex is coagulated. It is native of Brazil.
• The latex of Spanium indicum also produces rubber.

Medicine

• The castor oil obtained from the seeds of Ricinus communis is uses medicinally as cleansing agent.
• The seeds of Croton tiglium are the source of croton oil used as purugative.
• The fruits of Phyllanthus niruri (nela usiri) find their application in the treatment of jaundice and urinary troubles.
• Acalypha indica has pesticide properties and controls skin diseases.
• The roots of Jatropa gossypifolia are employed against leprosy and as an antidote for snake bite.

Dyes

• A red dye is obtained from the fruits of Mallotus philippensis (Kumkuma), Chrozophora tinctoria, Sapium sps are used in dying silks
• Candelila wax is extracted from the stems of Euphorbia antisyphylitica

Oils

• Castor oil obtained from the seeds of Ricinus communis is used as lubricant and illumination oil
• The oil obtained from the seeds of Aleurites foldii is called Tung oil. It is used in manufacture of varnishes and paints. The seeds contain oil which is used in paint and varnish industry. The seeds yield an oil used in soap industry and the oil cakes are used as a cattle feed and fertilizer.

Ornamentals

Some of the plant species of this family which are ornamental are as follows,

• Acalypha  hispida (Copper leaf)
• Codiaeum variegatum (Croton)
• Euphorbia antiquorum (Bomma jemudu)
• Euphorbia milii (Crown of thorn)
• Euphorbia nerifolia (Aku jemudu)
• Euphorbia tirucalli (Milk bush)
• Euphornia pulcherrima (Poinsettia)
• Jatropa panduraefolia (Garden jatropa)
• Pedilanthus tithymaloides (Red bird cactus)

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