Euphorbiaceae – Ricinus communis and its Economic importance
Euphorbiaceae and Ricinus communis and its Economic importance
EUPHORBIACEAE – the castor family
Systematic position
Class: Dicotyledonae
Sub-class: Monochlamydeae
Series: Unisexuales
Family: Euphorbiaceae
General characters of Euphorbiaceae
Distribution
Euphorbiaceae includes more than 300 genera and about 7,500 species.
It is world wide in distribution, but particularly well represented in Africa and South America.
In India, it is represented by more than 70 genera and about 450 species.
Habit
This family includes a large number of annual herbs (eg. Phyllanthus amarus) or shrubs (eg. Ricinus communis) or trees (eg. Phyllanthus emblica).
In several species of Euphorbia, the stem is modified to perform photosynthesis.
This modified stem is called cladode and it resembles cactus.
eg. E. tirucalli and E. antiquorum (Sadhurakkalli).
This family shows a great range of variation in vegetative and floral characters.
Almost all the plants have latex which is either milky or watery.
Root
A branched tap root system.
Stem Aerial, erect or prostrate (eg. E. prostrata), cylindrical, branched, solid or hollow (eg. Ricinus communis), usually contains milky latex (eg. E. tirucalli) or watery latex (eg. Jatropha curcas).
Leaf
Stipulate or exstipulate, petiolate, alternate (eg. Ricinus communis), simple, entire or deeply lobed or trifoliately compound (eg. Hevea brasiliensis) and with unicostate or multicostate reticulate venation.
The stipules are modified into a pair of spines (eg. E.splendens) or glandular hairs (eg. Jatropha curcas). In xerophytic species of Euphorbia, leaves are reduced or absent.
The leaves around the cyathium become beautifully coloured in E. pulcherrima (Paalperukki tree).
Inflorescence
The characteristic inflorescence of Euphorbia is cyathium.
It is a collection of unisexual flowers arranged in cymose manner on a condensed axis and enclosed within a cup-shaped involucre.
Each cyathium has a single central female flower surrounded by two to many male flowers.
Each male flower is represented by a single stamen. They are arranged in centrifugal manner.
The pedicel in female flower is short or long.
If it is short, the female flower remains hidden within the involucre. If it is long, the female flower comes out of involucre.
Extra floral nectar secreting gland is also located in the cyathium.
Various types of inflorescence are seen in the members of Euphorbiaceae.
In Ricinus communis, it is a panicle where female and male flowers are arranged in racemose manner.
Female flowers are at the top and male flowers below. In Croton sparsiflorus (Eli amanakku), the inflorescence is simple raceme, whereas in Acalypha indica (Kuppaimeni), it is catkin.
In Phyllanthus amarus, the male and female flowers are axillary and solitary.
Flower
Bracteate, ebracteolate, pedicellate, unisexual, monoecious or dioecious, incomplete and hypogynous.
In Euphorbia , the male flower is represented by a single stamen and female flower by a single pistil.
Perianth
In Croton sparsiflorus, the male flowers have two whorls of perianth whereas the female flowers have a single whorl of perianth.
The male and female flowers of Euphorbia are usually devoid of perianth i.e aphyllous.
The tepals are polyphyllous in Phyllanthus amarus and gamophyllous in Ricinus communis.
Androecium
Stamen one to many, free or united. In Ricinus communis, the stamen is polyadelphous and the filaments are branched.
They are fused into several bundles. Anthers are dithecous. Rudimentary ovary called pistillode is often present in male flowers.
Gynoecium
Ovary superior, tricarpellary and syncarpous.
The ovary trilocular with one or two ovules in each locule on axile placentation.
Ovary is distinctly three lobed. Styles three, each ending in a bifid stigma.
Fruit
Most commonly schizocarpic capsule or drupe.
It is regma in Ricinus communis, dehiscing into three cocci.
Seed
Endospermous.
Botanical description of Ricinus communis – Euphorbiaceae
Habit
Perennial shrub.
Root
Branched tap root system.
Stem
Aerial, erect, herbaceaous but woody below, branched and hollow. Young branches are covered with hair like outgrowth. Latex is present.
Leaf
Petiolate, exstipulate, alternate, deeply palmately lobed with 7 or more lobes. Venation is palmately reticulate divergent.
Inflorescence
Compound raceme or panicle and terminal. Male flowers are seen below and female flowers near the apex.
Male Flower
Bracteate, ebracteolate, pedicellate, actinomorphic and incomplete.
Perianth
Tepals 5, arranged in single whorl, gamophyllous, valvate aestivation and odd tepal is posterior in position.
Androecium
Stamens many, polyadelphous, filaments branched and united to form five branches.
Anthers are dithecous, globose, basifixed, introrse and dehiscing by longitudinal slits.
Gynoecium
Absent but pistillode is present. Floral Formula
Br., Ebrl., ⊕, , P(5), A∝, G0. Female Flower
Bracteate, ebracteolate, pedicellate, actinomorphic, incomplete and hypogynous.
Perianth
Tepals 3 arranged in single whorl and gamophyllous showing valvate aestivation.
Androecium
Absent but staminode is present.
Gynoecium
The ovary superior, tricarpellary and syncarpous.
Ovary trilocular with one ovule in each locule on axile placentation.
Styles 3, deep red and long. Bifid with feathery stigma.
Fruit
Fruit is called regma. It is covered by spinous outgrowths.
The fruit splits into three one seeded cocci.
Seed
Endospermous
Floral Formula
Br., Ebrl.,⊕, , P (3), A 0, G (3).
ECONOMIC IMPORTANCE of Euphorbiaceae
1. Food plants
The tuberous root of Manihot esculenta (tapioca) is rich in starch and forms valuable food stuff.
The fleshy fruits of Phyllanthus emblica (Gooseberry) are rich in vitamin C. The fruit is edible and pickled.
2. Oil plants
Castor oil extracted from the seeds of Ricinus communis (Castor) is used as lubricant, vegetable oil and purgative.
Jatropha oil obtained from the seeds of Jatropha curcas (Kattamanakku) is used as purgative, to treat skin diseases and to extract bio-diesel.
3. Medicinal plants
The entire shoot system of Phyllanthus amarus (Keezhanelli) is used to treat jaundice.
The leaves and roots of Jatropha gossypifolia are used in the treatment of leprosy and snakebite.
4. Rubber plants
Over 98% of total natural rubber produced in the world is obtained from the coagulated latex of Hevea brasiliensis (para rubber) and Manihot glaziovii (manicoba rubber).
5. Ornamental plants
Euphorbia pulcherrima, Codiaeum variegatum (croton of gardens), E. tirucalli (milk bush) are examples for ornamental plants.
QUESTION of Euphorbiaceae:
- Write the systematic position of Euphorbiaceae.
- What is cladode? Give an example
- What are different types of inflorescence seen in Euphorbiaceae? Give example for each.
- Mention the binomials of two rubber plants of Euphorbiaceae
- Describe the inflorescence of Ricinus
- Describe the cyathium inflorescence.
- Give an account of the general characteristic features of Euphorbiaceae.
- Describe the male flower of Ricinus communis.
- Describe the female flower of Ricinus
- Write a brief account on different types of inflorescences of Euphorbiaceae.
- Write a detailed account on the economic importance of Euphorbiaceae.
- Describe Ricinus communis in botanical terms.
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