EUPHORBIACEAE Family

Introduction to EUPHORBIACEAE - the castor family

Systematic position

Class:  Dicotyledonae, Sub-class:  Monochlamydeae, Series:  Unisexuales, Family:  Euphorbiaceae

General characters

Distribution

Euphorbiaceae involves more than 300 genera and about 7,500 species. It is universal in distribution, but specifically well presented in Africa and South America

Habit

This family involves a large number of annual herbs (example Phyllanthus amarus) or shrubs (example Ricinus communis) or trees (example Phyllanthus emblica). In various species of Euphorbia, the stem is changed to carry out photosynthesis.  This modified stem is termed as cladode and it resembles cactus.   Example E. tirucalli  and E. antiquorum (Sadhurakkalli). This family displays a great range of difference in vegetative and floral characters.  Approximately all the plants have latex that is either milky or watery.

Root

A branched tap root system.

Stem

1. Aerial,

2. erect / prostrate (example E. prostrata),

3. cylindrical,

4. branched,

5. solid / hollow (example Ricinus communis)

Generally consists of milky latex (example E. tirucalli) or watery latex (example Jatropha  curcas).

Leaf is

1. Stipulate / exstipulate,

2. petiolate,

3. alternate (example Ricinus communis),

4. simple, 

5. entire  /  deeply lobed /  trifoliately compound (example  Hevea brasiliensis) and with unicostate or multicostate reticulate venation. The stipules are changed into a pair of spines (example E.splendens) or glandular hairs (example Jatropha curcas).  In xerophytic species of Euphorbia,   leaves are reduced or not present. The leaves around the cyathium become beautifully coloured in E. pulcherrima (Paalperukki tree).

Inflorescence

The feature inflorescence of Euphorbia is cyathium. Cyathium is a collection of unisexual flowers that arranged in cymose way on a condensed axis and enclosed in a cup-shaped involucre.   Every cyathium comprise a single central female flower that surrounded by two to several male flowers. Every male flower is presented through a single stamen. They are arranged in centrifugal way.  In female flower the pedicel is short or long. If it is long, the female flower appears of involucres while If it is short, the female flower remains hidden in the involucre. Extra floral nectar secreting gland is also positioned in the cyathium.

Several kinds of inflorescence are seen in the members of Euphorbiaceae.   In Ricinus communis, it is a panicle in which female and male flowers are arranged in racemose manner.  male flowers below and Female flowers are at the top.  In Croton sparsiflorus (Eli amanakku), the inflorescence is easy raceme, where in Acalypha indica (Kuppaimeni), it is catkin.   In Phyllanthus amarus, the male and female flowers are solitary and axillary.

Flower is

1. Bracteate, 

2. ebracteolate,

3. pedicellate,

4. unisexual, 

5. monoecious or dioecious,

6. incomplete and hypogynous. 

In Euphorbia , the male flower is presented through a single stamen and female flower through a single pistil.

Perianth

In Croton sparsiflorus, the male flowers comprise two whorls of perianth while the female flowers comprise a single whorl of perianth. The male and female flowers of Euphorbia  are generally devoid of perianth that is aphyllous. The tepals are gamophyllous in Ricinus communis and polyphyllous in Phyllanthus  amarus  .

Androecium

Stamen one to several, free or united. The stamen is polyadelphous and the filaments are branched in Ricinus communis.  They are fused into various bundles. Anthers are dithecous. Rudimentary ovary termed as pistillode is frequently present in male flowers.

Gynoecium is

1. Ovary superior,

2. tricarpellary and

3. syncarpous.

Ovary trilocular along with one or two ovules in every locule on axile placentation. Ovary is distinctly 3 lobed. Styles three, every ending in a bifid stigma.

Fruit

Most generally schizocarpic capsule / drupe.  It is regma in Ricinus communis, dehiscing into 3 cocci.

Seed

Endospermous.

Botanical description of Ricinus communis

Habit

Perennial shrub.

Root

Branched tap root system.

Stem is

1. Aerial,

2. erect,

3. herbaceaous but woody below,

4. branched and

5. Hollow.

Young branches are covered along with hair like outgrowth.  Latex is exist.

Leaf is

1. Petiolate,

2. exstipulate,

3. alternate,

4. deeply palmately lobed with 7 or more lobes.

Venation is palmately reticulated divergent.

Inflorescence

Compound raceme / panicle and terminal.  Male flowers are that observe below and female flowers near the apex.

Male flower

1. Bracteate,

2. ebracteolate,

3. pedicellate,

4. actinomorphic and

5. Incomplete.

Perianth is

1. Tepals 5,

2. arranged in single whorl,

3. gamophyllous,

4. valvate aestivation and

5. odd tepal is posterior in position.

Androecium

Stamens many, polyadelphous, filaments branched and united to create five branches.   Anthers are dithecous, globose, basifixed, introrse and dehiscing through longitudinal slits.

Gynoecium

Not present but pistillode is present.

Floral  Formula

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Female Flower

1. Bracteate,

2. ebracteolate,

3. pedicellate,

4. actinomorphic,

5. incomplete and

6. hypogynous.

Perianth

Tepals 3 arranged in single whorl and gamophyllous displaying valvate aestivation.

Androecium

Not present but staminode is present.

Gynoecium

1. Ovary superior,

2. tricarpellary and

3. syncarpous.

Ovary trilocular with one ovule in every locule on axile placentation. Styles 3, deep red and long.  Bifid with feathery stigma.

Fruit

Fruit is termed as regma. It is covered through spinous outgrowths. The fruit splits into 3 one seeded cocci.

Seed

Endospermous.

Floral Formula

2385_EUPHORBIACEAE Family Homework Help 1.jpg

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