5.2. FLORAL FORMULA, FLORAL DIAGRAM AND PLANT FAMILIES

While classifying flowering plants various vegetative and floral characters are taken into consideration. A brief description of flower is represented in the form of floral formula and floral diagram.

The symbols used in writing floral formula are:

The number in suffix represents the number of floral leaves, a bracket indicates union or cohesion of members and union between dissimilar whorls or adhesion is shown by a line connecting two symbols. The diagram showing the relative position of different floral members is known as floral diagram.

 

5.2.1 Fabaceae:

This family was earlier called Papilionoideae, a subfamily of family Legurninosae. It is distributed all over the world.

Vegetative Characters:

Trees, shrubs, herbs; root with root nodules

Stem:

erect or climber

Leaves:

alternate, pinnately compound or simple; leaf base, pulvinate; stipulate; .venation reticulate.

Floral characters:

Inflorescence:

racemose

Flower:

bisexual, zygomorphic

Calyx:

sepals five, gamosepalous; imbricate aestivation.

Corolla:

petals five, polypetalous, papilionaceous, consisting of a posterior standard, two lateral wings(alae), two anterior ones forming a keel

(enclosing stamens and pistil), vexillary aestivation

Androecium:

Stamens ten, diadelphous, anther dithecous

Gynoecium:

Ovary superior, mono carpellary, unilocular with many ovules, marginal placentation, style single.

Fruit:

Legume;

Seed:

One to many, non-endospermic

Floral Formula:

Economic importance

Many plants belonging to the family are sources of pulses (gram, arhar, sem, moong, soyabean; edible oil (soyabean, groundnut); dye (Indigofera); fibres (sunhemp); fodder (Sesbania trifolium), ornamentals (lupin, sweet pea); medicine (muliathi).

 

5.2.2 Solanaceae:

It is a large family, commonly called, the 'potato family'.

It is widely distributed in tropics, subtropics, and even temperate zones.

Vegetative Characters:

Plants mostly herbs, shrubs and rarely small trees

Stem:

herbaceous rarely woody, aerial; erect, cylindrical, branched, solid or hollow, hairy or glabrous, underground modified stem in potato (Solanum tuberosum)

Leaves:

alternate, simple, rarely pinnately compound, exstipulate; venation reticulate

Floral Characters:

Inflorescence :

Solitary, axillary cymose as in Solanum

Flower:

bisexual, actinomorphic

Calyx:

sepals five, united, persistent, valvate aestivation

Corolla:

petals five, united; valvate aestivation

Androecium:

stamens five, epipetalous

Gynoecium:

bicarpellary, syncarpous; ovary superior, bilocular, placenta swollen with many ovules, axile placentation.

Fruits:

berry or capsule

Seeds:

many, endospermous.

Floral Formula

Economic Importance

Many plants belonging to this family are source of food (tomato, brinjal, potato), spice (chilli); medicine (belladonna, ashwagandha); ornamentals (Petunia).

5.2.3 Liliaceae:

Commonly called the 'Lily family' is a characteristic representative of monocotyledonous plants. It is distributed world wide.

Vegetative characters:

Perennial herbs with underground·bulbs/corms/rhizomes.

Leaves:

mostly basal, alternate, linear, exstipulate with parallel venation.

Floral characters:

Inflorescence:

solitary / cymose; often umbellate clusters.

Flower:

Bracteate, bisexual; actinomorphic .

Perianth:

tepals six, (3+3) often united into tube; valvate aestivation

Androecium:

stamens six , 3+3, often epiphyllous.

Gynoecium:

tricarpellary, syncarpous, ovary superior, trilocular with many ovules; axile placentation

Fruit:

capsule, rarely berry.

Seed:

endospermous.

Floral Formula:

Economic Importance

Many plants belonging to this, family are good ornamentals (tulip, Gloriosa), source of medicine (Aloe), vegetables (Asparagus), and colchicine (Colehieum autumnale).