Biology Today - February 2018

Floral Formula

• It is a symbolic representation of floral symmetry, presence or absence, number, cohesion and adhesion of various parts.
  It also informs whether the flower is bracteate or ebracteate its symmetry, sexuality, number and union of sepals, petals,
  stamens and carpels. All these conditions are represented by various symbols, which are summarised below:


• Symbols used to write floral formula

Br – Bracteate P – Perianth

Ebr – Ebracteate A – Androecium

• Actinomorphic or regular flower G – Gynoecium
  % – Zygomorphic or irregular flower G – Superior ovary
  ( ) – Bisexual flower G – Inferior ovary


• Female flower 1, 2, 3, 4, ... v – Number of sepals, petals, stamens or carpels


• Male flower () – Fused or united, HJ, C(5), LH, five petals
  of corolla fused
  K – Calyx C A – Epipetalous condition, LH, stamens attached
  to petals
  C – Corolla

Floral Diagram

• It is a diagrammatic representation of the pooled up informations from transverse sections of the flower bud in relation to mother axis.

DESCRIPTION OF SOME IMPORTANT FAMILIES

Table : A comparative account of Families Fabaceae, Solanaceae and Liliaceae

Characters Fabaceae Solanaceae Liliaceae

Systematic

position

Class – Dicotyledonae

Subclass – Polypetalae

Series – Calyciflorae

Order – Rosales

Family – Fabaceae

Class – Dicotyledonae

Subclass – Gamopetalae

Series – Bicarpellatae

Order – Polemoniales

Family – Solanaceae

Class – Monocotyledoneae

Series – Coronarieae

Order - Liliales

Family – Liliaceae

Inflorescence Raceme or spike

(panicle in 'DOEHUJLD)

Axillary or extra-axillary cyme,

rarely solitary axillary (3HWXQLD)

or terminal ('DWXUD)

Racemose, sometimes solitary or umbellate

Flower Bisexual, zygomorphic,

bracteate or ebracteate,

pedicellate or sessile,

perigynous occasionally

hypogynous, pentamerous

Bisexual, actinomorphic, ebrac-

teate or bracteate, pedicellate,

hypogynous, pentamerous, cyclic

Bisexual, actinomorphic, zygomorphic in few

cases, bracteate or ebracteate, pedicellate,

complete or incomplete, unisexual in

5XVFXV and 6PLOD[, hypogynous, generally

pentacyclic, trimerous

Calyx Sepals five, gamosepalous,

valvate or imbricate

aestivation, usually

campanulate

Sepals five, gamosepalous,

valvate aestivation, persistent,

accrescent (3K\VDOLV),

campanulate or tubular, hairy

Perianth : Tepals six (3 + 3), often united

into tube, valvate or imbricate aestivation,

sepaloid or petalloid

Corolla Petals five, polypetalous,

papilionaceous, imbricate

aestivation

Petals five, variously shaped,

infundibuliform, campanulate,

rotate, united, valvate

aestivation, plicate or folded

like a fan in bud