Floral Formulas

A Cool Way to Look at Floral

Anatomy

Floral Formulas

• System of notation• Display a ton of

information about the structure of a flower– Similar to the notation

we used when we learned about grasses

• Not standardized

Floral Formulas

• Using the 4 whorls of floral parts as our reference– Calyx (sepals)– Corolla (petals)– Androecium (stamens)– Gynoecium (pistils)

Floral Formulas

• K = calyx• C = corolla• A = androecium• G = gynoecium

Floral Formulas

Number of Parts• K5 = calyx of 5 sepals• C6 = corolla of 6 petals• A10 = androecium of 10 stamens• G2 = gynoecium of 2 carpels• C0 = corolla missing• A4[5] = androecium usually of 4 stamens, rarely 5

Floral Formulas

Number of Parts (a little more complicated)• A4+2 = androecium of 6 stamens, 4 in 1 set, 2 in

another• G2-3 = gynoecium of 2 or 3 carpel• Ax = androecium of a low unstable number (about

10-20) stamens• G∞ = gynoecium of high unstable number, more than

20 carpels

Floral Formulas

Symmetry• K = calyx actinomorphic (radially)• C = corolla actinomorphic• Kz = calyx zygomorphic (bilaterally)• Cz = corolla zygomorphic

Floral Formulas

Fusion of Parts• K4 = calyx of 4 separate sepals• C3 = corolla of 3 separate petals• K(4) = calyx of 4 fused sepals• G(2) = gynoecium of 2 fused carpels• G4 = gynoecium of 4 separate carpels• A5 = androecium of 5 stamens fused by their

filaments

Floral Formulas

Fusion of Parts (cont.)• A5G2 = androecium and gynoecium fused by

their upper parts• K C A = calyx, corolla, and androecium united

into a hypanthium

Floral Formulas

Ovary Position• G = ovary superior; flower hypogenous or perigynous• G = ovary inferior; flower epigynous• -G- = ovary half-inferior• G = ovary either superior or inferior

Floral Formulas

K5 Cz1+(2)+2 A9+1 G1

Given:

Floral Formulas

TranslationK5 Cz1+(2)+2 A9 +1 G1

• Calyx of 5 separate sepals• Corolla zygomorphic (bilaterally symmetrical); of 5

petals, 2 fused together, 2 free and forming a pair, and a 5th different from the others

• Androecium of 10 stamens, 9 joined by their filaments, the 10th free

• Gynoecium unicarpellate, the ovary superior

Interpreting Floral FormulasPractice

K(5) Cz(5) A2 or 2+2 G(2)

Interpreting Floral FormulasPractice

K3-5 C5 A∞ G(5-8)

Interpreting Floral FormulasPractice

K4 C4 A4+2 G(2)

Interpreting Floral FormulasPractice

K4 C4 A8 G(4)

Interpreting Floral FormulasPractice

K(5) C(5) A5 G(2)

Interpreting Floral FormulasPractice

K(5) Cz5 A2+2 G(2)

Writing Floral FormulasPractice

• Given the following description, write the floral formula:

• Flowers bilaterally symmetrical• 5 fused sepals• 5 fused petals• 4 stamens, 2 in one set and 2 in another• Superior ovary, 2 fused carpels

Writing Floral FormulasPractice

• Given the following description, write the floral formula:

• 4 sepals• 4 petals• 8 stamen• Calyx, corolla, androecium form a hypanthium• Inferior ovary, 4 fused carpels

Writing Floral FormulasPractice

• Given the following description, write the floral formula:

• 3-5 fused sepals• 5 petals• More than 20 fused stamens• Superior ovary, 5-8 fused carpels

Writing Floral FormulasPractice

• Given the following description, write the floral formula:

• 5 fused sepals• 5 petals• 10-many stamens, sometimes 4• Superior ovary, 1 carpel

Writing Floral FormulasPractice

• Given the following description, write the floral formula:

• 5 fused sepals• 5 petals, zygomorphic• 10 stamens• Superior ovary, 1 carpel

Writing Floral FormulasPractice

• Given the following description, write the floral formula:

• 4-5 fused sepals• 4-5 fused petals, zygomorphic• 4 stamens in 2 sets of 2• Hypogenous, 2 fused carpels

Homework For Next Time

• Using your notes from previous classes, try to figure out which plant families you have just written the floral formulas for

• Bring the names of the families with you to our next meeting