I. Flower structure - composed of four whorls of modified leaves (sepals, petals, stamens, and carpels)

A. Receptacle - holds it all together

B. Sepals (calyx) & petals (corolla) - together called the perianth

C. Male (stamens) and female (pistil / carpels) parts

1. Male (androecium) - stamen: anther & filament

2. Female (gynoecium) - carpel or pistil: stigma, style, ovary & ovule

Variations in floral structure

A. Completeness of flower

1. Complete flower - has all four sets of floral "leaves"

2. Incomplete flower - lacks one or more of the four sets

B. Perfectness of flower

1. Perfect - has both male (staminate) and female (pistillate) parts

a) If observed in whole plant, referred to as monoecious

2. Imperfect - lacks either the male or female part

a) If observed in whole plant, referred to as dioecious

C. Symmetry of flower

1. Regular or radial- petals are of similar shape and radiate from center of the flower

2. Bilateral - parts arranged so that perianth can be divided into two equal parts

3. Irregular

a) Whorls with dissimilar flower parts

b) Parts do not radiate from center

c) Parts not equidistant from each other

Ovary position

1. Superior ovary - gynnoecium (female stuff) is above perianth and androecium (other stuff)

2. Inferior ovary - ovary appears to be below the perianth and stamens

Monocot vs. dicot

A. Monocots in units of 3's

B. Dicots in units of 4's or 5's