BIO 402 – Field BiologyDr. Charles Horn

Newberry College

Presence of a complex reproductive structure = FLOWER

FLOWER (an organ) Commonly see both sexes together in

the same flower

Axis on which the flower parts are attached = RECEPTACLE

Four WHORLS (parts) to a flower

SEPALS – protect the developing flowercollectively called CALYXtypically green, leaf-like

PETALS – attract pollinators (transfer male reproductive cells to female reproductive cells)

collectively called COROLLA or PERIANTH

typically color related to type of pollinator

STAMENS – male reproductive composed of filament + anther

4 spore producing chambers per anther = LOCULE

CARPELS – female reproductivecollectively called PISTIL (stigma + style + ovary)

One to many chambers in each ovary each chamber = LOCULE contain OVULES one to many OVULES per locule

Diagrammatic version:

Ovule structure:a) integument (surrounding protective layer)b) embryo sac

MEGASPORE MOTHER CELL (2n) (meiosis … 3 die)

1 MEGASPORE (1n) (mitosis)

8-NUCLEATE EMBRYO SAC

3 antipodals + 2 polar nuclei1 egg cell +2 synergids +

All parts equal around receptacle = actinomorphic

Parts of different sizes = zygomorphic

PERFECT - both stamens & carpels in same flower

IMPERFECT - only one sex in a flower male and female flowers

MONOECIOUS - stamens & carpels on same plant (separate flowers)

DIOECIOUS – stamens & carpels on different plants

Based on number of flower parts

Monocots = flower parts in multiples of three (3, 6, 9 …)

Dicots = flower parts in multiples of four or five (4, 5, 8, 10 …)

Is a stem or branched system on which flowers are produced.

Can be simple (one stem with one flower = scape) or highly branched (=panicle)