Flower Parts are modified Leaves. This is not readily apparent in most cases. However, there are cases in which floral organs display a gradient of leaf traits starting with the Sepals which are most leaf-like to Carpels which are highly specialized and do not resemble leaves.

Receptacle = Place on Stem where Floral Parts originate & attach

Sepals = Lowest order of floral organs, first to develop, can be green & leaf-like, Collectively = Calyx

Petals = Inserted on the Receptacle just above the Sepals, usually brightly colored, Collectively = Corolla

 

Perianth = Collective term for Sepals + Petals

Tepal = Collective term for Sepals and Petals when thery are Identical (See example Clintonia above)

Stamens = Inserted above Petals, consists of Anther & Filament, Collectively = Androecium

Anther - Part of Stamen that Produces Pollen

Filament - Stalk that bears the Anther

Carpel = Inserted above Stamens, uppermost floral organ, Consists of Stigma, Style & Ovary, Collectively = Gynoecium

Stigma - Tip of the Carpel, Receptive to Pollen

Ovary - Base of the Carpel, contains Ovules

Style - Connects the Stigma to the Ovary

Apocarpous Gynoecium has Free Carpels

Hypogenous Flower has a "Superior Ovary" - Other floral organs attached below (Hypo = Below) the Gynoecium on the Receptacle.

Coalescence or Fusion - Fusion or union of floral organs from the same whorl or type -  Designated by Sym or Syn

A Syncarpous  Gynoecium has Fused Carpels

A Synandrous Androecium has Fused Stamens
Either the Filaments or the Anthers may be Fused

A Sympetalous Corolla has Fused Petals.

A Synsepalous Calyx has Fused Sepals.

	The Sepals and the Petals of this flower are Coalescent.
The Datura Flower is Synsepalous & Sympetalous

Adnation is the Fusion between Floral Parts of a
Different Kind

For Instance, the fusion of Calyx & Corolla would be an instance of Adnation, as would the fusion of the Androecium & Corolla.

Datura Flower with Adnation between the Corolla and Androecium

Hypanthium structure formed by the Adnation of the Calyx, Corolla & filaments of Androecium.

A Hypanthium is present in this flower. The Gynoecium stands alone in the center of the Flower. The rest of the floral organs arise from the Hypanthium which surrounds the Ovary of the Gynoecium. This is called a Perigynous Flower. The Perianth and Androecium arise from the Hypanthium which is around the Periphery of the Gynoecium BUT not Adnate to it.

Fusion of Hypanthium to Ovary produces an  Epigynous Flower with Inferior Ovary

Apple (Prunus) Flower with Petals removed. In this case the Hypanthium is Adnate to the Ovary. The other Floral Organs seem to originate from the top (Epi) of the Ovary (Gyno). This is an Epigynous Flower and has an Inferior Ovary.

MOOOOOOOre TERRRRRRRRMS!!

A Complete Flower has all four floral Organs

An Incomplete  Flower - One or more floral organs missing

A Perfect Flower has an Androecium & a Gynoecium

An Imperfect Flower is Missing the Androecium OR Gynoecium.

A Carpellate Flower: Imperfect Flower that has Carpels only.

A Staminate Flower: Imperfect Flower that has Stamens only.

A Monoecious (One House) Plant: Each Plant has BOTH Carpellate & Staminate Flowers.

A Dioecious (Two Houses) Plant: Each plant has only Staminate Flowers OR Carpellate Flowers

A Hypogenous  Flower - "Superior Ovary" - Other floral organs attached below the Gynoecium on the Receptacle.

A Perigynous Flower - Sepals, Petals & Stamens arise from a tubular extension of the receptacle called the Hypanthium which surrounds the Ovary but is NOT fused to the Ovary Wall.

An Epigynous Flower - "Inferior Ovary" - Stamens, Petals & Sepals appear to grow from the top of the Ovary.

An Actinomorphic Flower has Radial Symmetry.

A Zygomorphic Flower has Bilateral Symmetry.