There are two basic types of nectaries

These are Structural & Non-Structural

Structural Nectaries differ significantly
from the surrounding tissues.
These are usually complex, discernable structures, like the nectaries we have seen for Ricinis (Castor Oil Plant) & Passiflora (Passion Fruit)

Non-Structural Nectaries differ little
from the surrounding tissues, except for the fact that they secrete Nectar.

In order to understand the following exposition, it is a good idea to review some basic flower terminology!

Yes Drill Sargent!!!!!
I was greatly influenced by my experiences in the US Army!
I am passing that heritage to you, poor reader!!!!!

Basic Flower Structure

The Receptacle is the terminal part of the stem which bears the floral organs (Sepals, Petals, Stamens, Carpels).

Sepals = Leaf-like structures which protect the other floral organs during early development. They are usually distinct from the Petals. This can be due to morphological traits or color.

Petals = Colorful leaf-like Structures.

Stamens = Composed of Filaments & Anthers. The Anthers produce Pollen.

Carpels = Composed of Stigma, Style & Ovary.

The Stigma receives pollen and fosters its germination.

The Style provides a conduit for the Pollen Tube.

The Ovary contains Ovules which house the Egg.

Collective Terms

Calyx = All the Sepals

Corolla = All the Petals

Tepals = Collective term for Sepals and Petals which are identical in appearance.

Perianth is a collective term for the Sepals & Petals

Androecium = All the Stamens

Gynoecium = All the Carpels