Question

for a flower to be complete, it must possess what four types of floral appendages?

Answer 1

Yes, for complete flower, it must posses four floral appendages which are

Calyx: a whorl of sepals at the base.

Corolla: a whorl of petals above the calyx.

Androecium: a whorl of stamens, each comprising a filament and an anther.

Gynoecium: a whorl of the female parts of a flower: the stigma, style and ovary.

The plants which have all the four floral appendages are termed as Complete flower.
examples of complete flowers include hibiscus, roses, pea plants and tulips.

And the plants in which their flowers lacks any of the appendages are termed as incomplete flower.
Examples include maize (Zea mays) and members of the Cucurbitaceae (gourds, squash) 

among four of them calyx and corolla are non-essential floral appendages whereas Androecium and Gynoecium are essential floral appendages

Answer 2

$\huge{\boxed{\sf{ANSWER :}}}$

》The flower should have all the four types of floral appendages to be a complete flower.

The four whorls of a flower are as follows:

$\huge{\boxed{\sf{CALYX :}}}$

>> This is the outermost whorl of a flower protecting the bud.

>> Sepals are the members of calyx.

$\huge{\boxed{\sf{COROLLA :}}}$

>> Corolla is brightly coloured to attract insects for the process of pollination.

>> Petals are the members of corolla.

$\huge{\boxed{\sf{ANDROECIUM :}}}$

>> Androecium is the male reproductive organ of a flower.

>> It consists of filament and anther which produces the pollen grains.

$\huge{\boxed{\sf{GYNOECIUM :}}}$

>> It is known as the female reproductive organ of the flower.

>> It consists of stigma, style and ovary.