Flower Key – corolla and calyx – use this key to find what family the flower belongs to. To find other keys click HERE

To learn more about the Corolla and Calyx click HERE

Examine the corolla – is it made up of ‘free’ petals or ‘fused’ petals and what shape is it? There are 5 ‘free’ petal shapes and 8 ‘fused’ petal shapes below. 

Examine the sepals to see if they are fused into a calyx tube, an example is shown below.  

To learn more about the families click HERE

Flower Key – corolla and calyx. Flowering plant families can be identified using this key based on free petals shape, corolla shape or calyx tube shape.


20 families have species with free petals and an open arrangement as shown by this poppy but some families have flowers with free petals that are  arranged in a complex way to make access by pollinators to nectar more difficult.

Pea family

The ‘Pea’ flower has 5 free petals, a ‘banner’ , consisting of 2  petals which encloses the flower before it opens, 2 ‘wing’ petals and one ‘keel’ petal.

Iris family

The ‘Iris’ flower has 3 outward, downward-curving ‘falls’ and 3  inner, usually upright ‘standards’  which act to attract pollinators whilst the ‘falls’ act as insect landing sights.

Orchid family

The Orchid flower has 6 tepals in two whorls. The outer layer has 3 equal size ‘sepals’, the inner layer 3 ‘petals’. The central inner  ‘petal’ called the labellum, is enlarged and has 3 lobes.

Violet and Buttercup families have some species with individual petals that extend into spurs.



Botanists have developed a number of terms to describe corollas and calyx tubes formed from ‘fused ‘ petals or sepals. The shapes have evolved to make access to certain parts of the flower more difficult. 9 of these shapes are illustrated here.

Salverform – tube opens to a flat plate or salver

Phlox, Sea Lavender, Primrose and Periwinkle 

Funnelform  – tube opens up to a funnel entrance

Convolvulus, Borage, Nightshade and Honeysuckle

Personate –  2-lipped with a closed mouth. Plantain family

Rotate   – Short tube then spreading like a wheel

Iris, Phlox,Primrose, Borage, Nightshade and Plantain families

Campanula  – Bell-shaped

Bellflower, Plantain, Nightshade, Saxifrage and Asparagus families


Mint, Figwort, Bellflower (Lobelias), Honeysuckle families

Urceolate – Urn-like

Heath family

Tubular – cylindrical and hollow

Iris (Crocosmia), Asphodel (Red-hot Poker) families

Calyx Tube – tube formed from fused sepals

Pink, Loosestrife, Willowherb families