Sections in floral buds from different plants.

A reminder of the main morphological characteristics of flowers. The parts of flowers are arranged in whorls on the end of a stalk called a peduncle.
The two whorls of nonreproductive parts are sepals and petals that are modified leaves.
The outermost whorl of flower parts called sepals are known together as calyx. Then we have the petals, colorful modified leaves that attract pollinators that may be separate or fused in a tube. The whorl of petals is called corolla. The calyx and the corolla are known as the perianth.
After sepals we find the two reproductive parts of flowers: the stamens and the carpels.
The stamens are pollen – producing organs and consist of a filament terminated by an anther. This contains 4 pollen sacs arranged in pairs (one or more) producing the pollen grains.
After stamens we have carpels that lie inside the whorl of stamens. In most flowers the carpels are differentiated into 3 parts: (1) a lower round ovary where ovules lie; (2) the style through which the pollen tube will grow; (3) the stigma, terminal part to which pollen grains will adhere.
The entire carpels including the 3 parts is referred as pistil. The stamens are together known as the androecium and carpels, the female part of the flower bearing ovules are known collectively as the gynoecium.

Cross section at different levels of a floral bud perfectly complement macromorphological observations. They are useful for comparative study of phenotypes.

Below a list of plants for which paraffin sections have been made in floral buds. There are 4 dicotyledons ans 2 monocotyledons. 

Dicotyledones
. Geranium robertianum
. Jasminum odoratissimum  
. Lathyrus silvestris 
  
Monocotyledones    
. Agapanthus africanus
. Galtonia viridiflora     

Sections in floral buds of’ Arabidopsis thaliana embedded in Epon have been realized at the level of anthers.

Realization of sections and microphotographs

 – Floral bud of Geranium robertianum – paraffin sections.
Sections and their staining : Anne Utz – Technician & Dario Cessa Apprentice
Photographs and annotations : Dr Michèle Crèvecoeur.

– Floral buds of Jasminum odoratissimum, Lathyrus silvestris, Agapanthus africanus, Galtonia viridiflora –
Sections, staining of sections and photographs : Isabelle Chapalay –  Research and teaching collaborator.
Annotations of photographs: Dr Michèle Crèvecoeur.

Samples from the different plants have been collected in the Conservatory & Botanical Garden – Geneva and immediately fixed with FAA with collaboration of Dr Fred Stauffer – Curator

– Floral buds of Arabidopsis thaliana
Fixation, embedding in Epon, sections and photographs : Dr Michèle Crèvecoeur.
Samples were collected from plants cultured in the greenhouse from Department of Botany and Plant Biology- Geneva University.

See also the microphotographs of flowers and floral parts of Arabidopsis th. observed with a scanning electron microscope.